Probabilistic Power Flow for AC/VSC-MTDC Hybrid Grids Considering Rank Correlation Among Diverse Uncertainty Sources

A new, unscented transformation (UT) based probabilistic power flow method for Alternate Current/Voltage Source Control-Multiple Terminal Direct Current hybrid grids is presented herein. The method is able to accurately tackle various random variables, including renewable energy sources with uncertainties such as wind speeds and solar radiations, which are rank correlated and are likely to follow different types of probability distributions. The concept of Gaussian copula is adopted to transform the rank correlated random variables into a group of standard Gaussian distributions with Pearson correlation coefficients, so that the UT method can be later applied to select the critical sample points from Gaussian distributions in a proper and uniform way. The effectiveness of the proposed method is validated using a set of test results on the modified IEEE 39-bus system and IEEE 300-bus system.