Cold thinking behind the hottest UHV transmission

Cold thinking behind the UHV transmission boom

China is the testing ground for UHV transmission lines in the world. Compared with the common high-voltage lines in the past, UHV technology is much more efficient in ultra long distance power transmission

since 2006, China has built a total of 19 such transmission lines, each worth billions of dollars, with a total length of nearly 30000 kilometers, supplying 4% of the country's power demand. In contrast, no other country in the world has a fully commercial UHV line

however, China's enthusiasm for UHV began to weaken. There is a conflict of interest between power companies and the central and local governments, and this technology itself has not performed well. Some recent projects are in a dilemma due to excess power capacity

this means that the approval speed of new transmission lines begins to slow down, and power enterprises are unlikely to achieve the new construction goal

green: the starting city of power transmission, blue: the destination city of power transmission

grand plan for UHV line construction

China's coal, hydropower, wind and solar resources are concentrated in the interior, while energy demand is highly concentrated in the urbanized eastern coastal areas. Therefore, Chinese power enterprises hope to solve the problem of long-distance power transmission through UHV projects

if ordinary high-voltage transmission lines are used, a large amount of power will be lost during long-distance transportation. The advantage of UHV line is that it can greatly reduce this loss

there are two kinds of UHV lines currently used in China. The first is ultra high voltage direct current (UHVDC) line, which is suitable for transmission projects with a distance of more than 1000 kilometers between the two places; The second is ultra high voltage alternating current (UHVAC) lines, which are more suitable for shorter distances, but branch links can be left along the way

electric companies have been actively promoting this technology. Among them, the State Grid Corporation, whose business area covers 88% of China's territory, is particularly interested in this. According to its annual construction plan, the company plans to build 6 UHV AC lines and 13 UHV DC lines by 2013, and 10 UHV AC lines and 27 UHV DC lines by 2020. In Inner Mongolia alone, the state power company proposed to build 11 UHV lines covering coal and renewable energy hot spots in the region by 2020

however, the progress of relevant projects is very slow, and few analysts believe that the State Grid can successfully achieve its 2020 target. In fact, the national UHV backbone plan, the core project of the national UHV AC grand goal, seems unlikely to be achieved in the near future

the controversial UHV project

although the UHV plan of State Grid is full of ambition, it cannot always keep pace with the central and provincial policy makers

on this backbone issue, the opinions of central officials conflict with the state electricity. State power once planned to connect several regions under its jurisdiction into one electricity by building UHV AC with "three vertical lines, three horizontal lines and one ring". However, central officials are worried that this interconnected super large power may cause a chain reaction of nationwide blackouts. Analysts believe that the state power shelved this backbone plan for the time being and focused on the construction of UHV AC lines within each power company

at the same time, due to the slowdown in the growth of power demand, the economic benefits of UHVDC transmission line construction in inland areas also began to decline

the average growth rate of national power demand has decreased from 11.7% in to 4.5% in, of which 2015 was the lowest, only 0.5%. Data from Bloomberg new energy finance shows that the decline in demand growth has exacerbated the problem of overcapacity in China's power industry, with overcapacity as high as 35% in 2016

the general overcapacity means that the demand for new transmission projects will be reduced accordingly

in 2014, the notice of the National Energy Administration on accelerating the construction of 12 key transmission channels in the air pollution prevention action plan was issued. According to the plan, China will complete the construction of nine UHV lines by 2018. An official of the National Energy Administration said in December 2017 that the plan "can meet the power demand of China's major power consuming regions by 2020."

therefore, it is expected that the approval speed of new UHV projects (it will take three to four years to complete the construction) has been slow recently. Among them, only one project was approved in 2016 and only two in 2017

tense local relations

some regional governments planning to carry out UHV project construction also have doubts about it

compared with importing electricity from other provinces, the construction of self owned power plants can increase the GDP, employment opportunities and income of each province. Therefore, even if the new transmission line is supported by the central government. 2. The relaxation experimental machine adopts imported load sensors with high stability and precision, it is sometimes unacceptable to all provinces

for example, Sichuan UHVDC No.4 transmission line plans to transmit hydropower from Sichuan to Jiangxi Province, which has been officially included in the 13th five year plan. But officials from the National Energy Administration pointed out last fall that Jiangxi did not want this power. In 2018, Jiangxi will have multiple thermal power plants and generate electricity, so they want to postpone the construction of new transmission lines until after 2025. Similarly, after many years of negotiations, Hubei Province is still unwilling to accept the long-distance transmission line project from the northwest region

disappointing earnings

power companies have their own reasons for being cautious about UHV lines. The benefits of these large projects depend on the amount of electricity they can transmit. However, the utilization rate of existing lines is lower than expected, especially the low utilization rate of non hydropower lines

in addition, the impact of UHV on alleviating the problem of renewable energy power abandonment in inland China is also disappointing, which further weakens the reason for investment. The so-called "power abandonment" refers to the wasted power resources due to the lack of power consumption capacity or the congestion of coal and electricity quotas

UHV lines in China transmit wind, solar and coal power at the same time, and coal power is still the main source of power in China. However, a large amount of renewable energy can be transmitted from inland to coastal markets by occupying only a small part of the transmission capacity of UHV lines, which is a major reason why UHV technology supporters actively promote the promotion of this technology

however, after ten years of development of UHV technology, China's renewable energy waste level is still high. In 2016, the national average wind and light rejection rates were 17% and 10% respectively, especially in Northwest China. In Europe, however, the wind abandonment rate in countries with a relatively high proportion of wind power has been lower than 5%

environmental researcher darling dot; Mackey and geographer Thomas dot; Hennig's analysis shows that the total amount of abandoned electricity in Yunnan may reach 95billion kwh in 2015, which is more than six times the published amount of abandoned electricity, equivalent to the combined annual electricity consumption of Portugal and Singapore

backward wind and solar energy

in 2016, UHV lines successfully transmitted 172.5 billion kwh of renewable electricity, accounting for 3.2% of the total electricity consumption in China. However, 93% of the electricity comes from five dedicated hydropower lines

the renewable energy transmission capacity of some non hydropower transmission lines in China is lower than the supporters' expectations. In the lines that transmit coal power and renewable energy power at the same time, The target proportion of renewable power should be 3 "With the continuous improvement of social development and people's living standards, 0% has been achieved. At least for part of 2016, three such lines were in operation, but their performance was uneven. Among them, ningyinziqing is qualified. The renewable energy power of East Zhejiang and South Hami Zhengzhou lines accounted for 29% and 23% respectively, while the Ximeng Jinan line did not transmit any renewable energy power.

the initial plan of North Zhejiang Fuzhou line It is planned to transmit nuclear power and wind power, but no wind power was transmitted in 2016. As for whether the line began to transmit wind power later, there is no relevant report, but the line has begun to transmit coal power

I hope these problems are only temporary. A non hydropower UHV transmission line launched in 2017 actually transmits coal power at present, because the originally planned renewable energy supporting project has been postponed. Fortunately, overall, 4 Electromagnetic interference: the amplitude of electromagnetic field generated by electrostatic discharge can reach hundreds of volts/meter. It is said that China's first UHV transmission lines have achieved a significant increase in the total power transmission during the first five-year operation period

since the middle of 2016, many new renewable energy UHV transmission lines have been merged one after another. In the first nine months of 2017, the wind and light rejection rate decreased significantly

however, the space for new UHVDC projects is gradually shrinking, which has also become a problem that western provinces have been worried about. The construction of long-distance transmission infrastructure may not keep up with the rapidly growing demand for renewable energy power supply

deepen the reform of the power industry

the phenomenon of abandoning wind and light in China's inland areas can't just blame the extra high voltage transmission lines. In fact, China's power industry is facing a series of broader challenges, which is also the focus of the power reform that began in 2015, including several measures specifically aimed at UHV. However, in order to properly solve the many obstacles faced by the construction of UHV lines, we must carry out a more comprehensive reform of the power system

these include: 1) the reform of power trading market, so that coastal provinces and cities can quickly purchase power from inland areas (including local areas of course); 2) Take measures to improve the competitiveness of long-distance clean energy relative to local coal and electricity resources; 3) Through reform, disputes between the central and provincial governments on power planning will be reduced

nowadays, the reform has just begun. Although China's enthusiasm for developing UHV transmission lines is fading, this technology will still play a key role in China's renewable energy transformation. The success of the power sector reform will determine the role of this technology in China's renewable energy transformation process