Investigations on the Challenges and Opportunities with Residential Charging of Electric Vehicles

Abstract

This thesis investigates the challenges posed by residential electric vehicle (EV) charging newlineto the operation of distribution systems and proposes a few strategies to manage the newlinesame. The system impact is assessed in terms of the peak load, power loss and voltage newlineregulation. Owing to the inherent simultaneity between EV plug-in and the system s newlinepeak-load hours, distribution networks and the transformers that energize them could be newlinesubjected to severe overloads as the electrification of transport sector gathers momentum. newlineSustained overloads on the transformer could raise its internal temperature and newlinehasten insulation degradation. As EV deployment rises and the severity of overloads newlineincreases, the focus shifts from long-term effects that reduce transformer life to more newlineimmediate impacts that could disrupt normal functioning. The latter typically manifest newlineas the blowing of protection fuse, the triggering of pressure relief device, or the breakdown newlineof winding insulation, each of which could result in transformer outage. The newlineimpact of uncontrolled EV charging on the aging and service disruption of transformers newlineis analyzed in this thesis. newlineThe adverse impacts of EV integration such as transformer overloads, poor distribution newlineefficiency and undervoltage can be mitigated by employing controlled charging newlinestrategies, in which the distribution system operator coordinates EV charging to newlineimprove the technical or economic aspects of power distribution. A strategy that seeks newlineto regulate transformer loading by minimizing its variance over a day is formulated in newlinethis thesis. Another approach that seeks to ensure maximum user participation by minimizing newlinethe charging cost incurred is also presented. Cost minimization with respect newlineto static and dynamic tariffs are simulated and their performance compared. By employing newlinea dynamic real-time tariff, in which electricity price is a function of system newlinedemand, the cost-saving action is found to have a positive influence on the network newlineloading.