MUGIELECDevelopment of infrastructure and energy management systems associated with the electric vehicle

  • Program: ETORGAI
  • Project leader: ZIV
  • Technological coordinator: Tecnalia
  • Partners:
    • Companies: AEG, Fagor, Cementos Lemona, Gamesa, Iberdrola, Incoesa, Indra, Ingeteam, Ormazabal and Semantic Systems.

MUGIELEC is a project that brings together the main stakeholders in the electrical sector of the Basque Country to respond to needs arising from transition from the current mobility model to a more sustainable system based on the electrification of transport. In order to make this change viable it is necessary first to deploy a network for charging up electric vehicles.

Financed by: Industry, Innovation, Commerce and Tourism Department (Basque Government).

Basque Government


CIAD XXIIntelligent Transformation Center for the Distribution Automation

  • Program: ETORGAI
  • Project leader: ZIV P+C
  • Partners:
    • Companies: Usyscom, ZIV Medida, INCOESA Consultores, INCOESA Trafodis, GUASCOR Ingeniería and Asiris
    • Technological centers: Labein, Gaiker and ZIV I+D

CIAD XXI (Intelligent Transformation Center for the Distribution Automation) is a R&D project that will make possible to undertake the automation of the distribution of the medium voltage electric power and the remote and intelligent detection of breakdowns in this network. This new intelligent transformation center will be able to detect the failures and breakdowns in the electrical supply, to monitor and automate a solution for them and to offer previously unknown information.

CIAD will contribute to improve the quality for final users; It will easy the exploitation of the distribution network; It will reduce the maintenance costs of the new transformation centers; It will contribute to the reduction of energy consumption.

Financed by: Industry, Innovation, Commerce and Tourism Department (Basque Government).

Basque Government

Infrastructures and architectures for the integration of Smart Meters in a responsible and efficient management of consumptions

  • Program: ETORGAI
  • Partners:
    • Companies: Andago Ingeniería, S.L, DINITEL 2000, S.A, Ibermática, S.A, Indra Sistemas, S.A, Microelectrónica, MASER S.L, and ZIV Medida,S.L
    • Technological centers: Fundación Tekniker, Ikor Technology Center, S.L, Instituto Ibermática de Innovación (I3B), Universidad de Deusto and ZIV I+D

SOA4AMI (Infrastructures and architectures for the integration of Smart Meters in a responsible and efficient management of consumptions) is a project focused on infrastructures and applications close to final users and the management of the demand for them. This project tries to take advantage of the new features of consumption metering equipments (meters) and of their bidirectional communication possibilities. This is known as AMI (Advance Meetering Infrastructure), whose most important element is the SmartMeter.

The developments of the project are the following:

  • An open architecture that integrates all the agents taken part in the information flow for an efficient demand management.
  • Information services for the user.
  • Services for the individualized and contextualized management of the assets of a center (a house, a company, a public building or district), based on rules.
  • Control charts and indicators that easy the energetic management for public buildings energetic managers

Financed by: Industry, Innovation, Commerce and Tourism Department (Basque Government).

Basque Government

berriTRANSA control center for the new intermodal rail transport to obtain a sustainable, reliable and efficient operation and maintenance

  • Program: ETORGAI
  • Project leader: IKUSI, S.A
  • Partners:
    • Companies: Idom, LKS, Usyscom, Fensom Systems, SQS Software Quality System and CBT Comunicación multimedia
    • Clusters: Cluster of movility and logistics (MLC-ITS Euskadi)
    • Technological Centers: Innovalia, Tecnalia, Deusto, Vicomtech and ZIV I+D
    • Collaborating entities: TGG, Bombardier and Renfe

BERRITRANS is a R&D project focused in the definition of a integral transport management system. This system will be achieved by the development of a set of tools and products in charge of configuring a new generation integral control center for a sustainable efficient operation. This center must be open to the integration with new transport models,and must guarantee comfort in an operative and real time way.

Financed by: Industry, Innovation, Commerce and Tourism Department (Basque Government).

Basque Government


Improvement of the energy efficiency for the final users

  • Program: ETORGAI 2011
  • Project leader: ZIV Metering, S.L
  • Partners:
    • Companies: ZIV Grid Automation, S.L, Celaya Emparanza y Galdós Internacional, S.A, Instalaciones Elur, S.L, Trainelec, S.L, Ibermática, S.A, Rener Rehabilitación Energética, S.L, Oneka Arquitectura, S.L.P and Energyminds Solutions, S.L.
    • Centers that develop to the RVCTI ( Basque Science, Technology and Innovation network): ZIV I+D, Tecnalia, CAF, CIDETEC, Novia Salcedo and Instituto Ibermática de Innovación.
    • Collaborating entities: COAVN, Eraikune, Sestao berri, Ayuntamiento de Vitoria- Gasteiz, Ayuntamiento de Basauri, Cinco Días, Ingurubide, Roche, PFizar and cluster de la energía.

USER is a Project that tries to develop new products, processes and services that make possible to improve the energetic efficiency for the final users.It is focused on the following topics:

  • Energy managers in industrial processes aimed to improve energy efficiency. Their objective is to flatten the demand curve and improve the quality of the electric supply.
  • Energy managers aimed to improve qality of the electric energy’s quality in the railway sector.
  • Energy managers in the building to improve the energy efficiency of tertiary sector buildings. The project develops a product to manage the centralized air conditioning in the offices.
  • The development of systems for the storage and management of the power to integrate renewable energies in the electric micronetwork and to cover the electric demand in rush hours using the electricity storage in low hours.

Financed by: Industry, Innovation, Commerce and Tourism Department (Basque Government).

Basque Government

Automated Supervision of the low voltage electric network

  • Program: ETORGAI 2011
  • Project leader: Ormazabal Protection & Automation, S.L
  • Partners:
    • Companies: Corporación Zigor, S.A, Enlace Digital Barik, S.L, Iberdrola Distribución Eléctrica, S.A, Ingeteam Technology, S.A, Jema- Jesus María Aguirre, S.A, Semantyc Systems, S.L and ZIV Metering Solutions.
    • Agents that develop to the RVCTI ( Basque Science, Technology and Innovation network): Centro de Estudios e Investigaciones Técnicas de Gipuzkoa (CEIT), Fundación Tecnalia Research & Innovation, Mondragon Goi Eskola Politeknikoa, Ormazabal Corporate Technology, A.I.E, Zigor R&D, S.L. and ZIV I+D.

SAREBAT is a Project whose main aim is to develop a new distributed generation system. It is focused in the development of a new monitorization system for the generation in the distribution level, as well as solutions based on power electronics that make possible, on one hand to stabilize the network’s voltage and on the other to support the network’s operation when linked to many other distribution generation units.

The Project is mainly focused on Smart Distribution Networks, Smart Integration and Smart Energy Management.

Basque Government

Development of new multiparameter analysis techniques for the evaluation of gaseous mixings in the industrial and domestic areas

  • Program: ETORGAI 2011
  • Project leader: Naturgas Energía Distribución
  • Partners:
    • Companies: Naturgas Energía Servicios, ZIV Metering Solutions, Microelectrónica MASER, Urban Intelligent, DSM4 and SAREIN Sistemas.
    • Agents that develop to the RVCTI ( Basque Science, Technology and Innovation network): ZIV I+D and CEIT.

EVALGAS is a project whose main objective is to implement new multiparameter techniques that are based on microtechnologies that make possible to evaluate the quality of the natural gas and the environmental quality in the domestic and industrial sectors. These advances will make possible to manufacture some devices that are prepared to do the analysis of gaseous mixings in the domestic and industrial areas that include the next aspects:

  • A measure of the natural gaseous’ quality in the supply. This measure must bear the consumed gas’ volume and termias in mind.
  • A monitoring of the environmental quality in the environment, whose objective is to detect escapes or bad combustions.
  • The integration of these measures in the local sensors’ network.

The Project is mainly focused on Smart Distribution Networks, Smart Integration and Smart Energy Management.

Basque Government

4G revolution for the future connected Euskadi

  • Program: ETORGAI 2011
  • Project leader: Euskaltel, S.A
  • Partners:
    • Companies: Dorlet, S.A, GTS- THAUMAT XXI, S.A, IKUSI- Angel Iglesias, S.A, Navarra Tecnología del software, S.L, Symplio Lifestyle Technologies, S.L and ZIV Metering Solutions.
    • Agents that develop to the RVCTI ( Basque Science, Technology and Innovation network): Fundación Deusto, Fundación Tecnalia Research & Innovation and ZIV I+D.

4GIZAR is a Project oriented to the research and development of technologies, products an processes that help the deployment of LTE networks in Euskadi, as well as promoting their fast adoption in the industry and the society. The project selects as specific scenario the M2M communications due to their impact in the business world and the insterest showed by communication operators, who forecast in this market a potential and constantly growing source of benefits.

The Project is mainly focused on Smart Distribution Networks, Smart Integration and Smart Energy Management.

Basque Government

ECODISDesarrollo de tecnologías para la generación, distribución y gestión eficiente de los flujos de energía en entornos urbanos- industriales y su aplicación en la transformación de ciudades hacia un modelo Low Carbon City.

  • Program: ETORGAI 2012
  • Project leader: Técnicas Fotosolares, S.L
  • Partners:
    • Companies: Automatismos Maser, S.A, Everis S.L.U, Ferrovial Servicios S.A, Incoesa Consultores industriales S.A, Naturgas Energía Distribución S.A.U, Sematic Systems S.L, ZIV Grid Automation S.L and ZIV Metering Solutions
    • Agents that develop to the RVCTI ( Basque Science, Technology and Innovation network): CDTE- Centro de Investigación y Desarrollo de Tecnologías para la transmisión y Distribución Eléctrica XXI S.A and Fundación Tecnalia Research & Innovation.

ECODIS is a project whose main aim is to develop technology for the generation, distribution and efficient management of the energy flows in urban- industrial environments and to use this technology in the cities to become a Low Carbon cities.

The Project is mainly focused on Smart Distribution Networks, Smart Integration and Smart Energy Management.

Basque Government

GADActive and Efficient Electric Consumption Management

  • Program: CENIT
  • Project leader: Iberdrola
  • Partners:
    • ICT partners: GTD Sistemas de Información, S.A, Siemens S.A, Distribuidora Industrial de Automatismos y Teletransmisión S.A, ZIV Medida, S.L and Ericsson España, S.A.
    • Industrial partners (energy area): Iberdrola Distribución Eléctrica, S.A, Grupo Gas Natural and Red eléctrica de España, S.A
    • Industrial partners (goods area): Grupo Foresis, Fagor electrodomésticos S.Coop., BSH Electrodomésticos España, S.A, Altra Corporación Empresarial, S.L and Orbis Tecnología Eléctrica, S.A.
    • ICT Research Centers: CITIC, CTTC, Cedetel, Labein, Ikerlan, IIC, ITE and ITA.
    • Universities: Universidad de Alcalá, Universidad de Málaga, Universidad Politécnica de Madrid, Universidad Pontificia de Comillas- Instituto de investigación Tecnológica, Universidad de Zaragoza and Universitat Ramón Llull.

GAD (Active and Efficient Electric Consumption Management), is a project whose main mission is researching mechanisms for optimizing household electrical consumption. The vision of the project consists on developing solutions (hardware and software) from electrical control centers to customer homes, implementing the active demand side management, ina a transparent way for the end user, taking into account this comfort level. The objectives of the project include the next aspects:

  • Researching and developing tools for optimizing household electrical consumption, decreasing the electrical bill and the environmental impact.
  • Researching and developing devices for offering information to end users, about price and origin of the energy.
  • Researching the optimization of electrical infrastructures improving quality of supply and fostering the integration of renewable energies.

Financed by: CDTI- MICINN (Ministry of Science and Innovation- Spanish Government).



ENERGOSTechnologies for the automated and intelligent management of the future energy distribution networks

  • Program: CENIT
  • Project leader: Gas Natural/ Unión Fenosa
  • Partners:
    • Companies: Answare Tech, Brainstorm, DiagnostiQA, Dimat, Gas Natural Fenosa, Grupo AIA, Indra Sistemas, Indra Software Labs, Ormazabal CIA, Ormazabal P&A, SAC, Unión Fenosa Distribución, Usyscom, Visual Tools, ZIV Medida and ZIV P+C.
    • Technological centers: Ascamm, CTTC, DeustoTech, European Center for Soft Computing, Labein, Prodevelop, Robotiker and ZIV I+D.
    • Universities: Universidad Carlos III de Madrid, Universidad de Alcalá de Henares, Universidad de Cantabria, Universidad de Castilla la Mancha, Universidad de Coruña, Universidad de Gerona, Universidad de Oviedo, Universidad de Valencia, Universidad de Valencia I. Robótica, Universidad de Valladolid, Universidad Politécnica de Madrid, Universidad Politécnica de Valencia and Universidad Pontificia de Comillas.

ENERGOS is a research Project that makes possible to develop knowledge and technologies to advance in the implantation of smart electric distribution networks (Smart-Grid). The main feature of these networks is their capacity to integrate and manage in real time the actions of the users who are connected to them (producers, consumers and “prosumers”), in order to obtain an efficient, reliable and sustainable electric supply.

Financed by: CDTI- MICINN (Ministry of Science and Innovation- Spanish Government).



REDES 2025Development and implementation of technological solutions for the Spanish electric network in 2025

  • Program: Singular and strategic projects.
  • Project leader: Red Eléctrica de España
  • Technological coordinator: Tecnalia
  • Partners:
    • Companies: Endesa Network Factory, Gas Natural, INDRA, Ingeteam T&D, ZIV P+C, Siemens, Sac Maker, Iberdrola Ingeniería y Construcción, Unión Fenosa, HC Energía, Iberdrola, Usyscom, Fagor, Acciona Energía, Acciona Windpower, Grupo Isatur, Greenpower, ZIGOR, Everis, Ormazabal, Telvent, Nucleo, Grupo AIA and GTD Sistemas de Información and Telefónica I+D.
    • Technological centers: ZIV I+D, Labein, Inasmet, Robotiker, CIRCE and CEIT.
    • Universities: Universidad de Oviedo, Universidad de Mondragón, Universidad Politécnica de Madrid, Universidad Pontificia de Comillas, Universidad Politécnica de Cartagena, La Salle, AICIA, Incar- CSIC and IREC.

REDES 2025 is a singular strategic Project that has the particular aim of designing, specifying and developing technological solutions that are focused on applications based on power electronic, energy storage and superconsuctivity and tools for the integration into the grid of distributed energy resources and information management in the future electrial grid.

Financed by: MICINN (Ministry of Science and Innovation- Spanish Government) and FEDER (European Regional Development Fund).



CITYCHARGERecharge infrastructure for the electrical vehicle in urban environments

  • Program: Innpacto 2010
  • Project leader: ZIV Medida, S.L
  • Partners:
    • Companies: AEG Power Solutions Iberica, Automatismos Maser, Integral Park Systems and Ormazabal Corporate Technology A.I.E
    • Technological centers: Robotiker and ZIV I+D
    • Universities: UPV-EHU

CITYCHARGE (Recharge infraestructure for the electrical vehicle in urban environments) is a continuation of Cityelec, a singular strategic project, and its main aim is to develop and acquire the technologies to obtain an integral solution for the recharge of electrical vehicles as well as their integration in the electrical network. Citycharge faces different technological challenges, with the generation of knowledge in different areas:

  • Electrochemical cells for the storage of energy.
  • Control electronic for the management of batteries.
  • Efficient power converters.
  • Electronic and communications protocols.
  • Mechanics.

The Project has finished. The following developments have been done:

  • Secondary substation with an intermediate storage system, specially designed for the recharge of electric vehicles.
  • Semiautomatic car park for electric vehicles.
  • Special recharge stations for car parks.

In the previous three cases the viability of the systems has been confirmed and the results are planned to be put on the market.

Financed by: MICINN (Ministry of Science and Innovation- Spanish Government) and FEDER (European Regional Development Fund).


SECRETSecurity of the critical elements in the electrical remote controlled networks

  • Program: Avanza Competitividad I+D+i
  • Project leader: Telvent
  • Partners:
    • Companies: ZIV, S21sec labs, AT4 wireless and NICS
    • Universities: Universidad de Málaga

SECRET (Security of the critical elements in the electrical remote controlled networks) is a project with the aim of investigating the advanced technologies for the remote control and measure systems of electrical networks wich make possible to offer security to the critical elements of these infrastructures, bearing the recommendations of normatives in mind.

Financed by: MITYC (Ministry of Industry, Tourism and Commerce- Spanish Government) and FEDER (European Regional Development Fund).


Renewable distributed microgeneration/ minigeneration and its control.

  • Program: Innpacto 2012
  • Project leader: ZIV Grid Automation
  • Partners:
    • Companies: ZIV Metering Solutions and ZIV Communications
    • Universities: Universidad Complutense de Madrid and Universidad de Zaragoza.
    • Public Research Organism: CIEMAT

MIRED-CON (Renewable distributed microgeneration/ minigeneration and its control) is a project whose main aim is the installation of an advanced measurement and control infrastructure in a grid that is intended to be energetically automanaged, transforming this new grid in a reference of the future distribution networks.

This distribution network will be based on eolic, solar photovoltaic, minihydraulic and biomass cogeneration, storage (batteries as the basic system and inertia flywheel as the fast system), as well as active and passive loads. A network available in the CEDER (CIEMAT) will be used. This network offers some interesting features: different voltage levels, diverse topology, several secondary substations of different kinds, distributed generation, different types of consumption, controllable loads and energy storage.

Financed by: MINECO (Ministry of Economy and Competitiveness) and FEDER (European Regional Development Fund).


Cockpit for the continuous monitoring and internal audit of the security of the open communication infrastructures based on Security Assurance Profiles (SAC).

  • Program: Innpacto 2012
  • Project leader: Nextel
  • Partners:
    • Companies: Innovalia Group and ZIV Grid Automation
    • Universities: Universidad Politécnica de Valencia

UNIVERSEC (Cockpit for the continuous monitoring and internal audit of the security of the open communication infrastructures based on Security Assurance Profiles) is a project whose main aim is the development of an architecture based on an SGSI spread system, which enables to evaluate the fulfillment of the security rules parameters in information systems and give quantitative information related to the security assurance, all in real time. The project evaluates the methodology, the profiles, the patterns, the metrics and the system features as a whole in the environment of the critical infrastructures field.

Financed by: MINECO (Ministry of Economy and Competitiveness) and FEDER (European Regional Development Fund).


PRICERedes Inteligentes en el corredor del Henares

The electrical systems that are in use nowadays are globally facing important technological challenges, the prominent being the aging of the infrastructures, the growth of the demand, the increase in the presence of renewable energy sources, the integration of the electrical vehicle and the need to improve the safety of the supply as well as to reduce the dependency on non renewable energy sources.

Considering the perspectives of deployment growth of the distributed generation network, the architecture of the future power electrical network will not be passive. The power network as a whole should be designed as an integrated unit, and its operation should be performed by a multiple management of the system. Iberdrola Distribution and Union Fenosa Distribution undertake PRICE project to give a solution to these challenges. This initiative consists on the next projects: PRICE GDE, PRICE GDI, PRICE GEN and PRICE RED.

Financed by: MINECO (Ministry of Economy and Competitiveness- Spanish Government) and FEDER (European Regional Development Fund).


PRICE GDEGestión inteligente de la demanda

  • Program: Innpacto 2011.
  • Project leader: Iberdrola Distribución
  • Partners:
    • Companies: Gas Natural Fenosa, Red Eléctrica de España, Indra and Fagor.
    • Technological centers: ZIV R&D, ITE and Ikerlan.

The main objective of PRICE GDEis to develop a demmand minitoring system for customers allowing the implantation of the Smart Management of the power electrical network demmand. The purpose is to help end-users to achieve a more responsable and efficient use. Due to this, the correct communication between the system operator, distributors and commerciallizers in order to perform smart on the end- user’s demmand is one of the most important challenges in the Project.

Financed by: MINECO (Ministry of Economy and Competitiveness- Spanish Government) and FEDER (European Regional Development Fund).


PRICE GDIGestión de la generación distribuida

  • Program: Innpacto 2011.
  • Project reference: IPT-2011-1501-920000
  • Project leader: Unión Fenosa Distribución
  • Partners:
    • Companies: Iberdrola Distribución, Indra Sistemas, Indra Software Lab and Ingeteam Technology.
    • Technological centers: ZIV R&D and Tecnalia.
    • Universities: Universidad de Sevilla and Universidad Pontificia de Comillas.

PRICE GDIis focused on the search of solutions that allow a correct integration of distributed energy resources in the electric network. According to the current design, the electric network is not prepared for an scenario with a wide presence of renewables as the fluctuations they introduce prevent the correct operation of the network. In this context, PRICE-GDI will try to develop a new management system for distributed generation. A second aspect will be the development of the power electronics required for voltage stabilization as well as the solutions that allow that this power electronics joined together with lots of distributed generation units can help the network operation.

Financed by: MINECO (Ministry of Economy and Competitiveness- Spanish Government) and FEDER (European Regional Development Fund).


PRICE GENGestión energética

  • Program: Innpacto 2011.
  • Project leader: Unión Fenosa Distribución
  • Partners:
    • Companies: Iberdrola Distribución, SAC Maker, ZIV Metering Solutions, Current Iberia and Ericsson
    • Technological centers: CIRCE
    • Universities: Universidad Carlos III de Madrid.

PRICE GEN will be focused on the aspects linked to the energetic management of the Smart Grids using a new design of an interoperable and optimal network architecture. This architecture takes into account the requirements of the Smart Grid. PRICE GEN will also deploy this architecture using the development of new smart measurement devices which will offer punctual information of consumer consumptions and generations as well as the status of the electric network.

Financed by: MINECO (Ministry of Economy and Competitiveness- Spanish Government) and FEDER (European Regional Development Fund).


PRICE REDRed Inteligente

  • Program: Innpacto 2011.
  • Project leader: Iberdrola Distribución
  • Partners:
    • Companies: Unión Fenosa Distribución, ZIV Grid Automation, Indra Software Labs, ZIV Grid Automation, Indra Sistemas, Ormazabal Media Tensión, S.L and Sac Maker.
    • Technological centers: CIRCE
    • Universities: Universidad de Alcalá de Henares.

PRICE RED aims to create an international precedent in the development of a unique solution for the supervision and automation of the secondary substations.

Financed by: MINECO (Ministry of Economy and Competitiveness- Spanish Government) and FEDER (European Regional Development Fund).



RedNAIsolated Neuter Network

  • Program: Innpacto 2011
  • Project leader: Unión Fenosa Distribución, S.A
  • Partners:
    • Companies: General Electric, ZIV Communications, ZIV Grid Automation, E.O.N Distribución and Ingeteam Technology
    • Technological centers: ITE
    • Universities: Universidad de Sevilla

RedNA (Isolated Neuter Network), is a project whose main objective is to develop technological solutions that make possible to improve the operation of the isolated neuter network, to improve the quality of the electrical supply and the automation of this type of distribution network (smart network) in an economically viable way. The solutions include improvements in the communications using carrier wave systmes in the medium voltage network.

Technical aims of the project:

  • Improvement of the applied knowledge on the isolated neuter network.
  • Identify the requirements that must fulfill the algorithms for the fault and fault pass location in the isolated neuter and resonant networks.
  • Develop equipments and solutions based on the detected requirements and needs (protection relay, intensity transformers, fault pass detectors, communication signal injection).
  • Investigate and then demonstrate the application of the synchrophasors in the management of the isolated and resonant neuter network.
  • Contribute to the difussion of the experiences obtained in the project both in a continuous way and participating in national and international forums.

Financed by: MINECO (Ministry of Economy and Competitiveness- Spanish Government) and FEDER (European Regional Development Fund).



Conversion and protection solutions for electrical scenarios with high distributed generation penetration

  • Program: Innpacto 2011.
  • Project leader: Iberdrola Distribución eléctrica.
  • Partners:
    ° Companies: General Electric Power Management, S.A, Ingeteam Energy, S.A, Ingeteam Technology S.A, Ormazabal Protection Automation, S.L.U, Altel and ZIGOR Corporación S.A.

    • Technological centers: Tecnalia R&D and ZIV I+D.
    • Universities: UNED.
    • Agents out of the consortium: ITE (Instituto de Tecnología Eléctrica), Universidad de Extremadura, Oldar electrónica, Zigor R&D, Zigor T&C, Laboratorio Central Oficial de electrónica (LCOE), UPV, Pine instalaciones y montajes and Zabala Innovation Consulting.

PROINVER (conversion and protection solutions for electrical scenarios with high distributed generation penetration), is a project whose main aim is to develop new specific conversion and protection solutions for electrical scenarios with a high penetration of GD, that make possible to guarantee the quality and the safety of the supply.

This project is aligned with the SET PLAN strategy (The European Strategic Energy Technology Plan) for the development of technologies with low emission of carbone. inside the European initiative about the electrical network, there are three challenges related to future electrical networks , and they are faced in this project:

  • The creation of a real internal market.
  • The integration of some intermittent power sources that are in expansion.
  • The management of complex interactions between suppliers and clients.

The main aim of this project is to develop conversion and protection technological solutions that make possible for the electrical networks to adapt to new electrical scenarios that are characterized by a high level of distributed generation penetration. This guarantees the quality of the supply and the safety of future networks.

Financed by: MICINN (Ministry of Science and Innovation- Spanish Government) and FEDER (European Regional Development Fund).


GRID4EULarge-scale Demonstration of Advanced Smart GRID Solutions

  • Program: 7th Framework Program.
  • Project coordinator: ERDF.
  • Partners:
    • Companies: RWE Rheinland Westfalen Netz AG, EON New Build and Technology’s, Vattenfall Eldistribution AB, Tekla Corporation, eMeter Incorporation, KTH Royal Institute of Technology, Iberdrola Distribución, Iberdrola S.A, ITRON, Ormazabal, ZIV, Landis&GYR, Enel, Selta, CEZ Distribuce, a.s, CEZ, a.s, EDF, S.A, Alstom GRID, Armines, Siemens, Cisco, ABB. Current, RSE, S.PA and Kul.
    • Universities: University of Dortmund and Comillas Pontifical University.

GRID4EU is led by a group of European DSOs and aims at testing in real size some innovative system concepts and technologies in order to highlight and help to remove some of the barriers to the smart grids deployment (technical, economic, societal, environmental or regulatory). Grid4EU aims at testing in real size some innovative concepts and technologies able to remove part of the barriers to the smart grids deployment and the achievement of the 2020 European goals. The project focuses on how distribution system operators can dynamically manage electricity supply and demand, which is crucial for integration of large amounts of renewable energy, and empowers consumers to become active participants in their energy choice. GRID4EU is a project co-funded by the European Comission unther the 7th Framework Programme.

Main Objectives:

  • To develop and test innovative technologies and define standards through the set up of demonstrators.
  • To guarantee the scalability of these new technologies and replicability over Europe.
  • To Analyze SmartGrid Cost-benefits (B-Case).

Financed by: European Commision.

European Commission


GRID4EU in figures

  • 27 organizations from 15 countries working together during 51 months
  • 6 Electricity Distribution System Operators covering altogether more than

50% of metered electricity customers in Europe

  • €54 Million of total eligible costs and €25.5 Million of requested grant
  • An average of 70 Full-Time Employees making happen 19 innovative Use Cases
  • 6 demonstrators in 6 different European countries serving 275,000 consumers
  • Participation in 156 events all over the world (around 3 events per month)
  • More than 22,000 different visitors of the GRID4EU website

What is GRID4EU?

Designed in response to a call for projects from the European Commission[1], GRID4EU is a Large-Scale Demonstration of Advanced Smart Grid Solutions with wide Replication and Scalability Potential for EUROPE. The project was led by six electricity Distribution System Operators (DSOs)[2] from Germany, Sweden, Spain, Italy, Czech Republic and France, in close partnership with a set of major electricity retailers, manufacturers and research organizations. As a whole, the consortium gathers 27 partners.

GRID4EU consisted of six Demonstrators, which were tested over a period of 51 months in six different European countries. The project strived at fostering complementarities between these Demonstrators, promoting transversal research and sharing results between the different partners as well as with the wider Smart Grids community. A brief description of the six GRID4EU Demonstrators is provided in the figure below:


Five General Work Packages support the six Demonstrators to facilitate dynamic knowledge sharing, technical assistance and coordination. In particular, a way to analyze cost and benefits and validate technical solutions for all components, while participating to standards definition, has been implemented. Additionally, the project studied how to deploy the model at DSO scale (scalability) and then to spread it to other DSOs (replicability). As the DSOs involved in the project cover more than 50% of the metered customers in the European Union, the scaling-up and replication of the results obtained help contribute efficiently to reaching the EU 2030 energy targets.

Project partners


Project timeline


Innovative approaches tested in


The project aimed at testing innovative concepts and technologies in real-size environments, in order to highlight and help remove barriers to the deployment of Smart Grids in Europe. It focused on how DSOs can dynamically manage electricity supply and demand. The main topics addressed by the project are:

  • The improvement of MV and LV network automation technologies to face the constraints introduced by the increased amount of DER and new usages (e.g. electric vehicles, heat pumps) to reduce energy losses and maintain or increase quality of supply;
  • The optimized and smooth integration of an increased number of small- and medium-sized DER (photovoltaic, wind, combined heat and power, heat pump and direct or indirect storage);
  • The balancing of intermittent energy sources (including better prediction) with demand response, and different storage technologies and services;
  • The assessment of islanding as a solution to increase the grid reliability;
  • The increasing use of active demand including the potential future developments of new usages and evolving customers’ behaviours.

In particular, outcomes displayed in the table below have been measured.

[1] The GRID4EU project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement n°268206.

[2] The six DSOs are RWE, Vattenfall, Iberdrola Distribucion, Enel Distribuzione, CEZ Distribuce and ERDF. ERDF is the Coordinator of the project, while Enel Distribuzione is the Technical Director and Iberdrola Distribución the Chairman of the General Assembly.

Real proven solutions to enable active demand and distributed generation flexible integration, through a fully controllable LOW Voltage and medium voltage distribution grid

  • Program: H2020-LCE-2014-3
  • Topic LCE-2014: Distribution grid and retail market
  • Project coordinator: Iberdrola Distribución Eléctrica, S.A.U.
  • Partners: 19 Partners · 7 European Countries
  • Budget: 15,7 M€ · 11,9 M€ funded
  • Execution Period  01/01/2015 – 31/12/2017
  • Financed by:  the European Union’s Horizon 2020 research and innovation programme under grant agreement No 646.531


The project:
The UPGRID project started in the beginning of 2015 under the H2020 program and is being developed by a European consortium, composed of 19 partners from 7 European countries: Spain, Portugal, Poland, Sweden, United Kingdom, France and Norway.

The project includes 4 demonstrators that are being deployed from April 2015 to June 2017 at Bilbao area in the North of Spain, Parque das Nações in Lisbon (Portugal), Åmål in Dalsland in the South of Sweden, and Gdynia in Pomeranian Region (Poland).

The project will develop and validate solutions to enable the implementation of advanced functionalities over existing technology, to form a truly integrated intelligent system.

With this project, an improvement of the monitoring and controlability of low voltage (LV) and medium voltage (MV) grids is expected, as a way to anticipate technical problems associated with large scale integration of DER (Distributed Energy Resources), bringing also end users closer to system operation and planning.


European Commissionupgrid_logo-ZIV


OPEN meterOpen Public Extended Network Metering

  • Program: 7th Framework Program
  • Project leader: Iberdrola
  • Partners:
    • Companies: Iberdrola Distribución, Actaris, Advanced Digital Design. Cesi Ricerca, Current Technologies International, DLMS User Association, EDF, Elster, Endesa, Enel, NethbeheerNederlands, Kema, Landis+GYR, RWE, ST Microelectronics and Usyscom.
    • Universities: University of Karlsruhe.

OPEN meter (Open Public Extended Network Metering) is a project whose main objective is to specify a comprehensive set of open and public standards for AMI, supporting electricity, gas, water and heat metering, based on the agreement of all the relevant skateholders in this area, and taking into account the real conditions of the utility networks so as to allow for full implementation.

Financed by: European Commission

European Commission


ADDRESSActive Distribution networks with full integration of Demand and distributed energy RESourceS

  • Program: 7th Framework Program
  • Project leader: ENEL Distribuzione S.P.A
  • Partners:
    • Research: University of Manchester, Universidad Pontificia Comillas, Università di Siena, Università di Cassino, ENEL Ingegneria e Innovazione, VTT, VITO, Tecnalia, KEMA and Consentec.
    • Distribution and transmission network operators: ENEL Distribuzione, UK Power Networks, Iberdrola Distribución Eléctrica and Vattenfall.
    • Energy supply and retail: EDF-SA and ENEL Distributie Dobrogea.
    • Electric equipment manufacturers: ABB, Landis+Gyr and ZIV.
    • Home appliances manufacturers and consultants: Philips, Electrolux and RLtec.
    • ICT providers and Electric equipment manufacturers: Ericsson Espańa, Alcatel and Current.

ADDRESS (Active Distribution networks with full integration of Demand and distributed energy RESourceS) stands for Active Distribution network with full integration of Demand and distributed energy resources and its target is to enable the Active Demand in the context of the smart grids of the future, or in other words, the active participation of small and commercial consumers in power system markets and provision of services to the different power sytem participants.

Financed by: European Comission

European Commission


FENIXFlexible Electricity Network to Integrate the expected energy evolution

  • Program: 6th Framework Program.
  • Project leader: Iberdrola.
  • Partners:
    • Companies: Areva T&D Energy Management Europe, ECRO SRL, EDF Energy Networks, EDF, Gamesa, IDEA, Iberdrola S.A, Korona National Grid Transco, Poyry Consulting Ltd, REE, ScalAgent Distributed Technologies and Siemens and ZIV P+C.
    • Technological centers: Labein and ECN.
    • Universities: Imperial College London, ISET, the University of Manchester and Vrije Universiteit Amsterdam.

FENIX (Flexible Electricity Network to Integrate the expected “energy evolution”) is a project whose main objective is to boost DER (Distributed Energy Resources) by maximizing their contribution to the electric power system, through aggregation into Large Scale Virtual Power Plants (LSVPP) and decentralized management. FENIX is an integrated project included in the Sixth Framework Programme for Research of the European Union.

Financed by: European Comission.

European Commission


EDIANAEmbedded Systems for Energy Efficient Buildings

  • Program: 7th Framework Program
  • Project leader: Acciona Infraestructuras, S.A
  • Partners:
    • Companies: ATOS Origin, Elsag Datamat European Software Institute, FAGOR Electrodomésticos, Fidelix, Information & Image Management Systems, Infineon Technologies, Philips Electronics Netherlands, Philips Consumer Lifestyle, Philips Research, Quintor, ST Microelectronics and ZIV Medida.
    • Technological Centers: GAIA, IKERLAN, LABEIN and VTT.
    • Universities: Mondragon Goi Eskola Politeknikoa, University of Bologna and University of Rome La Sapienza.

EDIANA (Embedded Systems for Energy Efficient Buildings) is a project that addresses the need of achieving energy efficiency in buildings through innovative solutions based on embedded systems.

The eDIANA Platform is a reference model-based architecture, implemented through an open middleware including specifications, design methods, tools, standards, and procedures for platform validation and verification. eDIANA Platform will enable the interoperability of heterogeneous devices at the Cell and MacroCell levels, and it will provide the hook to connect the building as a node in the producer/consumer electrical grid.

Financed by: European Comission

European Commission


Papers and Case Studies

  • Authors: Aitor Arzuaga, Jose Antonio Moreno and Covadonga Coca
  • Company: ZIV
  • Date: 6-9 June 2011
  • Event: CIRED (21st International Conference on Electricity Distribution), Frankfurt- Germany
  • Keywords: Sensors, SmartGrid, Switchgear, Substations

The recent interest of the utilities for the automation of the electrical distribution in medium voltage grid, with the aim of improving service, while reducing operation costs, and at the same time managing the grid in real time, requires the installation of electronic equipment inside the secondary substations. These electronic equipment need sensors to measure the most important electrical parameters such as the voltages, currents and phases. At the same time, the necessary communications between equipment, located in the secondary substations that compose the medium voltage network, need, when using PLC (Power Line Carrier) technology, capacitive or inductive couplers, in order to inject the high frequency signals in the conductors.

The sensors and couplers installed in secondary substations must fulfil all the standards and existing regulations which apply to elements subject to high voltages and currents. They must be adapted in each situation to the available space, which differs greatly from one secondary substation to another, depending on its type, such as those of masonry, metalic air cabins or SF6 gas cells. However, there is currently no sensor solution for many of the existing swithgear in the distribution grid. As a result of this, a careful analysis of the requirements and existing scenarios, and available sound technology must lead us to the development of the required sensors.

  • Authors: Aitor Arzuaga, Javier Arriola, Zigor Ojinaga, Txetxu Arzuaga and Mikel Zamalloa
  • Company: ZIV and Iberdrola
  • Date:  June 2011
  • Event: PAC (Protection, Automation & Control) World Conference, Dublin – Ireland
  • Keywords: Single, Integrated, Solution, Device, SmartGrid

The introduction of SmartGrids in Secondary Substations, with the goal of automating the distribution grid, requires the addition of several different functions to the existing infrastructure, such as Smart metering Concentrators, LV/MV monitoring functions, automation functions, Communications Equipment, and sometimes ancillary devices, such as power back- up systems. These functions are very innovative and currently implemented by suppliers in separate boxes (products). These products are still young in their lifecycles, as the technology and applications are being developed right now.

But if the SmartGrid is going to succeed, and the existing electricty distribution installations upgraded in big numbers, all the functions mentioned above must be integrated in a single box solution, to drive down costs, ease the installation, improve asset and inventory management, and just make the process simpler. It is just a matter of economics and simplicity.

This paper will discuss the problem of integrating Smartgrid functionalities in existing secondary substations, which are already in operation. Most of secondary substations at a certain moment will be of this type. For new secondary substations, electronics and sensors can be custom built and integrated into the switchgear or transformer, so the issue of the single solution affects primarily the upgrading of the existing grid. We will introduce such integrated “Smart Grid for Secondary Substation” device concept and rationale, and analyze its key requirements, applications and challenges.

  • Authors: Rafael Quintanilla and Jose Miguel Yarza
  • Company: ZIV
  • Date:10-11 March, 2011
  • Event: CIGRE SEAPAC (South East Asia Protection & Automation Conference), Sydney – Australia
  • Keywords: SmartGrid, Distribution, Automation, Sensors, RTU, Meters, PRIME, PLC

It is a well- known fact that things are changing for the electrical network; during the last years, due to several factors:

  • Climate change
  • Fuel prices
  • Intensive use of electricity in the digital economy
  • Increased deployment of Distributed Energy Resources (DER) at different voltage levels
  • Evolution of traditional consumers of electricity that have become also producers, changing their role of users of electricity to users of the network

As a consequence of that, it is necessary:

  • To improve the quality of service and the quality of energy.
  • To be more efficient on the use of the energy.
  • To manage the demand actively to optimize the use of the network.
  • To incorporate the end users as active agents in the market of energy and services.
  • To be able to integrate effectively the DER.

All above requires increasing the smartness of the electrical gridm especially at distribution level, incorporating intelligence into the secondary substations, making them visible and capable of giving information about the state of the medium and low voltage network. That means installing sensors, measurement capability, communications, actuators, IEDs…And all this while the system continues working, coping with old installations that were not designed taking into account the new requirements.

This paper describes the experience obtained during the deployment of a supervision system in a real network in a medium size city located in the Mediterranean coast of Spain. It was necessary to develop different solutions that look into account the diversity of installations derived from the technical history of the utility owner of the network. A wide range of technologies were used to get an optimized application: electromagnetic sensors, materials engineering, Ethernet, power line communications, IEC 61850…

Finally, a glance into the future is provided, examining where the authors think the technology is going to, helping the network to achieve a revolution by evolution

  • Authors:Aitor Arzuaga, Txetxu Arzuaga and Rafael Quintanilla.
  • Company: ZIV R&D Smart Metering Networks, ZIV Grid Automation and ZIV Metering Systems
  • Date:November 12-14, 2012
  • Event: GCC Power 2012 (Conference & Exhibition), Omán.
  • Keywords:Smartgrid, Intelligence, Distribution, Operation, MV, LV, Automation, Communications, Metering

The introduction of the Smartgrids in electricity distribution networks is modernizing the infrastructure and adding an unprecedented set of technologies to the distribution substations. It derives from the need to enhance the grid with intelligence in order to gain efficiency, reduce CO2 emissions, integrate renewable energy generation, improve quality of supply and manage demand.

All these innovations are being put in place in new infrastructure, in sections where the assets are new. In many sections of the grid such as city centres, most of the MV/LV distribution grid is already in place, and a big challenge for the electricity distribution company is how to modernize and implement the benefits of the Smartgrid in those parts of the grid that are already in operations, for some years. Distribution assets are expensive and their lifespan ranges may be in order of years or decades, so it is just out of the questions to substitute secondary substations that are just 5 or 10 years old. Additionally, this infrastructure is diverse, coming from different periods, and they were not conceived to be upgraded in the future. Additionally, the MV/LV grid has not received a significant level of attention or investment in many places, just to keep it working.

This article will highlight the most important aspects that must be taken into account when tackling an existing (operating) distribution grid modernization project. And it will deal with the specific limitations for MV/LV grid supervision and automation, and how to overcome them.

  • Authors:Alberto Sendin, Iñigo Berganza, Aitor Arzuaga, Xabier Osorio, Iker Urrutia and Pablo Angueira.
  • Company: ZIV, Iberdrola and the Department of Communication Engineering of the University of the Basque Country.
  • Date:
  • Event:Multidisciplinary Digital Publishing Institute (a publisher of open- access journals).
  • Keywords:Smart Metering, Methodology, PLC, PRIME, Distribution Grid, Monitoring, LV line, LV phase, Detection.

Low Voltage (LV) electricity distribution grid operations can be improved through a combination of new smart metering systems’ capabilities based on real time Power Line Communications (PLC) and LV grid topology mapping. This paper presents two novel contributions. The first one is a new methodology developed for smart metering PLC network monitoring and analysis. It can be used to obtain relevant information from the grid, thus adding value to existing smart metering deployments and facilitating utility operational activities. A second contribution describes grid conditioning used to obtain LV feeder and phase identification of all connected smart electric meters. Real time availavility of such information may help utilities with grid planning, fault location and a more accurate point of supply management.

  • Authors: Miguel Angel Alvarez and Txetxu Arzuaga.
  • Company: CG Automation BU.
  • Date: November 13-15, 2013.
  • Event:CIGRÉ D2 (SC D2 Information systems and telecommunication), Mysore- Karnataka- India.
  • Keywords:Smartgrid, Cybersecurity, risk analysis, CIA model, McCumber cube, SGAM, SGIS.

The benefits in the evolution of traditional electrical grid into the Smartgrid, are more evident every day. However, this evolution is also offering more rewards to potential attackers as well as a wider range of potential attack vectors due to the increase in the use of communications and the integration of operational systems in the internet. This has led to an increased awareness of the need for implementation of Cibersecurity measures in the Smartgrid.

Cybersecurity field has not been part of the body of knowledge of electrical grid designers, though. So, even if equipment manufacturers are beginning to deal with the incluison of Cybersecurity features to their developments, they are not always following the best approach but trying to find and follow recommendations and best practices guides. However, there are no fixed rules that ensure the security of equipment yet.

The main aim of this paper is to use a pragmatic approach to create a reference guide for a first approach of equipment manufacturers to the world of cybersecurity. To achieve this, it is necessary to analyze very different aspects ranging from the work of public agencies such us NERC CIP or penetration testing techniques (such us those made by Digital Bond in S4), to international standards (IEC62351…), key management procedures. All of this should also be combined with the study of known Cybersecurity attacks such us Stuxnet.

This paper takes into account that the implementation of Cybersecurity is a quite different task compared with the ones usually tackled by manufacturers. On one hand, it must be considered that it is not a concrete and definite task, but a set of decision making and measurement implementation rules relatively unconnected to one another. However, they help in the prevention of a whole range of risks for equipment.

On the other hand, and, unlike what happens with other features, the implementation of security measures does not 100% guarantee the security of equipment, so the task does never end, and in addition to the prevention methods, detection methods should also be implemented to offer quick detection of new vulnerabilities. The combination of prevention and detection will sometimes fail, so a good Cybersecurity system must also consider mitigation and recovery techniques.

This paper proposes as a practical approach the descomposition of the system in use cases as concise and clear as possible. The different steps proposed for use cases are as follows:

  • Initial analysis based on abstract concepts such as confidentiality, integrity and availability (CIA model).
  • Analysys of risks and vulnerabilities, focusing primarily on scaled potential attacks.
  • Selection of generic methodologies for prevention, detection and response.
  • Selection of the security features both hardware (chip key storage, cryptographic coprocessors, biometric protection…) and software (security libraries, logs and event managers…).

Tracking a top-down methodology for writing use cases, favors Cybersecurity non based on “magic formulas”, but on common sense.

  • Authors: Roberto Cimadevilla
  • Company: ZIV Grid Automation, S.L.
  • Date: March 12-13, 2013.
  • Event:CIGRÉ Australia APB5, SEAPAC 2013, Brisbane- Australia.
  • Keywords:Zero- sequence filter, phantom tertiary, three- legged transformer, differential unit, directional comparison unit, harmonic blocking.

Delta- Wye transformer connections create discontinuities in the zero- sequence network as the zero- sequence current can flow at one side of the transformer without flowing at the other side. This effect generates a zero- sequence differential current that can make the differential unit trip. Traditional solutions applied to remove the zero sequence differential current where based on delta connected CTs. Zero- sequence filters in digital relays are software implemented.

In many digital relays the zero sequence filter can be enabled or disabled. On the other hand, some relays can remove the zero- sequence current calculated from the phase currents or from the ground currents (currents measured in the neutral grounding).

This paper reviews the transformer configurations that require the enabling of the zero- sequence filter by taking into account not only the connection group but also the construction of the magnetic core (this aspect is not always considered), explaining in detail the phantom or virtual tertiary effect of three- legged wye- wye transformers. Real false trips due to this effect are included.

The paper also explains the differences between both methods used for the zero- sequence current calculation (the one based on the phase currents and the one based on the ground current). The influence on the differential unit, harmonic restraint and common external fault detectors is analyzed. The first method can lead to a reduction of the differential current and to an erroneus phase selection during an internal fault. However, “2 out of 3” logics both for harmonic blocking and for a phase directional comparison unit can be implemented increasing the stability. The second method provides very good sensibility and phase selection but does not allow the implementation of the “2 out of 3” logics reducing the stability. Cases based on real events and RTDS simulations are reviewed.

  • Authors: Roberto Cimadevilla
  • Company: ZIV Grid Automation, S.L.
  • Date:-
  • Event:Texas A&M 2013
  • Keywords: Inrush, sympathetic inrush, harmonic blocking, harmonic restraint, cross-blocking, CT saturation.

This paper explains in detail the phenomena of inrush in single- phase transformers during three conditions: transformer energization, external fault clearing and sympathetic inrush. It then focuses on the inrush in three- phase transformers, explaining the influence of a delta winding and analyzing the types of transformer configurations that allows the flow of zero- sequence current.

The paper describes the influence of the inrush current on different types of protection functions as transformer differential, overcurrent, distance, busbar and line differential. It focuses mainly on the transformer differential describing the most common methods used for maintain the security during the inrush condition: harmonic restraint and harmonic blocking. Their differences are explained. It then explains the different crossed logics used and selects the most appropriate one. It finally describes a logic to inhibit the harmonic restraint/ blocking based on external fault detector. This logic reduces the tripping time of the differential unit mainly during internal faults with CT saturation. Different cases are considered based on real events and RTDS simulations.

  • Authors: Aitor Arzuaga Munsuri, Jose Miguel Arzuaga Canals and Mikel Zamalloa Aiartzaguena
  • Company: Usyscom
  • Date:   December 2010
  • Publication:  PAC (Protection, Automation & Control)  World Magazine, Winter 2011
  • Keywords: Telecontrol, GPRS, Networks

This paper introduces GPRS (General Packet Radio Service) technology and examines its applicability to the sphere of telecontrol communications in an electric utility. In order to do so we will perform an analysis of the technology and its possibilities, telecontrol protocols, and give specific examples of why traditional telecontrol applications which function correctly over point- to- point serial links require a reformulation which optimises their function over a communications technology such as GPRS. It will also be analyzed wether this technology fulfils the reliability requirements expected by utility communications.

  • Authors: Henrik Riis and Aitor Arzuaga
  • Company: Energinet.dk and ZIV
  • Date: October 19-20, 2011
  • Event: CIGRÉ (Conseil International des Grands Reseaux Electriques), Paris- France
  • Keywords: IP, Survey, Case Study, Substation, Communications Architecture

IP communication is being extensively introduced into the operation of the Electrical Power Utility. The substation IP network environment has evolved from acting as an extension of the office LAN to a state, where it is carrying multiple services, including the transport of critical and sensitive data.

Working Group D2.28 is currently developing a Technical Brochure which contains:

  • A compilation of user requirements and expectations cencerning existing and envisaged services in the new networked environment of the substation. This information was gathered by conducting a survey among Cigré members, major vendors and consultants.
  • A description of possible network migration processes.
  • Guidelines on how to choose an optium network architecture, covering services which require connectivity beyond the substation perimeter. The guidelines are intended to be in line with the ones given for substations in IEC61850-90-4.
  • A description of important parameters to be considered for each relevant technology. The description is not centered around specific applications and is therefore open to the usage of IP in different areas.
  • Five case studies, aiming at describing project and process experiences, rather than technicalties.

This is an extract which deals with the results of the user survey as well as giving an overview of the technical contents of our Technical Brochure. In addition, one of the six network case studies contained in our Brochure is reproduced.

  • Authors: Aitor Arzuaga, Txetxu Arzuaga and Josep Salat;
  • Company: ZIV
  • Date: October 19-20, 2011
  • Event: CIGRÉ (Conseil International Des Grands Reseaux Electriques), Paris- France
  • Keywords: MV, PLC, Secondary Substation Communications, WAN, OFDM, Spread Spectrum

Smartgrid functionality in distribution grids relies heavily in communications functions. This is a challenge because many existing distribution grid facilities such as secondary substation lack communications links. Sometimes there are existing fiber links, but most of the facilities are not connected.

As a result of this, every time that Smartgrids are deployed in a secondary substation, communications means must be added in order to connect the premises to the utility’s network, and this network must be able to deliver the required data rate and latency requirements.

Then there are some alternatives to choose from, but most of them rely on communications means which are not owned by the utility, if available, such as GPRS/3G, Satellite links or ADSL. Sometimes there are not any options to choose from, depending on the physical location of the substation. The consequence is that these communication links have operation costs and the availability of the communications network is outside the control of the utility.

In order to overcome these limitations, some utilities try to rely on traditional technologies already used in telecontrol applications such as VHF radio links. However, this technology cannot be used in most urban environments.

One way of solving the problem would be to use a communications technology which uses the existing infrastructure, and there is actually infrastructure which is available in existing secondary substations and which may be used: MV lines. However, it is a very noisy and lossy medium, and in order to establish links with the required bandwith and distance coverage deep analysis and test are required, both at the physical and MAC layers, and at the couplings.

This paper will describe new techniques to implement a layer two network device over MV lines, using different modulation techniques such as OFDM and Spread Spectrum.

  • Authors: Alberto Sendín, Iñigo Berganza, Aitor Arzuaga, Anssi Pulkkinen and Il Han Kim.
  • Company: ZIV, Iberdrola, Current Technologies and Texas Instruments.
  • Date: October 28-31, 2012
  • Event:IEEE Sensors 2012, Taipei- Taiwan
  • Keywords:

PRIME (PoweRline Intelligent Metering Evolution) is a narrowband Power Line Communications (PLC) technology targeted for use in smart metering applications. It is standarized as part of international Recommendations ITU-T G.9955 and G.9956, and there are currently a number of deployments by utilities in different markets which use it for a cost- effective, technically proven solution.

This paper is a continuation of two previous ones presented in the first and second SmartGridComm Conferences, in which PRIME background and status were discussed, including interoperability tests and first results in multi- vendor deployments.

This final article describes the network architecture which has been thoroughly tested and is currently being used by Iberdrola for its SmartGrid deployment, PRIME network deployment selections, a proposed classification for secondary substations based on experience and finally the tools which are being used for analysis and acceptance tests, along with performance results.

  • Authors: Aitor Arzuaga, Miguel Angel Alvarez, Sonia Martinez, Txetxu Arzuaga, Mikel Zamalloa, Hampesh T and J.R.Rao
  • Company: CG ZIV
  • Date: November 13-15, 2013
  • Event:CIGRÉ D2 (SC D2 Information systems and telecommunication), Mysore- Karnataka- India
  • Keywords: Communication, architecture, network, Smartgrid, WAN, distribution

This article presents an analysis of three different WAN communication architectures used in big scale Smartgrid projects. Two case studies analyse typical configurations in real life European scenarios, with a different approach in terms of dependability and complexity. The third case study analyses a typical configuration used in India for distribution automation programmes. All of these communication architectures make use of third party network providers (mainly cellular networks) in order to implement the Smartgrid communication network. However they follow very different approaches, which are discussed in the article.
Finally, the three communication arhitectures are compared, and analysis is included, and the main conclusions are discussed.

  • Authors: Fernando Castro, Jose Miguel Arzuaga and Aitor Arzuaga
  • Company: CG ZIV
  • Date: November 13-15, 2013
  • Event:CIGRÉ D2 (SC D2 Information systems and telecommunication), Mysore- Karnataka- India
  • Keywords: Cogeneration, Teleprotectionm Shannon’s Limit, Waveform Quality, Island Operation

Cogeneration plants will increasingly play an important role in the supply of electricity. Because of efficiency reasons electricity utilities buy energy generated in cogeneration plants and sell it to their customers.
Though this is indeed a good idea from the point of view of efficiency, it poses a number of technical problems. For example the waveform quality has to be preserved (voltage stability, frequency stability and phase), and islands of generation have to be detected and carefully controlled.

These two goals require new concept of teleprotection systems

  • The breaker has to be tripped even if there is no fault on the line.
  • A permanent state has to send to the autoproducer permises to prevent accidental reclosure operation.
  • Analogue values regarding voltage, power, reactive power and others have to be measured, transmitted to the remote end for proper monitoring and the corresponding decision- making process.

A new generation of teleprotection systems for cogeneration plants is described, together with the performance that should be achieved.

  • Authors: Roberto Cimadevilla, Iñigo Ferrero and Jose Miguel Yarza Narro.
  • Company: ZIV Grid Automation, S.L and ZIV R&D.
  • Date: March 12-13, 2013
  • Event:CIGRÉ Australia APB5, SEAPAC 2013, Brisbane- Australia.
  • Keywords: IEC61850-9-2, Process Bus, Sampled Values, Frequency Tracking, Resampling, Polynomial interpolation.

The Process Bus implementation provides many advantages to the utilities: copper reduction- cost reduction, engineering simplification, better failure detection system, lower risk of electrical accidents, interoperability, etc. The process Bus is based on two types of multicast messages, the GOOSE (defined in IEC61850-8-1) and the Sampled Values (SV, defined in IEC61850-9-2). After the successful implementation of the GOOSE message in the Station Bus, utilities are starting to use it in the Process Bus, together with the SV message. Pilot projects are currently in operation.

This paper focuses on the SV messages and their influence on the IEDs. Devices working with SV, coming from the Merging Units (MU) or from the non- conventional CTs (NCCT), have to cope with issues not considered with conventional IEDs: resampling, frequency tracking, counter- measures to be taken during loss or delay of SV, etc.

The paper explains the issues found during the development of an IED based on SV, describing the adopted solutions. Interpolation algorithms are used for resampling and for lost SV estimation. The frequency tracking algorithm is reviewed. Test results for different conditions are included.

  • Authors: Asier Llano, Alberto Sendin, Aitor Arzuaga and Sergio Santos
  • Company: ZIV Group and Iberdrola
  • Date:   April 2011
  • Event: IEEE ISPLC (International Symposium on Power Line Communications and its Applications), Udine – Italy
  • Keywords: PLC, DSP, Signal, Processing, Synchronous, Noise, Cancellation, PRIME, LV.

Low voltage power lines are attractive for communications in smart metering, but they are subject to many kinds of interferences. One important source of interference is the one which is synchronous with the power network frequency. This noise shares the mean periodicity with the mains, but it also ususally has some sort of time drift or jitter that shifts the position and phase of the signal from period to period. This paper refers to this particular kind of noise, which this paper will label as “quasi- synchronous”.  Several processing techniques have been used to cancel this component of a signal. The core of the algorithm is the predictor and its learning mechanism, which is able to provide a predicted version of the quasi- synchronous noise adjusted to the variations of the input phase, ready to perform the cancellation. The results of these cancelation technologies are described, applied to both, synthetic and real input signals, to demonstrate that quasi- periodic noise can be cancelled with affordable processing power consumption.

  • Authors: Alberto Sendin, Asier Llano, Aitor Arzuaga and Iñigo Berganza
  • Company: ZIV Group and Iberdrola
  • Date:   April 2011
  • Event: IEEE ISPLC (International Symposium on Power Line Communications and its Applications), Udine – Italy
  • Keywords: PLC, PRIME, Repetition, Noise, Three Phase, Cyclic, Switch

Power Line Communications (PLC) technologies and systems use state- of- the- art technical solutions to provide communication means for Smart Grid applications. PRIME is one of those systems, with a comprehensive Physical and Media Access Control (MAC) Layer specification for CENELEC A- band, used today in Smart Metering deployments.

PRIME systems have demonstarted to be capable of working in normal scenarios (urban, suburban and rural) covering long distances in typical noise conditions. However, there are locations where noise is harsher than the regular conditions. This kind of noise is usually found close to the premises where meters are located. It often shows a periodic nature, both in its origin and external effects (e.g. daytime and nighttime cycles).

This paper proposes a way to overcome the noise situation mentioned above, based on field deployable solutions. These solutions are based on the development of devices which, using the switching concept inherent to PRIME systems, can help affected meters to overcome noisy situations. Results from field experiments are provided, and the conclusions may be used to further develop products to overcome aggressive noise situations on field.

  • Authors: Alberto Sendin, Asier Llano, Aitor Arzuaga and Iñigo Berganza
  • Company: ZIV Group and Iberdrola
  • Date: April 2011
  • Event: IEEE ISPLC (International Symposium on Power Line Communications and its Applications), Udine -Italy
  • Keywords:PLC, PRIME, Repetition, Three Phase, Distribution, Transformer, Substation, Base Node, Smart Metering

Distribution transformers are found in secondary substations, and connect to three phase low voltage lines that deliver electricity to points of supply. Electricity customers are charged for their consumptiom based in the measurements registered in meters present at the pint of supply.

Power Line Communication (PLC) signal injection in distribution transformers is a key element in PLC signal propagation in distribution grids. PRIME is a narrowband PLC technology in CENELEC A band, used by utilities to communicate with meters at maximum data rates of 122,9 kbps. PRIME technology establishes subnetworks rooting at distribution transformers in secondary substations, where the so called Base Nodes are installed, to communicate with Service Nodes present at meters in Smart Metering environments.

This paper analyzes the alternatives for PLC signal injection, either single phase or three phase, through different field tests, in order to improve overall network constitution and performance of meters. The results and conclusions may be extrapolated to any other low voltage PLC technology in the same frequency band.

The conclusions of the paper make recommendations to use specific PLC injection configurations, depending on the topologies under study, and provide guidance for product development in this area which has fundamental influence in the results obtained for the PLC communication system.

  • Authors: Txetxu Arzuaga Canls and Aitor Arzuaga Munsuri
  • Company: ZIV Metering Solutions and ZIV R&D
  • Date:26- 27 October 2011
  • Event: JIEEC(International Electrical Equipment Conference), Bilbao- Spain
  • Keywords: Smart, Metering, Prime, Networks

This paper describes the main challenges a Utility needs to face in order to succesfully deploy an advanced metering infraestructure. We will focus on a PRIME based AMI. The first question to answer, prior to any technical analysis, is why should we base an AMI deployment on PRIME technology?.

We think that several arguments can be placed explaining the reasons for which most of Spanish Utilities have decided to deploy PRIME based AMI’s. Nevertheless, we would like to hightlight the most important ones:

  • It works. This may seem quite evident, but when discussing of a complex architecture, where multiple technologies (telecom, information systems, metering) need to work together for the AMI system to success, is not so evident. PRIME allows the customer to fulfill its business requirements, making it feasible to gather billing & consumption data every day from all smart meters, to operate the AMI and to appropriately respond to events generated in smart meters on time
  • Product interchangeability. This PRIME feature fulfills the ambition of any purchaser, i.e. to have multiple provision sources. This makes the Utility’s logistics procedures ligthter as any approved smart meter can be used at customer premises.
  • Future proof. Finally, PRIME technology is maintained inside an Alliance of more than 35 technology companies that represent the most important players in the AMI value chain. This fact assures its evolution.

As stated in the first paragraph, this paper will focus on just one aspect of the AMI challenge: The one related to PLC communications. In fact, we will focus on urban/semi- urban areas. In these areas, due to the distribution network nature, it makes sense to deploy AMI based on LV PLC technologies.

This paper is organized in several sections. The first one introduces an AMI architecture, so prior to focusing on the PLC part, we understand the full picture. Next section details the main challenges a LV grid poses to design an appropriate telecom technology, and the powerline injection problem. A third section provides the reader a brief summary of PRIME technology. A fourth section shows some figures and facts obtained with PRIME.

  • Authors: Sergio Santos, Asier Llano, Aitor Arzuaga, Txetxu Arzuaga, Laura Marrón and Mikel Zamalloa
  • Company: ZIV Metering Solutions
  • Date: August 2012
  • Event: CIGRE (Conseil International des Grands Reseaux Electriques), Paris- France
  • Keywords: Smart, Meters, Synchrophasor, Applications, Distribution, Grids

Synchrophasors are being used widely in HV/MV substation applications. In these facilities we have extensive synchronizing GPS receivers which are able to provide timestamping information to IEDs or other devices. However, up to now they are not being used in BT applications due to cost restrictions in the last section of the distribution grid.

PLC communication systems can be used to synchronize current and voltage measured by meters installed in the same circuit of a network. The above will provide advanced power network status information with no additional costs.

Power line communication systems are being nowadays widely used, and commonly we can find PLC modems either built-in or externally connected to the meter. It is possible to make smart meters on a network synchronized through a pattern based in PLC, to obtain simultaneous current and voltage measurements. This technology allows a wide range of new measurement options, such as overloaded neutral wires, voltage unbalances in different points, network instability due to uncertain loads (EV) or distributed generation (DER) including EVs with V2G capabilities, or calibration errors and tampering schemes.

This technology introduces an innovative methodology by which the measuring modules of the meters can take advantage of the PLC infrastructure obtaining additional useful information from the Low Voltage network and implicating smart meters, concentrators and basic PLC communication devices.

Normally, electrical input signals are measured by meters following an autonomous sample rate, based on their internal oscillator, and detecting zero crossings instants of the voltage as well. In this standard scheme, between two meters there is no interaction at all, and their sample instants are calculated based on their own measurements. In order to get the collaborative measurement, all the sample rates of both meters (and every meter involved in a specific algorithm), must be synchronized with a defined maximum time drift. This can be made by means of a PLC system. Regarding PRIME PLC technology we could get a synchronization error drift of near 5us, applying statistical and expert control systems, and 12 us by means of the standard preamble pattern.

In deployments of three phase systems, with only single phase meters, the power phase unbalance could be measured along the derivation points using this method, reading samples of every meter involved and applying the standard formulae for direct, reverse and homopolar sequences. Also neutral wire impedance and neutral current shape can be retrieved only applying basic Kirchoff rules.

Measurement results will be shown for a three- phase, for wires, and multiline deployment emulation. The real situation will be first tested in a laboratory. Error estimation comparisons for neutral current polyphase vector angles will be shown at different locations of the circuit, and also the time payload and maximum sampling frequency will be also studied. Device design issues are also being considered.

In summary, PLC infrastructure, apart from acting as a communication system for billing, event recording and other purposes, can be used to add new capabilities to the system, by making meters, placed in different locations of the power network, to operate in a synchronized manner. This paper will further analyze this technology and how they can be implemented for enhanced LV network monitoring applications, for instance in DER scenarios.

  • Authors: Txetxu Arzuaga and Aitor Arzuaga
  • Company: ZIV Metering Solutions and ZIV R&D
  • Date: August 2012
  • Event: CIGRE (Conseil International des Grands Reseaux Electriques), Paris- France
  • Keywords: IT, Architecture, Metering, Infrastructure

When discussing about IT, everyone tends to think on centralized systems in a ‘cooled air conditioning’ Data Processing Center. This is possibly also true in most of the utility IT systems. But there are some other utility applications that require tailored solutions, such as Advanced Metering Infrastructure (AMI). This paper will discuss the challenges an AMI poses onto this type of information systems.

First of all, it should be noted than an AMI deployment is no longer a centralized IT system but a geographically spread IT solution. Many AMI deployments- mainly in urban environments, where distribution MV to LV transformers can service up to several hundred users- are based on the installation of data concentrators at the transforming station integrating the readings of all meters connected to that transformer. In this case, the information system cannot be reduced to the Meter Data Management System that runs in the DSO central office. The data concentrators are also a key part of the Distributed Information System. And there will be thousands of them all over a region/ nation.

This new Distributed Information System for AMI should account for:

  • Systematic Meter Data Collection.
  • Complex Event Processing. Several thousands of small IT systems may trigger events simultaneously. How can we transform this huge amount of events into useful information?
  • IED’s management (in terms of configuration, firmware upgrade). Operation will be more and more complex.

In addition to the previously stated requirements, all the IT system must be provisioned in a secure way. Note that data concentrators will be installed in different sites, where the DSOs may not have their own telecom infrastructure available. As a result of this they will have to rely on third party communication links, which raises aditional security concerns.

The information system must be also scalable, since AMI deployments start servicing thousands of customers, but they must be able to cope with millions. The mechanisms and architectures must be able to scale up accordingly and in this field the service arcitecture between the central DSO information system and the distributed concentrators is crucial.

This paper will propose a distributed IT solution for AMI based on an architecture oriented to services. Also the costs of deployment and operation will be analyzed and accounted for. Note that Telecommunications and information systems are the most significative elements in AMI deployments as far as the investments and the operational expenses are concerned,and consequently are a key element (sometimes the key element) for their approval.

  • Author: Roberto Cimadevilla (ZIV)
  • Company: ZIV Grid Automation S.L
  • Date: February 06, 2016

The aim of this document is to explain the recommended settings related to the harmonic blocking or restraint feature of the IDV relay model.

1. Introduction

Energization of a transformer causes magnetizing inrush currents with high content of even harmonics (mainly, second and fourth harmonics). This phenomenon is aggravated by the possible residual magnetism in the transformer. During such process, the current is much greater at the energization side as magnetizing energy must be provided to the transformer core. This results into a strong differential current for up to several tens of cycles. If proper measures are not taken, the Differential Unit can operate.

On the other hand, the operation of the transformer in overexciting conditions (overvoltage and underfrequency) has similar characteristics with the appearance of differential current and high odd harmonic content (third and fifth harmonics)

To prevent the operation of the differential transformer realys in those situations, the harmonics present in the differential current are extracted and used to desensitize the measurement element applying the harmonic restraint or the harmonic blocking.

2.Harmonic restraint / blocking

The selection of harmonic restraint or harmonic blocking should be analyzed in detail because it will compromise the security and dependability and it also depends on the connection group and the transformer itself used in each case. For transformers with a delta winding (either real or phantom) which are energized from the wye winding/s the harmonic blocking with two out of three logic provides good balance between security and dependability. For other type of transformer connection groups or in a wyedelta transformer if the energization is done from the delta side the harmonic sharing logic (harmonic blocking with sum or 3 phase sum) is considered the best one and in order to increase the dependability a three-phase sharing second harmonic ratio is recommended.

Restraint or harmonics blocking could delay the tripping of the Differential Unit once the transformer is energized when there is for example an internal fault with CT saturation, due to the harmonic contamination caused by the differential current wave in that case.

There is logic that inhibits the harmonic restraint / blocking and it allows accelerating the trip applying the harmonic restraint or harmonic blocking just when it is necessary. It is called as Dynamic Mode. IDV-L model includes the blocking/restraint disable function by any harmonic (2nd, 3rd, 4th and 5th) and this function is based on two different principles/methods:

  • Blocking Restraint by Harmonics not based on voltage variation:
    • Blocking/Restraint by 2nd and 4th harmonic disable method based on currents. From the moment the energization of the transformer is detected (current in any of the windings exceeds the threshold value) the restraint / blocking from the 2nd and 4th harmonics is applied during a settable time. Once the transformer is energized, the restraint/blocking will be applied again when an external fault condition is detected during that settable time.
    • Blocking/Restraint by 3rd and 5th harmonic disable method based on Voltage/Frequency ratio. In order to detect over excitation situations, the relay will be continually checking the ratio between voltage and frequency. When it is above 1.05 times the ratio (Vrated/Frated), the restraint by 3rd and 5th harmonic will be enabled, but when there is no voltage information, blocking or restraint by 3rd and 5th harmonics is always working/operative if the corresponding setting is set to yes.
  • Voltage and restraint current change. In inrush or over excitation situations, there is a gap from the time when a voltage change is produced until the saturation of the power transformer takes place and, therefore, until the differential current increases. However, in internal faults, a voltage change will happen together with a differential current increase as shown in the figure 1. So, if during a number of consecutive samples from the time a voltage change occurs (detected based on instantaneous values), the differential current is very small, the relay will apply the harmonic restraint/blocking by all harmonics during the “Harmonic Disable Time” setting. The measured voltage must be taken from the transformer side of the breaker where the energizing takes place because by this way and using this method allows discerning close on to fault energizing.

Figure 1. Increment of Voltage / Differential current

Note that due to the fact that current-based restraint and blocking inhibition by harmonics is based on the External Fault Detector activation, restraint and blocking by harmonics will continuously be applied when that detector is disabled.


  • Use of harmonic blocking instead of harmonic restraint because the cross-blocking logic is not included in harmonic restraint.
  • Use of “2 out of 3” cross blocking logic for transformers including a delta winding energized from the Y side.
  • Use of “3-phase sum” cross blocking for transformers different from the one mentioned in the latter point.
  • Use of dynamic harmonic blocking if dependability problems have been found for internal faults with transformer relays using harmonic blocking due to CT saturation during internal faults that generate low differential current and therefore the non-restrained differential unit is not operating.
  • If dynamic harmonic blocking is used:
    • With no voltage only 2º and 4º harmonic blocking will be inhibited
    • With 3-phase voltage both 2º and 5º harmonic blocking will be inhibited:
      • If the 3-phase voltages are taken from the transformer side, the harmonic inhibition will be enabled even during the transformer energization (if a fault is detected).
      • If the 3-phase voltages are taken from the busbar side, the 2º harmonic inhibition will be enabled after the transformer energization (for faults with the transformer already energized).
  • You can find more information related to the harmonic blocking/restraint in the following documents:

  • Authors: Rafael Quintanilla (ZIV ), José Maria Yarza (ZIV)
  • Company:
  • Date:
  • Event:
  • Keywords:

This paper describes the experience obtained during the deployment of a supervision system in a real network in a medium size city located in the Mediterranean coast of Spain. It was necessary to develop different solutions that took into account the diversity of installations derived from the technical history of the utility owner of the network. A wide range of technologies were used to get an optimized application: electromagnetic sensors, materials engineering, Ethernet, power line communications, IEC 61850…


From last 70s, as a result of the political situation that led to a decline in oil production, the developed world became aware of its energy dependence and hence its vulnerability. On the other hand, the human habits of energy consumption have become an increasingly obvious influence in greenhouse gases and the threat for climate change. This situation is also coupled with growing energy demand, higher quality of service and demand response requirements, in addition to a greater difficulty in expanding conventional power infrastructure, resulting from a growing social awareness of environmental conservation.

In response to the above concerns, the grid began to change and paved the way towards the new paradigm depicted in figure 1. The road to reach this new scheme will not be easy and will need the intensive use of information and communication technologies, all of them already available.

There is no doubt that the intelligence should be incorporated at all levels of the electrical network, but it is at distribution level (medium and low voltage) where the investment in technology is more necessary; this level is the contact line between the DSO and the greater number of users of the electrical grid. Today, these users are changing their role, they continue being consumers of energy, but they are more and more true users of the grid, acquiring a more active participation and becoming more demanding of an excellent service and quality.

But when talking about improving the distribution grid, the number of installations is so large that it is difficult to justify the necessary investment, meaning that the steps to be taken need to be analysed and measured.

Figure 1: The Grid of the Future

1. Making the SmartGrid Real

The Grid of the Future, also called as SmartGrid needs to incorporate technology, but this is just a layer necessary not by itself but to build the foundation for the upper layers containing the software applications that constitute the true intelligence of the grid. No matter which functions we think on, the first step is to make the grid visible, that means to collect raw data (measurements, status of breakers and sectionalizers, alarms…) to feed the upper applications that will convert them in information and knowledge with a higher level of abstraction to be used by human operators or automatisms to manage not only the grid itself but also the users connected to it.

Making the end users visible is the first step to provide them with new services and also, to make them capable of participating as active players in the new scenario (active demand, DER providers…). it is necessary to install smart meters within its premises and also a communication system that transfers the energy information to the remote center and upper applications and sends information and commands from those centers and functions to the meters.

To make the distribution grid visible, we need to connect sensors and RTUs within the secondary substations. Those RTUs will be true IED (Intelligent Electronic Device) with more functions, as it will be seen later, than just gathering measurements and statuses of switchgear.

Finally, it is necessary to communicate the system with the remote centers where the upper level applications are located (SCADA, EMS, customer management…) through a flexible communication system.

figure 2 shows the global system architecture, in accordance with the ideas mentioned above.

Figure 2. Global System Architecture

2. Background

In Spain, all meters must be replaced by smart meters by dec 31st, 2018. The purpose of this is to give the end users the possibility of enjoying energy services other than just power. This is an important step on the way to the SmartGrid and constitutes an innovation driver because it makes necessary to deploy a communication infrastructure that opens the possibility of later installations of other electronic equipment and applications to incorporate intelligence to the grid.

In this new scenario, the utilities are, of course, interested in keeping the present situation of having several providers of technology and equipment without the telecommunication system being a barrier but an open field where several players can play and interoperate without problems. As a consequence of that, a great opportunity appears for utilities and meters manufacturers to work together and develop open protocols allowing multivendor solutions; this is the case of PRIME technology that will be briefly described below.

3. PRIME system

PRIME (PoweR line Intelligent Metering Evolution) is one of the prominent upcoming power line communication standards, targeted for use in smart metering applications. The PRIME PHY / MAC specifications are open and developed by the PRIME alliance, an industry consortium that includes utilities, meter vendors and semiconductor suppliers. PRIME employs OFDM modulation in the Cenelec A band (9 – 95 kHz), and achieves data rates from 21 kbps to 128 kbps at the PHY layer. The PRIME MAC is based on a tree structure, and features a novel node discovery and network building process. PRIME converges to IPv4 and IEC-432 at the network layer, and is evolving to support IPv6.

4. Pilot Projects

If we mix all previous ideas:

  • Obligation of installing smart meters
  • Deployment of a communication infrastructure up to the end user premises
  • Need of testing not only the interoperability of meters from several vendors, but also new functions to supervise the low voltage grid
  • Possibility of improving at a relative low marginal cost, once installed the communication network, the visibility, the operational characteristics and the efficiency of the distribution network

We have created the conditions to make very attractive the possibility of launching pilot projects to test those ideas in real conditions.

On that sense, IBERDROLA, one of the world bigger utilities, located in Spain, decided to put all those ideas above together and initiate the way to the SmartGrid by starting a project, called STAR, with the target of reaching valuable conclusions to get ready for the moment when a massive deployment is necessary.

For this purpose a medium size city, located on the Mediterranean coast, was chosen. The name of the city is Castellón de la Plana and the main parameters of the project (STAR project launched in 2009) are as follows:

  • 175.000 inhabitants
  • 100.973 points of supply
  • 583 Secondary Substations
  • Grid topologies and densities resemble the average of IBERDROLA’s Grid.

It is important to note that IBERDROLA and other utilities had already begun with medium to wide scale projects and deployments, but in all cases much smaller in size (several new blocks of apartments, instead of a complete city) and limited to the installation of meters from just one vendor (ZIV) and using non standard PLC technology.

The main goals of the project are:

  • Fulfill the regulatory requirements to install smart meters.
  • Take advantage of the above to modernize secondary substations and to add SmartGrid functions to them:
  • LV grid voltage monitoring
  • MV grid voltage monitoring
  • Directional Fault Detection
  • Alarms
  • Automation
  • Next generation central AMM System, SCADA

Just to give an idea of the difficulties found during the project, it could be interesting to describe the main differences between the previous initiatives and the STAR project:

  • The size of the test field – A city instead of just a few blocks
  • The existence of a network already in use that needs to be kept in service to continue providing energy to the users
  • The inclusion of the Secondary Substations, as part of the project, to accommodate new functions of distribution automation
  • Old Secondary Substation coming from all technologies stages: open air switchgear, gas isolated switchgear and masonry with a history of very low previous investment
  • Several providers for every type of equipment to be installed: meters, concentrators, communication nodes, remote terminal units…

5. Deployment and equipment

Besides installing smart meters, other equipment should be installed to fit the goals of the project. The meters were installed at the end user house or premises, but all other devices have been mounted within the secondary substations, acting as network communication nodes instead of previous grid energy nodes.

Figure 3 shows a diagram including all the generic functions, already mentioned, to be installed within the secondary Substations.

Figure 3. Secondary Substation Architecture

The global desired functionality has been split into different devices attending not only to technical considerations, but also to maximize the flexibility of adaptation to different types of secondary substations keeping on mind the possibility of procure the equipment from several vendors:

  • Metering concentrator connected to downstream smart meters and including low voltage supervision functions. There will be as much concentrators as number of MV/LV transformers installed in the substation.
  • Remote terminal units (RTU) connected to current and voltage sensors, switchgear statuses and other sources of alarm, to provide medium voltage supervision and automation functions. In this case, the number of units will depend on the topology of the substation and the number of lines to supervise. In general there will be N-1 terminals, being N the total number of lines.
  • Communication node connected to concentrator and RTU giving them the capability to communicate with the upper control centres (metering and SCADA).
  • Medium voltage sensors, connected to the remote terminal units, to capture the value of voltages and currents to be used by the MV and central SCADA supervisory functions.
  • Battery and charger to provide power to all other electronic equipment. As it will be explained below, there are substations where neither the battery nor the charger is needed; in this case the equipment is powered directly from the low AC voltage.

Figure 4 shows the relations among all the mentioned equipment (the charger and the battery not shown for clarity). It is important to note that, for safety reasons, there will be a 10 kV level of isolation between the remote terminal units and the remaining devices (concentrator and communication node).

Figure 4. Secondary Substation. Supervisory and communication equipment

6. Communication architecture

As shown in figure 4, there are several devices to be installed in the substation, and all of them need to communicate not only with some control centre but also among them. The communication architecture is also depicted in figure 4.

Ethernet has been chosen for all internal communications, applying different protocols depending on the application. The communication node acts as a router and it generates two different VLAN’s to keep the traffic separated between LV and MV supervisory applications.

All remote terminal units are connected to the same VLAN exchanging real time data by means of IEC61850 GOOSE services without a complete standard implementation, but making easier future standardization. Exchange of data to and from the control centre is done according to IEC 870-5-104 standard; but even when several devices can exist in the same substation, all of them are seen from the SCADA as a single one; for this purpose one of the devices has the role and function of gateway. By doing this, no matter how many units are used, the SCADA centre sees only the substation as a whole.

As said before, there are as many concentrators as transformers in the substation; all of them are connected to the same VLAN, different from the one used by the MV remote units. For this application, DLMS over web services is the protocol used. The concentrators receive data from the smart meters through the power lines by using the same DLMS protocol but over PRIME, the technology described in a former paragraph.

The communication node has the purpose of communicating the substation to the upper centres, data upwards and commands downward, as well as of providing with the maximum flexibility for the secondary substation external communication. Depending on its location, the optimal solution could be different and the node should support the maximum possibilities, even all of them if possible. In this project, the alternatives used were: GPRS, medium voltage PLC and ADSL; in the first case the GPRS modem is integrated within the communication node, but in the other two, it is necessary to use a separate modem to complete the solution. Only with GPRS and ADSL, the substation can reach the control centres, but when medium voltage PLC is used, the communication up to the centre is completed through the node installed in other substation that has any alternative out from the other two (ADSL, GPRS).

Figure 5. Communication architecture

7. Equipment characteristics

In the following paragraphs, the specific characteristics of the equipment used are summarized.

7.1 Remote terminal Unit. Medium voltage supervision

  • 7 analogue inputs ( 3 from voltage sensors plus 4 from toroidal current transformers)
  • 32 samples per cycle
  • 12 programmable digital inputs
  • 6 programmable contact outputs
  • 1 in service contact output

The equipment measures phase currents and voltages directly from external sensors and calculate sequence voltages and currents, phase to phase voltages, frequency, active and reactive power per phase and apparent power (S).

There are two different types of units:

  • Data acquisition unit (DAU). This is the “basic” unit with all the inputs, outputs and functions described above.
  • Central unit (CU). It also has the capability of retrieving data from the other “basic” units installed in the substation and sending them to the SCADA centre through IEC 870-5-104 protocol.

There will be always one CU unit per substation and depending on the topology, there will be zero, one or more CU units.

Figure 6. Different secondary substation topologies

The connection among the devices is done by means of an electrical Ethernet network and RJ45 connectors; the exchange of information is accomplished by using IEC61850 GOOSEs.

From the SCADA centre, no matter how many remote terminal units are in a secondary substation as all of them are seeing as a single equipment.

Figure 7. Remote terminal units interconnection

7.1.1Functions. Fault passage indicator

The fault passage indicator function is activated when any fault in the medium voltage circuit causes the trip of the primary substation line breaker. The coincidence of a directional overcurrent activation and a drop of voltage should occur to consider that there is a fault indication in the correct direction.

To get a reliable indication, the unit has several phase and ground directional overcurrent units, combined with inverse and zero sequence directional units and over/undervoltage units.

The activation of this function is received in the SCADA centre through the communication network. By examining the pattern of units activated it is very easy to know the line section where the fault is located and send the maintenance team directly to the right place to clear the problem.

In those secondary substation where the switchgear is motorized, the fault passage indicator initiates an automatism that works in combination with the line recloser (at the primary substation) to isolate the faulted line section, allowing to restore, very fast, the service to the healthy line sections.

9.1.2 Other supervisory functions

To improve the fault passage indication function in order to achieve a faster search for the fault, the device includes a fault distance calculation algorithm.

To supervise the wave quality, the equipment includes several measurement elements, in accordance with the standards (In Spain: UNE-EN 50.160):

  • Harmonic contents of (Va, Vb, Vc, Ia, Ib, Ic, In ) to the 9th harmonic
  • Harmonic distortion factor (FD)
  • Total harmonic distortion (THD)
  • RMS measurement of (Va, Vb, Vc, Ia, Ib, Ic, In)
  • Undervoltage counter
  • Overvoltage counter
  • Voltage and current unbalance counter

7.2 Low voltage concentrator

The low voltage concentrator is a fundamental element in the communication architecture for a remote metering management system (AMR and AMM). Its main functions are:

  • Smart meters polling based on a task program
  • Non volatile memory capacity for the data gathered from 2000 meters during one month
  • Automatic meters registering in and out without user intervention
  • Automatic configuration of routing to access all devices
  • Reading management and non volatile data memory for the information to be send to the metering centre. Memory capacity for 2000 meters / 1 month data
  • There is one energy meter included as part of the concentrator to totalize and check the energy supplied downstream

The concentrator acts as low voltage master. It keeps the list of meters connected to it and stores and manages a copy of the data gathered from them.

The retrieved metering information is:

  • Status of the Power Control Switch included in the meter (this switch, controlled by a thermal characteristic, opens the circuit when the consumption exceeds the contracted power)
  • Smart meters polling based on a task program
  • Instantaneous measurements of voltage, current, active and reactive power and power factor (total and per phase)
  • Load profile of all meters
  • Real time values and last billing (active and reactive energy, maximum power. Total values and per tariff)
  • Daily summary
  • Meters quality events

The equipment automatically detects the connected meters downstream according to an actualization interval table. It also has a programmable interval for unregistering the meters because a breakdown or because the meter has been uninstalled. This operation can also be done manually.

The gathered information will be send to the distribution company either automatically or on demand.

The characteristics of the concentrator allow other very useful low voltage supervisory functions:

Failure detection: As the concentrator includes a totalizer counter and the list of meters on every line, it can be used to detect the failure of a specific low voltage circuit. When a group of meters stops measuring energy consumption simultaneously, it indicates a failure in the circuit to which they are connected, as indicated in figure 8. Again, as in the case of the fault passage indicator, this allows the maintenance team reacting very fast to restore the service.

Figure 8. Failure detection

Fraud detection: When the energy measured by the meter embedded in the concentrator is not equal to the sum of the energies measured by the meters downstream, it indicates a problem that can be caused by a fraudulent intervention on some of them.

Figure 9. Fraud detection

Grid topology detection: This characteristic is based on a service provided by PRIME technology. When the voltage wave crosses through zero, the concentrator sends an interrogation to the meters; all of them answering with a zero crossing detection are supposed to be connected to the same phase.

Figure 10. Grid topology detection

Unbalance control and notification: As the concentrator is measuring current, power and energy in a per phase basis, it can detect any unbalance in the energy consumption

Figure 11. Unbalance control and notification

7.3 Communication node

As said in previous paragraphs, there are several technologies available to deploy a network to interconnect the secondary substation to the utility backbone. For that reason the proposed equipment to be used includes, besides an eight ports managed switch, three different options for the connection to the backbone:

  • Optical fiber
  • GPRS
  • PLC for MV
  • Up to 256 different VLANs

7.4 Sensors and couplers

To make the remote terminal unit capable of measuring the voltages and current in the medium voltage circuit, it is necessary to incorporate sensors with enough accuracy to be useful for the applications defined by the utility: 2% for currents and 1,5 % for voltages.

But the accuracy is not the only and more problematic requirement. It has to be taken into account that the grid and switchgear were old and they were designed without supervision and measurement requirements. This means that the sensors have to be designed considering the lack of space and the diversity of secondary substations available. To capture the currents toroidal transformers have been used, while resistor and capacitor dividers were employed for voltage measurement.

At this level of voltage there are no standards describing the interface between the sensors and the electronic so both elements are to be considered as two pieces of the same function being the supplier of the electronic and sensors the same to guarantee and optimal performance of the two parts.

We can summarize the problems to face up, considering the three different types of installation found:

  • Masonry Secondary substations
  • Isolator size determines the internal diameter of the toroidal transformers.
  • Because of the diversity of installation, resistor dividers have to be mounted on customized assemblies.
  • Energy service must be interrupted to rework it.
  • Secondary substations with open air switchgear
  • Current transformers in cables.
  • Wall-mounted resistive dividers.
  • Power supply must be interrupted to rework it.
  • Secondary substations with Gas Insulated Switchgear (GIS)
  • Size of “T” connectors.
  • Voltage capture with capacitive dividers.

Figure 12. Voltage and current sensors

7.5 Power supply. Charger. Battery

The main characteristic of the charger are:

Input voltage: 160 – 260 Vac 50 Hz

Output voltage: Regulated 48 Vdc

Output power: 50 W to the load

Battery charging current: 0,1 to 1,2 A (configurable)

Battery type: Watertight PB

Battery capacity: 2 to 15 Ah

As said before, not all secondary substations require battery and charger to power the installed equipment; the criterion to install a battery is to make sure that all information generated finds a path to reach the centre were the data are going to be processed and used. For example, in a substation where only low voltage supervision is installed, the existing equipment will be powered directly from the low voltage AC, without a battery, because if the installation loses the power, it will not be available data to be sent to the centre. On the contrary, when there are MV supervision functions implemented, there will be data that the SCADA needs to know even in cases when there is no low voltage available (for example, the low voltage can disappear if the sectionalizer is open, but the SCADA needs to know the status of the switch and the voltage at the MV side).

However, there is one case where the battery is still required under single LV supervision functions; this is when that particular communication node (using ADSL or GPRS comms) supports the communication of other neighboring node linked through MV PLC. Under this situation, that “key” node has to be necessarily powered-up to guarantee the correct data transfer coming from such neighboring MV supervised substation for example.

Therefore, as a general rule, the communication node is to be powered-up with the same type of source that powers the equipment to which is serving.

8. Physical implementation. Cabinets. Installation

As said before, the project was deployed in a grid that was in operation and with a lot of different types of secondary substations. Deploying such ambitious project, with the grid in operation, makes the task very difficult, so before starting with any installation it is necessary to examine the sites to decide which the best solution for every location is. The aim is to minimize the time during the station is out of operation and have the problems solved before final installation. The chosen solution should also be mounted and tested before starting installation in site.

The difficulties come not only because the grid has to be in service, but also because of the substation variety, keeping on mind the fact that they are old and designed without taking into account the present needs; even the available room is a big problem in some of the cases. In Castellon one can find three different types of installations: masonry, air switchgear and gas insulated, each with specific types of problems.

To have the possibility of having most of the work in advance, the equipment to be installed is mounted into cabinets of different sizes and functions, depending on the needs of the specific location where they are going to be installed. To keep maximum flexibility, the utility defined several types of cabinets to include the necessary equipment to be mounted in every substation.

The main criteria to decide how the cabinets should be were: room available, electrical separation between low and medium voltage supervision equipment, communications, electrical isolation, mechanical and environmental characteristics, accessibility… Putting all that together the size of the cabinets was defined and, as a consequence of that, the maximum size of the devices to be installed inside. Two of the several possible solutions is shown in figure 13.

Figure 13. Different cabinet solutions

9. The future

It is difficult to have an exact idea about the future of the grid considering all the variables that have some influence on it. The only think we can do is to make a reflection about the main lines of influence on this such interesting future.

Very likely, power electronics will be present in the secondary substations to cover different purposes: power conversion, reactive power compensation, voltage regulation, voltage dip compensation, flicker mitigation, harmonic compensation, waveform optimization, power loss reduction in HV/MV… and many others that the future will make appear.

Integration is a friend that always comes together with cost optimization and technological innovation; according with this tendency we will find fully integrated secondary substations with all required “intelligent” functions in a single device, two at the most. And probably energy storage will be part of this integration.

Supervisory functions will evolve to advanced automation features with the intelligence dispersed through the grid thanks to the application of all the possibilities the communication technology can support.

And do not forget the electrical vehicle that, for sure, will make new requirements to be implemented in the secondary substation, as they are interfaces between grid and loads that will have the purpose of optimizing the management of new energy services.

10. Conclusions

The need of implementing a remote meter management system makes necessary the deployment of a communication system. Once that this is done, it is reasonable to think about what other benefits we can be obtained from it in the way to the SmartGrid, and analyse the steps to be done. The supervision and monitoring of the grid appears as the first step to make the electrical world visible to other future applications.

It is important to develop a pilot project in the real world, not just a demo, to show the possibilities of the technology. Why? Because, for sure, the technology is ready, but we need to know in advance the problems we are going to find when we face up a large scale deployment.

Once the need of the pilot is clear, it is necessary to select the right and representative place and to establish a site survey to the installations to be refurbished. After these visits, we can conclude to review plans and targets to guarantee the final success.

And we must have always present that the grid have to be kept in operation while we work on it and also giving the same quality of service while evolving to the next level, what means that we need to make a true revolution, but by evolution.

Finally, it should be noted that the success depends on the existence or development of standards of different types: communication, measurement interfaces… to guarantee the flexibility to install equipment and application from different sources.


It is a well-known fact that things are changing for the electrical network; during the last years, due to several factors:

  • Climate change
  • Fuel prices
  • Intensive use of electricity in the digital economy
  • Increased deployment of Distributed Energy Resources (DER) at different voltage levels
  • Evolution of traditional consumers of electricity that have become also producers, changing their role of users of electricity to users of the network

As a consequence of that, it is necessary:

  • To improve the quality of service and the quality of energy
  • To be more efficient on the use of the energy
  • To manage the demand actively to optimize the use of the network
  • To incorporate the end users as active agents in the market of energy and services.
  • To be able to integrate effectively the DER

All above requires increasing the smartness of the electrical grid, especially at distribution level, incorporating intelligence into the secondary substations, making them visible and capable of giving information about the state of the medium and low voltage network. That means installing sensors, measurement capability, communications, actuators, IEDs… And all this while the system continues working, coping with old installations that were not designed taking into account the new requirements.

This paper describes the experience obtained during the deployment of a supervision system in a real network in a medium size city located in the Mediterranean coast of Spain. It was necessary to develop different solutions that took into account the diversity of installations derived from the technical history of the utility owner of the network. A wide range of technologies were used to get an optimized application: electromagnetic sensors, materials engineering, Ethernet, power line communications, IEC 61850…

Finally, a glance into the future is provided, examining were the authors think the technology is going to, helping the network to achieve a revolution by evolution.


Rafael Quintanilla was graduated in Electrical Engineering from the Escuela Técnica Superior de Ingenieros Industriales (Superior Engineering School) of Bilbao, Spain in 1977. He started working for General Electric in Zamudio, Spain as a Protection Design Engineer participating in the first project on modular relays for distribution developed by GE. During his work for GE, he had different responsibilities: Design Engineer, Application Engineer (as Line Protection specialist) and finally Design Manager.

In 1993, he started working for ZIV as Design Manager, being promoted to ZIV P+C General Manager some years later; nowadays he is the General Manager of ZIV Grid Automation division. Until now he has participated in the conceptual design of most products (software and equipment) from ZIV related to protection and control.

During his professional life, he has written several technical papers and nowadays he is a member of several technological platforms (distributed energy, active networks, embedded systems…) in Spain.

José Miguel Yarza holds a Bachelor Degree on Electrical Engineering from the University of Basque Country, a Master Degree on “Quality and Security in electrical energy delivery. Power system protections” from the same University, and a MBA from ESEUNE Business School.

He is currently Application and Development Manager for ZIV GRID AUTOMATION, where he has worked for 15 years.

He is a member of AENOR SC57 (Spanish standardization body), several CIGRÉ working groups, and IEC TC57 WG10.


  • Authors: Roberto Cimadevilla (ZIV), Rafael Quintanilla (ZIV ), S. Ward (RFL Electronics Inc.).
  • Company: ZIV & RFL Electronics Inc
  • Date:    October 25 – 27, 2005
  • Event: Presented to the 32nd Annual Western Protective Relay Conference Spokane, WA
  • Keywords:

Electric power systems are susceptible to frequency variations. While the US grid generally exhibits a very stable frequency during all but emergency conditions (such as cascading black-outs) there are regions in some countries in which such variations are extremely notable and recurrent and experience from these applications provide very good data for improving protection design.

Proper protective relay behavior is of key importance to minimize system degradation and to stabilize the system as quickly as possible. Incorrect relay response during frequency excursions is bound to aggravate an already deteriorating situation.

This paper describes how conventional distance protections are affected by frequency variations and how digital technology allows designing reliable protective relays that will behave correctly under such conditions.

Real cases are used for illustration, showing distance protection operations without any provisions for frequency changes. The cases are reevaluated with the same distance protection after adding adaptive algorithms to track system frequency.

The paper includes a description of the problems encountered when implementing the adaptive frequency tracking algorithms and the solutions chosen to ensure reliability independent of system conditions.


Frequency variations occur due to imbalance between generated and consumed power. This situation may be caused by:

• Variations in load demand or power generated: An overload of the system caused by excessive load and insufficient generation results in a decline in system frequency while disconnection of loads will increase the frequency.

• Power system faults or line switching: A redistribution of load flow by re-routing produces changes in power transfer between different portions of the system or between interconnected systems which result in frequency fluctuations until a new equilibrium is established between generation and load.

The magnitude and duration of frequency variations depend on the level of imbalance between generated and consumed power and the response to this imbalance by the generators (inertia of the rotating machines and generation control systems). If the frequency excursion is caused by a fault, the duration of the frequency variation is a direct function of how long it takes for the fault to be cleared.

Frequency variations can endanger system stability and may cause damage to generators and, in particular, damage of steam turbines. Frequency below nominal frequency produces, at nominal voltage, over-excitation of generators with severe heating as a result. In addition, when reducing the turbine’s rotating speed the frequency may approach the resonant frequency of the rotor blades and cause serious blade fatigue. The effect is cumulative so that the problem is exacerbated every time the turbine is subjected to an under-frequency situation. It is also important to note that low frequency could cause the power plant auxiliaries systems to trip out by reduced pump outputs and fan speeds with the result of having to take the generator station off line.

Generators are provided with regulation systems to correct any load-generation imbalance that may occur. All generators driven by turbines include a turbine governor (primary regulation) which changes the flow (of steam, water or fuel) that enters the turbine when the speed is no longer in synchronism with the system. The control slows down the frequency excursions by correcting imbalances between generation and demand, in case they are not excessive. However, while the primary frequency regulation may stop the excursion, it does not return the frequency to its nominal value. To achieve the last goal there is another control (Automatic Generator Control), which operates on a global level and is active over large areas of generation but with a longer reaction time.

When there is sufficient spinning reserve, a sudden increase in load demand can be compensated for via the regulating methods for generators previously mentioned. However, if the available generation has reached its maximum, the frequency will start to decline. In this case, it is necessary to initiate a selective disconnection of loads (load shedding) with the object of restoring the frequency to normal levels. Carrying out the load shedding in the required time frame is critical as otherwise a continuing decline of frequency may trigger the generator under-frequency relays and making the problem worse. In regions with lack of generation interconnection of grids is of great importance as it allows use of spinning reserves in a neighboring system.

If the generator control systems and system control load shedding operate as intended, the frequency can be maintained within the established margins. However, the reaction time of these systems may not be sufficiently short to handle large generation/load imbalances caused by loss of large blocks of generation or trip of an important tie line with severe frequency variations as a result.

Power systems lacking strong interconnections and without sufficient spinning reserves are likely to suffer frequency excursions. In addition, frequent defects or failures (or inadequate programming, which could increase reaction time) of the regulating control and these power systems often exhibit frequency variations far above admissible levels. This paper has taken into account real cases with frequency deviations larger than 10% from nominal.

Frequency variations have a major impact on protective relay response, especially for distance relays as will be discussed in detail in this paper. Frequency variations occur during stressed system conditions and it is critical that protective relays remain fully operational as the power system is very vulnerable to further disturbances at this time. Both loss of security (undesired tripping) and loss of dependability (no trip) could aggravate the situation. An undesired trip during a frequency excursion is counterproductive to the operational strategy to correct the problem. On the other hand, excessive restraint resulting in lack of tripping for a fault that caused the excursion or for a fault that occurs during the excursion, will further aggravate the situation.

Influence of Frequency Variations on Relay Measurement

Frequency variations in the power system with respect to nominal frequency produce errors in Fourier filter (DFT) calculations as the samples used no longer equal exactly one cycle. Figure 1 and Figure 2 show the resulting magnitudes and phase angles for phase voltages calculated at 48 Hz for a Fourier filter designed for a sampling frequency synchronized to 50 Hz. As it can be seen, there is a ripple in both magnitudes and angles. All the angles represented are relative to VR (phase A voltage). If they were shown as absolute angles, they would have a slope added apart from the ripple, directly related to the frequency variation.

If the system frequency differs greatly from the nominal frequency, the calculation from a filter without frequency tracking can result in considerable errors in the relay measurement.



Influence of Frequency Variations on Distance Relays

Distance relay measuring algorithms perform comparison of phasors derived from voltages and currents and settings related to the protected line. Frequency deviation from nominal frequency produces errors in the calculations used for measurement and may cause undesired tripping of the relay. Figure 3 is illustrating the apparent impedance of a 3-phase fault seen by a distance relay at 48 Hz frequency on a 50 Hz system. The impedance locus corresponds to the samples from half a cycle of the signal. As is evident from the illustration, the measured impedance is not constant but varies continuously. The amount of variation increases with increased deviation from nominal frequency.


However, the tendency of a distance relay to misoperate for a frequency variation is not predominantly caused by the previously mentioned impedance calculation errors as they are relatively minor even for a comparatively large frequency deviation. The main cause for undesired tripping is due to the way memory polarization is utilized, as will be discussed below.

Distance relays algorithms generally employ a memorized voltage taken several cycles before the fault inception in order to ensure correct operation for the following conditions:

• Faults with low voltage at the relay terminal, where the polarizing voltage is below the signal threshold required for accurate voltage measurement.

• Faults with voltage inversion on series compensated lines.

• Faults in applications with capacitive voltage transformers (CCVT’s) that may generate significant transients, especially for low voltage faults.

The memory times required for the polarizing voltage depend on the type of fault and the system characteristics. We will examine each of the above three cases separately:

Faults with low voltage at the relay terminal, where the polarizing voltage is below the signal threshold required for accurate voltage measurement.

In general, low- or zero-voltage faults occur for faults very close to the relay terminal where there is little line impedance between the relay and the fault location. Close-in faults are located within the relay Zone 1 reach. As Zone 1 trips instantaneously, the polarization memory time required is very short. Typically 2 – 3 cycles’ memory is sufficient.

However, in applications with high source-to-line impedance ratio (SIR) the voltage may drop to a very low value also for external faults, beyond the remote line terminal in Zone 2 or even Zone 3. The distance units should remain asserted until the corresponding timer has timed out and it may be necessary to increase polarization memory time up to Zone 2 or Zone 3 time delays.

Faults with voltage inversion on series compensated lines.

Forward faults on series compensated lines may cause a voltage inversion at the line terminal. In general this happens only for Zone 1 faults as for a fault within Zone 2, the inductive reactance between the voltage transformer and the fault location is larger than the capacitive reactance introduced by the series capacitor. Therefore, the polarizing voltage memory time can be comparatively short. However, in case clearing times of reverse faults by adjacent line protections are excessive, memory time might need to be extended to prevent undesired tripping until the relay protecting the faulted line section has tripped.

Faults in applications with capacitive voltage transformers (CCVT’s) that may generate significant transients, especially for low voltage faults. For applications with CCVT’s, the voltage polarization memory time should be long enough to last during the subsidence of any transient produced.

The use of longer polarization times presents a serious problem for distance protection in the presence of frequency excursions. A change in frequency will cause a phase angle shift between the frozen memory voltage phasor and the actual voltage phasor. This shift is especially detrimental for distance relay Mho characteristics.

The Mho characteristic is formed by comparison of the angle between an operating quantity and a polarizing quantity:




I = the fault current for the impedance measuring unit (AG, BG, CG, AB, BC, or CA)

V = the fault voltage for the impedance measuring unit (AG, BG, CG, AB, BC, or CA)

Vm = the polarizing memory voltage (AG, BG, CG, AB, BC, or CA)

Zn = Zone n reach setting

The mho characteristic operates when the angle between the operating quantity and the polarizing quantity is less than 90 degrees:



Figure 4 is showing the phasors and the resulting mho operating characteristic in an impedance plane.


Using the criterion in (2) we will examine the effect of a decrease in frequency on the mho characteristic. The example of the frequency variation used is a real-life event as experienced by a utility in South America on their power system. Figure 5 shows the frequency variations experienced by this utility during one hour time period.


Figure 6 shows the largest frequency variation over a short period of time. It can be observed that the frequency declines from 50 to 44 Hz in about 3 seconds, giving a rate-of-change of frequency of around -2 Hz/s.


The Zone 1 reach setting was 4 ohms. During the frequency excursion shown above, there was also a decrease in system voltage equal to about 1 V per second, measured on the secondary side of the potential transformer.

Before the frequency excursion occurred, the angle between the operating and polarizing quantity was close to 180 degrees FREQUENCY_FORM3 and consequently, the apparent impedance was far outside the mho operating characteristic. However, the frequency excursion produced a shift of the memory voltage phasor with respect to the actual voltage phasor as can be seen in Figure 7. This shift caused a decrease of the angle between the operating and polarizing phasor and in Figure 8 it can be observed that after about 450 ms, the angle approached the 90 degrees required to fulfill the trip criterion.



Consequently, even though there is no fault on the line (or external to the line) the use of very long polarizing memory time can cause undesired tripping by a distance relay mho characteristic during frequency excursion conditions.

The results obtained above for non-faulted conditions are also valid for a system under fault conditions; the mho elements tend to overreach for decreased frequency and underreach for increased frequency.

It is important to note that the tendency for a false operation by the mho characteristic does not only occur while the frequency varies with time but also for any discrete change, because in both cases there is a shift between the polarizing and operating phasors, although the shift is constant in the latter case, instead of varying with time.

For distance relay quadrilateral characteristic, the use of memory voltage is not as prone to cause misoperations during frequency excursions as for the mho elements. The reason for this is that the memory voltage is used for directional measurement only, and not for reach. It is possible that a large frequency variation could cause loss-of-directionality of the quadrilateral characteristic, but undesired tripping would still not occur as the apparent impedance would be outside the set reactive and resistive reach. However it could result in a missed trip for a forward fault or a trip for a reverse fault if the directional element makes an erroneous decision.

We can with simple means implement logic to restrain the use of memory voltage (at least for longer durations) during certain situations:

· The memory voltage should be used only during fault conditions to prevent possible misoperations under normal conditions when no fault is present. The memory voltage could therefore be supervised by fault detectors and would not be used unless a sensitive fault detector has picked up.

· The memory voltage could be used only when the available voltage has dropped to a level so low that is it not useful for measurement. A voltage threshold could be introduced, although this voltage level should not be very low when CCVTs are used as the transients can occur without very low fault voltages. On the other hand, in series compensated lines the voltage inversions can happen with relatively high fault voltages, so the voltage threshold should not be low either.

Despite the logics that restrain the memory voltage use, certain faults could require the use of memory voltage. If these faults happen during a frequency excursion, an undesired trip could occur. Only by controlling the memory voltage with a frequency tracking algorithm can this risk be eliminated.

Frequency Tracking Algorithm

The errors that are caused by the difference in frequency of the power system with regards to the sampling frequency can be eliminated by an algorithm with adaptable sampling frequency. Instead of using a sampling rate tied to a fixed frequency (50 or 60 Hz), the sampling is adjusted so the number of samples per cycle is fixed for a variable frequency.

The developed algorithm calculates the power system frequency by measuring the cycle (the inverse of frequency) from the waveforms of the three phase voltages. The measurement is using phase A voltage, as long as this voltage is above a certain threshold. If the voltage drops below the predefined threshold, the algorithm can use phase B or phase C voltages but only if they are above the threshold. The use of all three phase voltages for measurement ensures correct frequency tracking as long as one or two voltages are above the threshold, for instance during single pole reclosing dead time. The adaptable voltage measurement also enables use of the tracking algorithm for low voltage Zone 2 or Zone 3 single or phase-phase faults in a stepped distance scheme with long fault clearing times.

In order to consider a change of frequency (length of power cycle) to update the frequency presently used for sampling, it is necessary to detect a minimum change over a period of four zero crossings. This also ensures that the frequency measurement is not confused by a sudden change of phase angle. When a change is detected, the sampling frequency is modified to match the frequency based on the last zero crossing of the measured voltage waveform.

As shown in Figure 9, the criterion used to update the sampling frequency is:




A waveform as shown in Figure 10 does not result in a change of the sampling frequency as |T0 – T3| is smaller than the threshold and the update criterion is not fulfilled.


When the sampling frequency has adapted to actual system frequency, any measuring errors are eliminated and the polarizing memory voltage is synchronized to actual frequency. However, as the update is delayed by the time it takes for the voltage to make four zero crossings, the shift is again increasing if the frequency variation continues. The frequency variation during a time period of two cycles (four zero crossings) is very small and any resulting measuring errors and effect on the distance units from the shift in polarizing memory voltage are negligible. Although it has to be taken into account that this little shift is being accumulated.

Figure 11 is showing the developing shift in phase angle between the operating and polarizing phasors for the same frequency excursion applied in Figure 8. This time, there is a very small change in the phase angle between the phasors due to the adaptive algorithm that corrects the sampling frequency to match actual system frequency. While there is still a slight reduction of the angle from the initial 180 degrees, the shift is nowhere near the operating threshold of 90 degrees shown by the dashed line.

Figure 11. Phase Angle between Operating (OP) and Polarizing Phasors (POL) with Frequency Tracking Algorithm

However, during a prolonged frequency excursion and using long polarizing memory time, there could still be a risk of entering into the operating area. To overcome this problem, the frequency tracking algorithm is also adjusting the memory voltage phasor. Every time the sampling frequency is corrected, the memory voltage phasor is shifted by an angle equal to the shift accumulated during the four zero crossings previously discussed.

As illustrated in Figure 12, the resulting phase angle shift can be determined by calculating the time ∆T by comparing the zero crossings between the initial signal (solid line) and the signal with decreasing frequency (dashed line):



This time shift equals a phase angle shift of:



The frequency is adjusted to the cycle time measured at T4 every two cycles (four zero crossings). At this time, the phase shift between the two waveforms (the solid and the dashed line) is eliminated and the signals are returned to the initial stage. The phase of memory phasor is continuously adjusted to correspond to actual system frequency during frequency excursions, eliminating any risk of undesired operation of a distance relay mho element.

Figure 12. Variation between Voltages of Different Frequency during a Period of Four Zero Crossings

Figure 13 is showing the developing shift in phase angle between the operating and polarizing phasors for the same frequency excursion applied in Figure 8, now with frequency tracking and phase of memory phasor correction. As can be seen, the shift is practically non-existent.

Figure 13. Phase Angle between Operating (OP) and Polarizing Phasors (POL) with Frequency Tracking Algorithm and Memory Voltage Compensation

As a conclusion, figure 14 shows the developing shift in angle between the Operating and Polarizing Phasors in the three cases studied in this paper.

Figure 14. Phase Angle between Operating (OP) and Polarizing Phasors (POL) with and without applying the algorithm to adapt to frequency changes

The algorithm described is compensating for a phase shift between a memorized quantity and the actual measured signal caused by frequency variations. While the distance relay is using the algorithm for memory voltage, it is valid for any memorized signal and does not have to be a voltage. Other application may include situations where measurement is based on pre-fault quantities in order to eliminate influence of load for reactance measurement or phase selector operation. Frequency excursions can also introduce errors in these measurements (underreach or overreach) that can be eliminated by applying this same algorithm.


Despite the efforts by the power utilities to control the system frequency to operate very close to the nominal frequency, many systems are subject to frequency excursions during stressed system conditions.

Frequency variations can jeopardize system stability and may also cause damage to generators and turbines. Correct performance of protective relays during these conditions is critical in order to mitigate the effects and not to further aggravate the situation. Conventional distance protections have a tendency to misoperate due to frequency variations, mainly due to the phase angle shift between the memorized polarizing phasor and the operating phasor based on actual power frequency. This paper has described an algorithm that efficiently tracks actual system frequency and adjusts measuring phasors accordingly; preventing undesired trips from distance relay mho elements during frequency excursion events.


[1] D. Hou, A. Guzman, and J. Roberts, .Inovative Solutions Improve Transmission Line Protection,. 24th Western Protective Relay Conference, Spokane, WA, October 21.23, 1997.

[2] Instruction Manual for Distance Protection model 8ZLV, ZIV, Zamudio (Spain) Publication LZLV506A, July 2005

[3] Protecciones de Sistemas de Potencia, Andoni Iriondo Barrenetxea, Servicio Editorial Universidad del País Vasco

[4] Power System Relaying Second Edition, Stanley H. Horowitz y Arun G. Phadke, Research Studies Press Ltd. y John Wiley & Sons, 1996

[5] Problems and solutions for microprocessor protection of series compensated lines, Novosel, D.; Phadke, A.; Saha, M.M.; Lindahl, S.; Developments in Power System Protection, Sixth International Conference on (Conf. Publ. No. 434) 25-27 March 1997 Page(s):18 – 23.


Download PDF File

  • Authors:
  • Company: ZIV
  • Date:
  • Event:
  • Keywords:


This document describes the procedures required to interface with SEL communications processors utilizing the ZIVercom software Version 1.90 and up (older versions can be used but require Patch 20 and up to incorporate the SEL2030 module). The procedures listed below are specific to the SEL 2030, but can also be applied to the SEL 2020.

Download PDF file (Interfacing ZIV relays with SEL communications processors) 1 MB

  • Authors: M.G.Zamalloa, A.Gonzalez, A.Arzuaga and T. Arzuaga
  • Company: ZIV and Iberdrola
  • Date: October 2011
  • Event: OTTI SmartGrids & eMobility, Munich&nbsp- Germany
  • Keywords: Electric Vehicle, Smart, Distribution, Grid

This paper analyzes the challenges, risks and opportunities related with the introduction of the EV such as the positive impact of overnight charging for the demand curve and the risks of daytime charging depending on the grade of penetration.

An overview of the most important factors that infrastructure managers (both utilities and new market players such as EV charging infratestructure managers) should address is given: Grade of penetration, concentration of charge spots and the grade of intelligence of the infrastructure.

  • Authors: Aitor Arzuaga, Eduardo Zabala, Ana Gonzalez Bordagaray, David García Pardo, Mikel Rentería and Mikel Zamalloa
  • Company: ZIV, Tecnalia, Iberdrola and Semantic Systems.
  • Date:  October 2011
  • Event: OTTI Smart Grids & eMobility, Munich- Germany
  • Keywords: Comprehensive, Approach, EV, Recharge, Infrastructure

MUGIELEC is a publicly funded R&D project initiative in the Basque area which gathers many important players in the energy sector in order to collaborate on EV related technology and applications, with a strong focus in the infrastructure side. The project covers from system- level grid operation, to the infrastructure- to- vehicle communication, including critical subsystems such as recharge infratestructure scenarios, impact on the grid, V2G technical feasibility, customer behavior analysis…The project has a strong focus on promoting standarization activities in the areas related to the research results obtained in the project by the partners.

The project began in September 2010, and will run until the end of 2012. It has a budget of over 10M euros and a participation of 12 companies and 5 R&D institutions. It is now (as of June 2011) finishing the specification and requirement analysis phase in order to go into R&D activities. Later in the project schedule, two testbeds will be developed: a parking lot system solution and a fast recharge station, in order to validate the developments carried out during the project.

The MUGIELEC initiative, sponsored by the Basque Government, under the administrative lead of ZIV and technology coordination by TECNALIA, is formed by: AEG, CEMENTOS LEMONA, FAGOR, GAMESA, IBERDROLA, INCOESA, INDRA, INGETEAM, ORMAZABAL and SENANTIC SYSTEMS.

This paper will introduce MUGIELEC’s approach and objectives and will describe some of its first results for a business model and approach for the exploitation of the infrastructure for EV charging, the information and data base management in order to provide adequate services, and the communication and protocols among the different systems from the EV and charging point to the System Operator, considering also the charging point management system and the stationary management in the secondary substation.

  • Authors: A. Arzuaga, T. Arzuaga, D. García- Pardo, A. Gonzalez, E. Keller and M. Zamalloa
  • Company: ZIV and Iberdrola
  • Date: August 2012
  • Event: CIGRE (Conseil International des Grands Reseaux Electriques), Paris- France
  • Keywords: Polyphase, Recharge Point, Integration, Power, EV, Distribution, Grid

The new wave of Electric Vehicles has already arrived to our streets and highways. This kind of vehicles not only mean a change of propelling technology, but they also open the door for a new mobility paradigm by allowing new forms of customized energy supply that will let the user decide where, how, when and how much to charge thus easing two of the main drawbacks of EVs: reduced range and long charging time. This is feasible thanks to the ubiquity of the energy that is to be supplied (electricity), which, contrary to gas stations, is available anywhere in the urban areas of developed countries.

How will the electric grid face the challenge of integrating a large number of EVs while keeping the highest standards of quality of service and safety?. Public regulators claim that night- time low- power charges are the preferred solution if full profits from renewable sources (thus CO2- free) are to be obtained. Also this approach fits with the load profile flattening objectives, reducing peak power demand. This is obviusly the less challenging solution for EV recharge because it can be done with very little investment in charging spots and it does not require new generation facilities. But EV drivers require alternative ways of recharging their EVs, especially when they are on a long road trip or need to urgently refill their batteries, which will require fast charging capability.

There is a lot of talk about slow, quick, rapid and fast charging, but what does this really mean?. The time spent to charge a battery depends on several factors that are controlled by different industries:

  • The power that the charging station and the line that feeds it can provide. The electric equipment industry and electricity utilities are the main actors controlling this factor.
  • The charging power that on- board battery chargers support (for AC charging) and the charging power and charge curve that each type of battery supports. This depends on the automotive industry and battery manufacturers.
  • The energy storage capability of the battery and the state of charge, which depend on the battery manufacturer, use of the battery, temperature, etc.

The only factor of this list depends of the electric industry is the power that the charging station can provide so it makes more sense to focus the discussion on the power than on the time spent for the recharge, which as we just mentioned, depends on more factors that may substantially vary for each EV.

Is this high- power opportunity charging scenario a problem for the electric grid?. What are the problems involved?. Is it just a matter of power or are there some other factors to take into account such as the size of the charging station, flexibility of the charging cable, type of plug, etc, that set important restrictions for the design of a charging station?.

This paper will provide an overview of factors such as the availability of one to three phase low voltage power grids and their voltage ratings for some reference countries. This overview will set a framework to present a cost- benefit analysis for different alternatives ranging from low power AC charging to high power AC or DC charging, comparing pros and cons for each of the possible modes.This analysis will consider factors such as the supported powers for different types of IEC62196 plugs, the usability of different cables, possibility of residential installation of each type of charge spot, cost, impact on the electric grid, etc.

Copyright © 2017 ZIV. All rights reserved.

Log in with your credentials


Forgot your details?