Grid-Connected Inverter Based on Virtual Synchronous Generator Emulation in Wind Application

As the penetration of distributed generators like wind turbines increasing, more and more negative influences are reflected on power systems such as the balance of reactive power, the voltage quality and voltage stability. Variable speed wind turbines connect with grid through full or partial power ac-dc-ac converters. In order to improve the power system stability and voltage quality, virtual synchronous generator (VSG) control method is proposed for inverter control in this paper. The proposed method, which includes the electrical part, the excitation part and the mechanical part of the synchronous generator, makes the inverter imitate a synchronous generator's behavior. In the paper, the P-Q closed loops are respectively added to the virtual stator current control, and the inverter's output current references can be obtained. The active power and reactive power can be controlled independently by using the P-Q closed loop control. At last, a simulation model built in MATLAB/Simulink and the simulation results are presented to verify this control method. The effect of the P-Q closed loop control will be shown as well. Finally, the VSG method is verified to improve the system's stability and can make the grid-connected inverter work very well in wind application.