Measuring the charge density along the radius in concentric cylinders configuration by sensing system

Abstract

The measurement of space charge density caused by the corona discharge around the overhead transmission line is a tough problem till nowadays. For this problem, a system for measuring the one-dimensional (1D) distribution of space charge density in a coaxial cylinder model under negative corona discharge in ambient air is developed. This system is a scale model which can provide research basis for actual overhead line measurement. The system consists of acoustic emission, space charge generation, and signal-receiving systems. The sound wave of an ultrasonic transducer is used to stimulate space charge generated by a small corona cage, and the applied voltage ranges from −34 kV to −38 kV. Charge vibration produces an electrical field (E-field) that can be measured with an E-field antenna. After obtaining the E-field signal, the adaptive noise cancellation method is adopted to eliminate noise interference so that the accuracy of charge density can be improved. The Townsend's analysis solution is used to calculate the theoretical value of space charge density. Experimental results are consistent with the simulation value and thus confirm the validity of the proposed adaptive noise cancellation method and sensing system.