Dynamic arc modeling of pollution flashover of high voltage insulators

IV SUMMARY PhD Thesis DYNAMIC ARC MODELING OF POLLUTION FLASHOVER OF HIGH VOLTAGE INSULATORS Zafer AYDO?MUŞ Fırat University Graduate School of Natural and Applied Sciences Department of Electrical and Electronics Engineering 2000, Page:92 Increasing in demand of electrical energy in the world, transmission of large amount of electrical power to long distance has been necessary. As a result of this, new problems appear on both production and transmission. Most important problem on transmission is to satisfy electrical insulation. The performance of insulators used for insulation in high voltage decreases by atmospheric pollutions and some faults occur on the power line during operation. To remove this problem, some techniques has been developed by investigators, but a satisfactory solution has not been found yet. In this work, a new model has been developed to represent flashover phenomenon which occurs by means of surface pollution during operation conditions on high voltage insulators. By aiming, to solve this problem and to help contribute to the efforts for improving the performance. With this aim first, the physics of flashover phenomenon and studies on this subject were investigated. Then using Finite Element Method, potential and electricalfield distribution on a polluted insulator have been calculated. According to the calculated values, nodes which may cause discharges on insulator surface have been determined and controlled with flashover criteria. Propagation of time depended discharge causes on increase in the leakage current on insulator surface and results surface flashover. A computer program which considers all of this cases has been developed, The computer program can investigate the problem depend in both on the time and the conductivity variation. Electrical field strength variation on insulator surface, pollution resistance variations serial with arc and flashover voltages have been calculated and plotted. Then the results have been compared with other investigators results. Key Words: Insulator, Finite Element Method, Pollution Flashover, Flashover Equation, Dynamic Model.