Fault Through Technique of Synchronverter Based on Voltage Feedforward Compensation

When the power grid is in the fault state, the output three-phase unbalanced current and over-current of synchronverter in grid-connected operation can aggravate the instability of the power grid and reduce the coordinated operation ability of the grid-connected system. In order to address this problem, this paper analyzes the mathematical model of output power and current of synchronverter under power grid fault, and presents a new method to suppress the fault current. Firstly, the three-phase state evaluation and situation prediction of inverter output current are carried out. Then, the predictive current in the fault state is converted into the voltage variable that is inputted synchronous control system to realize voltage feedforward compensation, Realizing the fast prevention and control of fault current while ensuring the normal transmission power of the inverter. The simulation results show that the proposed method can effectively restrain the fault current when the grid voltage is unbalanced. The adaptability of synchronverter in grid-connected operation is enhanced.