Secure Large Scale Penetration of Electric Vehicles in the Power Grid

As part of the approaches used to meet climate goals set by international environmental agreements, policies are being applied worldwide for promoting the uptake of Electric Vehicles (EV)s. The resulting increase in EV sales and the accompanying expansion in the EV charging infrastructure carry along many challenges, mostly infrastructure-related. A pressing need arises to strengthen the power grid to handle and better manage the electricity demand by this mobile and geo-distributed load. Because the levels of penetration of EVs in the power grid have recently started increasing with the increase in EV sales, the real-time management of en-route EVs, before they connect to the grid, is quite recent and not many research works can be found in the literature covering this topic comprehensively. In this dissertation, advances and novel ideas are developed and presented, seizing the opportunities lying in this mobile load and addressing various challenges that arise in the application of public charging for EVs. A Bilateral Decision Support System (BDSS) is developed here for the management of en-route EVs. The BDSS is a middleware-based MAS that achieves a win-win situation for the EVs and the power grid. In this framework, the two are complementary in a way that the desired benefit of one cannot be achieved without attaining that of the other. A Fuzzy Logic based on-board module is developed for supporting the decision of the EV as to which charging station to charge at. GPU computing is used in the higher-end agents to handle the big amount of data resulting in such a large scale system with mobile and geo-distributed nodes. Cyber security risks that threaten the BDSS are assessed and measures are applied to revoke possible attacks. Furthermore, the Collective Distribution of Mobile Loads (CDML), a service with ancillary potential to the power system, is developed. It comprises a system-level optimization. In this service, the EVs requesting a public charging session are collectively redistributed onto charging stations with the objective of achieving the optimal and secure operation of the power system by reducing active power losses in normal conditions and mitigating line congestions in contingency conditions. The CDML uses the BDSS as an industrially viable tool to achieve the outcomes of the optimization in real time. By participating in this service, the EV is considered as an interacting node in the system-wide communication platform, providing both enhanced self-convenience in terms of access to public chargers, and contribution to the collective effort of providing benefit to the power system under the large scale uptake of EVs. On the EV charger level, several advantages have been reported favoring wireless charging of EVs over wired charging. Given that, new techniques are presented that facilitate the optimization of the magnetic link of wireless EV chargers while considering international EMC standards. The original techniques and developments presented in this dissertation were experimentally verified at the Energy Systems Research Laboratory at FIU

Challenges and Barriers of Wireless Charging Technologies for Electric Vehicles

Electric vehicles could be a significant aid in lowering greenhouse gas emissions. Even though extensive study has been done on the features and traits of electric vehicles and the nature of their charging infrastructure, network modeling for electric vehicle manufacturing has been limited and unchanging. The necessity of wireless electric vehicle charging, based on magnetic resonance coupling, drove the primary aims for this review work. Herein, we examined the basic theoretical framework for wireless power transmission systems for EV charging and performed a software-in-the-loop analysis, in addition to carrying out a performance analysis of an EV charging system based on magnetic resonance. This study also covered power pad designs and created workable remedies for the following issues: (i) how power pad positioning affected the function of wireless charging systems and (ii) how to develop strategies to keep power efficiency at its highest level. Moreover, safety features of wireless charging systems, owing to interruption from foreign objects and/or living objects, were analyzed, and solutions were proposed to ensure such systems would operate as safely and optimally as possible

Towards electric bus system: planning, operating and evaluating

The green transformation of public transportation is an indispensable way to achieve carbon neutrality. Governments and authorities are vigorously implementing electric bus procurement and charging infrastructure deployment programs. At this primary but urgent stage, how to reasonably plan the procurement of electric buses, how to arrange the operation of the heterogeneous fleet, and how to locate and scale the infrastructure are urgent issues to be solved. For a smooth transition to full electrification, this thesis aims to propose systematic guidance for the fleet and charging facilities, to ensure life-cycle efficiency and energy conservation from the planning to the operational phase.One of the most important issues in the operational phase is the charge scheduling for electric buses, a new issue that is not present in the conventional transit system. How to take into account the charging location and time duration in bus scheduling and not cause additional load peaks to the grid is the first issue being addressed. A charging schedule optimization model is constructed for opportunity charging with battery wear and charging costs as optimization objectives. Besides, the uncertainty in energy consumption poses new challenges to daily operations. This thesis further specifies the daily charging schedules with the consideration of energy consumption uncertainty while safeguarding the punctuality of bus services.In the context of e-mobility systems, battery sizing, charging station deployment, and bus scheduling emerge as crucial factors. Traditionally these elements have been approached and organized separately with battery sizing and charging facility deployment termed planning phase problems and bus scheduling belonging to operational phase issues. However, the integrated optimization of the three problems has advantages in terms of life-cycle costs and emissions. Therefore, a consolidated optimization model is proposed to collaboratively optimize the three problems and a life-cycle costs analysis framework is developed to examine the performance of the system from both economic and environmental aspects. To improve the attractiveness and utilization of electric public transportation resources, two new solutions have been proposed in terms of charging strategy (vehicle-to-vehicle charging) and operational efficiency (mixed-flow transport). Vehicle-to-vehicle charging allows energy to be continuously transmitted along the road, reducing reliance on the accessibility and deployment of charging facilities. Mixed flow transport mode balances the directional travel demands and facilities the parcel delivery while ensuring the punctuality and safety of passenger transport

Smart Grid Communications: Overview of Research Challenges, Solutions, and Standardization Activities

Optimization of energy consumption in future intelligent energy networks (or Smart Grids) will be based on grid-integrated near-real-time communications between various grid elements in generation, transmission, distribution and loads. This paper discusses some of the challenges and opportunities of communications research in the areas of smart grid and smart metering. In particular, we focus on some of the key communications challenges for realizing interoperable and future-proof smart grid/metering networks, smart grid security and privacy, and how some of the existing networking technologies can be applied to energy management. Finally, we also discuss the coordinated standardization efforts in Europe to harmonize communications standards and protocols.Comment: To be published in IEEE Communications Surveys and Tutorial

Enhancement of Inductive Power Transfer Technology: Iron-based Nanocrystalline Ribbon Cores

Inductive power transfer (IPT) has been studied extensively during the last decades, particularly for electric vehicle chargers (EV). Inductive chargers offer several advantages over standard plug-in ones. First, they reduce user interaction increasing comfort and mitigating safety concerns. Furthermore, they allow for the automation of the charging process and the implementation of opportunity charging schemes. Thus, distributed charging points can be deployed in strategic locations — such as traffic lights, public and private parking places, etc.— and EVs can be charged more frequently. This reduces the depth of discharge of the battery and increases its lifespan. Furthermore, IPT systems with bidirectional power flow can facilitate the adoption of vehicle-to-grid schemes (V2G). IPT technology is reaching a mature state. Nevertheless, several aspects of the technology can still be improved. First, the state-of-the-art systems are sensitive to misalignments between the transmitter and receiver pads. Second, the complete standardization of the pad's design has not yet been achieved. Consequently, the interoperability of systems designed by different manufacturers is not yet guaranteed. Third, the detection of foreign objects between the pads is a problem that has not been completely solved. Last, the power density of the pads can still be improved. Pads are generally large and heavy which hinders the adoption of this technology. This dissertation addresses some of these problems in an attempt to enhance the state-of-the-art of IPT technology. The largest portion of this thesis is dedicated to the study of alternative core materials for IPT charging pads. In particular, nanocrystalline ribbon cores are considered a promising material. This material offers a higher saturation flux density, a higher permeability, superior thermal performance, and mechanical robustness compared to the standard MnZn ferrites commonly used in IPT systems. A feasibility analysis of this material was carried using intricate finite element models and experimental measurements. The analysis concluded that higher power densities can be effectively achieved with nanocrystalline ribbon cores. However, eddy-current losses on the outer/lateral faces of the cores were identified as problematic. This motivated a new design approach in which the unique properties of this material were considered during the design stage. Guidelines for the design of nanocrystalline ribbon cores were derived. These were applied to the design of a WPT3, 11 kW pad. These pads showed superior performance as compared to identical pads with ferrite cores. Pads with nanocrystalline cores were 2% more efficient and achieved an 11% higher coupling factor. Likewise, up to 25%, lower flux leakage was obtained. Moreover, their performance concerning temperature variation outperformed the one from ferrite cores both in heat dissipation and thermal stability. Finally, the pads were tested near magnetic saturation. Nanocrystalline cores were able to transfer more power before reaching this point. Thus, higher power densities were achieved with this material. Finally, methods for reducing the eddy-current losses in the system were tested. Ferrite shielding, in particular, was found to be an effective method to improve efficiency and homogenize the temperature distribution within the core. As a minor contribution, a control strategy that uses the dual-resonant frequency characteristic of LCCL-compensated pads is also presented. This strategy was validated experimentally, and it can be used to increase the power transfer capability of pads under misaligned conditions. Moreover, this strategy can ease the interoperability of IPT pads designed by different makers which have different ratings and dimensions