In order to solve the problems that the instantaneous inertia of photovoltaic（PV） grid-connected power generation system is small and is easy to off-grid when suffering from different disturbances

a control strategy of a superconducting magnetic energy storage-fault current limiter（SMES-FCL） device is proposed to improve the transient stability of PV grid-connected power generation system. The SMES-FCL device is connected in series at the common coupling point between PV power station and distribution network through three-phase transformer

which has dual functions of current limiting and energy storage. However

due to the high-intensity nonlinearity and coupling of the SMES-FCL system

a double closed-loop sliding-mode control（SMC） method is adopted. SMC is used to stabilize the DC side bus voltage in the outer ring

and in the inner ring SMC is used to achieve rapid decoupling of current. The effectiveness of the control strategy is verified through simulations. The simulation results show that adding SMES-FCL devices outside can improve the fault-ride through（FRT） ability of PV grid-connected power generation system effectively

and reduce the impact of power fluctuations on the distribution network. Compared with PI control strategy

the proposed SMC control strategy enhances the disturbance resistance of SMES-FCL.