Application of ethernet peer-peer communication to a mesh corner delayed auto-reclose scheme

The paper presents an application of the UCA2 protocol to implement a delayed auto-reclose (DAR) scheme. The mesh-corner plant topology requires coordinated control logic and DAR. Using the generic object oriented substation event (GOOSE) element of UCA2 it is possible to satisfy the demanding time constraints for passing the control information between relays via Ethernet. The relay provides the full control logic and input-output (I/O) required for auto-isolation and DAR of a single corner of the mesh. Combining several of these devices, communicating over an Ethernet link, it is possible to control systems ranging from a single switch (circuit breaker) to a six-switch mesh corner scheme. The paper focuses on the experiences gained from this practical application; including the configuration tools required for the system, consideration of testing issues and the impact of degraded communication links (to ensure ´failsafe´ operation). A view of future applications will also be presented including the integration of other protection devices into the peer-peer scheme to provide the full substation information control and protection package. It concludes with a comprehensive summary of the benefits of the application of the peer-peer communications.