Impact of plug-in electric vehicles on voltage unbalance in distribution systems

Abstract

Plug-in electric vehicle (PEV) will soon be connected to residential distribution networks. They are considered as huge residential loads when being charged. However, as the battery technology and required facilities 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 PEV connection gradually increases, their connection points and charging/discharging levels randomly vary. Therefore, such single-phase bi-directional power flow can have adverse effect on the voltage unbalance of a three-phase distribution network. In this work, impact of plug-in electric vehicles on voltage imbalance in distribution system is presented. In G2V as well as V2G modes, the voltage unbalance analysis is carried out for various cases. Additionally, the voltage unbalance due to PEVs discharging and other types of distribution generator such as solar photovoltaic and wind turbines are investigated. Finally, some voltage unbalance mitigation techniques are summarized.

Keywords: Distribution Network, Electric Vehicle, G2V, V2G, Voltage Unbalance