Development of High-Speed Mechanical Switchgear with Vacuum Interruption Technology and Application in HVDC Circuit Breaker

High-speed switchgear is an essential part of HVDC mechanical circuit breakers. Taking advantage of faster dielectric recovery of vacuum interrupter, DC current interruption can be achieved by vacuum interrupter driven by high-speed operating mechanism and artificial current zero supplied with high frequency commutation current. The current frequency of commutation branch and the mechanical characteristic of high-speed switchgear are studied to develop a 50kV breaking unit as a building block of HVDC circuit breaker. A safe interruption zone where DC current interruption can be successfully made within a range of current frequency and gap distance is found out. Based on the developed building block, a scheme of ±500kV HVDC mechanical circuit breaker with a series of high-speed switchgears is developed successfully.