Experimental Study On The Bird Dropping Flashover Characteristics Of AC High Voltage Overhead Transmission Line

In recent years,with the improvement of ecological environment and the enhancement of people's awareness of environmental protection,the number of birds and the scope of activities are expanding day by day.Bird droppings flashover has become an important factor threatening the safe and stable operation of power grid.In order to reduce the occurrence of bird droppings flashover fault and improve the reliability of line operation,it is necessary to study the flashover characteristics of bird droppings.The research platform was built at Changping UHV Test Base in Beijing.In this paper,the flashover characteristics of bird droppings on overhead transmission lines under AC high voltage are studied in the following aspects.The flashover characteristics of simulated bird droppings were studied with 110 kV composite type I insulator strings as the research object.The flashover discharge characteristics of simulated bird droppings at different locations outside insulators were obtained by using simulated bird droppings to study the flashover voltage characteristics of simulated bird droppings at different locations abov e the equalizing ring under three simulated bird droppings.The ultraviolet and visible images of simulated bird droppings during flashover discharge were analyzed,and the relationship between flashover voltage of bird droppings and bird droppings shapes and falling position was obtained.Based on the combined gap discharge model,the flashover characteristics of segmented bird droppings were studied.The segmented bird droppings flashover is equivalent to three discharge models: rod-rod-plate,rod-rod-rod and ball-rod-rod.The discharge phenomena of combined gap under AC voltage are studied,and the corona discharge characteristics of suspended conductor at different spatial locations are obtained.The effects of length and number of segments of suspended conductor on breakdown voltage are obtained.A prediction model of combined gap breakdown voltage under AC high voltage is proposed.The model is used to calculate the combined gap breakdown voltage with potential suspended conductor.The calculation model has good accuracy.