Solid State Bridge Type FCL and Novel DC Circuit Breaker for HB MMC

Abstract:

This paper proposes a new and surge-less solid-state direct current (DC) circuit breaker in
a high-voltage direct current (HVDC) transmission system to clear the short-circuit fault. The main
purpose is the fast interruption and surge-voltage and over-current suppression capability analysis
of the breaker during the fault. The breaker is equipped with series insulated-gate bipolar transistor
(IGBT) switches to mitigate the stress of high voltage on the switches. Instead of conventional metal
oxide varistor (MOV), the resistance–capacitance freewheeling diodes branch is used to bypass the
high fault current and repress the over-voltage across the circuit breaker. The topology and different
operation modes of the proposed breaker are discussed. In addition, to verify the effectiveness
of the proposed circuit breaker, it is compared with two other types of surge-less solid-state DC
circuit breakers in terms of surge-voltage and over-current suppression. For this purpose, MATLAB
Simulink simulation software is used. The system is designed for the transmission of 20 MW power
over a 120 km distance where the voltage of the transmission line is 220 kV. The results show that the
fault current is interrupted in a very short time and the surge-voltage and over-current across the
proposed breaker are considerably reduced compared to other topologies.