Abstract:

With the increasingly widespread application of DC power systems, the problems caused by short-circuit faults have become more prominent. The DC short-circuit fault current rises rapidly and lacks a natural zero-crossing point. The transient large current generated by short-circuit fault poses great harm to power equipment and puts forward higher requirements for the breaking speed of DC switches. Aiming at this problem, a structure of fast mechanical switch based on piezoelectric actuator (PA-FMS) is proposed. By adopting a hybrid switch scheme, the fast DC interruption is achieved. In view of the working characteristics of the piezoelectric actuator, the constant-current drive circuit is designed. Through the optimization of circuit parameters, the overshoot and rebounce of the moving contact are reduced. A hybrid DC circuit breaker experimental system is constructed. The test results show that the fault current transfer time of hybrid DC circuit breaker is about 200 μs, and the full breaking time is less than 800 μs.

Key words: piezoelectric actuator, fast mechanical switch, hybrid DC circuit breaker, DC interruption