Research On Lightning Overvoltage Performance And Its Influence Factors Of UHV AC/DC Transmission Lines In Common Corridor

With the blossom development of UHV engineering in China, the height of transmission tower, the transmission capacity and the transmission distance get highly expanded. Along with these achievements, lack of land resource becomes a problem. Place for overhead transmission lines decreases while the coupling effect between UHVAC and UHVDC transmission lines sharing the same corridor becomes striking. What’s more, the UHV transmission system always locates in the wild, its easy to get lightning stroke which may cause regional blackout. In order to draw up more economical and rational lightning protection measures to prevent lightning fault, it is nessecary to look deeper into the research of the lightning properties and its propagation, by which tofind out the key influence factor on overvoltage distribution.Based on the operation experience of UHVAC/DC transmission systems and the occurance mechanism of lightning overvoltage, a lightning simulation model of UHVAC/DC transmission lines sharing the same corridor is established with the help of PSCAD/EMTDC. What’s more, the modeling process of subsystems such as lightning current, transmission tower, flashover model and transmission lines is expressed in detail. Lightning overvoltage is calculated in the situation of shielding failure, back striking and the situation when transmission corridor get lightning stroke without blackout. By analyzing the calculated results, the transmission process of lightning overvoltage through the corridor is imitated, by which to get the distribution and transmission characteristics of lightning overvoltage. Last but not least, the influence on the above characterstics caused by impulse corona is discussed detailly.In the simulation model, how the overvoltage in the corridor is changed by the influence of lightning current waveform and ampilitude, type of transmission tower and grounding resistance is studied in depth. The anasis results show that the lightning current waveform and ampilitude, type of transmission tower and grounding resistance can give affect the back strike overvoltage, while the shielding failure overvoltage gets affected only frome the changing of lightning current waveform and amplitude. The achievements in ths essay can be regarded as summary and prospect of the lightning protection in chinese UHV AC/DC as well as a theoretic guide of lightning protection enginerring for newly built transmission systems.