针-板模型交/直流电晕放电的紫外特征参量

Ultraviolet Characteristic Parameter of Needle-plate Model AC/DC Corona Discharge

紫外（UV）成像仪是检测电气设备电晕放电的一种常用手段,但是目前在工程应用中仍面临着紫外成像仪检测结果与放电故障类型难以确切对应的问题。为此,通过紫外成像研究了交/直流电压下针-板模型的电晕放电,提取了电晕放电光子数与紫外图像光斑面积,对比分析了针-板模型在不同交/直流电压下光子数和光斑面积的特性。结果表明：光子数和光斑面积能在一定程度上反映电晕放电强度;随着检测距离的增加,光子数和光斑面积均会衰减,衰减规律满足阿拉德定律;光子数随增益而呈现先增后减的趋势,而光斑面积随增益的增加而增加,具有明显的单调性;交流和负极性直流电压下,随着电压的增加,紫外特征参量呈现幂函数的增长趋势;正极性直流电压下,由于针电极的极性效应,电晕起始电压较高;由于放电初期的中和电离影响,光子数和光斑面积会出现跃升;此后,光子数和光斑面积随着起主导作用的电离形式发生变化而锐减;随后,光子数和光斑面积都随电压的增加而平稳增长,此时2种紫外特征参量与电压也呈现幂函数关系。因此,光子数和光斑面积可互为补充,从多个角度对电晕放电强度进行识别与表征。

Ultraviolet（UV） imager is commonly adopted to detect corona discharge of electrical equipment, however, the relationship between the detected result and the fault type of discharge is hard to be determined in engineering. Therefore, we adopted a needle-plate model to analyze the corona discharge characteristics of needle-plate model under AC/DC voltages by an UV imager. Meanwhile, the photon number and facula area of discharge from an UV imager were extracted, and the characteristics of photon number and facula area of needle-plate model under different AC/DC voltages were analyzed. Results show that the photon number and facula area can reflect the intensity of corona discharge to a certain extent, the photon number and facula area decrease with the increase of observation distance, and the attenuation law satisfies the Allard＇s Law. UV characteristics show a trend of the growth of the power function with the increase of voltages under negative polarity DC and AC voltages. Under positive polarity DC voltages, because of the polar effect of needle electrode, corona initial voltage is higher, and a sharp growth appears in the UV characteristics because of neutralization ionization. Then, the leading role of ionization is changed, and UV characteristics quickly decay. Finally, the UV characteristics grow gently, and the trend meets the power function. Therefore, photon number and facula area can complement each other, and identify and characterize the intensity of corona discharge from multiple angles.