Accurate power sharing and harmonic mitigation scheme for parallel operation of single-phase voltage source inverters

Inaccurate reactive power sharing and voltage distortion at the point of common coupling (PCC) always exist in a parallel inverter system due to feeder impedance mismatches and nonlinear load disturbances. An enhanced inverter control scheme through an output impedance adjustment is proposed to address these issues. Inverter output impedance is regulated considering fundamental and harmonic frequencies, and accurate power sharing and improved PCC voltage quality are realized at the steady state. In addition, the compensation scheme is easily applied in multiple parallel inverters without any prior knowledge of the feeder impedance. Experimental results with three parallel inverters validate the feasibility of the proposed control scheme.