engleski

A Novel Method for Three-phase Core-type Distribution Transformers Short-circuit Voltage Calculation

This paper describes a short-circuit voltage calculation method using conformal mapping that maps the transformer core window cross-section geometry to a unit circle where an analytical solution for magnetic flux density is easily obtained and then transformed back to the original domain. The short-circuit voltage is calculated by integration of magnetic energy of leakage field in the windings and the space around windings, excluding core. This method takes into account windings of different height, the fringing effect at the ends of the windings and any relative position of windings inside the transformer core window. Also, it is possible to calculate short- circuit voltage for multiple windings. Regarding the geometry of the problem, the Schwarz-Christoffel (SC) transformation has been chosen for conformal mapping between the physical domain (rectangular core window) and canonical domain (unit circle) where magnetic flux density is obtained and transformed back to the physical domain. The Schwarz-Christoffel Toolbox is a collection of MATLAB files for the computation and visualization of Schwarz-Christoffel conformal maps and it is used for numerical calculation of unknown coefficients of SC transformation. In the end, the proposed method is compared to measured values of short-circuit voltage and two analytical and analytical-numerical methods used in special computer programs for transformer design developed by the transformer manufacturer.

short-circuit voltage, conformal mapping, Schwarz-Christoffel transformation, distribution transformer

nije evidentirano