Solutions to probabilistic analysis of voltage stability in power systems with wind farms using advanced unscented transformation

This paper presents a method based on unscented transformation (UT) technique to solve probabilistic analysis of voltage stability in power system including large-scale wind farms, and the randomness of the wind farms' output power and the load increase direction are considered. UT technique is applied to transform the probabilistic analysis problem into some deterministic voltage analysis problems, and these deterministic problems are solved with interior point method. In order to improve the accuracy, a modified UT with proportion and higher order information is proposed. The numerical results of the modified IEEE 118 and 300-bus systems prove that, the proposed method is easy to be implemented and convenient to deal with the dependencies among the input random variables. Compared with Monte Carlo (MC) method, the calculation error of the proposed method does not exceed 1.5%, and efficiency can be improved several dozen times.