Finite Element Calculation And Analysis Of Two Dimensional Magnetic Field For Disintegration Power Transformer

With the increase of electric grid size and generator unit capacity, the capacity andvoltage level of single power transformer are also rising. When the power transformer’scapacity increases, its volume gets bigger. However, owing to the limitations of railwayand road transport conditions, power transformer’s volume has to be controlled within acertain scope. Thus, the disintegration transformer with extra high voltage and largecapacity is designed to solve the transportation problems. But the disintegrationtransformer structure happens to change, which affects magnetic field distribution,excitation current, no-load loss and the operating performance of the transformer.Therefore, in this paper, the magnetic field properties of the iron core in the disintegrationtransformer with no-load operation status were studied. The main content is as follows:Firstly, on the basis of deep study of the finite element analysis (FEA) method, themathematical model considering the direct field-circuit coupled method was derived tosolve the linear quasi-stable alternating electromagnetic field. Using a variational principle,the energy functional was discretized and the algebraic equations were obtained.Secondly, based on the linear discretization equations derived above, NewtonRaphson method was employed to derive the iteration form of FEA for the nonlinearquasi-stable alternating electromagnetic field. By using FORTRAN language, thecomputer program of the field-circuit coupled FEA was compiled and the solution oftwo-dimensional parallel plane field and axisymmetric field was achieved.Thirdly, the magnetic field of a DFP-380MVA/500kV single phase power transformerand a315MVA/35kV single-phase power transformer were simulated by the self-programming software with no-load and short-circuit status, respectively. The calculationresults from self-programming software were compared with those of commercial software,and the correctness of self-programming software was verified. Finally, an OSFPS9-360MVA/330kV three-phase five-column disintegrationtransformer product was analyzed and the exciting current and no-load losses werecalculated. The magnetic field distribution, exiting current and no-load loss values werecompared with two kinds of iron core model, i.e. the disintegration and thenon-disintegration of the transformer core, and the technical problems meeting withtransformer manufacturers were solved.