| With the increase of the electric power demand and the gradual increase of the power grid density, the new line corridors are increasingly constricted. In addition, due to the limit of the planning and construction speed of the power grid, the transmission capacity of the transmission lines has become the bottleneck of the development of power grid. Therefore, we must consider how to greatly increase the transmission capacity of existing transmission lines, so as to meet increase of the electric power demand. It’s an effective means to save the new lines’ number or to reduce the cost of building new lines. And the remarkable economic and social benefits are quite notable.This paper gives a systematic analysis on the calculation model "heat balance equations" and the transmission lines’ temperature-sag model "state equation method" for the maximum capacity of the transmission lines. And on this basis, it systematically researched and established the safety criterion and the early warning system, and provided theoretical support for the static capacity-increase analysis of the actual transmission lines. We take Guangdong transmission lines as a research object to analyze the static capacity-increase of the actual lines. Considering the change of the environmental temperature varies with seasons, this research calculates and analyzes the increasing conditions of transmission lines’ maximum capacity after reducing the lines’ operating temperature limit. Besides, this research calculates and analyzes he increasing conditions of transmission lines’ maximum capacity and the safety of the lines after enhancing the wind speed, considering the actual wind speed.This research shows that the static capacity-increase technology can improve the transmission capacity of existing lines and ensure the safety of transmission lines without increasing transmission corridors or extra investment. This result can also provide the reference for the actual transmission lines. |
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