Impact Analysis on Voltage Unbalance of Plug-in Electric Vehicle Home Charging in Thailand Distribution System

This paper proposes an impact analysis on voltage unbalance of Plug-in Electric Vehicle (PEV) home charging in Thailand distribution system. The voltage unbalance is calculated with the voltage unbalance factor (%VUF) according to IEC 61000-2-4: 2000-06 standards and impact assessment with the new criteria of Provincial Electricity Authority (PEA) standards. The study uses distribution network data of large cities in Thailand. A model of distribution network has been developed based on the DIgSILENT PowerFactory with DIgSILENT Programming Language (DPL). The assignment of PEV to each node and the number of PEV to each phase is performed by Monte Carlo method. Charging scenarios focus on overlaps of charging periods in each phase. PEV charging duration is about 6 hours. Simulation case studies of PEV single phase charging with point of charge far from substation are carried out for 5 cases. They are average point of charge, Max to Min charge, Min to Max charge, Central of the feeder charge, and Random point charge. Simulation results show that PEV single phase charging raises the voltage unbalance factor (%VUF), when there are overlapping charging time periods. A significant of the %VUF increases gradually along the length of feeder and has maximum value at the end of the feeder. Moreover, many case studies show %VUF exceeding criterion of 2.0% of the PEA standards.