Development and application of high-frequency sensor for corona current measurement under ultra high-voltage direct-current environment

Corona current measurement is essential for research into corona discharge under ultra high-voltage direct-current (HVDC) environment. The sensor is extremely important due to the small (microampere) amplitude of the corona current and the wide (dc to tens of megahertz) range in frequency. In this paper, a high-frequency sensor is described, and its application is introduced for accurate measurement of corona current under HVDC environment. Based on the finite-element method and the charge simulation method, the structure of the sensor is determined considering a ±1200-kV environment. The sensor is immune to the effects from the external environments such as vibration and temperature changes. Results indicate that the sensor is feasible for corona current measurement.