Influence of AC and DC Composite Voltage on Positive Streamer Discharge

Many UHVdc key equipment has to withstand the role of ac and dc composite voltage in operation, so the flashover discharge problem under the action of ac and dc composite voltage is a difficult and key problem in UHVdc insulation design and operation. The streamer discharge is the most important stage before flashover discharge, so it is of great significance to study the characteristics of the streamer discharge under ac and dc composite voltage. In this article, the key characteristic parameters of positive streamer discharge, such as stable propagation field, propagation velocity and luminous intensity, were measured in the three-electrode structure under the action of ac and dc composite voltage. It was found that the characteristics of streamer discharge under the action of ac and dc composite voltage changed with the phase, which were very different from the characteristics of the streamer discharge under the action of dc voltage. Through numerical simulation calculation method, the influence of space charge on the streamer discharge process under the action of ac and dc composite voltage was explored, and the role of ac and dc composite voltage was reasonably explained.