Harmonic Current Effect on Mechanical Dynamic Response of Converter Transformer Winding Based on Simulation Analysis

Ultra-high voltage (UHV) converter transformers are located at the core of alternating current (AC) and direct current (DC) changes. During operation, it is subject to a large number of harmonic currents with frequencies higher than the fundamental frequency. A series of harmonic currents will cause different degrees of vibration and deformation of the windings, threatening the normal operation of the converter transformer. This paper establishes a three-dimensional electromagnetic-mechanical multi-field coupling analysis model of the extra-high voltage converter transformer, and obtains the mechanical vibration distribution characteristics of the converter transformer winding under the influence of harmonic currents. The results show that with the increase of harmonic current content, the stress value of the converter transformer windings shows an increasing trend. The maximum value of the winding is shifted from the upper and lower ends of the winding to the middle of the winding. Different harmonic current frequencies have different degrees of influence on the stress values of the converter transformer windings.