The application of photoconductive switches in HVDC circuit interruption

A new type of semiconductor switching device, the photoconductive circuit element (PCE), appears to have potential for power system applications. The PCE consists basically of a piece of semiconductor material, which can be made highly conductive through applying laser or other intense optical excitation. The main objective of the work reported here was to investigate the basic suitability of the PCE switching device for application in HVDC circuit breakers. Computer simulation results, for a PCE in parallel with a conventional mechanical AC breaker, indicate a significant improvement in DC interrupting time and in maximum interrupting current compared to passive commutation methods. Studies also showed that inherently short arcing times and low transient recovery voltage will allow the use of lower-rated mechanical breakers