Synchronous reference frame based current controller with SPWM switching strategy for DSTATCOM applications

This paper presents sine pulse width modulation (SPWM) based switching strategy for two-level neutral-point-clamped (NPC) voltage source inverter (VSI), used in distribution static compensator (DSATCOM) for unbalanced nonlinear load compensation. DSTATCOM, is used for supplying harmonic currents and reactive power to unbalanced nonlinear loads. Thus, making the utility current balanced and sinusoidal with unity power factor (UPF) operation. Synchronous rotating (dq0) frame current controller with decoupled d, q and 0 components are used for generating the control signals, which are further used for developing gating signals for VSI using SPWM switching strategy. Neutral current compensation, which corresponds to `0´ axis component in dq0 frame is carried out for proper compensation of unbalanced nonlinear loads. Synchronous reference (dq0) frame theory is used for reference filter currents generation. A detailed simulation study to understand the compensation performance of DSTATCOM with dq0 current control under steady state and dynamic conditions are carried out using PSCAD 4.2.1 simulator, and the corresponding results are presented.