Analysis of The Unbalanced Operating Characteristics of Three-phase Distribution Transformers with Non-identical Winding Impedance

• Main Authors: Wei-Lun Gao, 高偉倫
• Other Authors: Wen-Chih Yang
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/39168365771287165451

碩士 === 臺北城市科技大學 === 機電整合研究所 === 103 === The aim of this thesis is to analyze the effects of the non-identical winding impedance of three-phase distribution transformers on the three-phase voltage and current unbalance ratios on primary and secondary sides. There are many winding connection schemes for three-phase distribution transformers. The major schemes are Y-Y, Y-△, △-△, △-Y, U-V and V-V. This thesis used a coupling-free technique to develop the equivalent mathematical models of above six distribution transformers, and then built their equivalent circuits in simulation software, Matlab/Simulink, to simulate the three-phase voltage and current unbalanced situations on primary and secondary sides of distribution transformers when the three winding impedances were not identical. Simulation results have been obtained and organized by this thesis. Effects of non-identical winding impedance on the three-phase voltage and current unbalance ratios on primary and secondary sides of three-phase distribution transformers have also been presented. In addition, the unbalanced operating characteristics of an example distribution system have been simulated and analyzed. The example system had several distribution transformers with non-identical winding impedance simultaneously. The research results can be used for the power system professionals to protect the safety and benefit of their power systems while they are buying and applying distribution transformers.