阶梯升压试验和恒定电压试验中油纸绝缘局部放电发展规律的对比

Contrast of the Developing Regularity of Partial Discharge of Oil-paper Insulation Using Step-stress Test and Constant-stress Test

实验室多利用阶梯升压试验来研究变压器中油纸绝缘局部放电现象,而现场实际中的变压器是在恒定电压下运行的。为了研究试验电压条件对油纸绝缘局部放电缺陷发展过程及规律的影响,构建了球板结构的浸油纸板局部放电模型,分别利用阶梯电压试验和恒定电压试验,研究了绝缘纸板从起始放电到纸板被击穿的放电发展过程中窄带脉冲电流信号的脉冲重复频率、累积放电量及1s放电量、脉冲放电量的最大值和平均值及脉冲相位分布的变化过程。研究结果表明,无论利用哪种试验,在球板放电缺陷的发展过程中,脉冲累积放电量、1s放电量、脉冲(平均、起始、终止)相位及脉冲重复频率等均呈现一定的线性或指数发展趋势。分析试验结果可知,试验加压条件对脉冲重复频率、脉冲相位分布、脉冲总放电量等特征参数发展趋势的影响不明显,但对脉冲放电量平均值、放电量最大值的发展规律有较大影响。

In laboratory,the oil-paper insulation partial discharge in transformer was mostly researched by using step-stress tests,while transformers in field operate under constant voltage.In order to study the influences of different test conditions on the developing process and regularity of oil-paper insulation partial discharge defects,a sphere-plate model was structured for long time high voltage experiments.By using the model,step-stress tests and constant-stress tests were performed to investigate the change of narrow-bandwidth pulse current signal in the duration between the start of discharge and the breakdown of paper insulation.According to the test results,no matter which kind of tests is adopted,during development of the defect,the total accumulative discharge capacity,the total discharge capacity in a second,the pulse phase（including average phase,initial phase and final phase）,and the pulse rate show linear or exponential change trends.Further analyses of the test results indicate that the test conditions hardly influence the developing trends of the pulse rate,the distribution of pulse phase,and the total discharge capacity,but they have a great influence on the developing regularity of the average amplitude and maximum amplitude of pulse.