现场变压器油纸绝缘时频域介电特征量提取及状态评估

Extraction of Time and Frequency Domain Dielectric Characteristics and Condition Assessment for Field Transformer Oil-paper Insulation

油浸式变压器的绝缘状态决定了变压器的运行寿命。为将时频域介电响应技术应用于变压器油纸绝缘状态的无损评估,对一台停运的500kV变压器进行了极化/去极化电流(PDC)与频域介电谱(FDS)测量。通过时域介电谱融合理论及FDS技术提取了反映变压器油纸绝缘状态变化的时域介电特征量与频域介电特征量,并分析了其变化规律。研究结果表明,时频域介电特征量对变压器油纸绝缘的老化情况较为敏感,可定性评估变压器的绝缘状况。

The service life of an oil-immersed power transformer is determined by its insulation condition. In order to preferably apply the time domain dielectric response method and frequency domain dielectric response method to nondestructively assessing the insulation condition of transformer oil-paper insulation, the polarization and depolarization current （PDC） and frequency domain spectroscopy （FDS） of a 500 kV-transformer which is out of service are measured first, then the time domain dielectric characteristic （TI）DC） and the frequency domain dielectric characteristic （FDDC）, which represent the insulation condition of oil-paper insulation, are extracted by the blending method of time domain dielectric response and FDS technique. Finally, the variation rules of TDDC and FDDC are illustrated in detail. Research results show that the TDDC and FDDC are sensitive to the variations of the insulation condition of power transformer, thus capable of qualitative evaluation of the insulation condition of transformer oil-paper insulation.