Effective output voltage quality control under nonlinear loads in islanded microgrid

A nonlinear load generally causes harmonic distortion, and harmfully affects the performance of other loads or other distributed generation (DG) sources connected to the point of common coupling (PCC). This paper proposed a new control strategy to reduce harmonic components such as fifth and seventh harmonics at the PCC under nonlinear load in the islanded microgrid which includes more than two DG sources. The DG source operated with the proposed control scheme has ability to share the power commanded by the control center as well as to compensate the harmonic components voltage at PCC. The control scheme is developed based on the current controller composed of the resonant controller and a proportional integral controller. Because the reference current is estimated from the voltage harmonic and the injecting power, the control scheme is implemented without any additional hardware devices. The simulation and experimental results are given to verify the effectiveness of the proposed control method.