Research on Simulation and On-site Inspection Technology of 500kV Mechanical HVDC Circuit Breaker

As a key technology for establishing and developing a multi-terminal flexible HVDC transmission network, HVDC circuit breaker has become one of the research hotspots in recent years. Mechanical HVDC circuit breaker is one of the research directions of HVDC circuit breakers. This paper introduced the current development of HVDC circuit breakers, analyzed the breaking principle of mechanical HVDC circuit breakers and the breaking scheme of 500kV DC circuit breakers. Based on the Zhangbei ±500kV flexible HVDC transmission system, a simplified PSCAD simulation model was established, a 25kA and 17kA bidirectional breaking and closing under fault conditions simulation was performed to verify the breaking capacity of a 500kV mechanical HVDC circuit breaker. Electric stress of mechanical switches, arresters, IGCTs were discussed. The maximum voltage of the mechanical switches and arresters are all over 800kV, the current flow capacity of the mechanical switches is required to be 58kA, and the energy absorption requirement of the arresters is more than 200MJ. Besides, the recommended items and schemes for the on-site inspection of the mechanical switches, arresters and IGCTs were analyzed.