This is the world’s most mature UHV power network system, which includes short and medium distance UHV alternating current and long distance UHV direct current composed of the UHV power network. Since the first line was completed in 2009, Beijing has announced plans to invest more than $10 billion in the project as it continues to build an ultra-high voltage grid to meet China’s growing power demand and looming pollution problems. More than 30 UHV lines in operation and more than 10 under construction have built the prototype of a complete UHV power grid for China. The project has been very successful, with the main power use centers in the east as the terminus, and the country’s central, northwestern, western, and southwestern UHV grids being built in large numbers. In China, this project, known as the West-East Power Transmission Project, and the South-North Water Diversion Project have become two of the most important livelihood projects in China in the 21st century. The price of the whole project is currently around 40 billion US dollars, the maximum operating voltage is 1100kV, the overall operation is smooth according to the construction objectives and has served more than 400 million people. The whole difficulty of building a power grid in China is to fight against the natural environment and the physics because it is an integrated state and most of it runs through uninhabited areas. Relative to the people’s livelihood problems encountered are not very many, so China’s ultra-high-voltage projects are also rare in the world with smooth progress. China’s high execution is worth learning from, so that clean energy can be promoted quickly.
Quebec Interconnection:
The Quebec high voltage grid system was the world’s first 735kV high voltage system, completed in 1965. At the time, the project was something of a miracle. The total length of high-voltage network lines is more than 11,000 km, and the entire length of power grid is about 34000km. The power transmission loss of Quebec’s high voltage grid is between 4.5% and 8%, depending on temperature and environment. Six main lines have completed the transmission of hydroelectric power to densely populated centers, and 25,000 megawatts of power has been transferred by the high-voltage grid. The overall project has been very successful. Quebec has access to clean energy for the majority of its electricity. At present, the project does not reduce the voltage operation, the overall operation is relatively stable. Moreover, due to the relatively concentrated personnel in Quebec, the construction cost was very low at that time. “12,500 towers, 13 electrical substations, 10,000 km (6,000 mi) of ground wire, And 60,000 km (37,000 mi) of electrical conductor at a cost of C$3.1 billion alone.” Even allowing for inflation, this is a bargain, and China’s ultra-high-voltage power projects are now far more expensive. This is something we can learn from. Of course, there are some problems with this project, and we can also learn from them. One is the use of alternating current. In 1989, there was a geomagnetic storm, because of the nature of alternating current, the power grid went out completely. One of the advantages of DC electricity is that this problem does not occur with a DC grid. On the other hand, the environment of Quebec region is relatively harsh and changeable, and the transportation mode based on electricity pylons on the ground makes the power grid weak in resisting natural disasters. If the UHVDC is replaced, not only the number of lines can be reduced, but also the impact of natural disasters on the grid can be reduced by going underground.
HVDC Itaipu:
This is the world’s first high-voltage DC power network officially put into use and in operation to this day, operating voltage of 600kV. This is the first time that the logic of “high voltage direct current can be transmitted over long distances with low loss” has been applied in reality and not just as a test line. The project was gradually put into operation in different parts from 1984 to 1987 and held the world record for at least 25 years until 2010, when China’s first 1000kV UHVDC grid was put into operation. The HVDC network line connects Brazil’s Itaipu hydroelectric plant to Sao Paulo, allowing low consumption of clean energy to be transported over a distance of 800km. With ABB’s conversion station equipment, the HVDC system has the largest transmission capacity and voltage in the world. And using digital control devices with microprocessors, which were thought to be very advanced at the time. But despite this, there were many problems in the early days of operation, including transfer station failures and a serious fire incident. HVDC Itaipu can be called the world’s trailblazer of clean energy high-voltage direct current grids, but even later China does not transport all the electricity generated by clean energy. It has been a success, working consistently at its transport rating, and has served as a wake-up call for other HVDC projects. Before the 21st century, the technical problem of HVDC was not completely solved — the reliability of the thyristor system was low. The failure rate and potential fire hazard make the whole line unreliable in the early stage.
Kita-Iwaki powerline:
This is the world’s first 1100kV UHVDC circuit, but it does not operate in the actual designed UHVDC mode, only in the 500kV HVDC grid. The distance of the grid is very short, the first line is 190km long, the second 240km long, neither of which can give full play to the advantages of low loss of HVDC at long distances. The circuit design is quite advanced, but since Japan does not need as much power transfer between Kata-Iwaki, it has not operated at peak performance. The project failed because it was primarily a pilot route and overestimated the amount of power needed to be transferred between cities. At the same time, such a short distance does not take advantage of the advantages of direct current, and because of the complex characteristics of the conversion station will increase the cost. In the case of Japan, UHVDC was not very practical, which led to the direct reason that Japan did not continue to develop UHVDC.