A Novel Octagonal Wound Core for Distribution Transformers Validated by Electromagnetic Field Analysis and Comparison With Conventional Wound Core

This paper analyzes a novel configuration of transformer core, called octagonal wound core (OWC), and shows the minimization of the excitation current and the reduction of the eddy-current losses. The OWC is compared with the conventional wound core (CWC) configuration. The comparison is based on two-dimensional and three-dimensional finite-element method (FEM) simulations, taking into account the nonlinear properties of the magnetic material of the core. The results show that the OWC reduces the excitation current and the eddy-current losses when compared with CWC. Moreover, several combinations of grades of the grain-oriented silicon steel (GOSS) were investigated so as to further reduce the eddy-current losses and the excitation current.

[1]  M. Breschi,et al.  Experimental and Numerical Analysis of Stray Field From Transformers , 2007, IEEE Transactions on Magnetics.

[2]  B. Polajzer,et al.  Determining Magnetically Nonlinear Characteristics of Transformers and Iron Core Inductors by Differential Evolution , 2008, IEEE Transactions on Magnetics.

[3]  P. Salgado,et al.  Eddy-Current Losses in Laminated Cores and the Computation of an Equivalent Conductivity , 2008, IEEE Transactions on Magnetics.

[4]  E.I. Amoiralis,et al.  Global Transformer Optimization Method Using Evolutionary Design and Numerical Field Computation , 2009, IEEE Transactions on Magnetics.

[5]  Nabeel A. O. Demerdash,et al.  A new approach for determination of eddy current and flux penetration in nonlinear ferromagnetic materials , 1974 .

[6]  A. Kladas,et al.  Multiple Grade Lamination Wound Core: A Novel Technique for Transformer Iron Loss Minimization Using Simulated Annealing With Restarts and an Anisotropy Model , 2008, IEEE Transactions on Magnetics.

[7]  A. Lakhsasi,et al.  A Practical Modeling Method for Eddy-Current Losses Computation in Laminated Magnetic Cores , 1996, IAS '96. Conference Record of the 1996 IEEE Industry Applications Conference Thirty-First IAS Annual Meeting.

[8]  N. Sadowski,et al.  Finite Element Three-Phase Transformer Modeling Taking Into Account a Vector Hysteresis Model , 2009, IEEE Transactions on Magnetics.

[9]  Stefanos D. Kollias,et al.  Prediction of iron losses of wound core distribution transformers based on artificial neural networks , 1998, Neurocomputing.

[10]  Oszkar Biro,et al.  Various FEM formulations for the calculation of transient 3D eddy currents in nonlinear media , 1995 .

[11]  James H. Harlow,et al.  Electric Power Transformer Engineering , 2003 .

[12]  K.W.E. Cheng,et al.  Calculation of Eddy Current Field in the Ascending Flange for the Bushings and Tank Wall of a Large Power Transformer , 2008, IEEE Transactions on Magnetics.

[13]  E.I. Amoiralis,et al.  A Parallel Mixed Integer Programming-Finite Element Method Technique for Global Design Optimization of Power Transformers , 2008, IEEE Transactions on Magnetics.