Capacitance-transformed self-calibrated floating-ground voltage sensor
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％.
capacitance conversionself-calibrationfloating voltage measurementequipotential shielding
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