Supervisor:
Zhe Chen

Co-Supervisor:
Yanbo Wang

Assessment Committee:
Sanjay Chaudhary (Chair)
Professor Vinko Lesic, University of Zagreb Faculty of Electrical  Engineering and Computing
Professor Giambiatti Gruosso. Politecnico di Milano

 

Moderator:
Dao Zhou

Abstract:

In the global effort to reduce carbon emissions, the development of electric vehicles (EVs) and renewable energy sources (RESs) has been significantly promoted. However, the rapid growth of EV and the extensive integration of RESs into the power grid have introduced several challenges. Firstly, power grids are increasingly stressed by the integration of intermittent RESs and the high penetration of EVs. Therefore, the flexible back-up energy sources, such as energy storage system (ESS) and EVs with vehicle-to-grid (V2G) capacity, should be investigated to support grid. Secondly, the additional power flow for V2G can accelerate the degradation of EV battery, affecting the battery lifespan and V2G efficiency. Therefore, the efficient and economical V2G solution considering the EV battery health should be developed. Thirdly, the expansion of EVs has outpaced the development of corresponding charging infrastructure. Due to the limitations of fixed charging stations, including limited availability, high installation costs, and uneven geographic distribution, more flexible and accessible charging solutions need to be developed. Therefore, this Ph.D. project focuses on the modeling and optimal management of integrating ESS and EVs into modern power grids, with an emphasis on developing the flexible, efficient, and economical solution for microgrids with high EV penetration.

Considering EV battery health, this project proposes an advanced EMS for EV aggregators in a V2G-integrated microgrid. The strategy aims to mitigate battery degradation while optimizing V2G efficiency. By incorporating a battery aging model into the EMS, the approach minimizes overall battery capacity loss. The EMS is modeled as a MDP and utilizes a DDPG agent to dynamically adjust V2G power sharing based on the real-time states of EVs. Furthermore, a hierarchical utilization strategy for EV batteries is presented under the proposed two-stage control framework for grid frequency regulation and peak shaving. During the first stage of energy management, the Walrus Optimization Algorithm is employed to minimize operational costs. In the second stage, a DDPG agent adaptively regulates power sharing among energy storage systems based on the condition of retired batteries. This dual-stage approach offers a practical solution for cascading EV battery usage, thereby improving both sustainability and cost efficiency.

For the development of flexible charging and V2G solutions, this Ph.D. project proposes a novel concept known as the smart mobile power bank (SMPB), which combines grid-friendly V2G functionality with an MC. The system structure, operation modes, and control framework of SMPB are explored. To enhance the utilization of SMPB, a multi-mode management scheme for SMPBs is developed, focusing on their routing and scheduling within a coupled power-transportation network. A temporal–spatial model is formulated to facilitate the efficient movement and operation of SMPBs by integrating functionalities such as mobile charging, green hydrogen production, and mobile V2G operations. Additionally, a comprehensive economic analysis is conducted to assess the feasibility and benefits of deploying SMPBs in various scenarios.

The key contributions of this project can be summarized as follows. (1) An EV-friendly EMS for EV aggregator in a V2G-integrated microgrid is proposed. (2) A novel EMS framework is proposed for hierarchical utilization of EV battery, which can improve the battery economics. (3) The concept, system structure and control framework of SMPB is proposed. The multi-mode temporal–spatial model is proposed to facilitate the routing and scheduling of SMPBs. Overall, the results of this thesis provide several flexible, efficient, and economical V2G solutions for microgrids with high EV penetration.