基于紫外成像技术的极不均匀电场电晕放电

Corona Discharge of the Severe Non-uniform Electric Field Based on the UV-light Imaging Technology

为监测电气设备外绝缘缺陷、灵敏观察和准确定位电晕放电,以紫外光谱特征量为量化电晕放电强度的表征参数,以相同工频电压等级下的放电水平和电晕脉冲电流峰值作为量化比较参数,在基本相同的大气条件下,利用紫外成像技术试验研究了极不均匀电场工频电压下电晕放电。结果表明,电晕放电强度量化表征参数与量化比较参数之间的对应关系很好;表征参数可反映电晕放电的几个阶段;结合紫外成像反映的放电形态,可分辨电晕放电过程的各阶段,且紫外光谱特征量在电晕放电过程各阶段的分布具有一定的统计规律。最后提出选取流注放电阶段的紫外光谱特征量交集作为空气间隙击穿的注意范围判据。

Corona discharge is being detected by UV-light imaging technology at home and abroad these years. There are many factors causing corona discharge. Many factors during the design, manufacture, installation, operation and maintenance of the electrical equipments will cause defect of external insulation, which results in electric field concentration and the phenomenon of corona discharge. The phenomenon of discharge could be detected by the UV-light imaging technology more sensitively and more conveniently so that the discharge points can be located very quickly and exactly at field. The external insulation structure of the most electrical equipments in power system has the characteristic of the severe non-uniform electric field. The typical physical models are the ＂rod-plate＂ gap and the ＂ rod-rod＂gap. While the electric field of the ＂rod-rod＂ gap is more uniform than the ＂rod-plate＂ gap （ the maximum electric field intensity of the former disperses near the top of the both rod electrodes, and that of the latter concentrates the rod electrodes）. Therefore, in the structure designs of the external insulation of HV electrical equipments and the air gap, the ＂rod-plate＂ gap is considered as the physical model to check and design. The characteristic variable of UV-light （the photon number within unit interval detected by the UV-light imaging device） is adopted as the characterizing parameter of quantifying the intensity of corona discharge; the discharge level （the quantity of discharge） and the corona impulse current at the same power frequency voltage level are adopted as the comparing parameter; under the circumstance of almost the same atmosphere, the study on corona discharge test under the power frequency voltage of the severe non-uniform electric field based on the UV-light imaging technology is conducted. The results illuminate that the corresponding relationship between the characterizing parameter of quantifying the intensity of corona discharge and the comparing parameter is accordant; the characterizing parameter can reflect each stage of corona discharge; it can also distinguish each stage of corona discharge and the distribution of the characteristic variable of UV-light at each stage of corona discharge accords with the statistical regularity. The criterion of selecting the intersection of the characteristic variable of UV-light at the stage of stream discharge as the advertent range is proposed.