Study On Method Of Steel State Detection Basing On Transformer Sound

Transformer is the most important installation in power system, but the phenomenonof using second used steel in transformer manufacture appears recent years, causingpotential quality problems. The second used steel is unload from eliminated transformers,and used in core production after reworking. Currently no effective method of steel statedetection is obtained. Transformer sound is generated in operation, which is mainly causedby the vibration of the core, so the transformer sound is definitively influent by the steelstate. If the relation between transformer sound and steel state was revealed, the method ofsteel state detection basing on sound can be obtained.The relation between transformer sound and magnetostriction of steel is studied in thisthesis. The theoretic analysis of transformer sound reveals that the sound is merely decidedby the magnetostriction of steel when the operation state, capacity and material oftransformers are similar. The relation between steel state and magnetostriction is obtainedby theoretic analysis of magnetostriction and the second used steel, revealing that the soundcan response the difference between steel states because of the difference inmagnetostriction. The transformer samples are selected in same capacity and material, butin different steel states in experiment, the platform of sound record and analysis isestablished, the sound of samples are record in no-load test, the difference between soundsis analyzed in frequency domain. Then the transformer is modeled in multi-physicssimulation software, the simulation in multi-physics is studied in different magnetostrictionof core, and the difference between sounds is analyzed in frequency domain.The result of experiment study indicate that the older the sample，the higher thefundamental frequency comparing to the harmonic in sound signal. The result of simulationstudy indicate that the larger the magnetostriction, the higher the fundamental frequencycomparing to the harmonic in sound signal. According to theoretical analysis, experimentstudy and simulation study, magnetostriction is influent by steel state, the better the steelstate is，the higher the fundamental frequency comparing to the harmonic in transformersound. The study result is meaningful to the method of steel state detection usingtransformer sound.