Analysis on the Influence of the DC bias on spatial magnetic flux leakage in the transformer

Magnetic flux leakage, as a basic physical parameter in power transformer, can be utilized to characterize the status of the winding. And the DC biasing, as a common abnormal operation condition, is caused by solar storms, DC power transmission and some railway power transmission. It can induce the current bias and the core saturation, further changing the distribution of the magnetic flux leakage. Therefore, it is significant and valuable to analyze the effect of DC biasing on spatial magnetic leakage flux. In the paper, we design a transformer finite element model with its physical fieldcircuit simulation module. The model with some detailed winding structure can obtain the accurate magnetic field signal. Then the effect of different degrees DC biasing on the magnetic leakage flux is analyzed in the inner key positions. And the 10kV shrunken experimental transformer imitating the 110 k V transformer is selected as the research object. Depending on the experimental platform, we obtain the actual magnetic field signals and explore the incidence relation between the magnetic leakage flux and the DC biasing.