Comparative Study On The Detection Of Mechanical Stability Of Transformer Windings Based On Vibration Frequency Response Method

According to the statistics of large transformer accidents,the short-circuit resistance of transformer windings due to the decrease of mechanical stability has become one of the most important causes of accidents,which seriously affects the safe operation of transformers.Judging from the existing transformer windings damaged by short circuit,most of the windings show a loose state.However,the initial and negative stages of mechanical stability such as loose,loose or slight deformation of the transformer windings are based on conventional electrical measurements(frequency response).Analytical method and short-circuit impedance method)The sensitivity is poor and cannot be accurately identified in time.With the cumulative effect of mechanical deformation,it will cause great safety hazard to the safe and stable operation of the transformer.Therefore,in the handover test after transformer installation,in the routine test after external short circuit or long-term operation,how to effectively detect and evaluate the mechanical stability state of the transformer winding early,determine whether the short-circuit resistance is declining,and then scientific guidance Transformer maintenance and repair work has become particularly urgent and important.Based on this,based on the existing transformer winding modal experimental research and transformer winding modeling research,the paper analyzes the test principle of transformer winding vibration frequency response method,and controls the power supply and vibration by constant current frequency conversion of transformer windings in accordance with field test requirements.The frequency response test system is used to carry out the research on the mechanical stability detection of the variable voltage winding based on the vibration frequency response method.Secondly,the frequency vibration excitation curve under different winding states is obtained by performing the frequency sweep excitation test on the three transformer windings,and the vibration intensity is studied.The correlation between the mechanical stability of the transformer windings,and the analysis of the vibration frequency response method compared with the conventional test method,for the superiority of detecting the mechanical stability of the transformer winding.The research results can be used as an important supplement to the on-site check of the large-scale transformer short-circuit capability,and also an important basis for implementing the power transformer state maintenance strategy.