Time-varying Inertia Estimation for Inverter-based Resources

This paper proposes a time-varying inertia estimation approach for the virtual synchronous generator (VSG) control-based inverter. A Thevenin equivalent is first employed to formulate the relationship between the terminal voltage phasor and the virtual frequency inside the VSG. This allows estimating virtual frequency directly, which is further integrated into the virtual swing equation and derived measurement function of the VSG. An improved adaptive Unscented Kalman Filter (IAUKF) is proposed to estimate the time-varying inertia. Numerical results show that, under various scenarios, the proposed inertia estimator is able to converge quickly, has high estimation accuracy, and filter out measurement noise.