Design on thyristor self-trigger protection action voltage threshold of series resonance fault current limiter

Failure of limiter controller is the worst fault state and can only rely on thyristor trigger protection which is called break over diode (BOD). Consequently, to improve the reliability of series resonant fault current limiter (SRFCL) bypass circuit and to reduce MOV of resonant capacitor energy consumption, we introduce a method of designing the threshold of self-trigger thyristor action voltage, in which BOD operation sequences are designed, and threshold factors are analyzed from the point of view of action time and surge arresters energy consumption. BOD action voltage threshold determines thyristor valve voltage protection level and trigger time. If voltage threshold is set low, BOD will complete with protection criterion. If voltage threshold is set high, the arrest energy consumption level will increase. In the background of East China Power Grid FCL demonstration project, current limiter simulation model is established. Moreover, the rule of voltage threshold effecting on arrester energy is summarized by simulation. Voltage threshold design specification is proposed and will benefit to engineering design.