An application of a protective relaying scheme over an ethernet LAN/WAN

This paper describes an installation where GOOSE messages over an Ethernet LAN/WAN are used between substations to protect 27 kV feeders in a blocking scheme. The 27 kV network consists of 5 main stations and 37 load modules distributed over the territory. Load feeders connect two main stations and are operated in an open loop configuration The Utility Communication Architecture Version 2 (UCA2) is a suite of protocols specifically prepared to address all communications needs of a utility. UCA2 implemented a peer-to-peer architecture and uses the Manufacturing Message Specification (MMS) for the exchange of real time control signals between relays. UCA utilizes object models called General Object Model for Substation and Field Equipment (GOMSFE) for the representation of physical or logical objects. One of the key services provided by this protocol is the unsolicited event notification. UCA2 uses the unsolicited event from MMS as a data model called GOOSE message (Generic Object Orientated Substation Event). The communications system for the 27 kV network consists of relays, 10BaseF Ethernet Switches and Synchronous Optical Communications (SONET) nodes connected in a ring topology. The relays perform protective relaying, control, monitoring and data acquisition. The Ethernet Switches are the local area network providing communication between relays within the substation and interface with the optical SONET for wide area communications. Two 51.84 Mbps Synchronous Optical Network (SONET) rings provide backbone communications over the wide area. SONET was selected because of the variety of services it supports, including Ethernet and its self-healing capabilities. Two HMI workstations in different stations provide SCADA functionality.