Research of voltage stability analysis method in distribution power system with plug-in electric vehicle

With the large-scale use of electric vehicles (EV), the impact of charging plug-in EV on the distribution power system will be growing in the future. The voltage stability of distribution network with plug-in EV is more and more concerned by people. The voltage stability mechanism of distribution network with large scale plug-in EV is analyzed and the voltage stability model considering the voltage characteristic of integrated load is proposed in this paper. The voltage stability boundary condition calculation model and voltage instability severity calculation model is build. Taking two-bus distribution equivalent system as an example, the impact of different proportions of constant impedance load, constant current load and constant power load on voltage stability are simulated and analyzed. The impact of equivalent impedance and total load of distribution system on voltage stability also be simulated and analyzed. Simulation results show that the voltage stability is related to the proportion of three types of load, equivalent impedance and the total load. The constant impedance load has a negative feedback effect on the recovery of voltage, while the constant power load has a positive feedback effect on the recovery of voltage. When the positive feedback effect is more than negative feedback, the voltage instability even the voltage collapse will happen. The voltage instability severity is related to the structure of distribution network and system total load.