电容变换的自校准浮地电压传感器

Capacitance-transformed self-calibrated floating-ground voltage sensor

在侵入式浮地电压测量中,由于探头与地的耦合电容受探头距地高度、安装位置下方带电导体的影响,导致传感器增益不稳定,无法准确测量待测电压。针对该问题,提出一种基于电容变换的侵入式浮地电压测量校准方法,实现传感器增益的自标定。介绍浮地电压测量的基本原理,并分析导致耦合电容发生变化的因素,进而提出基于电容变换的自校准方法。为了减少空间杂散电场对测量系统的耦合作用,设计具有对后端电路进行等电位屏蔽的传感器探头,并选取合理的电路参数。搭建实验平台进行幅值精度、相位精度、电场屏蔽抗干扰、不同高度适应性测试。实验结果显示:电压幅值最大相对误差为1.99%,相位绝对误差为0.51°;等电位探头对外界噪声具有屏蔽作用;针对传感器不同高度所重构的待测电压最大相对误差为1.66%。

In the invasive floating-ground voltage measurement,due to the impact of the height of the probe from the ground and the charged conductor below the installation position on the coupling capacitance between the probe and the ground,the sensor gain is unstable and the voltage is inaccurately measured.To address the problem,this paper proposes an invasive floating-ground voltage measurement and calibration method based on topology transformation to achieve self-calibration of sensor gain.First,the basic principle of floating-ground voltage measurement is introduced and the factors leading to the change of coupling capacitance are analyzed.Then,a self-calibration method based on topology transformation is proposed.To reduce the coupling effect of the spatial stray electric field on the measurement system,a sensor probe with equipotential shielding of the back-end circuit is designed and reasonable circuit parameters are selected.Finally,an experimental platform is built to test the amplitude accuracy,phase accuracy,electric field shielding anti-interference and adaptability at different heights.Our results show the maximum relative error of voltage amplitude is 1.99% and the absolute error of phase 0.51°.Our anti-interference experiment reveals the equipotential probe has a shielding effect on the external noise.The maximum relative error of the measured voltage reconstructed for different heights of the sensor is 1.66%.