PG&E 500 kV series-compensated transmission line relay replacement: Design requirements and RTDS® testing

Pacific Gas and Electric Company (PG&E) owns an extensive 500 kV series-compensated transmission line network. The availability of this network is critical to serving Northern California loads and regional power transfers from the Pacific Northwest to Southern California. PG&E identified six transmission lines requiring immediate replacement of faulty solid-state relay systems with modern, more reliable microprocessor-based relay systems to improve the reliability and maintain maximum availability of the 500 kV transmission system. This paper describes the PG&E design philosophy of the 500 kV transmission line relay systems and the protection challenges of series-compensated transmission lines operating in single-phase tripping and reclosing modes. In addition, the paper describes the relay system settings considerations and their validation using a Real Time Digital Simulator (RTDS^®). The paper demonstrates the analysis of RTDS results and the benefits derived during the engineering and commissioning stages of the project.