Voltage unbalance sensitivity analysis of plug-in electric vehicles in distribution networks

Plug-in electric vehicles (PEVs) will soon be connected to residential distribution networks. They are considered as huge residential loads when being charged. However as the battery technology improves, they will also be able to support the network as small dispersed generation units which transfer the energy stored in their battery into grid. Even though the increase in the PEV connection is gradual, their connection points and charging/discharging levels are random. Therefore, such single-phase bi-directional power flow can have adverse effect on the voltage unbalance of a three-phase distribution network. In this paper, a voltage unbalance sensitivity analysis and stochastic evaluation based on the connection point and charging and discharging levels of the PEVs in a residential low voltage distribution network are presented. The stochastic evaluation, based on Monte Carlo method, predicts a failure index of non-standard voltage unbalance in the network in the presence of PEVs.