Contents lists available at ScienceDirect Electric Power Systems Research journal homepage: www.elsevier.com/locate/epsr Probabilistic assessment of voltage quality on solar-powered electric vehicle charging station Jorge Henrique Angelim ⁎ , Carolina de Mattos Affonso Faculty of Electrical and Biomedical Engineering, Federal University of Para, Belem, Brazil ARTICLE INFO Keywords: Plug-in electric vehicles Monte Carlo simulation Distribution system Voltage quality ABSTRACT This paper evaluates the potential benefits the connection of photovoltaic generation can bring to a commercial building with electric vehicles charging stations considering voltage quality issues. Monte Carlo simulation is applied to model system uncertainties, and uncontrolled charging Level 2 is considered. Simulations are per- formed in the modified IEEE 37 node test feeder using OpenDSS software, using real load data and meteor- ological measurements, considering the seasonality effect of photovoltaic generation. Different scenarios are analyzed, varying the size of photovoltaic generation and electric vehicles connection time. The obtained results show voltage unbalance is not a major issue when charging at Level 2. Also, the use of photovoltaic generation can potentially reduce the probability of occurrence of undervoltage problems, transformer overload and losses, according to the penetration level of photovoltaic generation and daily electric vehicles charging demand. 1. Introduction The electrification of the transport sector is expanding rapidly. According to the International Energy Agency, the global electric ve- hicles fleet reached 5.1 million in 2018, representing 2 million more compared to the previous year [1]. Plug-in electric vehicles (PEVs) need to be connected to the grid to charge their batteries and represent an additional demand to the distribution system. This additional demand affects the overall load pattern and can cause several technical issues on the system, such as transformer overload, voltage unbalance and de- viation, requiring studies that assess the impacts of these loads on distribution system [2,3]. The photovoltaic generation (PV) is one of the fastest- growing sources of energy worldwide [4]. It can be connected to low and medium voltage distributed network, integrated to PEVs charging stations, installed on rooftops of parking lots or as a solar carport, helping to reduce the stress on the grid. Several papers have been proposed in the literature based on this approach. However, PEVs charging demand is highly determined by driver's behavior. The ran- domness of PEV connection in electric power grid creates complexity on power system operation and planning through the conventional de- terministic approach. Moreover, the intermittent nature of solar energy introduces many uncertainties. Thus, there is a need to develop a probabilistic model to estimate PEVs load pattern and assess the impact solar generation can cause on voltage quality. Several papers have been published in literatures during the last years. Reference [5] proposes a probabilistic model to provide PEV charging pattern in a residential distribution network considering var- ious factors such as vehicle class, driving habit/need, battery capacity and state of charge (SOC). References [6] investigates the effect of rooftop solar generation owned by residential prosumers on reducing distribution transformer aging caused by PEVs charging demand. The results have shown that rooftop solar PV has a positive effect in redu- cing transformer loss-of-life when 100% PV penetration was considered in the residential system. In [7], authors propose a strategy to shift the phase that PEVs will be charged, so they are connected to the less loaded phase of their feeder mitigating network unbalance. Simulations are performed using a real UK residential network. Reference [8] pro- poses an analytical method for sizing PV generation in order to reduce transformer hottest-spot temperature and loss-of-life, considering a commercial building with 8 electric vehicles charging stations. Although several studies have been conducted in this area, there still lack of research analyzing the impact of uncoordinated electric vehicle charging in distribution system, particularly in commercial buildings considering charging Level 2, evaluating voltage quality as- pects in an unbalanced three-phase system. This paper presents a probabilistic analysis of the potential benefits caused by the connection of PV generation in electric vehicles charging station, on voltage de- viation and voltage unbalance of a typical distribution system. The uncertainties related from PV generation, load and PEVs are considered https://doi.org/10.1016/j.epsr.2020.106655 Received 4 October 2019; Received in revised form 18 April 2020; Accepted 1 August 2020 ⁎ Corresponding author. E-mail addresses: jorge.angelim@itec.ufpa.br (J.H. Angelim), carolina@ufpa.br (C.d.M. Affonso). Electric Power Systems Research 189 (2020) 106655 Available online 10 August 2020 0378-7796/ © 2020 Elsevier B.V. All rights reserved. T