HVDC Circuit Breaker Test Bench Based on Cascaded H-Bridge Cells and an Auxiliary Capacitor Bank
This paper discusses the design and analysis of a modified test bench for high-voltage direct-current (HVDC) circuit breakers which consists of a power converter based on multiple cascaded H-bridge cells, a small-sized inductor, and an auxiliary capacitor bank. It is capable of producing output voltages up to several hundred kilovolts depending on the auxiliary capacitor bank while allowing for high current controllability via the power converter which is driven by phase-shifted pulse-width-modulated (PSPWM) signals. Consequently, the test bench can generate a wide range of controllable current waveforms and high current gradients, within hardware limitations, to simulate a wide range of fault conditions. The flexibility of the proposed design is complemented by higher reliability and longer lifetime. The concept of the test bench was verified by experiments using a down-scaled model based on nine cascaded H-bridge cells with an equivalent switching frequency of 92.5 kHz.