Calculation And Analysis On Short-Circuit Electromagnetic Force Of Large Transformer Winding

The power transformer is one of the main devices of power grid and its ability to withstand the short circuit strength directly relates to the safety and reliablity of the operation of power system.Baed on the example of large oil immersed power transformers, this paper calculates the winding of the magnetic leakage, short circuit strength as well as short-circuit force and so on with the finite element numerical calculation method and obtains some meaningful conclusions to the design and manufacture departments of transformers.This paper first introduces the background and significance of the issue and discusses the research status at home and abroad of some problems such as the transformer leakage magnetic field and short circuit force as well as winding short circuit strength. Then take the types of power transformer of SFZ11-120000/220and SFPS9-150000/220as for examples and choose the half of a single phase winding as the study object with the actual structure of the symmetry of the transformer, later separately establish simplified calculation models and make different calculations and analysis of the two dimensional leakage magnetic field in different tapping operation condition, thus obtaine the leakage magnetic field distribution of all windings. The effects of different tap running and magnetic shielding to the distribution are considered in the calculation. Thirdly, the winding dynamic and static forces of the SFZ11-120000/220type oil-immersed transformer are calculated and analyzed in three tap operations such as the maximum rated tap, and the smallest tap rated tap and the distribution of radial short-circuit force and axial short circuit force of each winding unit is obtained. Finally the short circuit strength and displacement of radial and axial as well as the force for clamping piece are calculated, meanwhile, the dynamic and static axial force of windings are compared. The calculated results indicate that the short circuit strength of this transform is sufficient to ensure its safe operation.