Evaluating Power Transformer State Based on Tank Vibration: A Graphical Approach

Transformer vibration monitoring holds significant potential for assessing internal mechanical states. However, comprehensive analysis of power transformer vibrations is limited by the complexity of vibration sources and transmission pathways. Vibration measurements, typically obtained from the transformer tank, are influenced by operational conditions - such as the applied voltage and load - as well as the mechanical structure's state. These multisource and multitransmission characteristics complicate the extraction of intrinsic features, posing challenges for effective transformer state evaluation. To address these challenges, this study proposes a graphical methodology for power transformer state evaluation based on tank vibration analysis. First, mathematical models for core and winding vibrations, as well as vibration propagation from internal components to the tank, are developed to provide a theoretical foundation for the proposed methodology. Subsequently, the methodology is formulated as a graphical "vibration intrinsic triangle,"with theoretical proof based on the derived mathematical models. The proposed methodology is further validated through laboratory experiments - including no-load and load tests - and field experiments. Experimental results demonstrate that the proposed methodology is robust to variations in operational conditions and sensor placements. In addition, analysis of publicly available faulty vibration data confirms the methodology's effectiveness in detecting internal mechanical failures. This novel methodology offers a convenient and intuitive framework for transformer state evaluation using tank vibration measurements.