Simulation Research On Electric Field Distribution Along Catenary Insulator In Sand-dust Environment

The desert regions of northwest China is widely distributed, sandstorm caused by landdesertification have seriously affected the operation security of the railway transportation,which have drawn worldwide attention. Sandstorm not only accelerates the sand depositionrate on the surface of insulator, but also changes the clean air arround insulator into the mixedmedia of air and sand. Sandstorm can distort the original electric field distribution alonginsulator. The electric field strength along insulator is closely related to the flashover. Thestudy could provide theoretical basis for the related research of insulator flashover undersand-dust environment.The analysis model of this thesis is the long rod ceramic insulator of QBN-25type,which is used in the catenary system of electrified railway. To study the influence of thesand-dust environment on the electric field distribution along insulator, the simulation modelof long rod ceramic insulator based on the finite element method of electrostatic field isestablished. The air area size of simulation model is defined reasonably, and the infiniteelement area is set to solve the dissipation problem of far field. According to theaxisymmetric characteristics of the model and the maneuverability of meshing, a simplifiedmodel of the complete simulation model is establish to reduce the computational scale. Thesimulation efficiency is improved obviously. The software of COMSOL Multiphysics is usedto calculate and analyse the electric field distribution along insulator in different sand-dustenvironment, such as deposition of sand-dust, electric field of sand-dust weather andsuspended sand particles.The results of simulation show that electric field strength along insulator are influencedby the geometry of insulator. The sand deposition decreases the electric field strength ofinsulator surface covered with sand. The electric field strength of the non-sand region will behigher than that of the nearby sand layer, when the non-sand region appears in the sand layeron insulator. Under the action of the additional electric field of different sand-dust weather,the electric field strength along insulator is not the same as the circumferential direction ofinsulator. The potential and electric field strength along insulator will be distorted slightly bysuspended uncharged sand particles. The distortion will be increased significantly when thesuspended sand particles carry the same charge. The quantity, diameter, charge-to-mass ratio,and charge polarity of suspended sand particles have a great influence on the distortion of thepotential and electric field strength along insulator. The distortion of the electric field strengthalong insulator with the hybrid particle swarm of charged and uncharged sand particles orwith the hybrid particle swarm of positive and negative sand particles is smaller than that withall the sand particles carrying the same charge in the swarm. Electric field strength along insulator is distorted in different degrees by different sand-dust environments, and the chargedsand particle is the main reason of the distortion.