Reactive power and voltage emergency control strategy of large-scale grid-connected wind farm

As frequent occurrence of large-scale wind turbines cascading disconnection to the power grid, it´s urgent to study the causes of as well as corresponding preventing strategy to these accidents. A real wind power delivery case with detailed power network topology and parameters is modeled, and based on it the transient process of large-scale wind turbines cascading disconnection is recurred. The dynamic reactive power response capabilities of wind turbines and reactive power compensation devices during the transient process are analyzed. A reactive power and voltage emergency control strategy of overall process with the consideration of above dynamic reactive power response capabilities is proposed. In the proposed emergency control strategy, the grid-side converters of wind turbines are utilized to dynamically provide reactive power to the grid to mitigate voltage drop in real time. In addition, reactive power compensation devices are actively disconnected to the grid before fault removal to restrain the transient overvoltage, and then reconnected to the grid according to voltage level in recovering period to provide reactive power support. The simulation validates the feasibility and effectiveness of the proposed control strategy.