Abstract: With the increase of grid-connected capacity of DFIG,it brings new challenges to the setting of relay protection for wind farm outgoing line. When the performance of the protective action is reduced,there is even a risk of rejection and misoperation. To this end,firstly,the characteristics of negative sequence current component of DFIG are analyzed. Then,the characteristic differences of the currents on both sides of the AC outgoing line when the wind farm is connected to the grid by AC or DC are further analyzed,and a new method of negative sequence current component pilot protection for the outgoing line of doubly fed wind farms is proposed. The method uses the amplitude ratio and phase difference of the negative sequence current on both sides of the double-fed wind farm outgoing line to form the protection action criterion. At the same time,uses the data delay to construct the negative sequence component under symmetrical faults,so that it can be applied to various fault types of the wind farm outgoing line,and has the advantages of high sensitivity and strong ability to withstand transition resistance. Finally,the electromagnetic transient simulation model of DFIG is built in Matlab/Simulink and PSCAD/EMTDC,to simulate and analyze the adaptability of the protection scheme on the AC/DC outgoing lines.