Power Transformer Running State Vibration Characteristic Under Study

Power transformer is important equipment in power system, its stable operation to ensure the safety of power grid is significance, but the actual operation of the transformer will have all kinds of faults inevitably. If the transformer winding is slightly deformed, the insulation performance and mechanical performance of the transformer will be decreased. The vibration analysis method can be used to monitor the winding deformation, but the theoretical basis of the diagnosis criterion is not enough. Therefore, it is necessary to study the vibration theory of the transformer.In this paper, based on the model for S11- M- 500/35, Yyn0 transformer connection group as the research object, analysis method of the vibration characteristics of transformers using finite element field circuit coupled analysis, magnetic structural coupling analysis and vibration test, the mechanical characteristics and electrical characteristics of the transformer are analyzed, and the magnetic field distribution of the transformer windings and iron core are studied, a modal analysis is carried out for the single phase winding under different pre tightening force. The harmonic response analysis is performed on the same pre tightening force and different current. The simulation results are verified by the load vibration test. The results show that the magnetic field lines of power transformer in operation state of the iron core to form a closed magnetic circuit in the middle column by column on both sides, two phase winding transformer A, C magnetic field distribution is symmetrical, the B phase winding flux density is the biggest, and by A, C phase leakage magnetic interference, so according to the winding vibration signal to judge transformer winding operation should be considered when the other two relative phase B interference. In this paper, the finite element model is built according to the actual size of the B phase winding of the transformer, using the modal analysis method, the natural frequencies of the 6 axial pre tightening force are calculated respectively, and the vibration mode of the 1-4 is analyzed, analysis of axial retightening force is 18 MPa, the four order natural frequency winding avoid the multiples of 50 Hz, thus determine the transformer winding preload can achieve optimal avoid transformer resonance occurs in the actual operation of the target. Through the magnetic structure coupling analysis of transformer windings and iron core, the power of the transformer B phase winding is the biggest, the B phase high voltage winding has obvious radial expansion trend, and the vibration acceleration of B is the biggest, which provides a theoretical basis for the selection of measurement points in the follow-up study.In this paper, the vibration signal of the transformer is analyzed by using the method of Fourier analysis, simulating analysis results from time domain and frequency domain. The results show that the simulation results are in good agreement with the experimental results.