A novel bidirectional nonuniform hybrid circuit breaker considering different direction protection requirements

Abstract

Hybrid switching technologies such as zero voltage switching (ZVS) and zero current switching (ZCS) are widely accepted to protect DC power systems from different kinds of faults. However, in some cases such as the protection of DC generators in the electrical distribution system of modern ships, different protection strategies are needed for faults in different directions and both ZVS and ZCS technologies may be needed in one circuit breaker. This special protection requirement will lead to being more complicated in the bidirectional protection of the system and limits the application of the hybrid circuit breakers. Therefore, a novel bidirectional nonuniform hybrid circuit breaker based on a special combination of ZVS and ZCS technologies is proposed to simplify the overall topology of the circuit breaker. The proposed scheme can interrupt high rate-of-rise fault current in one direction by ZCS technology while interrupting short-circuit current in another direction with short-circuit short-delay strategy by ZVS technology. First, the topology and working principle of the proposed bidirectional nonuniform hybrid circuit breaker are introduced. Moreover, three current commutation processes involved in both directions of fault current interrupting are analysed to achieve the optimal connection structure. Furthermore, a high-speed driving mechanism of the vacuum interrupter (VI) based on the flexible conjunction of an electromagnetic repulsion (EMR) driver and a permanent magnetic (PM) system is introduced and the structure of the optimal connection is designed. Finally, the proposed topology of the hybrid circuit breaker is validated using a realistic 800 V/1600 A prototype. The short-circuit breaking off tests of both directions are conducted. The feasibility of the proposed scheme is verified with these tests.