Low Frequency Oscillation and Ultra-low Frequency Oscillation Modes Identification Based on Generalized Variational Mode Decompostion
With the continuous expansion of hydropower penetration and grid interconnection scale,low-frequency and ultra-low frequency oscillations appear in power grids with high proportion of hydropower,which shows strong nonlinear and non-stationary characteristics,and consequently increases the difficulty of oscillation parameter identification.Aiming at the problem that the mode decomposition number K in variational mode decomposition(VMD)cannot be adaptively determined and that mode aliasing is easy to occur when dealing with time-varying oscillations,a generalized variational mode decomposition(GVMD)algorithm combined with Teager-Kaiser Energy Operator(TKEO)is proposed for fast modal parameter identification of low-frequency and ultra-low-frequency oscillations.Firstly,the modal decomposition number K is obtained through wavelet time-frequency analysis,and each mode is clearly defined in the time-frequency plane through generalized Fourier transform,so that the decomposition accuracy and reliability are greatly improved.Then,after the signal is decomposed by GVMD,the TKEO method is used to quickly complete the identification of oscillation parameters.Finally,the effectiveness and feasibility of the proposed method are verified by self-synthesized signal,EPRI-36 system simulation and measured power grid signal simulation.
high hydro-ratioultra low frequency oscillationgeneralized variational mode decompostionTeager-Kaiser energy operatormode identification
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