Fast Frequency Regulation Strategy for Improving Frequency Stability of Off-grid Microgrid

Due to the weak inertia and large power fluctuation of off-grid microgrid, the frequency regulation capacity of main power supply is insufficient when large power disturbance happens, which can easily cause system frequency instability. To improve the transient frequency stability of off-grid microgrid, a fast frequency regulation strategy considering secondary frequency regulation is proposed. Firstly, the frequency range of off-grid microgrid under primary / secondary frequency regulation is analyzed. Secondly, the control behavior and frequency characteristics of the main power supply under large disturbance are further studied by simulation. On this basis, the influence of secondary frequency regulation is analyzed. In the control strategy, the frequency range is dynamically divided by microgrid coordination controller. The output power of constant power supply can be regulated quickly and the emergency frequency regulation of the main power supply is applied to improve the stability of transient frequency. Finally, the effectiveness and feasibility of the strategy are verified by RTDS hardware in the loop test.