Flywheel-Battery Hybrid Energy Storage System Participating in Grid Frequency Regulation Based on Adaptive Inertia Emulation

Abstract

Low-inertia power system suffers from high Rate of Change of Frequency (ROCOF) and frequency deviation when facing a sudden imbalance in supply and demand. With the strategy of inertia emulation using Hybrid Energy Storage System (HESS) composed of Flywheel Energy Storage Systems (FESS) and Battery Energy Storage Systems (BESS), frequency regulation can be improved by rapid and long term power supply. In this paper, a coordinated frequency regulation control strategy for HESS is proposed. With the FESS adopting inertia emulation control strategy considering the flywheel’s own inertia and the grid frequency condition and BESS adopting droop control strategy, the ROCOF and frequency deviation are suppressed. Moreover, through coordinated control of the two types of energy storage systems (ESS), the State of Charge (SOC) of the FESS is maintained in an acceptable range, thus improving the ability of the FESS continuously participating in frequency regulation. The control strategy are promoted to the control of HESS array. Simulations are performed on the platform of MATLAB/Simulink.