Balanced and unbalanced three-phase voltage sag generator for testing electrical equipment

This paper proposes a balanced and unbalanced three-phase voltage sag generator and voltage sag control strategy for testing electrical equipment. The proposed system has a simple structure, by using three single-phase H-bridge inverters with the unipolar pulsewidth modulation technique. The control strategy is developed for generating sag voltage independently in each phase. The aim of the research is to improve the voltage sag generator to generate in balanced and unbalanced voltage sag conditions. The dynamic performance of the proposed system is validated with resistive-inductive and nonlinear loads situations. Simulation and experimental results confirm that the proposed system can be generated in both the balanced and unbalanced voltage sag conditions.