Research On Insulation Coordination Of UHVDC Converter Station

±800kV UHVDC transmits large amounts of electricity over longer distance and with lower loss, and is flexible for various operation mode and control. Such characteristics easily adapt UHVDC for transmitting electricity from major energy production basis to the far-away load center, fully utilizing land resources, and lowering investment costs. Considering its outstanding social and economic benefits, UHVDC meets China's energy development strategy and the current situation of the country. So far, there are two UHVDC projects running in China:"Xiangjiaba-Shanghai"±800 kV UHVDC project and "Yunnan-Guangdong"±800 kV UHVDC project.The insulation coordination, minimum air clearance and contaminated external insulation are the key technique of±800 kV UHVDC project. This thesis first talks about the advantages of separate arrangement of split smoothing reactor in UHVDC system both technically and economically. Then the features of UHVDC arrester in converter station, its layouts and configurations are discussed. In the end methods of selecting the parameters of arrester and the whole process of designing insulation coordination based on idiom methods.The minimum air clearance varies under different circumstances. In AC areas, the air clearance is decided based on standards; in valve hall and DC areas, the air clearance is calculated base on temperature, moisture and pressure.Both porcelain insulator and hybrid insulator are considered for the insulator selection in converter station. The creep distance of insulators is mainly decided by sewage pressure method, using the voltage curve of contaminated lightning resistance of the actual DC insulators under different level of contamination.In the end of the thesis, the design of insulation coordination, minimum air clearance of the equipments in valve hall and DC area, contaminated external insulation of Zhexi station which is the inverter of "Xiluodu-Zhexi±800kV UHVDC project are presented.