Global warming is the most concern to the environmental issues and the limited availability of conventional fossil fuels lead to rapid research and development for more sustainable and alternative electrical sources in recent years. Wind energy, as one of the most prominent renewable energy sources, is gaining increasing significance throughout the world. Distributed generation (DG) based on renewable energy has become a development trend for electric power industry in 21stcentury. But DG is affected by natural conditions being not able to output power continuously and steadily, so when large scale wind turbine generators incorporated into the grid will bring impact on electric power system stability.In order to ensure stable operation of electric power system, a super capacitor energy storage system (SCESS) superior to other energy storage technologies and doubly fed induction wind generator (DFIG) are presented in this paper, SCESS is connected to the grid at the point of common coupling (PCC). Matlab/Simulink software is used for modelling and simulation analysis, this paper is focusing on transient stability problem, the simulation results indicates that SCESS can improve transient stability of multi-machine wind turbine generators system connected to the grid, and using doubly fed induction generators also can improve electric power system stability.