Aging Condition Evaluation of Oil-Paper Insulation based on Depolarization Current Sub-lines
Wu Wenxuan1, 3, Zhang Konglin2, 3, Cai Jinding3, Shi Guangyu2, Li Anna3
1. Sate Grid Fujian Provincial Electric Power Company Limited, Fuzhou 350001; 2. Sate Grid Fujian Provincial Electric Power Company Limited, Electric Power Tecnology and Research Institute, Fuzhou 350001; 3. College of Electrical Engineering and Automation, Fuzhou University, Fuzhou 350108
Abstract:Depolarization current analysis is a better method for reflecting characteristics of the polarization process of dielectric response. The inner relaxation characteristics of depolarization current are studied in this paper. Two new characteristic quantities including sub-lines and its energy are introduced so as to further analyze the relationship between sub-lines energy and aging condition of oil-paper insulation, and the correspondence between sub-lines and the compositions of oil-paper insulation. And then a method to distinguish aging condition of oil-paper insulation is derived. Results show that, the sensitivity of sub-lines energy is sensitive to aging condition, sub-lines energy increases with the lower insulation level .The state of insulating oil is closely related to sub-lines of small time constant. The state of insulating paper is closely related to sub-lines of big time constant. So, depolarization current sub-lines and its energy can be accepted as the criterion of insulation diagnosis. The research will be one of effective means in the assessment of oil-paper insulation aging status.