A Probabilistic Assessment Method of Voltage Deviation Risk for Wind Power Access to Distribution Network Based on Total Probability Formula and Nataf Transformation

Abstract

Driven by the "dual-carbon" goals, the large-scale integration of wind power into distribution networks poses challenges to voltage stability due to its inherent volatility and uncertainty. To address it, this paper proposes a probabilistic assessment method based on the total probability formula that incorporates wind speed correlation to effectively evaluate voltage deviation. Firstly, the probability model of wind power is established according to the uncertainty of wind speed considering the correlation. Secondly, the wind power output is discretized and aggregated to ensure that the resulting random variables in the combined state approximately follow a normal distribution. Spatial correlations in wind speed are accounted for using the Nataf transformation. Furthermore, the probability of each aggregated wind power state determines its weight. These weights are then used to accumulate and integrate the probabilistic power flow (PPF) results. The total PPF calculation accounts for wind power uncertainty, following the Total Probability Formula (TPF) framework. Finally, considering the indexes with the probability and severity of voltage deviation, the comprehensive risk indicator for voltage exceeding limits is constructed. Based on the IEEE-33 bus test system, the proposed TPF method is compared with Monte Carlo Simulation (MCS) and the Two-Point Estimation Method (2PEM). The comparison demonstrates its superior computational accuracy and efficiency, establishing it as an effective tool for assessing the impact of wind power integration on distribution networks.