ASSESSMENT OF TRANSFORMER CORE AND WINDING CONDITIONS FROM SFRA MEASUREMENT RESULTS USING NUMERICAL TECHNIQUES FOR TNB DISTRIBUTION TRANSFORMERS

Power transformers are the main equipment in power systems especially in electrical distribution network. It is very crucial to prevent failures and detect problems in transformers as early as possible. The main components in transformer are core and winding. Therefore a diagnostic tool for evaluating transformer core and winding conditions is an essential. The SFRA measurement results consist of magnitude response with sweep frequency bandwidth from 20 Hz to 2 MHz. The frequency bandwidth is sensitive related to transformer core and winding conditions. Meanwhile in Tenaga Nasional Berhad (TNB) Distribution, only transformer winding is evaluated from the obtained SFRA measurement results not the core of the transformer. In this thesis, the evaluation is taken for both transformer core and winding conditions by using the proposed frequency sub-bands meanwhile numerical parameters are then used to interpret the SFRA measurement results. Twelve transformers with defect and non-defect conditions are used in this work. To verify the capability on transformer core and winding diagnosis using numerical parameters in SFRA measurement results, the comparison with the assessment from Omicron FRAnalyzer software and visual inspection of the defect transformers are made. From the results, the numerical parameters are capable for interpreting the SFRA measurement results through the proposed frequency sub-bands for evaluating transformer core and winding conditions. Finally, it is a successful work to evaluate TNB transformers core and winding conditions using numerical parameters from the proposed frequency sub-bands of SFRA measurement results