Contribution to power transformers leakage reactance calculation using analytical approach

In this paper, classical approaches to evaluate leakage reactance in power transformers, that is, the simple analytical model, the Rogowski and the Stephens methods, are compared with each other and its limitations are exposed. To generalize and to improve the accuracy of the transformer leakage reactance evaluation, the authors propose a new analytical approach whose parameters are determined using curve fitting method from solutions obtained by 2D Finite Element Method (FEM) simulations. Since these parameters depend on the transformer windows and windings dimensions, its values are determined using per unit systems and also for typical transformer height to width ratio from 2 to 4. Consequently, the proposed method can be applied directly for the leakage reactance calculation without performing FEM simulations and for a large family of transformers with different windings configurations. The proposed method is thus compared with the classical approaches and its results show a good agreement compared with those obtained through 2D FEM simulations for any window and winding configurations.