To solve the lack of inertia issue, this paper proposes the method of using flywheel energy storage systems (FESSs) to provide the virtual inertia and frequency support. As compared with batteries, flywheels have a much longer lifetime and higher power density.
With a weighted score of 4.3, flywheels (with lithium–ion batteries a close second) appear as the most suitable energy storage technology to provide inertia for power systems.
Energy storage technologies have emerged as a viable alternative to providing inertia through virtual inertia, i.e. inertia generated or simulated with power electronics and controls (Zhao and Ding, 2018, Zhang et al., 2019, Fang et al., 2017a).
By regulating the speed of the flywheel in proportion to the grid frequency, the flywheel serves as an energy buffer that absorbs and releases its kinetic energy to provide inertia support. Furthermore, the design methods of the virtual inertia emulated by FESSs are described in detail.
The present work focuses on the preliminary development of a novel energy storage system that makes use of real inertia to address short term supply/demand imbalances while simultaneously allowing for extended depths of discharge. The concept looks to combine flywheel and compressed fluid energy stores in order to power a synchronous generator.
The inertia response of an energy system limits the rate of change of frequency, known as RoCoF, when a sudden change in load is encountered . Systems such as thermal energy storage and pumped hydroelectric have very little associated inertia and may be thought of as providing slow response energy storage.