In order to improve the transient power angle stability of a wind power grid-connected system

the doubly fed induction generator（DFIG） parallel with superconducting magnetic energy storage device（SMES） is taken as research object

and a control method of joint SMES-DFIG is proposed. Through modifying and shrinking the node admittance matrix of system connected to wind farm

the relationship between the increase and decrease of equivalent mechanical power change and the power angle of system is analyzed based on the extended equal area criterion

the network topology connected to DFIG

and the information of equivalent power angle change of system during the transient period. Moreover

a power output control rule for SMES in parallel with DFIG is given to improve the stability of the transient power angle of system. The effectiveness of the control strategy is verified by simulation. The research results show that reasonable and accurate control of the power output of SMES can improve the change of equivalent power angle of system and accelerate the stable recovery rate of system. The research results can provide a reference for the control of using SMES to improve the transient stability of multi-machine system.