Study on the influence of SSSC on the distance protection

Static Synchronous Series Compensator (SSSC) is a new series compensation equipment of FACTS. According to different operating conditions, its operation mode, control parameters and control strategy vary, and so the relay protection will be influenced inevitably. This paper analyzes the influence of SSSC on distance protection based on power frequency and fault component of EHV line based on the study of its principle. The condition of reverse voltage is deduced for the power frequency relay according to the MOV (Metal Oxide Varistor) maximum withstanding voltage. And the action equation is deduced for the fault component relay according to the variation of working voltage. Then the relay action behavior is simulated and tested in PSCAD. The result shows that series of problems are brought to the distance protection, and whether MOV operating is the key of relay correct operation.