Coordination of the alternating current and direct current control and protection in China Southern Power Grid

Abstract

Many high voltage direct current (HVDC) inverter stations are located in Guangzhou. Huge accidents may occur with the great HVDC power lose if alternating current (AC) system fault leads to HVDC system shuts down. To solve the above problem, coordination of the AC and direct current (DC) control and protection is set based on operation features of AC system and HVDC system, and the possible mal-trip functions of HVDC control and protection are given accordingly. Combined with logical analysis, trip sequence research, digital simulation and other research means, 5 DC protection functions optimization ideas and schemes are given. Equipment tolerances were checked, and the improved protection schemes were verified by the 118 RTDS simulation tests. Finally, the improved protections schemes were put into effect in all China Southern Power Grid (CSG) HVDC projects. Experience shows that the above methods can effectively avoid the risk of HVDC system shutting down caused by AC system fault.