The introduction of Electric Vehicle (EVs) has a great potential for the reductions of carbon emissions and air pollution. Whereas, EVs are more likely to run out of energy and need to be charged during their journeys. This is mainly due to the limited EV battery capacity and long trip distance in big cities. Practically, this concern could be substantially improved by recharging EVs' electricity at deployed public Charging Stations (CSs) during journeys. However, even if the flexibility of public CSs could be improved and adjusted following the rapid growth of EVs, major technical challenges and contributions in this chapter involve decision making intelligence for the selection of CSs as charging plans, and the provisioning communication infrastructure for secure information dissemination within network.
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As the emerging key urban infrastructures, the Smart Grid and Intelligent Transportation Systems (ITS) have been playing increasing important roles in modern cities. This enables Electric Vehicles (EVs) that are expected to be widely adopted as individual, commercial, and public vehicle fleets. The application of EVs (Schewel & Kammen, 2010) has been recognized as a significant transportation option to reduce CO2 emissions and has attracted numerous attentions from both academia and industry. It is anticipated that EVs will represent a sizeable portion of the US national transportation fleet, with around 50% of new electric car sales by 2050 (Top 10 Electric Car Makers for 2010 and 2011). However, adopting EVs will pose new challenges to the electricity grid, particularly in terms of EV charging management. For example, a large number of EVs charging demands would result in unbalanced charging load at different CSs in power grid.
In addition to the use case considering home-based EV charging overnight, recent research works have also investigated the development of public Charging Station (CSs) in order to provide charging services during EV journeys. These public CSs are typically deployed at places where there is high concentration of EVs such as shopping mall parking places. In this case, on-the-move EVs requesting charging services during their journeys have the opportunity to select the best CS for charging, e.g., to experience a minimized charging waiting time. However, due to the relatively long charging time for EVs, how to optimally manage EV charging requests has become a critical issue. This is mainly because:
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How to manage EV charging according to their requests will have strong impact on charging efficiency at the CS side. This is particularly the case where a grid operator deploys multiple CSs and aims to optimize (e.g. balance) the charging demands across them.
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In addition, individual EVs can also benefit from smart charging scheduling in order to minimize their waiting time before being served.
In general, whenever an EV on the road requires charging, it needs to communicate with the grid or other third party who is interested in charging management, in order to be aware of its charging plan. The setting of EV charging use case in smart grid also introduces some unique security challenges, e.g., in public smart charging of EVs, where the sudden availability of charge details introduces a new incentive for attacks. This requires a design of more secure, resilient, scalable, and flexible than conventional information systems.
Driven by these requirements, this chapter introduces a Publish/Subscribe (P/S) enabled communication mode, in which different stakeholders in the ecosystem (e.g. EVs, CSs and the centralized controller implementing charging management) can exchange information based on dedicated topics depending on their interest for information subscription, instead of relying on the conventional point-to-point communication system. Also, due to decoupling between publishers and subscribers through the P/S paradigm, the end-to-end connections between CSs and EVs are avoided. As a result, the system benefits from scalability (i.e., the number of connections at CS sides does not depend on the number of EVs) and efficiency (i.e., fast connection establishment and reduced bandwidth usage), as the benefits of P/S based communication between CSs and EVs against point-to-point communication.