Control of DSTATCOM Using S-Transform

Stockwell-transform (S-transform) based operation and control for a distribution static compensator (DSTATCOM) is presented in this paper for power quality (PQ) improvement at point of common coupling (PCC). S-transform which is a timefrequency analysis technique is applied here to decompose the nonlinear load current to extract the harmonic components. The main active power element of load current has been estimated from the extracted fundamental component. The deviation of the reference active component from the actual load current is used to control the insulated gate bipolar transistors (IGBTs) of the voltage source converter (VSC). The VSC currents are added with load current for PQ improvement on grid side. A model of a DSTATCOM based on it is simulated using Simulink and Simpower tool boxes of MATLAB with linear and nonlinear loads configurations. Satisfactorily performance obtained on a developed laboratory prototype of DSTATCOM validates the projected control algorithm. The performance is compared and found to be better than the Dual-tree complex transform based algorithm under varying load conditions.