To address the frequency fluctuation issue caused by load mutations in the offline mode of virtual synchronous generators(VSG)and the insufficient dynamic response of traditional proportional-integral(PI)control

this paper proposes a VSG secondary frequency regulation strategy based on linear active disturbance rejection control(LADRC). First

the mathematical model of the off-grid VSG is established

and a LADRC-based frequency control scheme is designed.Its core employs a linear extended state observer(LESO)to observe and estimate the total system disturbances in real time

achieving dynamic compensation through linear state error feedback(LSEF).Finally

a simulation model is built on the Matlab/Simulink platform to conduct comparative analysis of the frequency regulation performance of PI control and LADRC under different load mutation scenarios.The simulation results demonstrate that

compared to traditional PI control

LADRC exhibits superior anti-disturbance capability and faster dynamic response speed

significantly reducing frequency fluctuations and enhancing the dynamic stability characteristics of microgrid frequency.Notably

it maintains stable control performance even under multiple continuous load disturbances. The research results provide a theoretical basis and technical reference for optimizing the frequency control strategy of off-grid VSGs

offering practical application value for improving the stability of microgrids or independent power systems.