Wide-area Ethernet network configuration for system protection messaging

Southern California Edison Company (SCE) is now designing and installing one of the world's most extensive high-speed wide area protection systems — the Centralized Remedial Action Scheme (C-RAS) [1]. C-RAS uses protective relays installed in transmission substations across the SCE service territory to monitor critical transmission line flows and other electrical measurements, as well as relay or breaker operations that remove lines from service and might trigger rapid transmission system collapse. These monitoring relays transmit high speed data to a pair of redundant central controller arrays using IEC 61850 GOOSE messages over a wide area Ethernet network (WAN) comprised of dual-redundant T1 and Ethernet data links. The central controller arrays decide how to remediate a line loss within milliseconds of receiving the line trip message, and trip loads or generation to maintain system stability using WAN links, GOOSE messaging, and mitigation relays at shedding substation sites.