考虑垫块瞬态应变的绕组变刚度动力学模型及暂态振动特征分析OA

To study the quantitative correlation between the deformation characteristics of windings and the deterioration of the structure,a winding deformation identification method based on the combination of numerical calculation and transient test analysis of the actual transformer is proposed.Firstly,an axial dynamic model with variable stiffness coefficients for the middle-voltage winding of the SFSZ7-31500/110 actual transformer considering the transient compression strain of the blocks is established.Quantitative analysis is carried out on the variation laws of the amplitude energy and natural frequency of the winding due to the sudden change in the height of the blocks.Subsequently,multiple short-circuit impact tests are conducted for transient vibration signal acquisition,and the structural parameters of the faulty winding are obtained through the inspection of the housing removal.Finally,the changes in the modal and mechanical parameters of the winding are calculated based on the proposed model,and quantitative calculations are carried out for the mechanical deterioration characteristics of the winding.The wavelet energy of the transient vibration signal is verified through the time-frequency distribution.The calculation results show that after the winding deforms,the amplitude of the vibration displacement decreases by 0.002 m,and the second-order natural frequency increases by 18.269 Hz.The wavelet energy of the forced vibration signal's main frequency continuously decays over time,the proportion of the fundamental frequency energy significantly decreases,and the distribution of the frequency band of the natural frequency in the free vibration stage becomes more complex.The proposed model and transient characteristic analysis in this paper enable accurate calculation of the mechanical deterioration parameters of the winding structure and rapid identification of winding deformation.