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Compared with the EHV transmission line, the UHV transmission has the advantages of large capacity transmission, long distance transmission and high utilization efficiency of line corridor, which play an important role in achieving the optimal allocation of resources, strengthening the regional power grid interconnection, and improveing safety and reliability of the grid in our country.Because of the special high voltage of UHV system, the insulation corporation of UHV system has its own features. Firstly, UHV system should have higher insulaton level to guarantee higher reliability. Seondly, for the investment of equioments’ insulation takes a large part in the total, determining the insulation level of equipments in saveing the investment. Last, because of the different dominanted overvoltage in insulation coordination, the coordintaion principle for UHV system distinguish with other system.Based on the research we have carried on UHV transmission technology, the polluted withstanding features and mechanical properties of different insularors have been compared, the suggestions on insulator selection have been recommended. Using two widely used methods:convention method and statistical method, we have calculatied the recommended number of insulators in different areas, and the air gap between the line and the tower. Also, the insulation coordination principle and method for UHV converter station have been introduced.
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