The adaptability of traditional phase selectors and directional relays in power systems integrated with wind farms is studied. Additional fault network is the basis for both traditional phase selectors and directional relays. The positive and negative sequence impedances of the wind power system vary widely and their amplitudes are both much larger than that of a regular power system during a fault. The impedance characteristics will then lead to a big difference between positive and negative current branched coefficients at the wind power side. Thus traditional phase selectors and directional relays based on equal positive and negative current branched coefficients are not necessarily suitable for wind power integration. Data from PSCAD simulation and field fault record have verified the theoretical analysis of adaptability. Eventually

research recommendations for phase selectors and directional relays suitable for power systems integrated with wind farms are given according to the adaptability analysis. This work is supported by National Basic Research Program of China (973 Program) (No. 2012CB215105).