The voltage support from conventional energy sources to doubly-fed induction generators (DFIGs) is analyzed by making the systems outside the coupling point of DFIG Thevenin equivalent. A short circuit calculating method based on pre-computed surface is proposed by developing the surface of short circuit current varying with the calculated reactance and the open circuit voltage. Moreover

for the transient feature differences of DFIG during the crowbar activation and deactivation

the rotor current peak is used to judge the activation

the relation between crowbar activation and post-fault terminal voltage is investigated. And the short circuit currents are derived by taking into account the rotor excitation and crowbar activation time delay. Finally

the pre-computed surfaces of short circuit current at different times are established

and the procedure for DFIG short circuit calculation is designed. The correctness of proposed method is verified by simulation. This work is supported by National Natural Science Foundation of China (No. 51277184) and National High Technology Research and Development Program of China (863 Program) (No. 2011AA05A107).