Research on Dynamic Equivalence Modeling of Wind Farm Composed of Double Fed Induction Generators Based on Crowbar Control Strategy

Abstract

In order to study the effect of low voltage ride through of doubly fed induction generator(DFIG) on dynamic equivalence of wind farm, a double fed wind farm dynamic equivalent modeling method based on crowbar control strategy is presented. Firstly, the rotor current is analyzed when DFIG is in power network fault, and the expression of rotor transient current in time domain is given. Then study two commonly used control strategies of the crowbar circuit effect on low voltage ride through under the different voltage drop and DFIG operation status. And the simulation results show that the two control strategies have their own scope of application. On the basis of this, the paper puts forward the crowbar circuit switching curve and control strategy selection area curve, which we can judge the selection of the lever circuit and the control strategy when the power grid fails. Taking into account the division of wind farm cluster at the moment before fault, the measured wind speed and the crowbar circuit is action as the clustering index when the grid is fault. The crowbar circuit unit from the original "N" cluster to form "N+1" cluster before fault, calculating the parameters of each cluster with the method of capacity weighting, multi machine equivalent model was established. Finally, a calculation case is constructed on MATLAB/Simulink platform and the simulation results show that the proposed equivalent scheme is effective and accuracy.