Magnetizing Power at One-Sided Saturation of Power Transformers with Armored Magnetic System

Abstract

It is shown that under space weather disturbances, quasi-direct currents in grounded high voltage windings affect the magnetization characteristics of a power transformer with an armored magnetic system. The intensity of the effect of quasi-direct currents on a power transformer depends on the state of its magnetic system, which is proposed to be distinguished by the value of the phase saturation angle as "weak saturation", "moderate saturation", "strong saturation". With an increase in quasi-direct currents, there is a multiple decrease in the equivalent inductive resistance of the magnetization branch and a multiple increase in the total magnetization power. The total magnetizing power is formed from two components. The first is the reactive magnetizing power, it is due to the fundamental harmonic of the magnetizing current, and the second is the distortion power, it is due to the higher harmonics of the magnetizing current. It is shown that the distortion power reaches its maximum value at the phase angle 90 deg. The obtained calculated expressions make it possible to determine the components of the total magnetization power in the entire range of changes in the magnetization reversal mode of a power transformer under the influence of quasi-direct currents up to a complete transition to the region of technical saturation.