Study On AC Icing Composite Insulators1Potential And Electric Field Distribution

The icing flashover is one of the key technical problems for external insulation oftransmission lines in China. With the rapid development of the power grid, there are more andmore high-voltage transmission lines across the region which is covering with the heavy ice.The possibility of icing flashover is growing. The insulation performance of high voltagetransmission line insulator strings decrease significantly under the accumulated ice.What isworse, it happens to the icing flashover. It is a tremendous threat to the safe and stableoperation of the power systems.The study of insulator’s potential and electric field distribution and grading ring’soptimization were relied on the clean glass, porcelain, composite insulators. There were fewinvestigations on the potential and electric field distribution of the icing composite insulator.The researchers did so many flashover experiments of the icing insulators in an artificialclimate laboratory. But the icing composite insulator flashover is a complex process. And thecomposite insulator flashover is closely related to the potential and electric field distribution.In addition, there are so many factors which affect the potential and electric field distributionof the icing composite insulators.Therefore, a systematic study of the potential and electricfield distribution of the icing composite insulators has both a very important academicmeaning and an engineering value.In this paper, the research of the potential and electric field distribution of the icingcomposite insulator on220kV/500kV transmission lines was carried out. Thetwo-dimensional axial symmetry models of the icing composite insulator were given by thefinite element method via ANSYS. We analyzed the differences of the electric field andpotential distribution between the dry ice and wet ice, and studied the potential and electricfield distribution after changing the axial ice length, and investigated the effect of the air gap,ice thickness, horizontal icing length, horizontal icing angle, horizontal icing location, icingdistribution on the potential and electric field distribution for the icing composite insulator.The results of the potential and electric field distribution under various conditions on theicing composite insulators were put out forward.The effect of the grading ring for improvingthe potential distribution on the220kV icing composite insulator by changing the parameters of the grading ring, including the ring diameter, the ring gauge, the elevation, wasinvestigated. Finally, the recommended geometric parameter of the grading ring for the icingcomposite insulator was put forward.