Abstract: Based on the two-machine parallel model,a method of collector network equivalence for wind farm is presented,which is suitable for low voltage ride through（LVRT）simulation.The equivalence of line reactance is based on the principle that the output reactive power of wind farm at the point of common coupling（PCC）before and after the transformation should be consistent during the grid voltage dip,and the equivalence of line resistance is based on the principle that the active power losses of collector network should be equal.By the impedance transformation of collector network,the wind farm can be made equivalent to a single-machine model connected to the PCC through an equivalent impedance.The line impedance equivalent method proposed is applicable to the equivalence of collector networks with tree like,radial or hybrid topology,and the calculated parameters of line impedance are constant which is convenient for actual application.Simulation results show that the equivalent model has high precision during apower system fault.