Impact on the Distribution System due to Plug-In Electric Vehicles and Changes in Electricity Usage

Licentiatavhandling, 2012

Replacing conventional vehicles by Plug-in Electric Vehicles (PEVs) would likely increase electricity demand and put higher stress on the electrical power system. This thesis presents an approach to evaluate the impact on electrical distribution systems (DSs) caused by charging PEVs and load management of heating loads. The approach considers both vehicle usage statistics and demographic data to estimate when PEVs could be charged in different parts of a DS. A case study was performed on a residential and a commercial part of the DS in Gothenburg. Three different control strategies for the charging were investigated, i.e. uncontrolled, loss-optimal and price-optimal strategies. The control strategies would have a significant effect on the timing of the charging, as well as the access of available infrastructure for charging. The results showed that if all vehicles were PEVs and charged uncontrolled, peak demand would increase by between 21 - 35% in the residential area and by between 1-3% in the commercial area. If customers were directly exposed to the spot price at the Nordic day-ahead market and would charge according to the price-optimal control strategy, peak power would increase by 78% for the residential area and 14% for the commercial area. If the charging were controlled according to the loss-optimal control strategy, the charging would be conducted during off-peak hours without increasing peak demand, even if all vehicles were PEVs. By controlling the heating loads in the residential area according to the price-optimal control strategy peak demand would increase by more than 80%, while peak demand would be reduced by almost 10% if the loss-optimal control strategy were applied.