Comparison Of Ultra-long-distance Transmission Mode

The long distance transmission, whether using DC or AC, has been argued for a long time. In recent years, as the steady development of power construction, the distance between energy base and load center increases accordingly. The selection of proper transmission mode has become an important issue in power construction at present. As a result, the study on the ultra-long-distance(distance between 2 000 km and 3 000 km) transmission system is significant during the development of power construction. The comparative research between large capacity transmission mode and ultra-long-distance transmission modes has been carried out in this dissertation. The practical requirement of ultra-long-distance transmission are then analyzed. Combining with existing transmission technology which is feasible in engineering and theory, four types of ultra-long-distance transmission mode, in terms of UHV AC transmission system, UHV DC transmission system(±800 k V and ±1 000 kV) and Half-wavelength AC transmission system(HWACT), have been introduced. The transmission capacity of UHV DC system has been calculated according to the power system angle stability and voltage stability limits. The rated transmission capacity of UHV DC system is determined by analyzing the flow capacity of each component. Then the transient stability limit of HWACT is obtained by considering the worst serious fault position. Furthermore, the failure outage rate and failure outage time is calculated by the reliability model of each system. The economy of listed transmission modes in this dissertation is comparatively analyzed based on the comprehensive cost of unit power by different transmission mode. The results show that HWACT has an great advantage in the ultra-long-distance transmission. The contributions of the paper are significant for the research on transmission system, which establishes the solid foundation of follow-up study, and provides powerful supports for the implementation of future project of ultra-long-distance transmission systems.