Reconfigurable low voltage direct current charging networks for plug-in electric vehicles

Mokgonyana, Lesiba and Smith, Kyle and Galloway, Stuart (2018) Reconfigurable low voltage direct current charging networks for plug-in electric vehicles. IEEE Transactions on Smart Grid. ISSN 1949-3053

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Abstract

An emerging theme in the development of supporting facilities for plug-in electric vehicles (EVs) is the cost-effective planning and utilisation of charging networks consistent with the uptake of EVs. This paper proposes a low voltage direct current (LVDC) reconfigurable charging network for plugin electric vehicles (EVs) and presents a functional energy management system (EMS) that is capable of planning and operating the charging network to minimise charging cost and to facilitate progressive infrastructure deployment based on EV demand. The charging network is connected to the main AC grid through one or more centralised AC/DC converters that supply a high power charge to EVs connected to the DC side of the converters. The EMS accommodates multiple parking bays, charging sources, AC constraints, non-linear EV battery loads and user charging requirements with a novel approach to managing user inconvenience. The inconvenience model is founded on the presence of user flexibility i.e., an allowance on charging time or battery SOC, providing the capability to increase asset utilisation and enable access for additional network users. Through a series of case studies and a stochastic forecasting approach, the reconfigurable network and EMS demonstrate the capacity to achieve savings over fixed AC and sequential DC systems.