Abstract
Due to the complex and harsh climate environment in Northwest China, the external insulation of power lines and high-speed train are exposed to strong wind-sand environment all year round, which brings severe challenges to the external insulation design and protection of the electric systems. Based on the theories of streamer discharge, the plate-plate electrode was taken as the analysis object, and a theoretical physical model of the strong wind-sand dielectric discharge is established. In this model, the analytical expressions of electron ionization coefficient and positive ion generation coefficient in a wind-sand environment are deduced considering the combined effects of the airflow velocity, the distortion of the electric field caused by sand particles, and the electrons captured by sand particles in the discharge process; furthermore, the streamer breakdown criterion in wind-sand environment is proposed. Research results can provide an important theoretical basis for the quantitative calculation of the breakdown voltage and the external insulation protection in a strong wind-sand environment.
Highlights
The strong wind-sand environment caused by the high-speed train from Lanzhou to Xinjiang running in the northwest region of China is the key factor to induce the abnormal breakdown or flashover of the external insulation of the train, which poses a serious threat to the safe operation of the train [5–7]. erefore, the investigations of gas discharge characteristics and dielectric breakdown model in strong wind-sand environment are of great significance for external insulation design, insulation coordination, and insulation protection of the electric system
In this work, based on streamer discharge theory, we presented a physical model of wind-sand dielectric streamer discharge by analysing the influence of airflow and sand particles on discharge process in strong windsand environment
E analytical form of the presented model can be used to quantitatively calculate the dielectric breakdown voltage in strong wind-sand environment. e following conclusions are drawn: (1) e variation trend of breakdown voltage with airflow velocity is in good agreement between strong wind-sand environment and pure airflow environment. e breakdown voltage decreases with the increase of airflow velocity, and the variation curve of breakdown voltage with airflow velocity under wind-sand condition is lower than that under pure airflow condition
Summary
The power system has developed rapidly, which is the energy foundation support for the stable and rapid development of the country [1, 2]. The breakdown voltage decreases with the increase of sand concentration, but the breakdown voltage-gap distance curve is lower than that under pure airflow. E simulation results show that the distortion of the local electric field caused by sand particles reduces the breakdown voltage. The distortion of the local electric field caused by sand particles is an important factor affecting gap discharge characteristics. Based on the above research results, it can be concluded that the main factor affecting the discharge of solid/liquid particles is the serious distortion of the local electric field in the mixture. On the basis of streamer discharge theory, we attempt to present a theoretical model of strong windsand dielectric discharge considering the combined effects of airflow and sand particles on the discharge process, and the breakdown criterion for strong wind-sand dielectric discharge is obtained, which can realize the quantitative calculation and effective prediction of the breakdown voltage in a strong wind-sand environment
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