Active Reduction of Short-Circuit Current in Power Distribution Systems

In this paper, a new concept of short-circuit current (SCC) reduction for power distribution systems is presented and analyzed. Conventional fault current limiters (FCLs) are connected in series with a circuit breaker (CB) that is required to limit the short-circuit current. Instead, the proposed scheme consisted of the parallel connection of a current-controlled power converter to the same bus intended to reduce the amplitude of the short-circuit current. This power converter was controlled to absorb a percentage of the short-circuit current from the bus to reduce the amplitude of the short-circuit current. The proposed active short-circuit current reduction scheme was implemented with a cascaded H-bridge power converter and tested by simulation in a 13.2 kV industrial power distribution system for three-phase faults, showing the effectiveness of the short-circuit current attenuation in reducing the maximum current requirement in all circuit breakers connected to the same bus. The paper also presents the design characteristics of the power converter and its associated control scheme.