Decentralized Evaluation of Low Frequency Oscillation Damping in Energy Storage Collaborative Doubly-Fed Wind Power Grid Connected System

In order to accurately evaluate the damping characteristics of energy storage collaborative doubly-fed wind power grid-connected system, a method based on variational mode decomposition (VMD) and oscillation energy analysis is proposed. In view of the non-stationary and nonlinear characteristics of the low-frequency oscillation signal in the wind storage system and the difficulty in revealing its local characteristics, the original oscillation signal is first decomposed into several intrinsic mode components (IMF) of different frequencies using VMD algorithm, and then the Hilbert transform is used to obtain the instantaneous frequency, instantaneous amplitude and other modal parameters of the specific IMF and extract low-frequency oscillation modes of the domain interval. From the perspective of internal oscillation energy dissipation in the system, the damping contribution index of each generator unit is constructed based on the dissipation energy function in order to decentralize the evaluation of the damping contribution of each generator unit to the system under different low-frequency oscillation modes. Finally, the effectiveness of the proposed method is verified by time-domain simulation of the two-region interconnected system.