Continuous charging coordination of PHEVs for voltage profile and stability improvements of unbalanced distribution systems

In this paper, demand response concept has been exploited to control the real time charging of plug-in hybrid electric vehicles. A developed voltage stability index is embedded in the continuous power-flow solution process adopted in distribution management systems (DMS). If the distribution system is unbalanced, positive sequence data is used for evaluating the voltage stability index (SI). The developed control strategy controls the charging level such that guarantees secure operation of the distribution system regardless the number of plug-in hybrid electric vehicles (PHEVs) connected to the distribution system. The developed control method uses fuzzy logic controller for evaluating the battery of each PHEV in the system level of charging and discharging. The controller will be a part of the smart charger and uses both of the battery state of charge (SOC) and (SI) as input variables. Based on the controller output, the interface converter of each PHEV decides the desired level of charging.