EFFECTS OF ELECTRIC VEHICLE CHARGING ON POWER DISTRIBUTION SYSTEMS AND ITS MITIGATION STRATEGIES

Abstract

Continuously depleting fossil fuel reserves, rising fuel costs and the adverse impact of fossil fuel use on the environment have paved the way for the use of Electric Vehicles (EVs) as a popular mode of transportation. However, with increased EV penetration levels, the existing distribution network may suffer from distorted hourly demand profile, depleted bus voltages, increased unbalance, enhanced line losses and power quality issues. Moreover, the EV load in itself is random, unbalanced and dynamic in nature making it challenging to model accurately. To prepare distribution networks for future situations where residential EV charging represents a significant portion of the total demand, two mitigation strategies are proposed to improve the network’s performance: employment of EV charging policies and deployment of adequately-sized shunt capacitor banks in the network at suitable locations. The optimal sizes and the locations of the capacitor banks are obtained via Particle Swarm Optimization (PSO) algorithm. Multiple case studies corresponding to different EV penetration levels are performed and the impact of the two mitigation strategies is analyzed on a practical 240-bus distribution system. In the Midwest U.S.A. The U.S. travel data extracted from the 2017 National Household Travel Survey (NHTS) corresponds to about 1800 EVs belonging to more than one thousand households. The results confirm the improvement in demand profile and the bus voltage profiles along-with reduction in system losses, thus validating the proposed mitigation strategies.