The Grid Voltage Sensorless VSG Control Strategy Based on Static Coordinate System

When the virtual synchronous control is adopted, the voltage of power grid may exist non-ideal factors such as voltage sag and distortion, which affect the stability of distributed generation system. Therefore, the voltage sensorless virtual synchronization control strategy in static coordinate system is proposed. Firstly, establish the VSG control state space model in the static coordinate system, and use the root locus method to analyze the stability of the system so as to reveal the influence of control parameters on system stability. Then the flux linkage observer is constructed by using stator current, DC bus voltage and control signal, and the network voltage is reconstructed in order to reduce the influence of non-ideal grid voltage on grid-connected system and improve the stability of inverter in weak grid. Finally, the accuracy of the model and the effectiveness of the improved control strategy are verified by simulation and experiment.