Research on overvoltage protection application in DC circuit breaker power supply systems

Flexible DC grid equipment is an essential carrier for large-scale renewable power integration and transmission. As the core device, power electronic switches rely on a reliable supply system for their gate drivers. Compared with traditional magnetic-coupling methods, the Cascaded Wireless Power Supply (CWPS) offers clear advantages in multi-load applications, but its reliability is constrained by overvoltage protection. This study investigates the protection mechanism of a metal oxide varistor (MOV) in a CWPS system with series-compensated capacitors on the transmitting side and a cascaded CLC network on the receiving side. Simulation results based on MOV nonlinear V–I characteristics show that lightning overvoltage of 18 kV and steep-front overvoltage of 12.5 kV can be suppressed to 540–680 V. The results verify that MOVs effectively mitigate overvoltage risks and provide theoretical and technical support for the protection design of wireless power supply systems for DC circuit breakers.