MECHEREF, RaniaBOUCHAHDANE, Mohamed (supervisor)2025-05-062025-05-062024https://dspace.univ-boumerdes.dz/handle/123456789/1526660 p.Power transformers are essential components in electrical power systems, responsible for the efficie nttransmission and distribution of electricity. Ensuring the irreliability is critical for maintaining uninterrupted power supply and overall system stability. One of the most effective techniques for monitoring transformer health is Dissolved Gas Analysis (DGA), which detects early signs of faults such as overheating, partial discharges, and arcing by analyzing gases dissolved in transformer oil. Interpreting DGA results, however, can be complex and requires significan texpertise .Traditional methods, including the Key Gas Method, Doernenburg Ratio Method, Rogers Ratio Method, IEC Ratio Analysis, and Duval Triangle Method, each have their own strengths and limitations, making manual application time-consuming and prone to errors. This thesis addresses these challenges by developing a MATLAB-based Graphical User Interface (GUI) that integrates multiple DGA interpretation methods. The primary goal is to create a user-friendly tool that automates the analysis process, making it more accessible to maintenance personnel and improving diagnostic accuracy. By applying this tool to real-world transformer data, the thesis demonstrates its effectiveness in identifying and diagnosing faults ,there by enhancing the reliability of transformer maintenance practices.enDissolved Gas Analysis (DGA)Graphical User Interface (GUI)Power Transformer CompositionThesis