Consensus Algorithm-Based Two-Stage Frequency Regulation Strategy With EVs Participating as VSMs

Isolated grids, with large-scale intermittent renewable energy sources (RESs), face more severe frequency stability issues. Fortunately, grid-connected electric vehicles (EVs) present an opportunity to provide frequency services. In this paper, a two-stage frequency regulation strategy, in which EVs participate in the form of a virtual synchronous machine (VSM), is proposed. First, a frequency response (FR) model is established for both charging stations (CSs) and battery swapping stations (BSSs) using VSM control. On this basis, a two-stage strategy is proposed to consider both frequency regulation performance and system economy. Specifically, in the day-ahead stage (DAS), a multi-unit economic dispatch (ED) model is designed to formulate the operation plan; in the real-time stage (RTS), a consensus-based power allocation strategy is designed for multi-units, responsive to real-time market prices. Case studies involving real-world data of load, RES, and CS illustrate the key benefits of the proposed method, including (i) decreasing frequency deviation, (ii) providing extra rotational inertia, and (iii) reducing dispatch costs.