Detection and distinction of partial discharges in air at DC voltage by using a non-conventional approach in the high-frequency range

Abstract

Conventional partial discharge diagnosis is a well-known and approved method for evaluating the condition of high voltage equipment at AC voltage. Increasing importance of HVDC transmission systems require adapted methods for partial discharge diagnosis at DC voltage. In this paper an alternative approach for defect identification at DC voltage based on the measurement and analysis of the electromagnetic spectrum emitted by the partial discharges is presented. For that purpose, a high voltage setup for measuring partial discharges via the conventional method is modified and supplemented by a broadband measuring system. With corona discharges and surface discharges, different artificial partial discharge sources are integrated into the measuring setup and the electromagnetic spectra are determined. After post processing, data are analysed, discussed and parameters for the distinction of partial discharges by capturing the electromagnetic spectrum are defined.