Analysis of winding vibration characteristics of middle-frequency transformer under non-sinusoidal periodic excitation
A numerical calculation model for the dynamic response of cylindrical and rectangular windings under non-sinusoidal periodic excitation was established to solve the vibration problem of the medium fre-quency transformer windings.The model considered the coupling relationship between electromagnetic-structure disturbance.A dynamic balance equation for the elastic-plastic deformation of the transformer winding was established.The sandwich model was introduced to simplify the calculation,and the spacing of the thin layers in the sandwich model was calculated,which could be used for effective modeling of winding stretching and compressing deformation.An example of a medium frequency transformer was used to measure the dynamic response of the winding under non-sinusoidal periodic excitation and numer-ical calculations were performed.Studies have shown that the vibration characteristics of the winding un-der triangular wave and sine wave loads are identical.However,under rectangular wave loads,the vibra-tion of the winding almost does not decay during the excitation period.In case of fault conditions,due to high frequency vibration,the residual deformation of the winding quickly accumulates.Under a 2 kHz rectangular wave load,the limit load strength of the winding can drop to 1/4 within 1 ms.
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