Effect Of Bird Droppings On Flashover Characteristics Of Integrated Lightning Protection Insulator

With the development of Chinese economy and society,the scale of the power grid is also constantly expanding.When the power system is operating stably,the insulators not only connect the high-voltage conductors and line towers mechanically to each other,but also ensure the electrical insulation between the towers and wires It plays a key role in the normal operation of the power grid.Frequent flashover trip accidents that have occurred frequently in recent years have caused serious threats to the safe and stable operation of the power grid,causing huge losses to economic and social development,and the guano flashover accounted for the largest proportion in flashover accidents.The integrated lightning protection insulator studied in this paper is a new type of insulator that integrates lightning protection and insulation functions.Because of its own insulation gap,bird droppings and foreign matter have a greater impact on the insulator’s electric field.Therefore,it is of great significance to study the influence of bird droppings on the electric field of this new type of insulator,to reduce tripping accidents of transmission lines,avoid economic losses,and ensure the safe operation of the power grid.This article focuses on the study of the effects of bird droppings on the electric field of integrated lightning protection insulators and the measures to prevent bird droppings.First,CAD and ANSYS simulation software are used to establish a two-dimensional axisymmetric model for 110 kV and 35 kV integrated lightning protection insulators.To study the effects of the clean and dry state,the distribution of bird droppings,the change of bird droppings resistivity,and the long string of bird droppings on the electric field along the surface of the integrated lightning protection insulator.When the dung drops to the low voltage end,it is compared with the change of the electric field of the ordinary composite insulator.The support vector machine method is used to establish a mathematical model of the insulator flashover voltage,and the magnitude of the flashover voltage is determined using the lifting method.Finally,according to the research results,relevant suggestions are made for the integrated lightning protection insulator to prevent bird droppings flashover.Taking the 110 kV integrated lightning protection insulator as an example,the simulation results show that: in a clean and dry state,the electric field distribution of the integrated lightning protection insulator is extremely uneven.At the pressure equalizing ring,it is 297.73V/mm;the middle insulation section withstands most of the voltage,and the lightning protection section voltage changes slowly;when bird droppings drop on the surface of the insulation section umbrella skirt,the electric field distortion is most obvious,from 103.97V/mm distortion to 274.97V/mm;the lower the bird droppings resistivity,the more serious the impact on the surrounding electric field,and the bird droppings resistivity increases,that is,the field strength of the bird droppings is constantly increasing during the drying process.The influence of the electric field is weakened;when a long string of bird droppings falls,the electric field at both ends of the bird droppings is distorted,and the internal field strength of the bird droppings is relatively small.When the bird droppings fall to the insulation section,the electric field distortion at both ends of the bird droppings is the most severe.The maximum value of the electric field appears in the air gap between bird droppings and the umbrella skirt,which is 1.917 kV/mm;the farther the bird droppings are from the integrated lightning protection insulator,the smaller the impact on the electric field along the surface;The method divides the known flashover voltage of the insulator,extracts the field strength,electric field unevenness and other electric field characteristics from the full field,the discharge channel,and the discharge path as the input of the support vector machine model,based on whether the gap breaks down As an output,the final predicted value of the flashover voltage is close to the test value,and the error is small.It can be widely used in integrated lightning protection insulators;when the bird droppings in the same state are distributed at the first umbrella skirt at the low voltage end or shorted to the low voltage end When the umbrella skirt,the electric field distortion of the common composite insulator is obvious,and the field strength of bird dung is greater,indicating that the integrated lightning protection insulator has more advantages in practical applications;the bird dung prevention strategy for the integrated lightning protection insulator in practical application It is recommended to use a large-diameter umbrella skirt for the lightning protection section or install an anti-bird dropping baffle above it.