Harmonic Current Influence on Temperature Rise and Mechanical Characteristics of UHV Converter Transformer Winding Based on Simulation Analysis

The ultra-high voltage (UHV) converter transformers are subjected to a large number of harmonic currents with frequencies higher than the fundamental frequency in the course of operation. This study formulates a dual-dimensional simulation framework for the converter transformer, predicated on an integrated theory of multiple physical fields, including electrical, magnetic, thermal, and mechanical forces relevant to the converter transformer’s dynamics. Accounting for the impact of harmonic currents on the properties of the winding material, this study conducts a simulation and analysis of the mechanical attributes of the converter transformer’s winding. Findings indicate an escalation in harmonic current content correlates with an augmented maximum axial and radial leakage in the winding. Concurrently, the winding’s hot spot temperature exhibits a power function growth, while the peak stress experienced by the winding demonstrates an exponential uptrend. Furthermore, as the frequency of the harmonic current rises, the winding’s magnetic flux density remains relatively stable, yet there’s a pronounced exponential escalation in the winding’s hot spot temperature. Simultaneously, the peak stress endured by the winding exhibits a progressively ascending pattern correlating with the frequency’s augmentation. This paper provides theoretical support for intelligent state sensing of converter transformers.