油纸绝缘变压器老化状态评估的极化/去极化电流技术研究

对一种非破坏性的,不需要对变压器吊罩处理的油纸绝缘老化评估方法--极化/去极化电流(polarization and depolariza-tion current)测量方法进行了实验室及现场试验研究.在阐述了该方法的基本理论基础之后,在实验室对影响PDC测量结果的主要因素进行了试验研究,发现绝缘结构、纸板含水量及绝缘的老化程度等对PDC测量结果有着显著影响.研究发现油纸绝缘结构中绝缘油的状态对应PDC测量曲线起始部分的变化,而绝缘结构及纸板的状态则对应了测量曲线的中段和末段部分.现场试验表明,通过对变压器进行PDC测量及对PDC测量曲线的分析,可以对绝缘油的状态及纸板的状态分别进行合理的老化评估.

Study of polarization and depolarization current measurements for assessment of aging state of oil-paper insulated transformers

Polarization and depolarization current (PDC) analysis is a non-destructive dielectric test method for determining the aging state of insulation materials of power transformers. The main influence factors are studied af-ter describing the basic theory of PDC in this paper. The insulation structure, conductivity, moisture level and aging state have great influence on the test results of PDC method. The initial period of the polarization/depolarization current curve is found to be governed by the oil properties and the long time values of these currents are primarily determined by the insulation structure and paper/pressboard condition. Field test shows that the conditions of both the oil and paper can be separately estimated through analyzing the PDC measurement results.