不同电场下CVT电容单元膜纸绝缘损坏机理研究OA

Capacitor voltage transformers(CVT)are used widely in EHV/UHV power systems.The failure of CVT not only affects the accuracy and reliability of electric energy measurement but also the stable and safe operation of power grid.In this paper the CVT capacitor unit with the highest fault rate is taken as the research object.By making the sample suitable for reflecting the electrode defects of CVT capacitor core,the corresponding experimental plat-form is set up to perform the breakdown experiment under different electric field conditions and analyze the break-down point distribution of the sample.Moreover,the damage mechanism of film paper insulation under power fre-quency voltage,positive and negative polarity lightning impulse voltage and AC superposition impulse composite electric field is studied.The experimental results show that the edge defect of aluminum foil electrode of CVT capaci-tor core is the main cause for the insulation damage of film paper,and the types and changes of electrode defects de-termine the spatial distribution of breakdown points.However,the difference in the'trap'effect of polypropylene film on positive and negative space charges will lead to transformation of the dominant type of breakdown point under different superposition amplitude and phase.