Design of D-STATCOM for voltage regulation in Microgrids

Fluctuating power resulting from renewable energy sources is strictly challenging power quality in Microgrid systems. This paper presents a Distributed-STATCOM (D-STATCOM) to alleviate variation of both positive-sequence and negative-sequence voltages at the fundamental frequency. The D-STATCOM operates as separate conductances at the fundamental positive- and negative-sequence frequency, respectively, to restore the positive-sequence voltage to the nominal value as well as suppress the negative-sequence voltage to an allowable level. The conductance commands are dynamically tuned according to voltage fluctuation at the installation location, so voltage variation could be reduced in response to load change and variable renewable energy. A resonant current regulation is implemented for fundamental current tracking as well as harmonic current reduction due to high voltage distortion in low-voltage Microgrid. This feature is a significant advantage in practical applications. Supporting results from computer simulations are provided to validate effectiveness.