Emergency control strategy for island microgrids based on fault early warning

Abstract For island microgrids, droop-based primary control often introduces frequency/voltage errors, which are usually corrected by a microgrid central controller (MGCC) in the secondary control. In this paper, an emergency control strategy is proposed and integrated into MGCC based on fault early warning, which can accelerate response speed and reduce fluctuation amplitude during severe disturbances. The first component is an emergency controller based on the rate of change of frequency (RoCoF) and voltage (RoCoV), incorporating additional compensatory signals into the proportional-integral (PI) control loop to enable rapid response to disturbances. The second component is another emergency controller designed to proactively detect abnormal switch operations in critical equipment, implementing feedforward compensation to prevent fault propagation. Simulations conducted in MATLAB/Simulink validate the efficacy of the proposed method, showing substantial reductions in system response time and enhanced stability of microgrid operations.