Transmission Line Voltage Calibration-Free Measurement Method

Abstract

Voltage sensing technology is crucial in realizing distributed voltage sensing at critical nodes of the power grid and providing key state variables to provide information support for control decisions. Among the existing voltage measurement methods, voltage transformers have problems such as high insulation performance requirements and limited installation locations. However, non-contact voltage sensors designed based on the electric field coupling principle have sensor accuracy problems due to the instability of the coupling capacitance. Based on the above problems, this paper first proposes a floating ground measurement system based on an equipotential and differential structure. It also proposes a dual capacitance equivalent model for AC voltage measurement on transmission lines. Based on this method, a calibration method for the amplitude and phase of the sensor is built. Under the voltage test at 50 Hz operating frequency in the voltage range (100–300 V), the maximum relative error of the voltage amplitude is 0.89%, and the maximum relative error of the voltage phase is 0.68°. The maximum relative error of voltage amplitude under a 50 Hz operating frequency voltage test in the voltage range (600 V–10 kV) is 4.48%. In the final scenario adaptation analysis, the method’s specific height amplitude accuracy error was experimentally verified to be 0.88%, with a maximum difference of 0.52% for multi-type conductor testing.