Defect Analysis and Preventive Measures of Main Transformer Bushing Based on Frequency Domain Dielectric Spectroscopy

The health status of main transformer bushing is directly related to the safe and stable operation of power grid. This paper introduces an abnormal dielectric loss factor of glass fiber reinforced plastic dry bushing of 220 kV main transformer. Firstly, the casing defects were determined based on the frequency domain dielectric spectrum. Then, the causes of the casing defects were analyzed by the partial discharge test, the casing disintegration inspection, the final screen dielectric loss test and the electromagnetic field simulation calculation. Finally, the diagnosis method and the preventive measures of the glass fiber reinforced dry casing defects were proposed. The research results of this paper have certain reference and guiding significance for the safe operation of this type of main transformer bushing.