Power Transformers in Electrical Engineering

Harmonic phenomena in three phase transformers are quite important. It is because under certain conditions the exciting current harmonics may cause inadvertent operation of the protective equipment and may also cause interface with communication circuits. The study is to discuss the harmonics in three phase transformers. For the harmonic analysis of power systems it is essential to have all compenents represented in the harmonic frequency domain. This study shows how nonlinear elements can be directly represented in the harmonic domain by using a convolution equivalent to time domain multiplications. The procedure is then applieed to power transformers. The three-phase models with the specially connected transformers offered in this study distinctly represent the feeding system by means of the physical three-phase circuirt and the symetrical–compenent equivalent circuit. The three-phase model could be joined to three-phase load flow program to exactly analyse the system imbalance in the future. Transformer models for harmonic studies based on rated parameters are presented.