Integration of electric vehicles and management in the internet of energy

Abstract

Due to the environmental and energy crisis, many countries around the world are electrifying transportation, which will significantly change the way the current power grid operates. It is expected that the deployment of future smart grids will allow two-way energy and information flows through plug-and-play operation of small distributed mobile power generators like electric vehicles (EVs) to benefit the prosumers and at the same time make the grid more efficient and robust. However, the issues associated with the energy and information transfer, battery technologies, battery charging schemes, their standards and management need to be addressed in order to achieve the full benefits of EV integration in the future smart grids and internet of energy (IoE) with local renewable generation. As the current grid with existing infrastructure cannot ensure maximum benefits from EVs, this paper reviews the EV technologies, their connectivity, impacts on grid and standards required for the efficient and economic operation of EVs with distributed energy resources in the IoE. The evolution, comparison, and storage potential of EV technologies are thoroughly discussed. This paper also extensively reviews the connectivity issues, for example current EV charging schemes, software tools required to design smart charging, associated challenges, and possible solutions. The architecture of distributed energy management schemes with EVs and the IoE is discussed in detail. Finally, the standards related to EV integration, energy transfers, and safety aspects are provided. Based on the comprehensive review, future directions are put forward which will be useful for researchers and engineers working with EVs.

Introduction

The future smart grid, alternatively known as the internet of energy (IoE) is expected to be more decentralized and disaggregated, which could fundamentally shift the way power has traditionally been generated, transmitted, or distributed. A significant amount of the future power demand will be generated from renewables, and some loads will be mobile, such as electric vehicle (EV), electric boat, and electric ship [1], [2], [3]. The current development of electric vehicles’ bidirectional energy transfer through vehicle-to-grid (V2G), and their expected penetration in the IoE, introduces a promising feasibility to exchange energy between vehicle and grid. This bidirectional energy transfer could potentially bring a benefit in emission reduction and optimal renewable energy integration [1]. However, potential challenges arise in managing EVs in smart grids through V2G, for example the location where EVs connect to the grid, grid load conditions, EV supply equipment management, EV battery management, powertrain, charging level, charging type, charging timing and charger topology [2].

Various segments of the IoE, such as consumers and utilities, are also actively involved in the V2G system, either economically or technically. In both charging and discharging of EVs from/to the grid, it is required to consider the grid load conditions to ensure a reliable power supply with maximum economic benefits. The coordinated charging-discharging of EVs can potentially contribute to both power quality and economy [3]. To control the bidirectional energy transfer through charging-discharging, bidirectional information transfer among the devices and controllers is mandatory. By ensuring reliable information exchange among EVs, utilities, charging stations, and controllers, their impacts on the grid can be minimized while maintaining power quality.

In the future IoE, every device will be connected as plug-and-play like the USB in computers without reengineering the original systems [90]. Any energy device or consumer will be a prosumer, and will either sell or consume energy depending on the grid and economic conditions. Therefore, it is expected that in the near future a number of energy devices like EVs will penetrate largely on the internet of energy [2]. At the same time, the need to manage all these energy devices by controlling their bidirectional energy flow along with a bidirectional information flow will be a great challenge.

Although most renewable energy devices and EVs are integrated to the system through plug-and-play, they still need to maintain different standards prescribed by different organizations such as SAE, IEEE, ISO, IEC etc. [24]. Currently, different regions follow different EV charging standards, which will be a barrier for the plug-and-play operations of the IoE. The exponential rise of EVs demands the development of new charging stations, reliable communication technologies, and robust control algorithms to integrate and manage them in the IoE. Considering all the facts and challenges of the present power grid and the future IoE, this review paper describes various aspects related to the EV’s integration and management in the IoE. The key contributions of this paper are: (1) to analyze the EV’s integration in smart grids, specifically on the charging and discharging issues, (2) to evaluate the benefits, technical and economic feasibility of EV storage, (3) to analyze the EV’s management in smart grids (4) to provide new insights in distributed energy management, (5) to provide an outlook of the standards of EV integration to grid, and (5) to review the software tools required for analyzing the effects of EVs on smart grids. All these contributions of the paper are focused on three main topics, (I) EV technology, (II) EV connectivity to the grid, and (III) EV management in the IoE. A pictorial representation of the total outline of the paper is in Fig. 1.

The organization of the rest of the paper is as follows.

Section 2 highlights the EV technology. The main focus of these highlights are to discuss the challenges of EV technology, comparison between EV technologies, evolution and powertrain of EV technologies, and storages of EV technology.

Section 3 focuses on the EV’s connectivity to the grid. The major ideas covered in this section are EV charging schemes, EV charging options, charger topologies, charging station location solutions, and challenges and potentialities of the EV’s integration to the grid.

Section 4 discusses the EV’s integration management to the grid. The key points in this section are the evolution and characteristics of power grids, management of the EV’s connectivity to the grid, energy management in the IoE, power flow management in the IoE, information flow management in the IoE, and energy management recommendations.

5 Standards of different levels of EV modeling and interconnection to smart grid, 6 Tools to analyze the EV’s integration and management to grids discuss the standards and computational tools required to model and analyze the EV’s integration to the IoE.