电热联合作用下交流油浸纸套管绝缘特性

Insulation Characteristics of Oil-impregnated Paper Bushing Under the Combined Electrical-thermal Effect

为研究交流油纸绝缘套管实际工程运行中的绝缘特性,建立了套管电热联合试验平台,针对交流油纸绝缘套管,开展了不同油温和不同负荷条件下的绝缘参量特性试验。掌握了不同油温和不同负荷条件下交流油纸绝缘套管介质损耗因数、电容量、绝缘电阻及频域介电谱的变化规律,并根据电介质极化理论系统分析了参量变化规律机理。研究结果表明:变压器油温变化会引起油纸绝缘套管各绝缘性能参量的规律性变化。不同负荷对套管绝缘性能的影响主要集中于热效应上,承受的负荷变化最终体现为套管内部温度变化。相同油温条件,联合施加电压电流的套管在变化的负荷作用下,其绝缘性能相比于单一考核因素的绝缘性能更低。故开展电热联合作用下套管绝缘特性试验能更为准确地掌握套管绝缘性能,为套管状态评估和绝缘诊断提供有力支撑。

In order to investigate the insulation characteristics of AC oil-impregnated paper bushing during its operation,a combined electrical-thermal test platform was established to carry out the insulation characteristics tests under different oil temperature conditions and different load conditions.The change law of dielectric loss factor,capacitance,insulation resistance and frequency domain dielectric spectrum for AC oil-impregnated paper bushing under different conditions were investigated,and the mechanism of the change law was analyzed systematically based on the dielectric polarization theory as well.The results show that the change of transformer oil temperature will lead to the regular change of insulation performance of bushing.The influence of different loads on the bushing is mainly concentrated on the thermal effect,and the change of load will be finally reflected by the change of the internal temperature of the bushing.At the same oil temperature,when the bushing which is applied with voltage and current simultaneously is under the different load condition,it has worse insulation performance than the one with single assessment factor.Therefore,it can be more accurate to grasp the insulation characteristics of bushing when tests with a combined electrical-thermal effect are performed,providing a strong support for the evaluation and diagnosis of bushing.