E Tijdschrift IEC 61850
24 Revue E tijdschrift – 126ste jaargang /126ème année – n° 4-2010 (december/décembre 2010)
IEC 61850 – for much more than substations
Nicholas Etherden, Carl Öhlen, STRI AB, Sweden
Keywords: IEC 61850, Smart Grid, Distributed Energy Resources, DER
IEC61850 is a standardized concept for information handling and communication for power utility automation. It is NOT just another protocol. IEC 61850 is today being expanded to apply to many domains beyond the original scope of the substation. Figure 1 illustrates the Expansion of IEC 61850 world to both control centre communication and modelling of communication with renewable energy resources.
La norme CEI 61850 est un concept normalisé pour le traitement et la communication de l’information à des fins d’automatisation dans les entreprises de service à l’énergie. Il ne s’agit PAS simplement d’un nouveau protocole.
La norme CEI 61850 est actuellement en expansion en vue d’être appliquée à de nombreux domaines au-delà du champ d’application original du poste électrique haute tension. L’illustration 1 montre l’expansion de la norme CEI 61850 dans le monde, aussi bien dans le cadre de la communication avec les centres de contrôle que pour la modé- lisation de la communication dans les installations de production d’énergie renouvelables.
S U M M A R Y R É S U M É
De standaard IEC 61850 is een gestandaardiseerd concept voor gegevensverwerking en -communicatie voor de automatisering van nutsbedrijven voor elektriciteitstransport. Het is NIET zomaar een nieuw protocol. De IEC 61850- standaard wordt momenteel uitgebreid om te worden toegepast in tal van domeinen die verder gaan dan het station, het oorspronkelijke toepassingsgebied. Afbeelding 1 illustreert de uitbreiding van de IEC 61850 in de wereld, zowel om de centrale communicatie te controleren als om de communicatie met installaties van hernieuwbare energiebronnen te modelleren
S A M E N V A T T IN G
Fig. 1: Expansion of the IEC 61850 world showing extensions of the standard series to cover substation-to-substation communication, mapping to IEC 600870-5-104 as well as modelling of wind, hydro and distributed energy resources. Future applications will cover also seamless communication to network control centers and use in medium voltage networks and Smart Grids.
Revue E tijdschrift – 126me année /126ste jaargang – n° 4-2010 (décembre/december 2010) 25
Revue E IEC 61850
Introduction
When the IEC 61850 standard was first released in 2004-2005 it was titled “Communication networks and systems in substations”. However, the key concept proved to be possible to extend and apply to several new areas of applications. Hence the standard series has been renamed “Communication networks and systems for power utility automation”. IEC 61850 is today one of the key candidates for use in the future Smart(er) Grid and has been consistently pointed out as a vital compo- nent to achieve interoperability between devices. A few of the key features behind this success are described in this article.
Expanding application domains
As shown in Fig. 1 the IEC 61850 standard has grown substantially in the first five years after its publications.
It has been applied outside the substations and in the coming years the original parts of the standard will be complemented with technical specifications and guide- lines as shown in Fig. 2.
Today there are conformance tested relays, called Intelligent Electronic Devices (IEDs) developed in 16 countries by more than 40 different manufacturers.
However, the success of the standard is not only due to its wide implementation. Its ability to meet varying
requirements and adapt to different communication pro- tocols lies at the core of the standard architectural design and has made it attractive to be used in the domains other than substation automation. Fig. 3 shows how the standard separates the relatively steady data models (.i.e. the standardized names for functions and appara- tuses) and the communication means used to exchange this data. Through this approach also other IEC Technical Committees have been able to apply the modelling prin- ciples and standardize names while manufacturers have been able to use the same tools and software stacks to configure and communicate the information.
In the case of wind power TC88 has for example modeled communications for monitoring and control of wind power plants according to IEC 61850 within their standard series IEC 61400. This model has even been mapped to addition protocols (web services and OPC) that are not mapped today within the IEC 61850 series.
The mappings are made possible by a high level of abstraction in the standard. Non protocol specific abstract services in IEC 61850-7-2 can be mapped to appropriate existing state-of-the-art communication technologies as shown in Fig. 4. (Like the previous three figures this figure is fetched from the upcoming and revised introductory part of the IEC 61850 series, coauthored by STRI.) In the future additional protocols may be used to transport IEC 61850 data and execute its services while having little effect on the users engineer- ing process and asset descriptions.
Fig. 2: Content of the IEC 61850 series today including links between the various parts
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Arguably the biggest advance with IEC 61850 compared to previous standards for the power system is that an engineering device or systems can be described in machine readable configuration language. This gives the basis for exchange of information between configuration tools. The tool interoperability is in practice a pre-requi- site to be efficiently being able to engineer interoperability systems with multi-vendor equipment. Admittedly there were some initial flaws to this interoperability. The first editions of the standard left many issues open for interpretation. Conflicting implementations mainly in the vendor tools resulted. With the second edition one comes one step closer to defining the exchange of data uniquely and some emphasis has been on stipulating the different roles of IED and system tools and what these tools may – and may not – do.
Possibilities for integration and decentralized control
With the standardized IEC 61850 modelling applied to such diverse assets as wind turbines,
hydro plants, substations and distributed energy resources it becomes feasible to connect IEC 61850 compatible IEDs throughout the power system and exchange data when required. Currently there is some research focus to look at decen- tralized schemes implementing logic in a semi-autonomous way. Whatever is meant with the word Smart Grid (indeed some proposals have little to do with the grid and are questionably smart) the possibilities with IEC 61850 are attractive to use. The US Department of Energy has developed a Smart Grid Interoperability Maturity Model (SGIMM) used for rating the various proposed technical solutions for smart grid demonstra- tion projects. Using such objective means the IEC 61850 has consistently been appraised as the most advanced and useful architecture standardized
today. IEC 61850 is therefore included in no less than 9 out of 17 NIST Smart Grid Priority Action Plans, with several of the other protocols used to day instead stated as legacy. The IEC has also set up a special group to revise its offering for the Smart Grid and pointed out IEC 61850 as a key technology in areas of distributed resources, control centre communication, security hard- ening as well as – of course – the area of substation automation.
So how could IEC 61850 be used in a Smart Grid power system? Let’s take an example implemented for Energinet.dk (Cigré 2010 session, paper C6_109). Here an IEC 61850 compatible PLC in a power plant receives measurement of the reactive power flow between distri- bution and transmission network from a nearby substa- tion. It interfaces the control system of the power plant and can control set points for the reactive power produc- tion. This the PLC does with the aim of minimizing the reactive power flow through the remote substations power transformer. Such exchange of information is sim- plified when a common standard like IEC 61850 allows seamless integration of data and reporting of the average measurement values. With only information of its location in the power grid topology a smart devices may in the future search for the measurements they need and present their ability to participate in network sta- bility schemes. They may even request services from multiple small power production units in a smart grid in order to coordinate network stability actions that no longer can be managed as today in lieu of dominant cen- tral power plants.
At STRI a Research Development and Demonstration (RD2) platform is being developed within a project led by the High Voltage Valley consortium and financed by the Swedish Governmental Agency for Innovation Systems. Starting with a refurbishment of the STRI high voltage laboratories substation with a multi-ven- dor IEC 61850 installations the system will use IEC 61850 to interfaces small scale renewable energy storages with wind, solar and fuel cells for energy pro-
IEC 61850
26 Revue E tijdschrift – 126ste jaargang /126ème année – n° 4-2010 (december/décembre 2010)
Fig. 3 : Principle behind division of application modelling and communication
Fig. 4: Mapping principle to various communication protocols implemented at different levels of the Internet ISO layers
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duction. The platform can store energy in battery packs and through hydrogen generation as well as possibilities to spread load over time. Interfaced with a SCADA sys- tem at a nearby University the system may in its final stage link field installations at a couple of hydro and wind units totaling production of some 40 MW in the vicinity of Ludvika. This creates a platform for testing communication system as well as protection and control algorithms as shown in Fig. 5.
IEC 61850 compatible units may in the future be confi- gured to act as if they were on a common Ethernet net- work. They can join in cooperative actions to form a vir- tual power plant. The power plant is virtual in that the control and response of several small units are coordi- nated to appear as a larger power plant when controlled by the distribution system operator. In this way it may help to meet the demands from a transmission operator to stabilize the connected distribution network.
With more intermittent generation from wind and solar energy, as well as more use of electrical vehicles, it is more difficult to predict load and generation patterns.
Improved overview and controllability of the power sys- tem will then become a must. This calls for more real time communication within the components of the power system and also between systems of systems.
Engineering such a system would be a challenging and a very resource full task without the use of configuration and communication principles of the IEC 61850 stan- dard. Consistent data modelling over its complete planned scope will be advantages. With IEC 61850 tools and later the devices themselves can exchange their configurations capabilities and services and meet the challenges of tomorrows grid.
The authors
Carl Öhlen from STRI has a MSc in Electrical Engineering at The Royal Institute of Technology in Stockholm, 1973. He has more than 30 years of experience in protection, con- trol and substation automation working for Vattenfall, Programma and ABB in Sweden, Switzerland, Brazil and USA. He has a broad experience of network management including IEC61850 and is at present working with the design of a RD2 (Research Development Demonstration) platform for Smart Grid.
Nicholas Etherden from STRI has a MSc in Engineering Physics from Uppsala University in Sweden, 2001 and is currently an industrial postgraduate student at Luleå University of Technology. He has several years experience from the development of a new IED family for IEC 61850 as application engineer, project manager and product marketing manager at ABB. Since 2008 he is responsible for the STRI IEC 61850 Independent Interoperability Laboratory. He is active in the IEC 61850 standardisation work and member of IEC TC 57 working group 10 and UCA Iug testing sub- committee.
Fig. 5 : With IEC 61850 implemented consistently throughout distribution network small loads and production units could be managed by a few dispersed control units. These Intelligent Electronic Devices (IEDs) would run simple logics and do coordinated operations initialized by a distribution or even transmission system operator. The STRI Smart Grid Research and development Platform at STRI acts as a cell controller.
The cell controller is a concept developed by Energinet.dk for organizing distributed generators into controllable Virtual Power Plants.
