The economic comparison between UHV power transmission and ultra-high voltage power transmission is generally based on the cost of power transmission, and the cost of power transmission for two voltage levels to transmit the same power and the same distance is compared. There are two comparison methods: one is to compare their one-time investment costs according to the same reliability index; the other is to compare their life cycle costs. The basic data required by these two comparison methods are: equipment prices and construction costs that constitute the statistics of the two voltage levels of power transmission projects. For the cost comparison of UHV power transmission and UHV power transmission project planning and design, the equipment price and its construction cost can be based on the statistical average price or price index. Both comparison methods require reliability analysis and calculation. Through analysis and calculation, the expected reliability index of power transmission project is proposed. Economic comparisons using the life cycle cost approach also require statistical data on economic losses due to interruptions in transmission.
The transmission capacity of a 1100 kV UHV transmission line can reach more than four times that of a 500 kV conventional transmission line, that is, the transmission capacity of 4-5 circuits of 500 kV transmission lines is equivalent to that of a 1100 kV transmission line. Obviously, in terms of operation and maintenance of lines and substations, the cost of UHV transmission will be much less than that of UHV transmission. Line power and electrical energy losses account for a considerable proportion of operating costs. In the case of transmitting the same power, the power loss of the 1100 kV line is about 1/16 of that of the 500 kV line. Therefore, UHV transmission has a stronger competitive advantage in terms of operating costs.