Impacts of maximizing plug-in electric vehicle penetration on urban power distribution network

Abstract

Electrified vehicles are a recent developing trend in transportation. It is a good solution for the reduction of fossil fuel usage on the transportation and hence the reduced CO2 emission. Plug-in Electric Vehicles (PEVs) are driven by the electricity stored in its battery and therefore zero tailpipe emission. Thus, PEVs attract much interests of public due to its environmental friendliness and they will possibly emerge widely in city areas in the short-term future mainly for short distance travels. Most of the countries provide incentives (tax credits, grants) to purchase plug-in electric vehicles as promotion of green vehicle. During last two years usage of PEVs was increased in Sri Lanka. PEVs are becoming more popular due to the reduction of importing tax and the developing infrastructure in Sri Lanka. However, in worldwide, increasing number of PEVs will become a substantial load to the existing power grid which can be characterized as an unusual type of load. Therefore, it is essential to pre-investigate the inevitable impacts on the power system. Lot of studies has been carried out worldwide to investigate the both positive and negative impacts on power grid. But in Sri Lankan context, a proper study had not been carried out to examine the challenges we have to face due to the increasing penetration of PEVs. Thus this research study is aimed to evaluate the level of impact due to the residential and fast charging of increasing number of PEVs. Anticipated impacts on power system such as voltage drop, voltage unbalance, transformer overloading, line losses and current harmonic effect are addressed in this study. Charging behavior of PEVs is unpredictable due to the variation of travel needs and the driving patterns. This study basically evaluates the impacts on distribution network due to this uncoordinated charging of increasing number of PEVs. It also addresses the mitigation methods and the maximum number of PEVs can be charged during off-peak hours from the distribution feeder modeled.