Harmonic analysis in three phase multi-limb power transformer by Harmonic balance technique using the magnetic circuit model

The harmonic balance technique and Newton Raphson method are used to predict the harmonics generated by three phase transformers. A magnetic circuit model of a three phase multilimb power transformer is established for harmonic balance, by combining the magnetic flux balancing equations and the magnetic force balance equations. The mathematical model is linearized in harmonic frequencies. The convergence for both original linearized model and the simplified model is then examined under overexcitation and DC biased conditions. Harmonic analysis was carried out for overexcitation and small DC winding current conditions, Some characteristics of the exciting current are presented.