The characteristics of positive corona discharge of rod electrode in high-speed airflow are studied in this paper.The experiments were carried out in a wind tunnel with a maximum flow speed of 100 m/s in a dark room.T...The characteristics of positive corona discharge of rod electrode in high-speed airflow are studied in this paper.The experiments were carried out in a wind tunnel with a maximum flow speed of 100 m/s in a dark room.The discharge voltage and current were recorded and the corona patterns were captured by a digital single lens reflex(DSLR)camera during the experiment.A discharge transition in rod electrode from streamer corona to mixed streamer-glow corona,and finally to stable glow discharge was observed with the voltage increased.The increase of airflow speed resulted in a decrease of each corona inception voltages.The streamers will be suppressed and shifted towards the upwind side,while the glow layer will be promoted and shifted towards the downwind side in low and upwind side in high voltages.The glow corona current and the voltage show a quadratic function and the higher the airflow speeds,the bigger the coefficient of square of voltage.The distributions of peaks,pulse widths and interval times of streamer pulses were analysed,showing good correspondence with the streamer images.The measurements were explained by combining particle transport and local air pressure distribution.展开更多
Converter transformers are the core device in ultrahigh voltage direct current(UHVDC)transmission systems,and the oil-paper insulation at its rectifying valve side deals with the composite AC-DC voltage.A detailed inv...Converter transformers are the core device in ultrahigh voltage direct current(UHVDC)transmission systems,and the oil-paper insulation at its rectifying valve side deals with the composite AC-DC voltage.A detailed investigation of the partial discharge(PD)mechanism in the oil-paper insulation under the composite AC-DC voltage is,therefore,very important.The oilpaper insulated needle plate electrode simulation model for the electric field and charge distribution can be established using hydrodynamic drift-diffusion theory and bipolar charge carrier theory,and the simulation results can reflect the morphological changes of PD.The development characteristics of PD under composite AC-DC voltage are researched.In addition,the effects of simulation time,the AC-DC component proportion,and model parameters on PD are also explored.Results indicate that differences in applied voltage,interface charge,and geometry structure can cause changes in the electric field strength,which consequently influences the PD process in the simulation model.Oil-immersed paperboard is a type of liquid-immersed dielectric(LID).When the LID is arranged in perpendicular,only the positive streamers have narrow channels oriented toward the LID.When the LID is arranged in parallel,the PDs are in the form of creeping discharges and the negative streamers are more dispersed.The development characteristics of PD and its influencing factors reported here may provide theoretical and simulation support to explain the physical mechanism of PD at the rectifying valve side of the converter transformer.展开更多
基金National Natural Science Youth Foundation of China,Grant/Award Number:52207168National Natural Science Foundation of China,Grant/Award Number:52377154。
文摘The characteristics of positive corona discharge of rod electrode in high-speed airflow are studied in this paper.The experiments were carried out in a wind tunnel with a maximum flow speed of 100 m/s in a dark room.The discharge voltage and current were recorded and the corona patterns were captured by a digital single lens reflex(DSLR)camera during the experiment.A discharge transition in rod electrode from streamer corona to mixed streamer-glow corona,and finally to stable glow discharge was observed with the voltage increased.The increase of airflow speed resulted in a decrease of each corona inception voltages.The streamers will be suppressed and shifted towards the upwind side,while the glow layer will be promoted and shifted towards the downwind side in low and upwind side in high voltages.The glow corona current and the voltage show a quadratic function and the higher the airflow speeds,the bigger the coefficient of square of voltage.The distributions of peaks,pulse widths and interval times of streamer pulses were analysed,showing good correspondence with the streamer images.The measurements were explained by combining particle transport and local air pressure distribution.
基金This work was supported in part by the Science and Technology Project of State Grid Corporation of China(No.52060020002P).
文摘Converter transformers are the core device in ultrahigh voltage direct current(UHVDC)transmission systems,and the oil-paper insulation at its rectifying valve side deals with the composite AC-DC voltage.A detailed investigation of the partial discharge(PD)mechanism in the oil-paper insulation under the composite AC-DC voltage is,therefore,very important.The oilpaper insulated needle plate electrode simulation model for the electric field and charge distribution can be established using hydrodynamic drift-diffusion theory and bipolar charge carrier theory,and the simulation results can reflect the morphological changes of PD.The development characteristics of PD under composite AC-DC voltage are researched.In addition,the effects of simulation time,the AC-DC component proportion,and model parameters on PD are also explored.Results indicate that differences in applied voltage,interface charge,and geometry structure can cause changes in the electric field strength,which consequently influences the PD process in the simulation model.Oil-immersed paperboard is a type of liquid-immersed dielectric(LID).When the LID is arranged in perpendicular,only the positive streamers have narrow channels oriented toward the LID.When the LID is arranged in parallel,the PDs are in the form of creeping discharges and the negative streamers are more dispersed.The development characteristics of PD and its influencing factors reported here may provide theoretical and simulation support to explain the physical mechanism of PD at the rectifying valve side of the converter transformer.
