Coordinated Charging of Plug-in Hybrid Electric Vehicle for Voltage Profile Enhancement of Distribution Systems

Because of increasing in the number of plug-in hybrid electric vehicles (PHEV) is expected in the next years, so it will have impact on the power system performance, stability, voltage profile and system loses. Consequently, it is necessary to study the strategy and control methods of the PHEV charging strategies. In this paper, a new technique is used for charging the batteries of PHEVs in real time. The objective of the developed control strategy is to keep the system voltage in secure operation irrespective of the number of vehicles and their place along the distribution feeder. The strategy adopts the steady state voltage profile of the system that is easy to compute using the smart-grid load flow program implemented in the distribution management systems. The developed control method uses fuzzy logic controller. The developed strategy uses real-time Network voltage and the PHEV state of charge as the main inputs of the fuzzy controller. Based on the controller output, the bi-directional converters of each PHEVs converter decide the desired level of charging. This ensures secure operation of distribution systems during charging whatever the number of connected PHEVs to the grid. Besides, the control strategy decides the level of charging for each PHEV according to its state of charge. The Newton-Raphson method is used as the continuous power-flow solver in the distributed management system for network voltage calculation. Lithium-Ion battery is used for each PHEV is used to test out the developed control strategy.