Economic analysis of long-distance ultra HVDC transmission for remote renewable energy resources in China as affected by their spatiotemporal complementarities

China´s renewable energy resource such as wind and solar energy resources mainly distributed in the northeast, northwest, north China, while China´s electricity load centre is in the eastern and central regions. Therefore, longdistance, large-capacity and cross-regional transmission of wind power is one of the significant challenges for China´s renewable power development and utilisation. Based on a certain optimization method for the transmission capacity determination the transmission cost can be minimized due to the spatiotemporal complementarities of dispersed renewable energy resources, which has been well known for a long time but never been studied in terms of the capacity optimization of transmission lines. Hence, base on the real wind data provided by China Meteorological Administration (CMA) and the idea that this paper investigates the complementary effect of dispersed renewable energy resources on the capacity optimization of ultra HVDC lines.