Harmonicas

Total Losses and Maximum Power Determination for Distribution
Transformers Feeding Non-Linear Loads

L. R. Lisita

J. W. L. Nerys

A. J. Batista

Universidade Federal de Goiás [e-mail] Universidade Federal de Goiás [e-mail] Universidade Federal de Goiás [e-mail] A. M. de Oliveira

A. C. Moreira

Universidade Federal de Goiás [e-mail] Universidade Federal de Goiás [e-mail] Abstract — As a consequence of the increasing technological development of electrical and electronic equipments, which are supplied by distribution transformers, the current and the voltage of transformers have presented distorted waveforms. These non-sinusoidal currents and voltages in transformers result in additional losses, which cause increase in temperature and reduction to the transformer insulation and lifetime. These additional losses cause decrease in the transformer efficiency, reduced reliability, increase in the excitation and in the neutral currents, increase in the audible noise and, in extreme operation conditions they may result in the transformer failure. The purpose of this work is to analyse the behaviour of the voltages and currents of distribution transformers when they are supplying energy to non-linear loads and, from this analysis, to calculate the core losses (PNL), the resistive losses (Pcu), the maximum current, the efficiency and the effective capability of power transfer. The measurements are performed using the back-to-back configuration and the adopted model is the three-phase instantaneous model with measurements and calculus made per phase. This work is implemented using some data from previous tests and the programming language is LabVIEW.

alta densidade de perdas se tornam um dos principais fatores na determinação do desempenho e da vida útil de transformadores. II.

MODELAGEM

A modelagem matemática utilizada neste trabalho para
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