An adaptive droop control strategy with smooth rotor speed recovery capability for type III wind turbine generators

Abstract

This paper presents an adaptive droop control scheme with smooth rotor speed recovery capability for doubly-fed induction generators (DFIGs, type III wind turbine generators) to improve the frequency nadir, minimize the second drop in the frequency, and regulate the time to meet the MPPT curve. To this end, an adaptive droop gain that decays with time is proposed, the initial value of which determined according to the wind speed. The effectiveness of the proposed adaptive droop control scheme is verified using a modified IEEE 14-bus system under various wind speeds, wind power penetration levels, and variable wind speed conditions. Simulation results in EMTP-RV indicate that the proposed adaptive droop control scheme is beneficial to improving the frequency nadir, preventing DFIGs from stalling, and minimizing the second drop in the frequency under various conditions.