Probabilistic evaluation of long-duration voltage variations in distribution networks with wind power plants

The main aim of this study is to estimate long-duration voltage variations considering uncertainties associated with stochastic fluctuations in the output power of the wind distributed generation (DG) and system load. In the proposed methodology the uncertainties were represented using the time series models: Fourier analysis and auto-regressive moving average. These models were used in the quasi-sequential Monte Carlo simulation method to generate the system operation scenarios. The Monte Carlo simulation method was also used to model failures in the DG. The proposed methodology to estimate long-duration voltage variations was tested in a test system with 33 buses. The results showed that the insertion of wind DG in the system has a significant impact on the voltage profile. Furthermore, it was demonstrated that failures in DG and fluctuations in the load and wind speed caused large variations on the nodal voltages.