How to Analyze and Test the Location of Partial Discharge of Single-winding Transformer Model

Abstract: In order to detect transformer fault accurately and quickly, a continuous single winding transformer model is established. The multi-conductor transmission wire model consists of 180 turn wires and takes the winding continuity of first-end of all turns as boundary conditions, in which the current is extracted from grounding wires of bushing and winding end extracts the current from grounding lines. With this model, the current transmission functions of different windings from the first position to the final position is discussed. Based on the consideration of the great difference of the current transmission function between different discharge locations, the position of the partial discharge of transformer is realized via the distance function method. The current transmission functions of a 180-turn single winding transformer are measured. The theoretical results are compared with the measured results. The comparison of current transmission functions show that the method is effective.   

Introduction 

The fault detection and treatment of power transformer is essential to stable and reliable operation of power. For manufacturers and on-site staff, how to detect the fault quickly and accurately is one of their core tasks. With the development of high voltage technologies and grid technologies, there have been many advanced methods and technologies for identifying transformer faults up to now. These methods and technologies can detect any possible faults, such as DC resistance, insulation resistance, absorption rate, and faulty features, including temperature, micro-water and oil level. However, these methods cannot determine whether there is partial discharge in the power transformer and accurately locate it. Hence, special research is needed to further analyze the partial discharge fault of power transformer and locate them, which is of significance to elimination of faults and normal operation of electrical system. At present, the most studied methods are ultrasonic wave location and electrical location. It is quite difficult to apply the ultrasonic wave location method on site because ultrasonic wave signals will be affected by many factors when transmitting through different medium such as oil, paper and metals of power transformer. When power transformer has partial discharge, impulse signals transmit to the measuring terminal along windings. Then the partial discharge is targeted according to electrical transmission features in the signals. The electrical location is mainly used for inaccurate location of partial discharge and rarely utilized on site, which needs further researches.