基于光辐射强度的日盲紫外放电检测结果一致性校准方法

Consistency Calibration Method for Solar-Blind Ultraviolet Discharge Detection Results Based on Optical Radiation Intensity

随着紫外放电检测技术的广泛应用,为解决不同型号日盲紫外成像仪的检测结果缺乏一致性和可比性的问题,该文基于MODTRAN模型分析了温度、湿度、气压和检测距离等不同因素对日盲紫外波段光辐射的大气传输过程的影响特性,建立了紫外检测辐射传输模型,搭建了辐射计量一致性校准平台,提出了紫外检测结果一致性校准方法。利用该方法建立了3台不同型号紫外成像仪的检测结果一致性校准公式,可将紫外成像仪测得的光斑面积换算为检测目标产生的光辐射强度。使用3台紫外成像仪对棒-板模型电晕放电和氘灯光源进行紫外放电检测,由一致性校准公式所得检测目标的光辐射强度计算值的相对标准偏差均小于0.1,验证了一致性校准方法的普适性。

Solar-blind ultraviolet(UV)imaging technology has been widely used in the detection of external insulation discharge of electrical equipment,thanks to its strong anti-interference capability,long detection distance,non-contact operation,and accurate discharge location positioning.Existing research on UV discharge detection typically uses photon count or spot area as the UV detection parameters for assessing the external insulation condition of electrical equipment.However,for different models of UV imagers,the variations in their optical system structure and signal processing algorithms lead to significant differences in the numerical values of UV parameters obtained by the instruments,resulting in a lack of consistency and comparability.To address this issue,this study reveals the impact mechanisms of various factors such as temperature,humidity,pressure,and detection distance on the atmospheric transmission of solar-blind UV radiation and proposes a consistency calibration method for the detection results of UV imagers.Firstly,the impact characteristics of different factors such as temperature,humidity,pressure,and detection distance on the atmospheric transmission of solar-blind UV radiation were analyzed based on the MODTRAN model.An empirical calculation formula for the atmospheric transmittance of UV radiation in the wavelength range of 240 to 280 nm was obtained.It was found that,in weather conditions suitable for UV detection with humidity below 80%,humidity does not affect the transmission of UV radiation in the wavelength range of 240 to 280 nm.The impact coefficients of pressure,temperature,and detection distance on the atmospheric transmittance of UV radiation in the wavelength range of 240 to 280 nm are−0.0188,0.0001 and−0.0014,respectively.Additionally,in the UV discharge detection of external insulation of electrical equipment,the discharge point was treated as a point source uniformly emitting light into the surrounding space,based on which a UV detection radiation transmission model was established.Then,a radiation metrology consistency calibration platform was constructed,and a consistency calibration method for UV detection results was proposed based on the UV detection radiation transmission model.The optical radiation intensity generated by the discharge point was selected as the standard parameter for the consistency calibration of UV detection results.Using this method,consistency calibration formulas were separately established for three different models of UV imagers.By converting the spot area measured by different models of UV imagers into the optical radiation intensity generated by the discharge point using the consistency calibration formulas,it ensures that the detection results of different models of UV imagers are consistent and comparable.Finally,based on the consistency calibration formulas for UV detection results,UV detection was performed on a rod-plate model of corona discharge using the three UV imagers.The relative standard deviations of the calculated optical radiation intensities for each UV imager were 0.080,0.087,and 0.098,respectively,and the relative standard deviation among all the calculated optical radiation intensities was 0.090.For UV detection of a deuterium lamp,the relative standard deviation of all the calculated optical radiation intensities was 0.063,with an average deviation of 5.78%from the actual optical radiation intensity of the light source(1593μW/sr).The effectiveness of the consistency calibration method for UV detection results was demonstrated.