Research On Magnetic Flux Leakage Control Technology Of Large Capacity Single-phase Autotransformer

The Ultra-High Voltage (UHV) transformer plays a crucial role in modern power transmission system. UHV power grid technology is gradually mature and the transformer tends to high voltage and large capacity. Compared with the same level of power transformer, single-phase autotransformer has the advantages of small size, low loss, and higher capacity. The corresponding increase of magnetic leakage may cause the increase of additional loss of transformer, local temperature rise exceeding standard in structural parts and winding mechanical force increases and other negative effect, which threats to the economic, security and stable operation of the transformer seriously. Therefore, research on internal magnetic flux leakage distribution of the large capacity single-phase autotransformer deeply and take magnetic flux leakage control measures or design reasonable, effective program in reducing the stray loss, prevent local overheating, has an important practical significance and economic benefits. The main contents are as follows:Firstly, by using the advanced finite element method (FEM) analysis software Elmag-3D, the time harmonic field calculation method is used to analyze the size and distribution of the internal leakage magnetic field of single-phase autotransformer with different capacity and different voltage levels.Secondly, the ODFPS-500000/750 single-phase autotransformer is regarded as a research object. In the absence of the tank shielding conditions, based on the magnetic flux leakage distribution and temperature rise on the structural parts, the research of shielding effect of plate type, lung type, L type, and strip type body shielding are carried out respectively. In addition, the shielding effect of tank magnetic shielding and copper shield are taken without body shielding.Finally, the ODFPS-700000/750, large capacity single-phase autotransformer is adopted to the three-dimensional modeling and simulation analysis, to determine the optimal overall leakage control scheme of the model. The prototype is made and test plan is confirmed. The validity and rationality of the magnetic flux leakage control technology in this model is verified by the load loss test and temperature rise test.