Corona Cage-based Corona Loss Characteristics Of Conductors For UHV AC Transmission Line

Corona loss is one of the important research contents of UHV AC transmission line corona discharge effect, corona loss mechanism, as well as the study on assessment of UHV AC transmission line corona loss has a far-reaching theoretical significance and an important practical value. Based on the generation mechanism of conductor corona, this paper established the corona loss calculation model of AC conductor in corona cage, researched the corona loss of UHV corona cage AC bundle conductors at different altitudes, and analyzed the corona loss of test line under different meteorological conditions, contrasted corona loss between the bundle conductor in corona cage and test line, and conducted a comprehensive assessment on actual line corona loss of UHV AC transmission project. The main work are as follows:Considering the generation mechanism of conductor corona, and the complexity of the calculation on corona cage AC conductor, on each side of the cage mirror image, this paper judged whether occurred corona at each point on conductor surface, simulated the generation, migration, composite and a series of processes of positive and negative ions in the electric field, established a corona cage AC conductor corona loss calculation model.Conducting an experiment of corona loss in cage for UHV bundle conductors8×LGJ-400/35,8×LGJ-500/35,8×LGJ-630/45in space between different divisions, and under the conditions of dry,artificial rainfall and so on, corona losses for UHV AC transmission line test data basis for assessment. This paper extended the corona cage AC corona loss calculation model to the bundle conductor corona loss calculation, and verified the correctness of the calculation model further.A removable corona cage in artificial environment laboratory at the UHV AC Test Base, is adopted to research AC conductor corona. This paper obtained the test data of corona loss under the conditions of dry, artificial rainfall within19m-4000m altitude range. The corona inception voltage calculation model of bundle conductor in corona cage at different altitude was established. And based on this model, considering ion mobility changes with altitude, this paper expanded and improved the corona loss calculation model further, established a model that considering the influence of different altitude, and compared with experimental results, so as to verify the correctness of the calculation model.The optical fiber digital corona loss monitoring system was applied to monitor the corona loss of the UHV AC test line. This paper obtained the corona loss mornitoring results of UHV AC single test line and UHV AC in the same tower double circuits test line in different weather conditions. The results provided important reference to UHV AC transmission lines corona loss assessment. Through the analysis, the approximate linear relationship between different rainfall rate logarithm and corona loss logarithm was found for UHV transmission lines. Using corona loss equivalence calculation and analysis, corona loss test results of corona cage and test line were effective, and this provided an important method to apply UHV corona cage bundle conductors'corona loss equivalence to UHV AC transmission line corona loss assessment.Based on the corona loss research of the UHV corona cage bundle conductors and UHV AC test line, corona loss of UHV AC transmission project transmission lines were assessed, and the UHV AC transmission line corona loss assessments of our country were obtained, including transmission line's corona loss in one year, annual average corona loss power, the maximum corona loss power key parameters, and this provides important reference for China's UHV AC transmission line corona loss evaluation.