Dynamic performance of an enhanced STATCOM current control scheme for reactive power compensation

The switching frequency of solid-state devices, at high power levels, is reduced resulting in diminished quality and distorts waveforms of both currents and voltages in FACTS applications. This paper investigates a control system appropriate for STATCOM with reduced switching frequency. The proposed system comprises of a Current Regulated Pulse Width Modulation CRPWM inverter using a novel space vector modulation SVM based hysteresis current controller HCC. The proposed methodology exploits the combined advantages of both HCC and SVM techniques. In attempt to reduce the number of switching, a set of space vectors, including the zero vectors, is derived from two sets of hysteresis comparators. One comparator set has a larger hysteresis band resulting in considerable reduction in the number of switching and thus improvements in the efficiency of the system. Simulation results obtained from PSCAD/EMTDC package are used to illustrate the merits of the proposed scheme.