Frequency performance analysis of multi-gain droop controlled DFIG in an isolated microgrid using real-time digital simulator

Abstract

With the increased share of wind power in Microgrid (MG), wind farm is expected to have significant contribution in overall grid frequency regulation. Wind farm impersonating synchronous generator with conventional droop control method may threaten the grid stability during low frequency oscillations. In this paper, synthetic inertia with a novel frequency dependent multi-gain droop control strategy is proposed to regulate wind farm for providing primary frequency response. The proposed multi-gain droop control is combined with a proportional and proportional-integral type pitch angle controller for comparative analysis. A 20% power reserve is conserved for primary frequency regulation. The influence of multi-gain parameters (power-frequency) and numerous power margin of wind farm is also examined under different contingency events. The relative performances of the proposed control scheme are investigated in a small isolated MG with 20.8% and 41%wind penetration in real-time. Simulation results show that it is possible to achieve optimum frequency control performance with the proposed multi-gain droop control scheme compared with the conventional droop control. It is also found that parameter selection for multi-gain droop control portrays significant domination on the overall frequency control outcome. Moreover, the proposed multi-gain droop method performs satisfactorily at different power margin of wind farm.

Keywords

• Dynamic multi-gain droop
• Primary frequency control
• Wind energy
• Pitch control