Received: 1 July 2019 Revised: 24 September 2019 Accepted: 30 September 2019 DOI: 10.1002/2050-7038.12226 RESEARCH ARTICLE Charging cost minimisation by centralised controlled charging of electric vehicles Harshavardhan Patil Vaiju N. Kalkhambkar Department of Electrical Engineering, Rajarambapu Institute of Technology (Affiliated to Shivaji University, Kolhapur), Islampur, India Correspondence V. N. Kalkhambkar, Department of Electrical Engineering, Rajarambapu Institute of Technology, (Affiliated to Shivaji University, Kolhapur), Islampur, India. Email: kvaijnath@gmail.com Summary With the recent breakthroughs in battery technology and large scale production, electric vehicles (EVs) are becoming cheaper. In a few years, mass deployment of EVs will put severe stress on the electricity network. Charging of EV during peak hours may overload the distribution grid transformer, and EV owners may have to pay more money for electricity during peak hours. To address these issues, a coordinated scheduling model is proposed in this paper. A mathematical model is formulated to minimise the charging cost of each EV while satisfying the con- straints. In this work, time of use (ToU) tariff from the utility and actual power demand from household and EVs are used to conduct simulation for one week in summer and winter season with different levels of EV penetration. The results demonstrate that the proposed scheduling model can significantly reduce the charging cost for the EV owner and power peaks in the distribution network. KEYWORDS controlled charging, cost minimisation, economic benefits, electric vehicle, grid-integration, optimal scheduling, peak shifting, unidirectional charging 1 INTRODUCTION Electric vehicles (EVs) with their zero-tailpipe emission have attracted much interest in recent years as an eco-friendly and cost-effective alternative to traditional internal combustion engine (ICE) vehicles. Although ICE vehicles outperform EVs in terms of range, availability of fuel, and price, EV has many advantages over ICE, in terms of efficiency, noise, emission of gases, and maintenance. An EV has an electrical motor as a drive, which is powered by an electrical energy source. Most of the EVs have the capability of regenerative braking, which can reduce external energy consumption by 20% in urban areas. 1 Plug-in electric vehicles (PEVs) have to be charged regularly to satisfy the daily driving requirement. EV owner may opt for level 1 and level 2 charging at home or level 3 fast charging at public and commercial charging stations. 2,3 In uncontrolled charging, ie, during the absence of a centralised controller responsible for optimal charging of EV, EVs are charged as they arrive. Since most of the EVs arrive at home during evening hours, uncoordinated charg- ing demand from EV results in a power peak that coincides with evening peak from residential loads (i.e., lighting and home appliances). Overlapping of these two power peaks might increase the maximum demand during peak hours. 4 This increase in the energy demand has to be satisfied by additional generating units in the existing network. Electricity demand from residential customers rises with an increase in the penetration of EV. This large scale integration of EV with an existing distribution network poses several challenges for the utility. In recent years, many studies have been presented related to the impact of large scale integration of PEV on the distribution network. 5-10 Charging demand from EV can overload a distribution transformer resulting in overheating. This nonoptimal operation can deteriorate the transformer life. Some studies have tried to evaluate the impacts of EV charging on transformer loading. 11-13 EV charging affects not Int Trans Electr Energ Syst. 2019;e12226. wileyonlinelibrary.com/journal/etep © 2019 John Wiley & Sons, Ltd. 1 of 13 https://doi.org/10.1002/2050-7038.12226