Digital implementation of sliding mode control technique on SSC for load balancing and reactive power compensation

Abstract

This paper presents an implementation of a new control scheme of a 3-phase solid-state compensator (SSC) to compensate reactive power and to balance unbalanced loads. An IGBT- based current controlled PWM voltage source inverter (VSI) with a dc bus capacitor is employed as an SSC. A sliding mode controller (SMC) over the dc bus voltage of the SSC is used to derive reference supply currents in phase with supply voltages. The SMC closed loop controller over dc bus voltage of SSC provides robust control and transient free dynamic response of the system. An indirect current control over the reference and sensed supply currents is realised for generating the gating pulses for the IGBTs of the SSC. Test results of the SSC for the cases of single-phase and 3-phase lagging power-factor loads are presented and discussed in detail to demonstrate the reactive power compensation and loads balancing capabilities of the SSC.