满足0.2级的光纤电流互感器信噪比分析(英文)

SNR of optical fiber current sensor reaching 0.2 accuracy class

电流比值误差和相位误差是检验互感器的重要指标,噪声对其有较大影响。光纤电流互感器不同于传统电流互感器的重要特征之一即是存在较大噪声,在测量小电流时表现尤为显著,已经成为阻碍光纤电流互感器实用化进程的重要难题。分析了高斯白噪声背景下电流比值误差和电流相位误差的统计特征,研究了0.2S级下电流互感器数字输出信号信噪比所需满足的条件,探讨了电流互感器信噪比的计算方法以及影响信噪比的因素,并设计实验验证了理论分析的正确性。分析表明,为满足0.2S级光纤电流互感器信噪比需达到136,在额定电流以及数据更新率一定的情况下,仅有通过降低噪声以及增加敏感线圈缠绕圈数的方法可以提高系统信噪比。

Current ratio error and phase error, which are impacted by noise, are fundamental index of current sensor. Compared with conventional current sensor, optical fiber current sensor contains much more noise, thus has lower measurement accuracy for small signal. This has restricting practical use for optical fiber current sensor. Statistical characteristic of current ratio error and phase error under white Gaussian noise was analyzed, so was the standard of signal to noise ratio （SNR） when it can meet 0.2 accuracy class. Furthermore, formula of SNR was deduced and influencing factors of SNR was discussed. Theoretical analysis and experiments indicate that the SNR of optical fiber needs to be 29 dB to meet the demand of 0.2 accuracy class. When the rated current and update rate are confirmed, only reducing noise and increasing the number of loops of optical fiber current sensor can improve SNR.