China's UHV power transmission technology is unparalleled in the global UHV power transmission project with rapid development
Ride the Electric Power Highway
Our reporter Wang Zhen
Inspection and elimination, completion acceptance, system debugging... On June 16th, in the Yucheng converter station in Changshu, Jiangsu, the staff were busy busy, making the final preparations for the upcoming "big test" for live trial operation. .
It is expected that by the end of June, the first batch of 4 million kilowatts of clean hydropower from Baihetan Hydropower Station, the second largest hydropower station in my country, more than 2,000 kilometers away, will pass through Sichuan, Chongqing, Hubei, and Anhui provinces and cities. Development injects strong impetus.
One is the rushing river, and the other is the lights of thousands of homes.
The "channel" connecting them is the UHV transmission project called "electric highway".
Today, my country's UHV technical standards are international standards, and UHV transmission technology has become a business card of my country's manufacturing industry.
At the recent press conference on the theme of "China This Decade" held by the Central Propaganda Department, Wang Zhigang, Minister of Science and Technology, said that UHV transmission is at an advanced level, and major technological breakthroughs have driven the rapid development of UHV transmission projects.
So, what is UHV?
As the most advanced power transmission technology in the world, where is the "speciality" of UHV?
How does China's UHV transmission technology stand out in the world?
The reporter recently interviewed the relevant responsible comrades of the State Grid.
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Long power transmission distance, large transmission capacity, low operating loss...
UHV makes "electricity from afar" a reality
In the Hainan Green Industry Development Park in Gonghe County, Qinghai Province, in northwestern my country, the blades of wind turbines swivel in the wind, and the sun shines on the blue panels... The wind and light are "captured" into the power lines.
According to reports, the installed capacity of photovoltaic, wind power and solar thermal new energy here exceeds 20 million kilowatts.
Through the Qinghai-Henan ±800kV UHV DC transmission project, the people of Henan, located in the Central Plains, can share this "green dividend".
UHV transmission technology refers to the transmission technology of AC 1000 kV, DC ± 800 kV and above, and it is the transmission technology with the highest voltage level and the most advanced technology in the world.
This transmission technology subverts China's traditional energy transmission model.
As we all know, the electricity used in our production and life is sent to factories and buildings and thousands of households through the power grid.
The power grid is composed of different voltage levels such as low voltage, medium voltage, high voltage, ultra-high voltage, and ultra-high voltage.
For example, residential electricity is usually 220 volts and 380 volts, which belong to the low-voltage category; industrial electricity is generally in the medium-voltage category.
From this point of view, UHV is thousands of times higher than the voltage we use in our daily life.
Before my country developed UHV transmission technology, the 500 kV UHV transmission system strongly supported my country's economic and social development.
In the traditional power supply model, power plants are usually built wherever there is a shortage of electricity.
However, my country's energy resources and demand are distributed in reverse, that is, more than 70% of energy demand is concentrated in the central and eastern regions, while a large number of available energy resources, such as fossil energy, water energy, wind energy, solar energy, etc., are far away from the demand center and are concentrated in the northwest, Southwest Region.
How to send large-scale energy in the west, especially clean energy, across thousands of kilometers to the east?
UHV transmission technology has become an inevitable choice.
"For the same distance of power transmission, the higher the voltage level, the larger the transmission capacity, the smaller the power loss, and the stronger the power transmission capacity of the power grid." Chen Songtao, director of the Planning Department of the Construction Department of State Grid Jiangsu Electric Power Co., Ltd. told reporters, and Compared with 500kV ultra-high voltage transmission, UHV transmission has many advantages.
The reporter learned that the size of the power transmission capacity of the power grid is proportional to the square of the voltage, and the transmission loss is inversely proportional to the square of the voltage.
This means that when the grid voltage is increased from 500 kV to 1,000 kV, the transmission capacity can be increased by 4 times, and the transmission loss can be reduced to a quarter of the original.
"UHV transmission lines are like electric highways. Compared with ordinary lines, the transmission capacity is larger and the transmission efficiency is higher." Wang Shiwei, deputy director of the Engineering Department of State Grid Jiangsu Xingli Engineering Management Company, gave reporters an analogy, " The operation loss is small, and the transmission distance is longer, which can reach 2,000 kilometers or even more than 3,000 kilometers, which can cover all large energy bases and electricity load centers in China."
Not only that, because UHV technology greatly improves the utilization efficiency of overhead lines, it can also save a lot of land resources.
With many advantages, UHV is regarded as the main artery of the transmission network.
In 2009, my country's first and the world's first UHV project - Jindongnan-Nanyang-Jingmen 1000 kV UHV AC test demonstration project was put into commercial operation, successfully sending Shanxi coal and electricity to Hubei, thousands of miles away, allowing " Electricity from afar" became a reality.
After more than ten years of development, there are dozens of UHV transmission lines built in my country.
The State Grid Corporation of China alone has built a total of 29 UHV projects, including 15 UHV AC projects and 14 UHV DC projects. The line length of the projects in operation and under construction has reached 46,000 kilometers, and it can circle the equator more than once.
During the "14th Five-Year Plan" period, the State Grid has planned and constructed a total of "24 to 14 straight" UHV projects, involving more than 30,000 kilometers of lines.
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Comprehensive breakthroughs have been made in theory, technology and equipment...
Independent innovation makes China's standard a world standard
June 15, Changshu, Jiangsu.
Early in the morning, Chen Songtao came to the valve hall of the ±800kV UHV Yucheng converter station.
Looking up at every component, bolt, and pipe on the valve tower, he was filled with emotion.
As the receiving end station of the "West-East Power Transmission" core hub project—Baihetan-Jiangsu ±800 kV UHV DC power transmission project, Yucheng Converter Station is about to face the test of live trial operation.
"This is the result of our efforts for more than a year." Chen Songtao, who participated in the construction of the project throughout the process, was very excited. He told reporters, "It's like watching his children grow up and leave home."
What makes Chen Songtao, who has 20 years of working experience in the power industry, so excited is that the Yucheng Converter Station is the first converter station in the world that adopts the conventional DC and flexible DC hybrid cascade connection method, which is another example in the field of UHV power transmission. Technological innovation.
"At the same time, it takes into account the characteristics of conventional DC transmission with large capacity, flexible long-distance and flexible DC control, and strong voltage dynamic support capability." Chen Songtao told reporters.
The converter station is the most critical link in the UHVDC transmission system.
"Most of the electricity we usually use is alternating current. In the DC transmission project, the alternating current must be converted into direct current at the power generating end, and then the direct current will be converted into alternating current after passing through the transmission wire to the receiving end." Wang Shiwei explained.
Taking the Baijiang Line as an example, it starts from the Butuo converter station in Liangshan, Sichuan, and ends at the Yucheng converter station in Changshu, Jiangsu.
The clean power from Baihetan Hydropower Station enters the Butuo converter station after being boosted, completes rectification at the Butuo converter station, and goes directly to the Yucheng converter station through the "highway" one station. , and then distributed through the AC power grid in Jiangsu area.
The converter valve is the core equipment of the converter station, which can be called the "heart".
More than 20 years ago, my country's DC converter valves still depended on imports, and they had to be "buy together with the turf in the converter station".
Therefore, my country's DC converter valve research and development project is also known as "competing gas valve".
In just over a year, my country's R&D team has completed the research and development of the "striking valve", and it has the incomparable advantages of foreign products: higher rated current and larger commutation capacity than other converter valves.
"From ultra-high voltage to ultra-high voltage, from AC to DC, these series of technological innovations have brought all-round challenges to system design, equipment research and development, on-site construction, commissioning and operation." Wang Shiwei told reporters that it is necessary to ensure that the ultra-high voltage project is in accordance with the The safe and stable operation of the design standard puts forward higher standards and requirements not only for the converter valve, but also for a series of key equipment and key technologies such as converter transformers, control and protection systems, and commissioning and operation.
Since the 1960s, many traditional power powers have spent a lot of energy on the research and development of UHV technology, but they have not been successful.
For my country, it is even more difficult to study UHV due to the complex terrain and changeable climate.
Completely from scratch.
Since 2004, the State Grid Corporation of China has joined forces with all parties to make comprehensive innovations and breakthroughs in UHV theory, technology, standards, equipment, engineering construction, and operation, and has mastered UHV transmission technology with independent intellectual property rights. Technology and equipment were exported abroad, and it took the lead in establishing a complete technical standard system, and made Chinese standards a world standard, realizing "created in China" and "led by China".
Today, Chen Songtao, who is in Changshu, occasionally goes to No. 1088 Weiye Road, Suzhou Economic and Technological Development Zone to take a look.
There is an ultra-long-distance GIL (gas-insulated metal-enclosed transmission line) pipe gallery project model with the highest voltage level, the largest transmission capacity and the most advanced technology in the world.
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Monitoring equipment automatically alarms, robots climb autonomously to clean up...
Intelligent devices protect power grid security
Feng Xinyan, the fifth-level staff member of the Substation Maintenance Center of the Super High Voltage Company of the State Grid Shandong Electric Power Company, the deputy monitor of the electrical test class, and the chief expert of the State Grid Corporation of China.
His work is aptly called "Grid Doctor".
It is an important part of its work to "physically examine" UHV power grid equipment, find hidden hidden dangers in the equipment in time, eliminate hidden dangers in the bud, and provide technical support for the safe and stable operation of the power grid.
This time is the busiest time of the year for him.
In order to fully guarantee the safe and stable supply of electricity during the peak summer season, he and his colleagues will conduct a round of inspections on all UHV lines, substations, and converter station equipment in the province.
"I have a few more 'new colleagues'." On June 16, when the reporter contacted Feng Xinyan, he had just finished working at the Changle Substation, the terminal station of the Yuheng-Weifang 1000 kV UHV AC power transmission and transformation project. work.
What the reporter did not expect was that the "new colleagues" in his mouth were actually a few small cuboid cabinets.
"It is equipped with an intelligent monitoring device, which can monitor the insulation state and operation status of the core components of the transformer, such as bushings, in real time. Once any bushing is in an abnormal state, the intelligent monitoring device will send an alarm to the background." Feng Xinyan explained that on the basis of Shandong power transmission and transformation equipment health assessment system, the use of "smart doctors" further reduces the work intensity and danger of power maintenance personnel and improves work efficiency.
The first ±800 kV UHV DC transmission project in Shandong Province, the receiving station of the Inner Mongolia Zalut to Shandong Qingzhou transmission project, the Guanggu Converter Station, has just completed its annual maintenance.
A dedicated cleaning robot for insulators based on automatic intelligent operation technology was applied for the first time in this inspection. The robot is equipped with an intelligent pollution identification chip and a multi-task management module, which can independently perform insulator climbing, umbrella skirt identification and dirt identification. Etc., to complete the insulator cleaning work safely and efficiently, effectively solving the problems of low manual cleaning efficiency and high safety risks in climbing operations.
According to the relevant responsible comrades of the State Grid Shandong Electric Power Company, in the annual overhaul of the UHV project, "intelligence" has penetrated into every work scene, providing a strong guarantee for the province's UHV daily operation and maintenance and safety management and control.
According to professionals, the maintenance of UHV equipment is very difficult due to the high voltage level of UHV transmission, the large surrounding electric field strength, the generally long transmission distance, and the lines crossing mountains, rivers and seas.
In recent years, with the popularization, application and iterative upgrading of modern technologies such as helicopter inspections, UAV inspections, online monitoring, laser scanning, and digital twins, as well as intelligent equipment, the maintenance of power grid equipment has become more and more "smart".
Not long ago, in Huzhou, Zhejiang, the country's first live operation of helicopters in the UHV intensive channel was also realized, which successfully eliminated two hidden defects in the UHV intensive channel and ensured the safe and stable operation of the UHV large power grid.
"While overcoming the technical difficulties of UHV intensive channel operation, we innovatively applied two different construction methods of hanging baskets and slings to carry out live helicopter operations to eliminate defects continuously for different defect types, and the repair was completed in just over an hour." Yue Lingping, deputy director of the Transportation Inspection Department of State Grid Huzhou Power Supply Company, introduced that the operation has improved the maintenance efficiency by 80%, reduced the power outage time by 5 hours, and increased the power transmission to the Yangtze River Delta by 18 million kWh, which is equivalent to the electricity consumption of 3 million households in one day. It marks a new breakthrough in my country's UHV operation and maintenance technology.
"Traditional power transmission line inspections mainly rely on people. Whether the inspection can be done in place to see the weather and find problems and defects depends on the eyes, and fault analysis and judgment rely on experience. The technical means are single, and the work efficiency is low. The transformation from machine patrol' to 'intelligent patrol'." Li Min of the transmission maintenance center of the ultra-high voltage company of the State Grid Shandong Electric Power Company told reporters.