基于磁感应原理的自积分式冲击电流测量系统校准

Calibration of Self-integrated Impulse Current Measurement System Based on Magnetic Induction Principle

研制的基于磁感应原理的自积分式冲击电流测量系统可以用于在变电站或高压试验室内测量雷电或操作冲击电流,针对冲击电流幅值高、频谱宽的特点,需要对测量系统频率响应特性和刻度因数进行严格的校准。为此分析了测量系统的测量原理,提出了基于阶跃响应的校准方法,自行设计搭建了校准试验平台,分析了A类和B类测量不确定度,完成了测量系统的校准。校准结果为:测量系统低频截止频率最佳估计值为0.952 Hz,扩展不确定度为0.025 Hz,有效自由度为9;高频截止频率最佳估计值为14.09 MHz,扩展不确定度为0.17 MHz,有效自由度为10;刻度因数最佳估计值为10.1 m V/A,扩展不确定度为0.18 m V/A,有效自由度为36。可见,该测量系统可以满足冲击电流测量要求。

The self-integrated impulse current measurement system is developed to measure lightning impulse current and switching impulse current in substation or high voltage test laboratory. Due to the characteristics of high amplitude and wide spectrum of impulse current, strict calibration is required for the frequency response and scaling factor of measurement system. We firstly analyzed the principle of the measurement system and proposed a calibration method based on step response. Moreover, we designed and built a calibration platform, analyzed the measurement uncertainty of class A and class B, and performed the calibration of the measurement system. Calibration results are as follows： the optimum estimated low-frequency cutoff frequency is 0.952 Hz with the expanded uncertainty of 0.025 Hz and the effective degrees of freedom of 9. The optimum estimated high-frequency cutoff frequency is 14.09 MHz with the expanded uncertainty of 0.17 MHz and the effective degrees of freedom of 10. The optimum estimated scaling factor is 10.1 m V/A with the expanded uncertainty of 0.18 m V/A and the effective degrees of freedom of 36. Therefore, the developed measurement system meets the requirements of impulse current measurement.