A fault protection scheme for series active compensators

A protection scheme for a series active compensator, which is composed of a unified power quality conditioner (UPQC) or a hybrid active power filter, is presented and analyzed. In this paper. The proposed series active compensator operates as a high impedance "k(Ω)" with the fundamental components when over current occurs in the power distribution system. Three control strategies are proposed in this paper. The first is a method by detecting the fundamental source current through the p-q theory. The second is by detecting the fundamental component of load current in the synchronous reference frame (SRF) and the third is by detecting the input voltage. When the overcurrent occurs in the power distribution system, the proposed scheme protects the series active compensator without the need of additional protection circuits. The validity of the proposed protection scheme is investigated through experimental results in the hybrid active power filter systems.