The real-time

accuracy

and reliability of voltage measurement are the fundamental guarantees for the safe operation of power systems. In non-contact voltage measurement

the coupling capacitance between the wire and the sensor is affected by factors such as wire diameter

insulation material

and relative position

making it difficult to determine the sensor gain; The capacitance measurement at the picofarad level is affected by factors such as instrument accuracy

parasitic capacitance

and environment

which makes it difficult to accurately measure the capacitance value and leads to large errors in voltage inversion calculations. To address the issues

this article presents a three-electrode capacitive coupling method for non-contact voltage measurement. Additionally

the capacitive voltage division method and the least squares method are employed to compute the structural capacitance at the picofarad level

facilitating the calculation of the sensor gain coefficient. The sensor structure design is guided by the principle of minimizing calculation errors

based on voltage error and sensitivity analysis. Finally

an experimental platform was established to perform precision testing

variable wire diameter testing

and transient performance testing on the sensors. The accuracy test shows that the maximum relative error of the voltage effective value inversion calculation is 0.53%. The results of the variable diameter test show that the maximum relative error is 2.68%. The transient experiment of the switch gate shows that the sensor has good transient response performance

and the input and output voltage waveforms are basically overlapped.