The rapid increase in the proportion of new energy sources causes great changes in the structure and stability characteristics of the system, and a new type of oscillation appears with multi-mode and broad-band characteristics. In order to predict, locate and suppress broad-band oscillation, it is necessary to identify the mode parameters of broad-band oscillation signals accurately and quickly. First, Both low noise and high noise signals are simultaneously decomposed by VMD, a criterion based on permutation entropy (PE) is used to distinguish between high and low noise signals. Then, improved variational mode decomposition (IVMD) is used to efficiently denoise high noise signals. Finally, hilbert transform (HT) is used to identify decomposed modes, and short-time fourier transform (STFT) provides time-frequency characteristics to help restore oscillations. The simulation and actual oscillation data verify that both obvious oscillation signals with low noise and ambient signals with high noise are effectively identified, and results reveal that the proposed method outperforms the other similar methods in accuracy and time of use.

Wind-thermal bundled power transmission system with series compensation (WTBPTSSC) is widely used in the power system. Power system stabilizer (PSS) and traditional supplementary damping controller (TSDC) are often installed to mitigate low-frequency oscillation (LFO) and subsynchronous oscillation (SSO) in the power system. In this paper, the damping characteristics and interaction of the controllers are analyzed to guide the coordinated control of different controllers. In light of this issue, a small-signal state-space model of WTBPTSSC was built first. Then, the path-damping torque coefficient method combined with the small-signal state-space model is proposed. The damping characteristics of PSS and TSDC were analyzed, at the same time, PSS and TSDC providing damping in different frequency bands were pointed out. Finally, through theoretical analysis and simulation verification, the conclusion is that there are few interactions between PSS and TSDC, but due to their damping characteristics, PSS should be configured in priority when the controller parameters are configured, which can make both low-frequency oscillations and subsynchronous oscillations well suppressed.