When?
In 2001, China began a national project for the new century, the transmission of electricity from the west to the east. “West to East Power Transmission” means to convert energy from the western provinces, which are rich in coal and hydropower resources, into electric power resources and deliver them to the eastern coastal areas, where electricity is scarce. “West to East Power Transmission” will form the north, the middle and the south power transmission lines: the northern channel: the upper and middle reaches of the Yellow River and Shanxi, Inner Mongolia kengkou thermal power plants to the Beijing, Tianjin and Tangshan regions. Middle passage: send hydropower from the Three Gorges and Jinsha River tributaries to East China. Southern Channel: the hydropower of Wujiang River in Guizhou and Lancang River in Yunnan, Nanpan River, Beipan River and Hongshui River at the junction of Guangxi, Yunnan and Guizhou, as well as the electric energy of pithou thermal power plants in Yunnan and Guizhou provinces will be developed and transmitted to Guangdong. One of the priorities of the project is to build a new ultra-high voltage grid to carry large amounts of power transmission in a low loss manner. China, which began construction in 2005, has put in place at least 30 UHVDC or UHVAC transmission lines. UHV transmission has obvious economic benefits. It is estimated that one 1150 kV transmission line can replace the transmission capacity of five to six 500 kV lines, or three 750 kV lines. It can reduce the steel tower material by one-third, save the wire by half, and save the cost of the power grid, including the substation, by 10 ~ 15%. The 1150 kV UHV line corridor is only about a quarter of the corridor required for a 500 kV line with the same capacity, which would bring significant economic and social benefits to countries and regions with high population, precious land or difficult corridors.
Scope:
Since this is an ongoing project, China defines an UHV grid as an AC or DC network line with a voltage of 800kV or greater. At present, most of the UHV networks that have been put into use are 800kV and 1000kV, and the ones above 1000km are mostly UHV DC, and the ones below 1000km are mostly UHVAC. The highest UHVDC voltage is 1100kV and the distance is 3200km. According to the rule, the farther the distance, the higher the voltage is, in order to reduce the loss of long-distance transportation. At present, the whole project is operated in accordance with the original design voltage, and there is no line to reduce the voltage due to insufficient demand.
Successfulness?
Undoubtedly, China’s UHV grid is the world’s largest, highest carrying capacity, highest voltage, and newest UHV grid system. China has its own intellectual property rights on all the technologies, which have been in smooth use for 10 years. In this respect, China is a success. All the parts that have been built in China have fulfilled the original design goals, and the later projects will continue due to the smooth progress in the early stage. Of course, the success of a project cannot be analyzed solely from the point of view of whether the goal is achieved. China has invested more than 500 billion yuan in the project over 20 years, and it is unclear whether the project has fully returned. But according to Chinese government figures, the indirect benefits of the UHV grid project go far beyond the amount of money invested. From this, we can conclude that China’s UHV grid has been a success so far.
What can we learn from it?
When China first decided to build an ultra-high voltage power grid, it met many problems. China solved them one by one in its own way. Here are some problems we can learn from: The question of whether the project can really save land.
According to China’s own data, we can reduce the land use of the grid by about 25% through the UHV grid. But after China’s announcement of an ultra-high voltage grid, the question abroad is whether coal and gas transmission lines will save more land. China first ruled out the possibility of reconstructing coal-fired power plants in densely populated areas. Building highly polluting coal-fired power plants in densely populated areas can indeed reduce electricity consumption, but it will increase pollution per capita, which is not good for the green development of cities and countries. At the same time, in addition to the vast area and sparsely populated area, China’s western region also has excellent green power generation methods such as wind power and solar power. In addition to the hydroelectric power already available in the south-west, green energy conversion ahead of the construction of an ultra-high voltage grid is an important part of completing the Paris agreement. When we don’t have the grid, the transmission of wind farms, photovoltaic farms, and hydroelectric plants will hamper the spread of clean energy. But when those grids are in place, we just need to switch from coal to clean energy.
This is of great reference significance for the construction of Supergrid in Europe. Since 2012, Europe’s ultra-high voltage grid has been caught in a chicken-and-egg paradox with the construction of photovoltaic and wind farms in North Africa. There has been little progress so far, apart from disagreements in Europe over power projects (France is pushing ahead with nuclear power but others are abandoning it in search of cleaner alternatives; Countries close to Africa want to use cheap clean energy from Africa, while Nordic countries prefer to use their own clean energy.) There is also the impact of the order in which the two projects are started. What we can learn is to start with a grid that connects the whole of Europe through one or more ultra-high voltage networks (alternating current for short distances, direct current for long distances). Connectivity will then be shared across Europe through smart grid deployment, and everything will be built and then connected to new clean energy plants using an established ultra-high voltage grid. Only when there is a beginning can all the projects be carried out gradually.