Equivalent Winding Capacitance Network for Transformer Transient Analysis Based on Standard Test Data

Abstract

This paper proposes an equivalent winding capacitance network for the transformer low- and mid-frequency transients analysis, based on the standard test data. The proposed model can accurately represent the positive- and zero-sequence winding capacitances. Therefore, it is physically correct and more accurate than the existing modeling approaches. Based on the winding voltage profile, the equivalent winding capacitances are analytically determined using the measured capacitances in the dielectric test, winding connection, and vector group which are available in the transformer standard data. The calculated capacitances are validated with the time-domain simulations. A general method based on complex turns ratio and complex ampere's law is also proposed to obtain the equivalent winding capacitance seen from the energized winding and thereby determine the lumped capacitances to be connected at the terminals of the transformer model. The methods to estimate the missing parameters in the standard data are also discussed. Furthermore, the differences with the existing modeling approach in estimating the winding capacitances and the analysis of transient phenomena are highlighted through the analytical solutions and time-domain simulations.