VSG-Controller Inverters with High Power Quality Based on Improved Grid Voltage Feedforward Compensation

Virtual synchronous generator (VSG) techniques have been applied to grid - connected inverters. This is aimed at enhancing the ability of distributed generations to support the grid, thereby helping to address the instability problems in the commercial power grid with a high proportion of renewable power generations. Nevertheless, because of the VSG's inherent voltage source nature, the inner impedance of the inverter is relatively low. Consequently, when the grid has background voltage harmonics, the output power quality of the VSG will be severely impaired. In this paper, a harmonic current elimination method grounded in enhanced voltage feedforward is put forward to enhance the power quality of the VSG. The proposed method adopts a simple control structure, which benefits to save implementation time in the practical digital controller. Two methods that are theoretical model analysis and experimental test for design the control parameter of the proposed method are provided, which can identify the required control parameter even the system parameters of the VSG are unknown. The admittance of the VSG is test and the effectiveness of the proposed method is verified by simulations.