Contactless circuit breaker protection for AC line commutated thyristor converter

Solid state power devices can be more easily damaged by load disturbances, faults and overcurrents. The AC line commutated high power thyristor converter is a reasonable power converter. It needs a fast acting short circuit protection against internal faults due to inverter commutation failure (flop) or faults in the DC line. A high speed thyristor circuit breaker is used as a current limiter and an interrupting device for the AC line commutated thyristor converter. This paper introduces the main features of the thyristor circuit breaker protection (TCB) for AC line commutated thyristor converters. TCB circuit breaker protection systems are based on computer simulation of switching processes at the clearing DC side fault As a reference some experimental results taken from short circuit tests performed on an industrial TCB model are used. The TCB model has been used as a short circuit protection for a test stand with a thyristor converter. The comparison between the simulated results and the experimental results indicate that both concur.