Modeling and evaluation of SOC-based coordinated EV charging for power management in a distribution system

Authors: MURAT AKIL, EMRAH DOKUR, RAMAZAN BAYINDIR

Abstract: The importance of using clean energy in electrical energy generation and transportation network planning has recently increased due to carbon footprint rising. In this direction, the use of electric vehicles (EV), known as ultra-low carbon emission vehicles, has become widespread in addition to renewable energy sources (RES) such as wind and photovoltaic (PV) power generations. The trend of EVs to be preferred the primary means of transport has revealed the effects of charging an additional load on the grid. There is a need to create coordinated charging methods by considering the approaches for real-time charging models of EVs. In this paper, SOC-based EV coordinated charging was proposed for power management to prevent adverse effects including transformer overload, instantaneous peak loading and line overload in the existing distribution network. The proposed coordinated EV charging method was tested on the modified Roy Billinton test system (RBTS) Bus 2 network. AC 11 kW uncoordinated charging units have been respectively 123.76% distribution transformer and 115.16% distribution line overloading for 500 EVs on the grid with 13,9% diversity factor. However, these values that are 72.05% of distribution transformer and 67.01% of distribution grid overloading according to permittable level were decreased by the proposed coordinated charging method. Also, the state of charge (SOC) based coordinated method can increase 3.5% rate the diversity factor of charging capacity at the charging station with PV and battery energy system (BES) while ensured grid stability and energy efficiency.

Keywords: EV charging coordination, energy efficiency, power management, photovoltaic power generation

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