A static voltage stability assessment scheme of power systems considering charging state of electric vehicles and load fluctuation limits

Aiming at studying the influence of the charging uncertainty and load fluctuation characteristics in power system with electric vehicles (EVs) plugged in, a static voltage stability assessment scheme which considers both of the charging characteristics and load fluctuation limits is proposed. First, a mixed approach based on continued power flow (CPF) and probabilistic load flow (PLF) is employed to search for the critical states of the power system voltage instability. Then, the marginal operating states of power systems can be analyzed statistically. Thirdly, several evaluation indicators are presented to determine the weakened areas in the voltage stability. These weak regions will usually in advance experience voltage violation when system voltage collapse happens and they can be served as important monitoring objects. Finally, the analysis results of IEEE 30-bus system verify the accuracy and effectiveness of the presented scheme.