Probabilistic load flow for distribution systems with wind production using Unscented Transform method

In this paper, an approximate scheme called the Unscented Transforms (UT) method is proposed for probabilistic load flow studies. The proposed method involves carefully choosing a few selected points to approximate the probability distribution function of random variables within the system so as to significantly reduce the computation time. Since a power grid with embedded wind production is considered, the wind speed random variation is represented using a 3-parameter Weibull distribution. The wind power generated by the variable speed turbine is approximated as a composite distribution made up of the truncated Weibull-degenerate distributions. The Cumulative Distribution Function of the output variables are plotted using the Cornish-Fisher expansion technique. The effectiveness of the proposed method is proven by comparing the results obtained from it with those from the Monte Carlo simulation method using a simple 3-bus test system.