Plug-in hybrid electric vehicles (PHEVs) represent a promising future direction for the personal transportation sector in terms of decreasing the reliance on fossil fuels while simultaneously decreasing emissions. Energy used for driving is fully or partially shifted to electricity leading to lower emission rates, especially in a low carbon intensive generation mixture such as that of British Columbia’s. Despite the benefits of PHEVs for vehicle owners, care will need to be taken when integrating PHEVs into existing electrical grids. For example, there is a natural coincidence between peak electricity demand and the hours during which the majority of vehicles are parked at a residence after a daily commute. This research aims to investigate the incremental impacts to distribution networks in British Columbia imposed by the charging of PHEVs.

A probabilistic model based on Monte Carlo Simulations is used to investigate the impacts of uncontrolled PHEV charging on three phase networks in the BC electricity system. A model simulating daily electricity demand is used to estimate the residential and commercial demand on a network. A PHEV operator model simulates the actions of drivers throughout a typical day in order to estimate the demand for vehicle charging imposed on networks. A load flow algorithm is used to solve three phase networks for voltage, current and line losses. Representative three phase networks are investigated typical of suburban, urban and rural networks. Scenarios of increasing PHEV penetration on the network and technological advancement are considered in the absence of vehicle charging control.

The results are analyzed in terms of three main categories of impacts:​ network demands, network voltage levels and secondary transformer overloading. In all of the networks, the PHEV charging adds a large amount of demand to the daily peak period. The increase in peak demand due to PHEV charging increases at a higher rate than the increase in energy supplied to the network as a result of vehicles charging at 240V outlets. No significant voltage drop or voltage unbalance problems occur on any of the networks investigated. Secondary transformer overloading rates are highest on the suburban network. PHEVs can also contribute to loss of transformer life specifically for transformers that are overloaded in the absence of PHEV charging. For the majority of feeders, uncontrolled PHEV charging should not pose significant problems in the near term. Recommendations are made for future studies and possible methods for mitigating the impacts.