Optimization of Hybrid Current-Injection Circuit Breakers Including Mechanical Switch Limitations

Circuit breakers with current injection enable fast interruption of fault currents in DC grids. Independent of the topology, a high number of semiconductors and capacitors is required. The minimum required number of semiconductors and capacitors depend mainly on the system voltage and the maximum fault current. However, also the MS characteristics have considerable influence on the required number of semiconductors and capacitors. Therefore, in this paper the influence of the MS characteristics on the arc extinction and the influence of the arc voltage on the DC-CB design is presented. In addition, optimization procedures for current injection circuit breaker are presented, which include the MS characteristics and four different possibilities to include the arc voltage. Finally, three DC-CB topologies are compared in terms of number of semiconductors and capacitors.