Oil-immersed transformer eddy current loss is reduced about 69%
The maximum eddy current density and maximum eddy current loss density of oil-immersed transformer are the highest, while the maximum eddy current density and maximum eddy current loss density of oil-immersed transformer occur at both ends of the winding. The maximum eddy current density and maximum eddy current of the scheme The loss density occurs at the lower end of the winding; so when the impedance voltage value reaches 17% (more than 70% beyond the national standard), it is not appropriate to open a slot, not only the eddy current loss of the oil-immersed transformer is high, but also there is local overheat hidden dangers.
Calculation of electromagnetic field distribution of oil-immersed transformer shrinkage model
In order to compare the electric field distribution and the magnetic field distribution of the crude oil-immersed transformer and the reduction model, the electric field distribution and the magnetic field distribution of the original model and the reduction model were simulated by the finite element method. The original model and the reduction model imposed a similar boundary condition. When the electric field and the magnetic field act on the transformer together, the electromagnetic field distribution results of the original transformer model and the reduction model show that the potential distribution and magnetic flux density distribution of the reduction model are consistent with the original model.
Based on oil-immersed transformer shrinkage model, building a test platform to measure the distribution of the impulse voltage of the high-voltage winding of the transformer. Based on the transformer shrinkage model impulse voltage distribution test platform, the pulse width generated by the nanosecond pulse generator is 1400 ns and voltages of different voltage amplitudes are applied to the winding high voltage side, the series low voltage winding of oil-immersed transformer and the parallel low voltage winding, respectively. And by measuring the voltage waveform of each tap of the high voltage winding, the winding voltage distribution under different applied voltages is obtained. From the test results, it can be seen that the voltage distribution of the winding of oil-immersed transformer is very uneven under the effect of impulse voltage, the voltage distribution trend under different voltages is basically the same, and the voltage at the first end of the high-voltage winding is relatively large. The main reason is that the existence of stray capacitance between the windings of oil-immersed transformer makes the voltage distribution of the windings extremely non-uniform, and its shunt effect makes the voltage distribution of the high-voltage windings extremely non-uniform and the first end of the high-voltage windings withstands large voltages.
In comparison, the eddy current loss of the oil-immersed transformer is reduced by about 69%, the maximum eddy current loss density is reduced by about 82.1%, and the maximum eddy current density is reduced by about 75.6%. About 86.3%, the maximum eddy current density is reduced by about 62.9%, and the improved effect is very significant.