Research on fatigue fracture failure of high-voltage bushing conductive rods under complex conditions

This study focuses on the failure of 750 kV main transformer bushing under complex conditions. First, the failure mechanism of high voltage bushing under fatigue fracture, conductive rod loosening, capacitance core moisture, and load is analyzed. The calculation of fatigue fracture of a conductive rod under different temperature and stress is carried out. The tensile test and simulation verification of the scale model are completed, and the stress concentration factor is calculated. Second, the experiment of dielectric properties of main insulation under different humidity is carried out, and the relationship curve between water content and dielectric loss angle is given. The temperature field calculation model under typical faults is established, and the temperature and mechanical properties of bushing under fault conditions are calculated. Finally, a dual CNN-LSTM high-voltage bushing fault diagnosis method is proposed. The surface temperature gradient, the stress concentration factor of the conductive rod, and the dielectric loss are used as the characteristic parameters. The CNN is used to extract the image features, and the LSTM is used to model the long-term dependence of the dielectric loss. This method significantly improves the overall accuracy of high-voltage bushing fault diagnosis and the accuracy of typical fault diagnosis and provides a new method for 750 kV main transformer bushing fault analysis.