Research on the External Electromagnetic Interference Influence on the Errors of Low Frequency Voltage Transformer

In this paper, the anti-electromagnetic interference simulation is carried out in view of the magnetic field interference faced by 220 kV low frequency voltage transformer in actual operation. Firstly, the mathematical model and structure of voltage transformer are introduced. Then the principle of voltage transformer and the error expressions of ratio difference and angle difference and Maxwell's electromagnetic field theory formula are introduced. Then, the two-dimensional simulation model established by finite element software is introduced, and the influence of interference source distance, current intensity, radius, shell thickness, frequency and phase on the ratio error and angle error of transformer is analyzed. The research shows that the distance, current intensity, frequency and phase of the interference source have a great influence on the error of the voltage transformer, which should be paid attention to, but the shell can effectively reduce the external electromagnetic interference. In this paper, by increasing the distance of the interference source from 0.5 m to 4 m, the ratio error of the transformer is reduced by 9.7 %. When the thickness of the transformer shell is increased from 2mm to 12mm, the ratio error of the transformer is reduced by 1.64%. It shows that when the shell has sufficient thickness, it can effectively shield the external electromagnetic interference.