Multi-Objective Adaptive Inertia and Droop Control Method of Wind Turbine Generators

With a higher wind power penetration level (WPPL), the inertia and droop control of wind turbine generators (WTGs) is an effective solution to the system frequency problems. In this article, a multi-objective adaptive inertia and droop control method of WTGs is proposed, considering both active frequency support and rotor speed recovery. The proposed method tunes the inertia and droop gain in accordance with the process of a frequency disturbance. The inertia gain changes based on the dynamic relation between rotor speed and system frequency, and it remains zero after the frequency Nadir (FN). The droop gain includes two variable components, one varies with the stages of a frequency disturbance considering the disturbance severity and system composition. The other is related to the releasable kinetic energy. Besides, in order to restore the rotor speed and prevent an aggravated quasi-steady-state frequency deviation, the droop gain will decrease to zero before primary control finishes. Finally, to validate the performance of the proposed method, the simulations are implemented considering different wind speeds, disturbance severities, and WPPLs. The results verify that the proposed method can adapt to different scenarios, and achieve multi- objective optimization in terms of the FN, secondary frequency dip and quasi-steady-state frequency deviation.