| With the development of China’s high-speed railway, the railway has become an important support for our economy, which promotes huge improvement of Chinese high-speed rail transport capacity. Safe and stable operation of the high-speed train is a prerequisite for security of railway system. At the same time, roof insulator is important high-voltage devices of motor train unit, which plays a key role in supporting the pantograph, busbar and other high voltage equipment. Its operational failure not only results in interruption of rail transport, but also brings adverse social impact. In recent years, the development trend of high-speed trains has carried out several large-scale Speeds. The high-speed rail network coverage is gradually expanding. For example, Lanzhou-Xinjiang railway line, as the representative of the new high-speed railway, has gradually deep into the desert sand area. High-speed trains will face a high-speed airflow, the impact of the harsh environment of sand and also suffer from the invasion of northern fog, so the roof insulator is bound to be subjected to these challenges. So the study flashover characteristics of roof insulator in dust and fog environment can provide theoretical support for the secure and stable operation of roof insulator in these harsh environments.When trains is running at high speed, irregularly distribution of high voltage, low-pressure area, complex air flow and pressure distribution formed around the insulator will make the insulator flashover characteristics become complicated. Three-dimensional finite element model of the flow field is established in line with the actual condition of the roof. The interaction of airflow between the three insulators is analyzed. And Fluid field characteristic of insulator is researched under the high speed airflow. Furthermore, a wind tunnel test system is built to measure flashover voltage of insulator at different airflow. And impact of high-speed airflow on insulator flashover voltage is explored.Sand and dust from sand the environment lead to the electric field near the insulator undergone some distortion, influencing the insulator flashover characteristics. Based on wind tunnel test system, the impact of the environment on the sand insulator flashover characteristics is explored and insulator flashover voltage was measured under the condition of high-speed and air dust.At the same time, when compared with insulator flashover voltages under condition of sand and dust-free, insulator flashover voltage trends is obtained under dusty environments. And we discuss the impact of the flow of dust, sand grain size on insulator flashover voltage. In additions, impact of sand particle size on electric field distortion and insulator flashover voltage is analyzed.In allusion to problems of insulator flashover that has polluted by the sand in the heavy fog weather, the operation condition of the train and reason of fog flash is analyzed. Based on the laboratory of stream and fog, discharge inhibition test system is designed and the insulation insulator performance at different polluted degree over time in heavy fog weather is monitored. Furthermore, the change of insulator insulation performance under the heat flow is discussed, and the optimal scheme that heat flow impedes discharge is proposed. |
