A Power Decoupling Method for Virtual Synchronous Machine in Low Voltage Micro-grid

With the distributed power source connected to the power grid with a high penetration rate, virtual synchronous generator (VSG) control technology has become a hotspot in inverter control strategy research. Power coupling is one of the problems faced by VSG systems, especially in the low-voltage power grid, the impedance of the line is resistive and inductive, which seriously affects the performance of VSG control. This paper mainly does the following work on VSG control: firstly, VSG control model is established by introducing the active-frequency loop and the reactive-voltage loop to achieve external characteristics. Then, compared with droop control, the influences of the moment of inertia and damping coefficient on the control performance are analyzed under the island and grid connection conditions, respectively. Finally, the power coupling mechanism is analyzed. Based on the existing control, the voltage feedforward link is introduced through the virtual impedance to realize the VSG power decoupling control, and it is verified by the more stable way of the VSG external characteristics. The above work is simulated on MATLAB/Simulink platform.