Relay protection
Smart grid and digital substation

Smart grid and digital substation

Software, data communication and control, etc, is standard in modern substations. Though the development and implementation of IEC 61850 since mid 2000’s, the way to design, configure and run the substations have changed. This IT influence brings many advantages but also introduce new challenges to the industry.

This chapter falls under the name digital substation. The digital substation have many different sub categories but if narrowed down to the everyday work for substation test engineers it mainly come down to IEC 61850 with its abstract data models defined can be mapped to several protocols. Current mappings are to MMS (Manufacturing Message Specification), GOOSE (Generic Object Oriented System Event), SMV (Sampled Measured Values).

IEC 61850 GOOSE interoperability

Interoperability is a property of a product or system, whose interfaces are completely understood, to work with other products or systems, present or future, without any restricted access or implementation. The interoperability requirement of the IEC 61850 standard has beneficially increased the “interoperability among different engineers” working for companies that are formally in competition. With field experience of IEC 61850 GOOSE communication in protection and control applications, it is possible today to list the main reasons for interoperability problems for multi- and single-vendor systems; however, the list of causes of interoperability failures would be longer than what indicated in this document, especially if considering the cases found during the beginning of the use of GOOSE messages. Read more here.

Lessons learned from a 400 kV busbar misoperation utilizing the IEC 61850 standard

The implementation of IEC 61850 standard for substation design and commissioning is fast-phased method of defining grid protection schemes throughout the world.  The protection logic that involves dc control circuits are executed internally in the Intelligent Electronic Devices (IEDs) and effectively communicated between the IEDs via GOOSE. Any error in the mapping of GOOSE signals will result in undesired operation of the protection schemes.

Megger was involved with this case study where an investigation of the tripping of a 400 kV substation due to improper operation of a bus-bar protection scheme was in focus. This incident happened when a Zone 2 fault occurred on one of the 400 kV line feeders, immediately triggering a breaker-failure condition caused by an incorrect mapping od the Breaker-Failure Initiate (BFI) signal to bus-bar IEDs. This minor error caused the entire substation to be out of service. This paper discusses the methods of testing so that would help prevent this situation.