| Summary: | There are unique challenges and opportunities related to the integration of electric vehicles into the future power grid, especially the modern distribution grid since electric vehicle (EV) charging facilities and fast-charging stations are usually tied to low-voltage and medium-voltage power networks. The grid-connected EVs, if properly controlled, can operate as distributed energy storage and provide various ancillary services, such as peak shaving, fast-response reserve capacity, frequency regulation, voltage control and reactive supports.
The purpose of this thesis is to integrate EVs to the power grid and provides suitable ancillary services to improve the grid reliability and stability. The larger future penetration of EVs and renewable energies is also taken into account to develop the vehicle-to-grid (V2G) control scheme with the constraints of EV charging and communication infrastructures. The main contents include: V2G mathematical model and system configuration; impact evaluation of EV integration and the V2G control framework; energy scheduling of EVs integration; V2G dynamic regulation services; control method of EV aggregator for dispatching a fleet of EVs; and the evaluation of V2G control scheme and hardware-in-the-loop experimental system design.
In the thesis, the impact of EV charging demand on the conventional distribution grid is firstly estimated to reveal the negative effects of the arbitrary EV charging and the necessity to control the EV charging process. The potential benefits EVs can bring into the power grid support are discussed and a V2G control framework is proposed to perform the V2G optimization and various regulation services. The current power electronics applied EV charging facilities and communication network are integrated into the V2G operation in the future distribution grid with microgrid and smaller installation of renewable generation units.
Next, mathematical model of V2G power control is formulated. Two optimization methods are proposed to schedule the EV charging and discharging energy to minimize the power losses and the operating cost while satisfying the mobility needs and the power system limitations. Subsequently, the dynamic regulation of V2G power is investigated to unleash the potential of EVs to provide multiple ancillary services simultaneously. In addition to V2G optimal energy scheduling, EVs can also be employed for dynamic power regulation which requires the fast response to the instantaneous imbalance between the power supply and demand. V2G power is controlled to mitigate the power fluctuation caused by the intermittent wind energy resources, and thus stabilize the system frequency and voltage.
Finally, an EV-centric hybrid energy storage system is proposed, which combines the merits of V2G operation and superconducting magnetic energy storage (SMES) to enhance the power quality and system frequency stability. The critical issues in V2G applications are summarized in the end. === published_or_final_version === Electrical and Electronic Engineering === Doctoral === Doctor of Philosophy
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