Correlated probabilistic load flow using a point estimate method with Nataf transformation

Wind speed as well as the power output of wind turbine generators (WTGs) have high correlations and may not be normally distributed. In this paper, the method of Zhao's point estimate method (PEM) combined with Nataf transformation was applied into correlated probabilistic load flow (PLF) calculation. This method can deal with correlated input random variables (RVs) with normal or non-normal probability distributions. Instead of joint probability density functions (PDFs) of multivariate RVs, this method only requires data of the marginal distribution function of each input RV and their correlation coefficients. The effectiveness of the proposed method is demonstrated by the numerical tests on IEEE 14-bus and the IEEE 118-bus systems. Besides, relative average errors compared with correlated Monte Carlo Simulation (CMCS) are analyzed.