Comprehensive probability analysis on voltage stability of power grid with wind farm connected

In this paper, voltage stability probabilistic analysis and critical buses identification using multiple indices were performed to power system with wind farm connected. Considering the uncertainty of wind speed, Monte Carlo method was selected to perform the probabilistic analysis. Firstly, total transfer capability (TTC) of power system under voltage stability constraint, bus voltage change index, sensitivity index of bus voltage with respect to active power, reactive power margin and sensitivity index of reactive power with respect to bus voltage were calculated by P-V curve and Q-V curve respectively. The statistic information of TTC was employed to research the impact of wind farm on voltage stability and the probability of voltage instability of power system. Integrating the four bus voltage stability indices, a comprehensive evaluation method which combined entropy method and technique for order preference by similarity to ideal solution (TOPSIS) was proposed to identify the critical buses. Furthermore, the simulation analysis basing on IEEE 10- generator-39-bus test system was carried out to reveal the impacts of wind generation uncertainty on voltage stability and TTC, and to demonstrate the practicability of the proposed identification method.