A new synthetic inertia system based on electric vehicles to support the frequency stability of low-inertia modern power grids

Abstract

The increasing share of renewables into modern power systems has resulted in lower levels of existing rotational inertia accompanied by conventional generation units. This issue results in an increase in system frequency fluctuations, which leads to system deterioration and instability. To overcome the ever-decreasing issue of inertia, several endeavors in inertia emulation have been provided based on external sources of energy (e.g., energy storage systems (ESSs)). However, the high capital and running costs associated with the adoption of these sources for inertia enhancement significantly deter their wide applications. Hence, to tackle these issues, this study proposes a new synthetic inertia control (SIC) system that relies on electric vehicles (EVs) as a pre-existing energy source in low-inertia modern power grids to expand inertial emulation capability and support frequency stability. In this way, the power system inertia can be imitated by exploiting the surplus stored energy in already existing system resources (e.g., EVs) without changing system hardware, thus decreasing the ESS’s required capacity. The proposed SIC is constructed based on the derivative control technique, where it is utilized to estimate the rate of change of frequency (RoCoF) to add adequate inertia power to the power grid set-point during contingencies, thereby improving frequency stability of low-inertia systems. The usability and superiority of the suggested SIC system based on EVs are validated by comparison with the traditional frequency control system against variant load/renewables disruptions, uncertainties, and physical constraints. The simulation results verified that the suggested SIC system exhibits ameliorated system performance and reliability, which could greatly support low-inertia modern power grids against contingencies.