Abstract
This thesis investigates the behavior of multi-winding three-phase transformers, particularly during inrush current events, which pose significant operational challenges, including mechanical stress, electromagnetic interference, and potential damage to equipment. The study aims to comprehensively analyze core losses, construct and interpret the B-H curve, and optimize testing facilities to enhance measurement accuracy and efficiency.Experimental and analytical methods, including Open Circuit (No-Load) and Closed Circuit (Short Circuit) tests, were employed to gather essential data on transformer behavior under various operating conditions. These tests were conducted at the Austrian Institute of Technology (AIT), leveraging advanced facilities to ensure high-quality data collection. The results highlight the significant deformation and decentralization of the B-H curve during inrush events, complicating accurate modeling with the Jiles-Atherton (JA) model due to its simplified assumptions. The sinusoidal waveform of the current exhibited marked distortion during inrush, impacting the shape and stability of the B-H curve and leading to increased hysteresis and eddy current losses.
Analysis revealed that higher voltage levels exacerbated power losses during inrush, following an exponentially decreasing trend. The study underscores the necessity of new mitigation strategies to reduce losses and improve transformer efficiency. Factors such as core saturation, residual magnetization, and temperature variations were identified as primary contributors to B-H curve deformation. These insights inform the development of more accurate and robust models for predicting and mitigating inrush current effects.
The findings underscore the limitations of the basic JA model in capturing the complexities of deformed and shifted B-H curves. The need for ongoing refinement of the model is emphasized to better address the dynamic interactions occurring during inrush events. This research lays the groundwork for subsequent investigations aimed at formulating strategies to reduce power losses and enhance transformer reliability and performance. The dissemination of these findings through academic publications will contribute to advancing the field of electrical engineering, promoting more efficient and stable power systems.
Date of Award | Aug 2024 |
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Original language | English |
Supervisor | Rastko Zivanovic (Supervisor) |