EV Users Research Articles

Clustering algorithms applied to usage related segments of electric vehicle charging stations

Abstract Here, a data set collected within the large network of charging stations located in one of the electromobility leading countries the Netherlands, is analysed. The data set consists of more than one million charging transactions that took place in more than 1700 charging stations in the time period of four years. Clustering algorithms such as k-means, dbscan and agglomerative hierarchical clustering are applied to identify usage related segments of charging stations. The selection of features was made based on main classes of factors that are expected to define the use of charging stations (e.g. popularity, temporal characteristics, utilization). The resulting segments of charging stations are compared and interpreted. Better understanding of the charging behaviour of EV users can help improving planning of charging infrastructure and exploitation of smart charging technologies.

Location Planning of Electric Vehicle Charging Station

The development of electric vehicles is not in harmony with the construction of charging facilities. In the development of electric cars, there is a general focus on the development and renewal of vehicles. But not too concerned about the construction of charging facilities, resulting in the phenomenon of cars without piles and piles without cars. The large-scale construction of charging facilities is a prerequisite for the popularization and application of electric vehicles. In the construction of charging facilities, location and capacity is an essential part. Reasonable planning of charging facilities can not only improve the convenience of EV users charging. It can also speed up the promotion and development of electric vehicles. It is of great significance to solve the problems of energy shortage and environmental pollution in China.

Optimal Planning of Charging for Plug-In Electric Vehicles Focusing on Users’ Benefits

Many electric vehicles’ (EVs) charging strategies were proposed to optimize the operations of the power grid, while few focus on users’ benefits from the viewpoint of EV users. However, low participation is always a problem of those strategies since EV users also need a charging strategy to serve their needs and interests. This paper proposes a method focusing on EV users’ benefits that reduce the cost of battery capacity degradation, electricity cost, and waiting time for different situations. A cost model of battery capacity degradation under different state of charge (SOC) ranges is developed based on experimental data to estimate the cost of battery degradation. The simulation results show that the appropriate planning of the SOC range reduces 80% of the cost of battery degradation, and the queuing theory also reduces over 60% of the waiting time in the busy situations. Those works can also become a premise of charging management to increase the participation. The proposed strategy focusing on EV users’ benefits would not give negative impacts on the power grid, and the grid load is also optimized by an artificial fish swarm algorithm (AFSA) in the solution space of the charging time restricted by EV users’ benefits.

Planning of electric vehicle charging station based on queuing theory

EV charging station is a very important link in urban planning, and the design of the position and capacity of charging stations are not only to meet the public demand for traveling, but also to maintain the stability of operation and management in power grid. Considering the non-simultaneity and randomness of the EVs arriving at the charging station, the capacity of EV charging stations is calculated by using queuing theory in this study. This study proposes a model which has considered the EVs' charging requirement, economy, and power grid safety to solve the problem of planning EV charging station. Firstly, determine the location of charging station by traffic satisfaction. Secondly, the EV charging stations' charging capacity is optimized with the minimum cost as the optimization target, with the EV user' waiting time patience limit and the distribution network running safety as the constraint condition. Finally, the service area of charging station is divided by the Voronoi diagram. In this study, a 25_nodes traffic network with 24_nodes distribution network underground is modelled in the MATLAB environment to demonstrate the effectiveness of the proposed method. In addition the authors solve the model by the genetic algorithm in MATLAB.

An Anonymous Authentication Scheme for Vehicle-to-Grid Networks

Vehicle to grid technology allows bidirectional energy exchange between electric vehicles and the power grid for achieving many known benefits. However, V2G networks suffer from certain security threats, such as EV’s privacy and authentication problem. In this paper, we propose an anonymous group authentication scheme for V2G communications. This scheme realizes dynamic joining and revocation of EVs, and greatly reduces the overhead of EV revocation. Through the theoretical analysis, this scheme can ensure identity privacy of EV user and security of data transmission in the process of charging and discharging.

A discrete two-level model for charge pricing of electric vehicles based on evolution game theory

According to the present vehicle-to-grid situation and existing pricing strategy in China, this paper proposed a two-level evolution game model for pricing analysis problem. The model contains two level game models: the up level game operated between monopoly electricity sale enterprise and small electricity sale enterprise; the second level is game between electricity sale enterprise and EV user; a pay-off matrix in ternary nonlinear equation form is built to descries the evolution process under different strategies. After the Linearization of nonlinear equations, the evolution stable strategy (ESS) is deduced for evolution game model. Analysis work is carried out depending on the ESS. Finally, the numerical results are given by computer simulation. Several suggestions of pricing strategies in China’s electricity market are obtained.

Evaluation of a PV Powered EV Charging Station and Its Buffer Battery

This research analyses the operation of a solar PV powered electric vehicle charging station with energy storage that has been developed and demonstrated at the University of California – Davis, West Village, the largest planned zero-energy consumption community in the U.S. The intelligent energy management approach introduces solar PV electrical energy forecasting and EV charging demand projection to optimize the state of charge (SOC) of the buffer battery. The charging station has been operated continuously and routinely used by several EV users for a year. The actual operation shows that a workplace charging station equipped with a buffer battery and with intelligent energy management can lower and reduce the station’s peak power demand and reduce the energy exchange with the utility grid by a factor of 2. The battery recharging power demand was shifted away from the on-peak time periods to the off-peak time periods, which will benefit the charging station owner from less energy use during peak periods when time-of-use rates are higher. The standard cell voltage deviation of the 220 cells was calculated to analyse the battery cell consistency during the resting, charging, and discharging periods. The analysis shows that the 220 50Ah cells show excellent voltage consistency with voltage deviation of less than 0.005 V within the battery SOC of 20-80%. The voltage deviation doubles when the battery SOC reaches 90%. The comparison of cell voltage deviation at the beginning and after one year operation indicates that the battery shows perfect cell voltage consistency and there is no obvious consistency deterioration during the battery resting, charging and discharging periods.

Norwegian electric car user experiences 2014

The Norwegian Electric Vehicle Association has for the three last years conducted an EV user survey among their members and other EV users and owners in Norway. The survey shows that nearly 100 % of the Norwegian EV owners are satisfied with their electric car. And for every satisfied EV owner, there will be three more. The main conclusion from the Norwegian experience to start a sustainable market for EVs, is that the purchase price for an EV must be competitive with a similar car model. In Norway, this is achieved with a combination of high taxes on cars with high emissions and zero tax for zero emissions cars. Because of the policy, Norway has the highest number of electric cars per capita in the world. By January 2015, Norway reached 40,000 electric cars in a country of 5 million inhabitants. In Norway, about 12 % of all new cars sold in 2014 were electric. Over 1.5 % of 2.5 million cars in Norway are now electric. Norway is a frontrunner in the EV market.

An Efficient Power Plant Model of Electric Vehicles for Unit Commitment of Large Scale Wind Farms

An efficient power plant model of electric vehicles (E-EPP) considering the travelling comfort levels of EV users is developed to investigate the contribution of EVs on the unit commitment (UC) of large scale wind farms. Firstly, a generic EV battery model (GEBM) is established considering the uncertainties of battery parameters. Then, a Monte Carlo Simulation (MCS) method is implemented within the E-EPP to obtain the available response capacity of EV charging load over time. And a UC strategy using the E-EPP based on power flow tracing is developed. Finally, a modified IEEE 118-bus system integrated with wind farms is used to verify the effectiveness of the E-EPP for the UC of large scale wind farms.

Norwegian electric car user experiences

Norway has the highest number of electric cars per capita in the world. In June 2013, Norway reached 13,000 electric cars in a country of five million inhabitants. The experiences from the members of The Norwegian Electric Vehicle Association can give decision makers valuable input. In this paper, we present and analyse the results from the 2012 and 2013 Norwegian electric car user survey. In the 2013 survey, 1,858 EV users contributed with their experiences and opinions. The typical Norwegian EV user is a middle–aged family father with higher education and income, and he owns a Nissan LEAF as one of two cars. He drives his electric car on a daily basis instead of a traditional petrol or diesel car. In order to get more people to buy an electric car, the EV users highlight longer range and predictable EV policy as the two most important requirements.

Electric vehicle parking in European and American context: Economic, energy and environmental analysis

The transportation sector faces increasing challenges related to energy consumption and local and global emissions profiles. Thus, alternative vehicle technologies and energy pathways are being considered in order to overturn this trend and electric mobility is considered one adequate possibility towards a more sustainable transportation sector.In this sense, this research work consisted on the development of a methodology to assess the economic feasibility of deploying EV charging stations (Park-EV) by quantifying the tradeoff between economic and energy/environmental impacts for EV parking spaces deployment. This methodology was applied to 4 different cities (Lisbon, Madrid, Minneapolis and Manhattan), by evaluating the influence of parking premium, infrastructure cost and occupancy rates on the investment Net Present Value (NPV). The main findings are that the maximization of the premium and the minimization of the equipment cost lead to higher NPV results. The NPV break-even for the cities considered is more “easily” reached for higher parking prices, namely in the case of Manhattan with the higher parking price profile. In terms of evaluating occupancy rates of the EV parking spaces, shifting from a low usage (LU) to a high usage (HU) scenario represented a reduction in the premium to obtain a NPV=0 of approximately 14% for a 2500€ equipment cost, and, in the case of a zero equipment cost (e.g. financed by the city), a NPV=0 was obtained with approximately a 2% reduction in the parking premium. Moreover, due to the use of electric mobility instead of the average conventional technologies, Well-to-Wheel (WTW) gains for Lisbon, Madrid, Minneapolis and Manhattan were estimated in 58%, 53%, 52% and 75% for energy consumption and 66%, 75%, 62% and 86% for CO2 emissions, respectively.This research confirms that the success of deploying an EV charging stations infrastructure will be highly dependent on the price the user will have to pay, on the cost of the infrastructure deployed and on the adhesion of the EV users to this kind of infrastructure. These variables are not independent and, consequently, the coordination of public policies and private interest must be promoted in order to reach an optimal solution that does not result in prohibitive costs for the users.

Research of Electric Vehicles' Discharging Price

Through the vehicle to the network (V2G) control, the objective of the "load shifting" is possible. Reasonable charging and discharging price is the fundamental driving force for EV users to participate in V2G and the analysis of the game process of the grid company and the EV users becomes critical. A bilevel programming problem is established which makes company the largest gains and consumers the minimum cost. Through a control scheme whose purpose is minimizing the sample variance of load, the relationship of annual discharging electricity energy and peak load decrement is obtained. At last the optimal discharging price of power grid company and the corresponding proportion of EV participating in V2G is calculated by chaos algorithm. It provides a reference for company to formulate discharging price.

Effective Measures for Load Leveling of EV Charging Considering Convenience of EV Users

Effective Measures for Load Leveling of EV Charging Considering Convenience of EV Users

Global Service Provider for Electric Vehicle Roaming

Due to the rising number of electromobility business entities (electric vehicle supply equipment operators and electromobility service providers), electric vehicle users are faced with a growing complexity in the use of public charging infrastructure, especially on a greater geographical scale. The development of electromobility calls for interoperability between all electromobility entities in order to enable roaming of EV users and remove the present barriers in EV users’ access to the public charging infrastructure. The paper describes the elementary processes related to EV charging (charging, reservation of charging spot, billing of charging service fee), the roles of electromobility entities in these processes, and their importance for the development of the roaming system. ETREL has developed an integrated roaming solution introducing a new entity, the global service provider, which mediates between the electromobility entities to enable roaming. The paper discusses the architecture and functionalities of the roaming scheme which comprises the global service provider. The paper also describes individual elements of the global service provider’s ICT system. The EV charging processes are explained again, this time in relation to roaming and with a focus on global service provider’s role in the processes. The final section of the paper proposes further steps to expand the roaming scheme functionalities and its geographical scope, where standardization or at least an agreement on ICT interfaces, application level protocols, and software services plays the key role.

Real-time push middleware and mobile application for electric vehicle smart charging and aggregation

This paper presents a real-time push middleware and mobile application for data and multimedia content delivery to enable electric vehicle smart charging and aggregation. Intelligent aggregation and charge scheduling software can leverage the battery capacity of an EV to level peak loads by delaying or throttling charging during peak loads, 'valley fill' during off-peak times, and contribute to demand response and spinning reserves by sending electricity into the grid. EV users are updated on the status of their vehicle and may set their charge parameters via web or native mobile application. Facility and utility operators can monitor and control garage and microgrid status through a separate web or mobile application. The content to facilitate aggregated smart charging and monitoring may come from a variety of sources including web servers, ftp servers, Bluetooth or Zigbee or other protocol sensors, and local or remote databases. The middleware will accept content upload and database storage, securely provide content to outside entities, match content to user subscriptions, use user context including connection speed, device type, and location to deliver appropriately formatted content, and provide a reliable mechanism for push content delivery to a multitude of devices including mobile phones and tablet.

V2G Reserve Power Supply Coordination Based on CVaR Model

this paper establishes the revenue functions of both electric vehicle users(EV users) and power company, further analyzes users’ intention to reserve power and the feed-in tariff strategy of power company with CVaR criterion, for better V2G( vehicle to grid) reserve power supply coordination. The simulation shows that the users tend to reserve a specific quantity of power which is equal to the expected lowest reverse power supply in the condition of high risk aversion degree; however it will increase with the rise of feed-in tariff when the degree is low. In addition, the double marginalization which occurs in the reverse supply chain of V2G reserve power results in that the optimal reserve power of users cannot achieve the maximum mutual profit, in decentralized decision mode. Therefore two different coordination strategies for users with different risk aversion are proposed in this paper.

Allowing for Off-Peak Price Incentives to Reduce Electric Vehicle Distribution Grid Congestion

Maryland legislators have set in motion financial investments, tax incentives and Public Service Commission directives to encourage and accommodate electric vehicle market expansion in the state. To combat potential capacity reliability disruptions caused by EVs, electric utilities must begin to design residential electricity price signals that will incentivize EV users to plug in their vehicles off-peak, where demand congestions are least likely to occur.

The pricing of charging for electric vehicles in China—Dilemma and solution

The number of electric vehicles in China is expected to grow rapidly, triggering the nationwide large-scale construction of charging stations. At the same time, a reasonable charging price has not been established. This article records the views of station operators and EV users and calculates a charging pricing range. The price should not only ensure the profit of operators, but also help reduce EV users’ expenditure compared to using internal-combustion-engine vehicles. Based on current energy prices and battery costs, charging stations are unable to make profit, and the pricing shortfall is up to 0.78 RMB yuan(kWh) −1. Only with a 25% increase in energy price or 25% reduction in battery cost can charging stations become profitable. Several suggestions are proposed to improve station profits. First, ensuring a high station load is helpful to increase profits, and it is estimated the reasonable number of chargers in Beijing is approximately 6000, distributed among 672 stations. Second, the use of storage batteries for on/off-peak electricity self-management can also increase the annual profit by 600,000 RMB yuan. In addition, other methods like a jointed station alliance, multiple energy supplement approaches, vehicle-to-grid technology and state subsidy can also accelerate the development of the charging service industry.