Solid-state circuit breaker based on active thyristor topologies

Solid-state circuit breakers (SCBs), based on modern high-power semiconductors, offer considerable advantages when compared to mechanical circuit breakers with respect to speed and life. For instance, voltage quality of a power grid can be improved during a short circuit because the fault current is reduced. The interval over which voltage distortions occur, caused by a three-phase short circuit, can be limited to a few 100μs. In contrast to this, present circuit breaker technology requires at least 100ms to clear a fault. Major drawbacks of all SCB solutions presented so far are material costs and on-state losses. Primarily because of these disadvantages, SCB systems have not been widely used yet. Consequently, new solutions should be developed which are more cost effective and offer reduced on-state losses. This paper presents a conceptual approach based on active thyristor circuits. It is proven that these topologies can lead to a wider integration of SCBs in existing grids due to the economical advantages of silicon-controlled rectifiers compared to turn-off semiconductors. After a brief introduction and a presentation of the fundamentals, different topologies are described and assessed in this paper.