Mitigation of Voltage Fluctuations at Transient Period using D-STATCOM in High Level Penetration of Distribution-Generation Systems

Voltage fluctuations mainly resulting from variable output power of renewable energy sources; these are strictly challenging power quality in distribution-generation systems. The paper presents control method for D-STATCOM to relieve variation of positive-sequence and negative-sequence voltages. DSTATCOM continuously operates as fundamental positive –sequence admittance and negative-sequence conductance to restore the positive-sequence voltage to the nominal value and negative-sequence voltage to the allowable level. At transient period both admittance and conductance are dynamically tuned to improve the voltage regulation performance. A controlling of fundamental current of the D-STATCOM and reduction of harmonic current is accomplished by the proportional-resonant current regulator with selective harmonic compensation. The voltage imbalance factor %VUF is discussed at all buses and maintained in acceptable level . The paper presents the computer simulation of D-STATCOM with transient period of distribution-generation system. Index Terms—D-STACOM (Distributed-static compensator), voltage imbalance, voltage fluctuations, micro-grid.