Thesis Examination Committee
Prof Chin-Tau LEA, ECE/HKUST (Chairperson)
Prof Danny TSANG, ECE/HKUST (Thesis Supervisor)
Prof James SHE, ECE/HKUST
With the increasing load from the integration of electric vehicles (EVs) and the increasing uncertain supply from renewable energy sources (RES), it becomes increasingly challenging to maintain the reliability and stability of the power system, especially for its most vulnerable part, namely, the distribution network. Therefore, a larger amount of ancillary services are needed. Ancillary services are those services to balance the demand and supply so as to maintain the reliable operations of the power system. Leveraging the deferrable property and charging flexibilities of EVs, we propose to coordinate the charging power of EVs in the demand side to provide ancillary services. In doing so, the distribution system operator (DSO) can not only reduce energy costs and avoid overload of gird components, but also gain profits for providing ancillary services.
In this thesis, we aim to minimize the net cost of the DSO by coordinating the charging of EVs to provide multiple ancillary services simultaneously in an optimal way. Specifically, in the first part of the thesis, we design a two-step strategy to provide frequency regulation and valley filling services jointly by coordinating the active charging power of EVs in distribution networks. Simulation results prove the feasibility and performance of the proposed strategy. In addition to controlling the active charging power of EVs, we can also utilize EVs to provide reactive power for voltage regulation, thanks to the recent advance of the EV charger technology. Thus in the second part of the thesis, we propose a joint voltage and frequency regulation strategy by coordinating both the active and reactive power of EVs in distribution networks. The effectiveness and performance of the proposed strategy are demonstrated by numerical simulations as well.