Identification method for power system low-frequency oscillations based on improved VMD and Teager-Kaiser energy operator

An improved variational mode decomposition (VMD) method is introduced into the mode recognition of low-frequency oscillation of power system in this study. First, fast Fourier transform is used to determine the number of VMD components, and the approximate fitting formula of the best balancing parameter a is obtained by a large number of tests. The original signal is decomposed into several modes via improved VMD (IMVD) method. Then, Teager-Kaiser energy operator is applied on the fitting of each component to get the amplitude, frequency, and damping factor of it. By the constructed test signals, the proposed method is compared with the methods of non-parametric VMD, empirical mode decomposition, total least-squares estimation of signal parameters via rotational invariance techniques, and Prony on the performance of mode parameter identification. Results show that the IVMD method effectively overcomes the shortcomings of those methods mentioned above in dealing with mode mixing, noise sequence, and non-stationary signals. Finally, the feasibility of the proposed method in extracting the low-frequency oscillation mode parameters of power system is verified by the simulation signals of the IEEE two-area four-generator power system and the New England 39-bus system.