A New Detection Method for Corona Discharge in High Voltage Power Modules Based on Decomposition Gas Analysis

摘要

Power electronics modules are widely used in energy conversion and are important for the development of energy internet. However, some fault such as corona discharges may happen in these modules. To monitor or detect this kind of defect many methods are developed. As in this paper a new method called decomposition gas analysis method based on air by-products is proposed to detect corona discharges happening in air. As one knows Ozone and NOx generate when discharge happens in airside, a lot problem still exists. In this paper the possibility of this method is studied. Firstly, the chemical reaction of air under discharge is analyzed; then a typical corona discharge - protrusion defect discharge is simulated using needle-plane electrodes in a semi-closed test cell. The relations between corona discharge and decomposition gases concentrations are studied. The experiment results show the ozone and NOx concentrations increase as the maximum PD or applied voltage increase with different inception PD capacity or voltage. Meanwhile, the growth rates of both gases are varying against different voltage. These properties imply discharge faults can be detected by measuring and analyzed the gas concentrations. Besides, the humidity as one of the most key influence factor to the ozone and NOx production under corona discharge is studied. The humidity of air in the test cell is tuned and the affection is studied. The experiment results show the fluctuation of humidity has impact on the production of O3 and NOx.