Interaction Stability Analysis between the Grid and the Voltage Source Controlled Direct-Driven Wind Turbine with Energy Storage

To address the issues of lacking frequency regulation and susceptibility to instability of high-proportion wind power system, this paper proposed a voltage source control strategy for the direct-driven wind turbine with energy storage on the DC side. Then, the output impedance of wind turbine is built, and interaction stability is researched based on the frequency-domain modal analysis method. Next, the interaction mechanism between the voltage source controlled wind turbine and the grid is revealed based on the complex power coefficient method. Research results show that functions of inertia response and primary frequency regulation are able to be achieved through the added control loops in the energy storage converter, without affecting the wind turbine's operation mode of maximum power point tracking. Besides, ancillary control loops in the energy storage converter can improve the voltage source controlled wind turbine's stability margin. Finally, the effectiveness of the theoretical analysis and control strategy are verified by simulation.