A 320kV hybrid HVDC circuit breaker based on thyristors forced current zero technique

This paper presents a hybrid HVDC circuit breaker topology with bidirectional interruption based on thyristors forced current zero technique for voltage sourced converter-high voltage dc (VSC-HVDC) system. In normal operation, the mechanical switch and small amount of IGBTs handles the low conduction loss. In case of interruption, the commutated current is forced to zero by injecting a current inversely in order to turn off thyristors. Moreover, snubber circuits are employed for voltage balance among semiconductors. And a conceptual breaker is applied to a high voltage application of 320kV system whose short current is 15kA. The principal operation of the beaker has been simulated and tested to demonstrate the fast dc fault clearing. Compared with other solutions, this proposal can interrupt short current with relatively low cost and increase the fault current interrupting capability, so it is more suitable for practical HVDC grid.