Design of solid-state circuit breakers for medium-voltage systems

Solid-state circuit breakers can provide significant advantages in speed and functionality compared to mechanical switches. Today, several high-power semiconductors are available up to 9 kV. In contrast to conventional power electronic systems, minimizing conduction losses of solid-state devices is of greater importance than their switching performance. In addition, in today´s power systems cost consideration, not only investment costs but also life cycle costs is of utmost importance. As a result, the optimization and selection of power electronic switch topologies is critical. In this paper, different semiconductors are briefly compared considering the requirements of a solid-state switch integrated into a 20 kV medium voltage grid. Based on these semiconductor characteristics, various switch topologies are developed. Next, these topologies are compared under technical and economical aspects. It is found that the technical performance or functionality of the selected topologies differs slightly. Hence, economical aspects in form of costs are the decisive factor to select a topology.