One of the major concerns about the growing penetration of renewable energy into the power network is the analysis of the impact of such penetration on system stability. The Local Thevenin Index (LTI) based on the Wide Area Monitoring System (WAMS) is a novel technique in scientific research to assess the voltage stability of power systems integrated with renewable energy. From the standpoint of grid voltage stability, this index aids in determining the best location for integrating the wind farm into the existing power system. The effect of a significant penetration of doubly-fed induction generator (DFIG) based wind farms on the voltage stability of a large power network is analyzed in this research. The novelty of this research is to find the effect of the rise in wind power penetration level and additional distributed loads on a wind farm integrated large power system for voltage stability analysis. The MATLAB-Simulink platform is used to validate the proposed work with the New England 16-machine 68-bus power system.