采用无源磁传感标签的交流电流无线监测:测量及标定

Wireless monitoring of AC current using passive magnetic sensor tags:Measurement and calibration

本文所采用的传感标签利用无源无线传感技术传递数据和能量,再通过内置的传感模块检测电缆线周围的磁场强度,可实现免电池维护、无线缆连接的电缆电流测量。但受射频供电微瓦量级功率的限制,传感标签采样点数少、采样频率低和磁场敏感元件的非线性使得传感数据和电缆电流间映射关系复杂,导致传感标签标定、测量困难。针对该问题,本文提出先通过粒子群与内点法结合的优化算法对传感数据进行傅里叶级数拟合提取特征值(频率和有效值)再标定的方法。在测量时对传感数据分组进行傅里叶级数拟合获取特征值,再将特征值代入标定时建立的传感模型,实现频率为47~60 Hz、有效值为5~45 A内的等振幅电流测量,电流频率和有效值的相对误差分别低于0.4%和1.9%。实验结果表明,采用该方法搭载传感标签的测量系统不仅可实现电缆电流的无源无线测量,也能实现国内电力系统标准所允许的最大电流波动测量。

The sensor tag in this article uses passive wireless sensing technology to transmit data and energy.It uses the built-in sensing module to detect the magnetic field intensity around the cable,realizing cable current measurement without battery maintenance and cable connection.However,due to the limitation of microwatt power supplied by radio frequency waves,the number of sampling points of the sensor tag is restricted,the sampling frequency is low and the nonlinearity of the magnetic field sensitive element makes the mapping relationship between the sensor data and the cable current complicated.Hence,it is difficult to calibrate and measure the sensor tag.To solve this problem,this article proposes an optimization algorithm combining particle swarm optimization and interior point method to extract the characteristic values(frequency and effective value)from the sensing data by Fourier series fitting and calibration.During the measurement,the characteristic values are obtained by Fourier series fitting of sensor data groups.Then,the characteristic values are substituted into the sensor model established during calibration.The constant amplitude current measurement with the frequency of 47~60 Hz and an effective value of 5~45 A is realized,and the relative errors of current frequency and effective value are less than 0.4%and 1.9%,respectively.The experimental results show that the measurement system equipped with the sensor tag can not only realize passive wireless measurement of cable current,but also can realize the maximum current fluctuation measurement allowed by domestic power system standards.