Bidirectional Current Injection MVDC Circuit Breaker: Principle and Analysis

The medium-voltage dc (MVDC) interruption technology has grown in recent years, driven by increased interest in using MVDC system for integrating distributed renewable energy and improving the efficiency of power supply. In this paper, two topologies of current injection MVDC breaker are focused on. The first topology is based on conventional precharged capacitor that utilizes a bridge-Type commutation branch to realize the freewheeling for the interrupter and bidirectional breaking. With the help of simulation, the effect of stray inductances on the current commutation capability is analyzed in detail, and then, a prototype of the MVDC breaker is built to test the fault current breaking performance. The second topology is an improved MVDC breaker based on magnetic induction current commutation module (MICCM). With MICCM analyzed carefully in terms of circuit and structure parameters for determining their optimal values, the prototype of the improved 10-kV dc breaker is built and tested, which validates the feasibility and effectiveness of improved topology.