A Hybrid Compensator for Mitigation of Power Quality Issues in Distribution Systems

Abstract

This paper proposes a hybrid compensator for mitigating power quality problems in distribution systems. The hybrid compensator constitutes of Thyristor Switched Capacitor (TSC), Thyristor Controlled Reactor (TCR), a lower rating D-STATCOM and a 5th harmonic tuned passive LC filter. The Static var Compensator (SVC) or the TCR-TSC combination works in a coordinated way for the base var compensation. The D-STATCOM works in a coordinated scheme with the SVC and the single tuned LC filter to compensate fundamental var, reduce voltage flicker and also attenuate harmonic currents at the Point of Common Coupling (PCC). The D-STATCOM thus serves a dual role as a var compensator and as an active filter in Selective Harmonic Compensation (SHC) mode to attenuate the 7th harmonic current, hence improving the var compensation and harmonic current filtering at PCC. The proposed hybrid configuration exhibits very low line current THD in accordance with the relevant standards. Also the chance of resonance of the fixed passive filter with the source inductance has been eliminated in the coordination scheme. The simulation results show that the proposed hybrid system compensates var, reduces voltage flicker and harmonic currents at the PCC effectively. The proposed control and coordination scheme is simple to execute besides the hybrid system being highly robust in performance.