Effect of wind turbines integration on voltage stability

With the increasing large-scale wind power integration, wind power will influence the voltage stability of power systems due to its fluctuating nature. For evaluation the impact of adding wind energy to traditional power systems accurately, a detailed voltage stability margin evaluation scheme was developed for power systems including wind power resources. A linear equation model was established with a parametric power flow equation. When applying semi-invariant theory and superposition principle, with the sensitivity and covariance matrix calculated directly the average and the variance of load margin, according to load parameters of the feature of normal distribution. Then superimposed the two results and expanded edge worth series for getting the distribution of the load margin. Based on it, calculated the lose steady probability in the non-normal operation. Simulated and test on IEEE 30 node sample system to show the feasibility and validity of algorithm.