The analysis of maximum access capacity of wind power plant integrated into power system is an important issue in the development of wind energy because the variability of wind power affects the stability of power grid significantly. Impact of large scale wind power integration in a local grid typically in China has been presented. Based on electromagnetic analysis software DIgSILENT/PowerFactory, the interconnected wind farm model and VSC-HVDC model as well as HVAC model are set up. Comparative analysis of performance of grid with different type of tie-line has been conducted. The digital simulation results show that VSC-HVDC is a better choice to solve the problems of system instability due to large wind farm integration in comparison with HVAC. With VSC-HVDC transmission system, the stability of system can be improved better by flexible operation and control. Analysis of this paper should be provided as academic reference for improving design of interconnected wind farm system.