Corona loss characteristics of bundle conductors in UHV AC transmission lines at 2200Â m altitude

Corona loss is the key parameter for evaluating operating economy of ultra-high voltage (UHV) and extra-high voltage (EHV) alternating current (AC) transmission lines and is one of important factors that need to be considered in line design and operation. At present, corona losses of 8 × LGJ-630 conductors, which are commonly used in ultra-high voltage alternating current (UHV AC) double-circuit transmission lines on the same tower, and 8 × LGJ-720, and 10 × LGJ-720 bundle conductors with a larger cross-section and more bundle number in high-altitude areas have not yet been studied. In the paper, the corona losses of the 8 × LGJ-630, 8 × LGJ-720, and 10 × LGJ-720 conductors were measured under conditions of dryness, artificial moderate rain, heavy rain and a wet conductor, based on the UHV corona cage built in Ping'an County, Xi'ning, China at an altitude of 2,200 m. By taking typical 1,000 kV UHV-AC double-circuit transmission lines on the same tower as an example, the electric field strengths on the surface of conductors in the corona cage and the actual lines were calculated. On this basis, the corona loss of the UHV-AC double-circuit transmission line in a high-altitude area was analyzed. The research results can provide data reference for constructing UHV transmission lines in high-altitude areas.