| The first±660kV DC Transmission project in the world----the Ningdong---Shandong±660kV DC Transmission demonstration project, has already been the construction stage at present. It will be put into operation in October,2010. As the cross-region networking DC transmission line, its bipolar capacity will achieve 4000MW during operation. So it is beneficial for the maintenance to be taken under operation. Therefore, the research of Live Working on±660kV DC Transmission Line should be put into operation all-round, in order to adapt to the need of safe and the reliable operation of the±660kV DC transmission line.The over-voltage level of Live Working on±660kV DC Transmission Line was determined by theoretical analysis and calculation. Safe distances for Live Working were studied in variety of operating conditions based on testing. According to the flash-over characteristic of different safety distance, combined with phase to ground over-voltage multiplier, the minimum safe distance for Live Working on±660kV DC Transmission Line below the altitude of 2000m was calculated.The united gap tests are carried out based on the workers on the position of equal potential process of±660kV DC transmission lines. Based on the flash-over characteristic, combined with phase to ground over-voltage multiplier voltage, the minimum united safe gap for Live Working on±660kV DC single circuit below the altitude of 2000m was calculated.According to the research results and field experiences of Live Working on EHV AC/DC, the Live Working content and methods were designed. It is given that the process and safety precaution for Live Working, such as replacing single insulator in a strain insulator string. This thesis is able to provide the basis and the technical support for Live Working on±660kV DC Transmission Line. |
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