长空气间隙50%放电电压的测量不确定度分析

Uncertainty in Measurement Analysis of 50% Discharge Voltage of Long Air Gap

受试验设备、试验方法及环境因素的限制,利用试验的方法测量长空气间隙的50%放电电压U时,试验结果与客观真值存在偏差。以阀塔均压罩对地构成的长间隙放电试验为例,建立了“升降法”测量U不确定度分析方法,对试验结果的不确定度从试验方法、高压发生器测量系统、测试过程中的温湿度变化等方面进行计算分析。研究表明,试验结果的不确定度同现有长空气间隙的放电电压计算模型的计算结果偏差处于同一数量级,在验证放电电压计算模型的有效性时,有必要将试验值本身的不确定度纳入考虑;高压发生器测量系统引入的不确定度最大,提高高压发生器的测量及控制精度,适当减小“升降法”的加压极差,能减小50%放电电压的测量不确定度。

Due to the limitations of test equipment, test methods and environmental factors, when the 50% discharge voltage of long air gap is measured in the test, the results deviate from the objective truth values. Taking the long gap discharge test of the valve-tower grading shield to the ground as an example, this paper establishes an uncertainty analysis method of Umeasurement by "up-and-down method", calculates and analyzes the uncertainty of the test results from the aspects of statistical methods, high-voltage generator measurement systems, temperature and humidity changes during the test. The calculation and analysis show that the uncertainty of the test result is in the same order of magnitude as the deviation of the calculation result of the existing long air gap discharge voltage calculation model. When verifying the validity of the calculation model, it is necessary to take the uncertainty of the test value into consideration. The uncertainty introduced by the high-voltage generator measurement system is the largest. Improving the measurement and control accuracy of the high-voltage generator, and appropriately reducing the voltage difference of up-and-down method can effectively reduce the measurement uncertainty of 50% discharge voltage.