使用光学电流互感器(Optical Current Transducer ,OCT)测量小电流时,测量得到的内部噪声信号往往大于光电信号,测得的读数不能正确反映电流的真实值。有效滤除噪声,提高信噪比是OCT信号处理的关键所在。本文介绍了基于法拉第磁光效应的光学电流互感器的基本原理和信噪特性,在被测电流为交直流混合信号的情况下,建立合适的滤波状态空间模型,采用序贯卡尔曼滤波的方法在LabVIEW上进行仿真。结果表明序贯卡尔曼滤波算法能够对测量电流实时进行信噪分离,同时准确分离出交流和直流分量,提高了输出信噪比和测量精度。
英文摘要:
When Optical current transformer (OCT) is used to measure small current, internal noise signal measured is often greater than the photoelectric signal.The measured reading can not accurately reflect the true value of the current. Effectively filtering out noise and improving signal to noise ratio is the crux of OCT signal processing. This paper introduces the basic principle and the signal to noise characteristics of the optical current transformer based on Faraday effect. In the case of the measured current with AC and DC signals, we establish the appropriate filter state-space model, and use sequential Kalman filter method on LabVIEW simulation. The results showed that the sequential Kalman filter algorithm can real-time and effectively perform signal noise separation to the measuring current, while accurately separate the AC and DC components, and improve the output signal to noise ratio and accuracy.