Development of 500kV modular cascaded hybrid HVDC breaker for DC grid applications

摘要

This paper proposes and demonstrates a modular cascaded hybrid HVDC breaker to meet the application requirement of the four-terminal voltage source convert (VSC) based high voltage direct current (HVDC) grid planned in Zhangbei, China. The project is rated at ±500kV/3000MW and is being constructed to promote the development and utilization of renewable energy in Zhangbei area as well as to support Beijing Winter Olympics in 2022. Most multi-terminal VSC-HVDC systems lack of a HVDC breaker has to trigger AC circuit breaker to clear DC faults which means the whole system will shut down once fault occurs. This problem is successfully solved in Zhoushan five-terminal VSC-HVDC project constructed by State Grid Corporation of China (SGCC) via deployment of a hybrid breaker, which realize fast clearance of DC faults while the healthy parts remain in operation. Therefore, the HVDC breaker constitutes an essential piece of equipment for Zhangbei DC grid. This paper gives a detailed description of the hybrid HVDC breaker, including its topology designs, operation principles and test results. The paper also presents the development of a prototype and the main components such as semiconductor switches, the ultra-fast disconnector (UFD) and the high potential power-supply unit. In addition, key component tests and overall unit tests are implemented to verify the performance of the prototype. Test results show that the modular cascaded hybrid HVDC breaker can fulfill the application requirements of DC grid and is planned to be installed in the Zhangbei DC grid in 2019. The main parameters of the hybrid HVDC breaker are as follows: 1. Rated voltage: 500kV; 2. Rated current: 3kA; 3. Maximum interruption current: 26kA; 4. Interruption time (excluding fault clearance time): 2.6ms; 5. Transient interruption voltage (TIV): 800kV; 6. Re-closing time: 300ms.