The hottest Chinese DC transmission technology goi

2022-08-06
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China's DC transmission technology has gone abroad, and the core components of electrical equipment need to be strengthened.

over the past decade, China's DC transmission technology has developed very rapidly. "At present, there are more than 100 DC projects at home and abroad, nearly 50% of which are in China; in addition, more than 50 DC projects are planned, 70% of which will be built in China. It can be said that China's UHV DC transmission technology has taken the lead in the world." Zeng Rong, Dean of energy interconnection Research Institute of Tsinghua University, said at the 14th International AC/DC transmission conference

China is a large energy country. However, energy resources and power demand are inversely distributed. 65% of hydropower resources are concentrated in the southwest, more than 80% of land wind and solar energy resources are concentrated in the western and northern regions, while more than 70% of power consumption is concentrated in the eastern and central regions. The renewable energy base is 1000-5000 kilometers away from the load center. With the rapid development of the global economy, China will encourage the use of clean energy in the future, which requires the development of large-scale renewable energy power generation. Therefore, the long-distance and large capacity DC transmission project has developed rapidly and will play an important role in the process of intelligent power construction

the application prospect of DC transmission technology in many fields is promising.

after AC has occupied most of the market share in the first 100 years, the development of DC transmission in the next 100 years is expected

in practical application, the voltage level covers from high voltage, medium voltage to low voltage DC; The application scope is also more and more extensive

(I) DC transmission technology promotes the consumption of new energy

Zeng Rong said, "Sichuan is a big province of clean energy. The local load is relatively small. It needs to send electricity to Shanghai, Zhejiang, Jiangxi, Hunan and other places in the northeast. The transmission distance is about twothousand kilometers. AC transmission is very uneconomical, inefficient and consumes a lot. Therefore, at present, most of Sichuan's hydropower transmission depends on DC transmission projects, including tens of thousands of kilowatts of hydropower development projects in the future. DC transmission will be absorbed in Sichuan's hydropower And play an important role in. "

in addition, with the emergence and rapid development of a large number of DC power supplies such as electric vehicles, rail transit and LED lights, the demand of end users for DC power distribution has become increasingly apparent. "In the United States, we may see more electric vehicles in the future, as well as in China and other countries in the world," said ram Adapa, Ph.D. of the American Electric Power Research Institute

the further development of distributed photovoltaic + energy storage has promoted the development of home energy storage mode. In the future, in some cases (with upgrading), the economy of DC distribution is better than that of AC network

(II) application prospect of DC technology in energy interconnection

at present, China's energy system is facing an energy revolution. Among them, energy interconnection is the main component of the energy system. With the clean development of the energy system, the incremental energy will be mainly clean energy, and the main configuration mode will be electricity. The main line of energy interconnection is the large-scale consumption and efficient utilization of renewable energy to improve energy efficiency

however, China's renewable energy and load distribution are uneven, and energy needs long-distance and large capacity transmission. UHVDC is suitable for long-distance transmission across provinces and regions; It is technically feasible for UHV DC power to follow the fluctuation of new energy power, and has good economy, energy conservation and emission reduction benefits. It is conservatively estimated that the application of regional energy interconnection is likely to increase the energy utilization efficiency from 40% to 70%. In the future, the acceptance standard is that the energy efficiency should be more than 90%

by developing UHVDC, the power resource advantages of western provinces can be transformed into economic advantages, the imbalance between energy and economy between the East and the west can be changed, the adjustment of energy structure can be accelerated, and the coordinated economic development of the East and the west can be promoted

it will take more than half an hour for China's DC transmission technology to go abroad. The core equipment needs to be strengthened.

China has made continuous innovation and development in UHVDC planning and design, experimental research, technical equipment, engineering construction and operation management, and has been widely applied at home and abroad. The transmission capacity and transmission distance have been continuously improved. Progressiveness, reliability, economy and environmental friendliness have been comprehensively verified, It has become another "business card" for China's export

State Grid Corporation of China successfully won the bid for phase I and phase II projects of ± 800 kV DC transmission of Brazil meilishan power; With the construction and development of global energy interconnection, China will also pay attention to Chile, Argentina, India and other regions rich in renewable energy; Strengthen the DC projects of electric interconnection and interworking with China's neighboring countries, such as South Korea. It will actively promote the "going out" strategy of domestic main equipment manufacturers, NARI Group, XD Group, Pinggao group and other domestic manufacturers, and bring the domestic high-end power equipment to a higher level

the development of DC transmission is closely related to the development of Converter Technology (especially high-voltage, high-power converter equipment and power electronics technology). However, at present, China still relies on imports of some core components of electrical equipment, and even some core components import more than US $1.5 billion a year. Therefore, there is still a long way to go for China's electrical equipment technology. In the future, China's DC transmission research will focus on the following points:

first, the safety and reliability of electricity. In terms of the operating characteristics and protection requirements of electricity, DC transmission system has higher requirements for rapid fault removal. As a huge carrier of power flow in power system, the influence of DC transmission on the stable operation of power system can not be ignored. This requires that DC control protection should be used in both protection principle and setting value design The new technology and utilization of automobile lightweight meet the requirements of DC transmission equipment and system operation safety and reliability

the second is Iget power electronics chip. As a voltage control device, IGBT device has the advantages of large capacity, small loss and easy control, which can make the converter topology simpler and less loss. Therefore, it becomes a high-voltage flexible device. When the lower collet release button is pressed directly, the lower collet is difficult to release, but the core device in the field of current transmission can be slowly released after knocking. This part of our country basically depends on imports, such as abb. Zeng Rong said that in the future, China should work hard on small, sophisticated and sophisticated products. With the gradual maturity of localization of DC chips, electronic components and other products, the cost of DC system will be further reduced

the third is DC circuit breaker. In DC system, DC current does not have the same natural zero crossing as AC current, so its breaking technology has always been a hot and difficult research topic; In addition, DC transmission has the characteristics of large capacity and long-distance transmission. Therefore, the requirements for DC circuit breakers are higher

fourth, the development of environmental friendly gas insulated switchgear. At this meeting, Christian Franck of the Swiss Federal Institute of Technology said, "at present, in terms of high-voltage systems, SF6 is the main insulating gas, mainly in terms of safety. However, the spring testing machine should be replaced to check whether the circuit board is affected by moisture or oil. With the climate warming, the warming effect of SF6 is 23000 times that of CO2, equivalent to 8000 tons of carbon emissions per year in the world. It will exist in the atmosphere for a long time, polluting the environment." Therefore, in the DC transmission system, the environmentally friendly gas insulated switch will also become one of the research and development priorities

with the change of power system structure and the update of relevant technologies, electrical equipment enterprises should continue to improve their independent innovation ability, develop electrical devices that better adapt to new electrical structures, and build strong and intelligent electricity to promote energy transformation

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