Risk Assessment of Power System Voltage Security for Operational Planning

The growing penetration of renewable energy sources causes significant increase of system uncertainties and system operation complexity. It is of considerable importance to conduct accurate and fast risk assessment with probabilistic load flow analysis to ensure secure operation of power grids. Thus, Monte Carlo simulation with Newton-Raphson method is undesirable as it requires a long computation time and suffers from convergence problem. To overcome these challenges, an analytical probabilistic approach using non-iterative Holomorphic Embedding Load Flow method is proposed to obtain explicit rational probabilistic distribution function expressions for bus voltages assuming that the complex power injections at some of the buses depend on one wind power generation model while other buses have deterministic power injections. Computational time and accuracy of the proposed approach are evaluated to validate the performance and effectiveness of proposed algorithm. This paper is a preliminary trial for analytical method of probabilistic load flow study and provides insights into the impacts of renewable energy sources on power system operational security. It helps system operators to evaluate and control the potential risks associated with voltage fluctuation by considering the severity of the consequence and the likelihood of the occurrence.