The Calculation Of The Composite Short Circuit Impedance And The Eddy Current Loss In The Oil Tank For Traction Transformer

As the core equipment to train-borne traction supply system of electric locomotive,traction transformer undertakes the important task of supplying traction power. As thetraction transformer is a single-phase and multi-winding one, calculation of compositeshort-circuit impedance is one of the focuses of designers and manufacturers.Requirements on transformer impedance value become higher, distribution of leakagemagnetic field becomes complex, thus design becomes more and more difficult, and localheating and temperature rise become increasingly prominent. In this paper, essay conductstheoretical analysis, experimental test and simulation analysis on the aspects of compositeshort-circuit impedance of traction transformer and eddy-current loss of oil tank, whichprovides important theoretical reference to the design of electric-magnetic structure oftraction transformer.Theoretical analysis is based on calculation method between two windingshort-circuit impedance of coupled field-circuit method, magnetic circuit method, andenergy method. To quickly acquire short-circuit impedance between two windings ofmulti-winding transformer, this paper offers a calculation method of short-circuitimpedance between two windings equivalent to single-turn inductance matrix. It deducescalculation formulas of composite short-circuit impedance of multi-winding transformer,and gives solution steps in detail.It presents the definition of transformer leakage magnetic field and its main causes.Based on basic theories of magnetic field and definition of commonly used boundaryconditions, this paper analyzes and calculates the calculation steps of finite elementmethod. Combining the characteristics of edge unit finite element method, it proposessimulation analysis method based on analysis calculation of traction transformer leakagemagnetic field and eddy current field by applying edge unit theory.Taking traction transformer of new Uzbekistan locomotive as the study object, thispaper adopts ANSOFT finite element software to acquire12equivalent single-turninductance matrix, and just-for-once obtains short-circuit impedance value between anytwo windings via preparing related computer program. Combining the theoretical formulaof composite short-circuit impedance of multi-winding transformer, it proposes a newcalculating method for composite short-circuit impedance of multi-winding transformer onthe basis of equivalent single-turn inductance matrix. By comparing theoretical calculation value with experimental test conclusion, paper verifies the efficiency and feasibility of thismethod.Taking traction transformer of new Uzbekistan locomotive as study object, it adoptsANSYS FEM software to establish3-D finite element simulation, and uses edge unit finiteelement method to analyze and calculate interior leakage magnetic field and eddy currentfield of oil tank, on the basis of theoretical formula of eddy current loss. Duringpost-processing section, it conducts calculation on eddy current loss via preparing relatedpost-processing program, to offer important theoretical data to design the cooling system.