Online evaluation and response characteristics analysis of equivalent inertia of a doubly-fed induction generator incorporating virtual inertia control

The introduction of virtual inertia control improves the frequency regulation ability of a DFIG. However, its manifestation of inertia depends on different control modes, resulting in different response characteristics. It is important to determine an accurate perception of its inertia level and change characteristics. In this paper, the quantitative characterization and response characteristics of the equivalent inertia of a DFIG based on virtual inertia control of rotor kinetic energy are studied. First, a simplified model of a DFIG in rotor speed timescale is established based on a virtual inertia control strategy utilizing rotor kinetic energy, and then the mathematical expression of equivalent inertia constant of the DFIG is derived theoretically. Secondly, given that there is a problem of unknown control parameters, an online evaluation method of control parameters based on adaptive extended Kalman filter is proposed. The equivalent inertia constant of the DFIG is calculated and the inertia support ability of the DFIG is quantitatively evaluated based on the measurement information of the DFIG in steady-state operation. Finally, the accuracy of the proposed method is verified on an improved 4-machine 2-area simulation system, and the simulation results show that the virtual inertia control parameters mainly affect the initial stage and recovery stage of the inertia response process, and the speed controller parameters mainly affect the recovery stage and stability stage of that process. © 2022 Power System Protection and Control Press. All rights reserved.