A Local control scheme for voltage harmonic compensation and improvement of reactive and harmonic powers sharing for PV inverters with LCL filter in islanded microgrids
Document Type : Original Article
Author
Department of Electrical Engineering, Urmia Branch, Islamic Azad University, Urmia, Iran
10.22059/jser.2025.387597.1510
Abstract
This paper proposes a local control scheme to improve voltage quality and achieve accurate reactive and harmonic power sharing for photovoltaic (PV) inverters with LCL filters in an islanded microgrid (MG). The proposed control structure uses a modified reactive power-voltage (Q-E) droop controller to achieve reactive power sharing and prevent overloading of PV inverters, where the droop coefficient is precisely adjusted by considering the limited inverter capacity and the harmonic power of the load. Additionally, an adaptive virtual impedance (VI) loop is employed in the structure to compensate voltage harmonics and improve the sharing of fundamental and harmonic current components among the PV inverters. The proposed adaptive VI loop, based on the circulating currents of the fundamental and harmonic components, adaptively enhances the sharing of reactive and harmonic powers. In contrast to conventional VI schemes, where load sharing is achieved at the cost of additional harmonic voltage distortions, the proposed adaptive VI structure has a minimal impact on the output voltage quality of the PV inverters. The design process and parameter determination of the proposed structure are thoroughly explained, and simulation results in MATLAB/Simulink are provided to demonstrate the effectiveness of the proposed method.
Keywords
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