Research on the Typical Characteristics and Development Patterns of Multi-Parameter Signals of Inter-Turn Insulation Partial Discharge in Large Transformer Windings

The inter-turn insulation fault is one of the most common faults in large transformers. In order to investigate the variation of characteristic parameters during the development process of inter-turn insulation partial discharge, this study focuses on the pig-tail model and establishes an inter-turn discharge test platform. A multi-parameter signal measurement system is constructed, which includes conventional pulse current, ultrasound, high-frequency CT, and ultra-high-frequency sensors. The experimental method of step-up voltage is employed to record the changes in multi-parameter signals during the discharge process. Based on the analysis of the experimental results, this study divides the inter-turn discharge process into three stages and provides the characteristics of multi-parameter signals at each stage, as well as the variation patterns of the discharge development process. The experimental results provide diagnostic basis for the multi-parameter monitoring of inter-turn insulation discharge and offer technical references for the further development of combined monitoring methods.