Install "brains" for the dam and "quilts" for the heart wall
Lianghekou Hydropower Station is the world's largest
The main stream of the Yalong River, about 25km upstream from the county seat of Yajiang County, Sichuan Province, the once turbulent river has become a Gaoxia Pinghu. my country's highest one million kilowatt hydropower station - Lianghekou Hydropower Station spans the Yalong River and is firmly embedded in V-shaped canyon.
The 295-meter-high earth-rock dam is the world's largest in altitude, the world's largest construction scale for high slope groups, and the world's largest hydropower construction scale for flood discharge, anti-scour, and rotary excavation piles... Recently, with the completion of the 72-hour trial operation of the last unit Putting into commercial operation, this hydropower station, which has created nine "world's most" projects, has all been put into operation to generate electricity.
Facing a series of world-class problems, what "black technologies" are used in engineering construction?
The reporter will take you to find out -
The swing of the main rotating part is only one-half the diameter of a hair
Electromechanical equipment achieves "special quality"
With the opening of the water inlet gate, the galloping river water enters the turbine through the high-pressure pipeline, which drives the equipment to rotate at a high speed and emits a strong current.
At the same time, the duty personnel of the Lianghekou Hydropower Station adjust the guide vane opening according to the dispatching situation, and monitor the vibration, swing, tile temperature and other parameters of the generator set through the intelligent monitoring system in the monitoring room to ensure the stable operation of the generator set.
Electromechanical equipment is regarded as the "heart" of the power station.
As the 100,000-kilowatt hydropower station with the highest altitude in China, the Lianghekou Hydropower Station has a powerful "heart" -- 6 single-unit 500,000-kilowatt large-scale hydro-generator units.
After the completion of the 72-hour trial operation of all units, there are no hidden safety hazards and quality defects, setting a precedent for all large-scale units in China to be transferred to commercial transportation without maintenance.
One detail that technicians still remember is that due to the high altitude, large storage capacity and long water storage period of the Lianghekou Reservoir, the generator set has been running under low head conditions for a long time, which has brought great stability to the core components of the set runner. test.
How can the unit run efficiently and smoothly at high altitudes?
Large-capacity hydro-generator set line bar anti-corona, stator power frequency magnetization test resonance problem, stator and rotor roundness control, and unit axis adjustment, etc., these problems that have plagued the industry for a long time are all urgently needed by technicians. hard bones".
It took more than nine months and with the joint efforts of all parties, the electronic wire rod of Lianghekou generator was successfully developed, achieving a core breakthrough in insulation technology, and setting a world first in the anti-corona technology of stator wire rods for large-scale high-altitude generators.
In the end, the stable operation capacity of the unit was increased by 10%, the swing of the hydro-generator unit of the power station was controlled within 100 microns, and the vibration was within 30 microns.
Among them, the swing of Unit 2 is controlled within 40 microns, which is equivalent to one-half of the diameter of a hair.
Relevant technicians put out such a set of data to the reporter: the diameter of the runner of the unit is 6.25 meters, the diameter of the rotor is over 10 meters, and the total shaft from the runner to the upper end of the rotor is 18.4 meters.
For such a huge rotating system, it is difficult to imagine how difficult it is to control the swing to a few tens of microns at a high speed of 166.7 rpm.
In particular, it faces the major challenges of difficult manufacturing at high altitudes and obvious degradation of man-machine efficiency.
What's the special code behind this?
"Quality is life." According to reports, Yalongjiang Company has put forward the strategic deployment of "special quality" of electromechanical equipment from the beginning, and is committed to creating high-quality electromechanical equipment for Lianghekou Hydropower Station.
Take the generator rotor as an example.
The rotors of the Lianghekou units are over 3 meters in height, 10 meters in diameter and 805 tons in weight.
As the heaviest and largest core component in the generator set, it is composed of nearly 10,000 4mm-thick 750 MPa yoke punched sheets, and the maximum linear speed during operation can reach 340 km/h.
A slight deviation in the installation accuracy will directly threaten the safety of the entire unit.
The rotor is not round, and thermal expansion is the most critical.
Through collective efforts, the team finally developed a special plan for rotor thermal expansion that can effectively cope with the plateau alpine climate, so that the rotor roundness is controlled within 0.4 mm.
The intelligent dam system grasps the health status of the dam body in real time
Engineering construction realizes the leap from digitization to intelligence
How big is the combined volume of 6 "bird's nests"?
The answer can be found at the Lianghekou Hydropower Station - as the highest earth-rock dam in my country, the total filling volume of the Lianghekou dam reaches 43 million cubic meters.
If it is decomposed into 1 cubic meter cubes, it can circle the earth more than once.
In an environment with an average altitude of 3,000 meters, it is a huge challenge to complete such a large amount of reclamation.
Before the two river mouths, there is no mature experience that can be used for reference at home and abroad.
what to do?
Faced with a series of world-class problems such as high altitude, high core wall rockfill dam, and high filling volume, the project builders have embarked on a "smart" way: they have built the first domestic building with "intelligent construction in the whole process". The 300-meter-level ultra-high earth-rockfill dam built with "technology" fills the gap in the construction of ultra-high earth-rockfill dams in alpine regions, and realizes the leap from digitalization to intelligence in dam construction.
Yu Liangsong, an important builder and witness of the Lianghekou dam project, the project manager of the 12.5 consortium of Power China Lianghekou Hydropower Station.
On April 6, when the reporter contacted Yu Liangsong, he was sorting out the project completion materials.
He couldn't hide his pride and excitement when talking about the "smart" road of Lianghekou.
According to reports, with the help of advanced technologies such as high-precision satellite positioning, artificial intelligence, the Internet of Things, and big data, they installed a keen "neural perception system" and a developed "intelligent brain" on the dam, thus realizing the realization of dam materials. Real-time monitoring of the whole process of mining, transportation, paving, and rolling.
"More than 1,300 sensors of different sizes and appearances are buried inside the dam. They are like 'nerve endings' all over the body of the dam, feeding back the sensed temperature, humidity, wind speed and other information to the 'smart brain'- —Intelligent monitoring system platform for Lianghekou dam, so as to realize real-time monitoring and analysis of the operation status of the dam." Yu Liangsong told reporters that with the help of the intelligent dam system, the on-site staff can grasp the "health" status of the dam in real time, and solve problems in real time. Take targeted measures.
Among them, the new intelligent unmanned roller compactor used in the construction must be mentioned.
According to reports, compaction is the most critical step to make the dam withstand the water pressure of nearly 300 meters high and 10.8 billion cubic meters of storage capacity.
The 295-meter-high earth-rock dam is equivalent to a 100-story building.
For every 30 cm of earth and stone to be filled, a roller compactor needs to be rolled back and forth ten times to compact it to 26 cm.
In this way, a total of 1,100 layers need to be filled, and the accuracy should be controlled at the centimeter level.
Yu Liangsong, who has 25 years of work experience in hydropower construction and has participated in the construction of several hydropower stations, told reporters that in the past rolling construction of earth-rock dams, the number of times was often recorded by manual flip count, and the rolling trajectory was also determined by the eyes of the supervising engineer. judge.
In the construction of the two estuary dams, parameters such as rolling speed, trajectory, number of passes, and compaction thickness can be displayed on the relevant interface of the intelligent dam system, and the system can also automatically alarm in real time when encountering problems.
"Unlike the traditional roller compactor, the new intelligent unmanned roller compactor is completely unmanned." According to the person in charge of the project, they have refitted and completed 18 roller compactors of various "thinking" types, realizing the realization of the dam The operation status of the roller compactor and the intelligent perception of obstacles, the centimeter-level positioning of the operation trajectory, and the remote control interconnection of the fleet at the 100-meter level make the construction safer, the quality is more stable, and the construction efficiency is increased by about 15%.
Research and development of "insulation quilt" fast retractor to solve the problem of frozen soil
Create a precedent for large-scale continuous construction of soil core walls in winter in plateau permafrost regions
Lianghekou Hydropower Station is located in the western Sichuan Plateau climate zone, with a large temperature difference between day and night, and the lowest temperature can reach nearly minus 20 degrees, belonging to the seasonally frozen soil area.
The permafrost problem almost stopped the entire project at the beginning.
According to reports, in order to retain water and prevent seepage, a protective wall, the core wall, must be built in the central area of the dam.
However, every three or four months from mid-November to early March of the following year, the soil material of the dam core wall will freeze, which has become one of the key constraints affecting the quality and progress of the dam.
"Its scientific name is high-frequency short-term frozen soil, which freezes at night and melts after the sun comes out during the day." Wang Jinguo, director of the Two River Mouth Construction Management Bureau of Yalong River Company, said that after repeated freezing and thawing, the soil particles will become finer and finer. , there are more and more holes, and the impermeability is getting worse and worse. Once a dam is built with such soil materials, it will face the risk of dam failure.
In order to solve this problem, industry-university-research institutes have jointly tackled key problems, and developed a complete set of technical systems for soil mining, transportation, mixing, paving, and rolling in winter, to ensure that "frozen soil does not go to the dam, the frozen soil is not rolled, and the not freezing".
"In order to prevent the core wall from freezing, we will use geomembrane to fully cover the core wall area in winter." Yu Liangsong told reporters that every night, on-site construction workers will cover the core wall with "insulation quilts" weighing dozens of tons. , Uncover it to continue construction after the temperature rises during the day.
In order to improve work efficiency, project technicians have also successively developed two generations of "insulation quilt" quick retractors.
"It used to take about 4 hours to manually uncover the 'insulation quilt'. With this equipment, it can be reduced to 1 to 2 hours, so that the rapid and continuous construction of the core wall all-weather and the entire warehouse surface under the large temperature difference in winter and the high and low temperature environment has become a reality. "Yu Liangsong said.
In addition to the permafrost problem, the Lianghekou hydropower station construction project also faces the problem of a lot of rain.
It is understood that the area where the hydropower station is located is the rainy season from June to October every year, and the average precipitation in July and August exceeds 700 mm.
In this season, the steel wheel of the roller compactor cannot compact the soil due to the hanging mud. "Sometimes the scraped soil is more than the filling volume, and the lower the core wall is filled."
In order to cope with sudden rainfall, the project builders introduced weather radar, set up small weather stations on the stockyard and dam, and combined with satellite cloud images to predict rainfall information in advance.
At the same time, the construction efficiency is improved by combining the tortoise-back construction of the filling surface and the rapid rotation construction of the small warehouse surface.
"After receiving the warning information, the construction personnel quickly sealed the turtle-backed soil layer with flat rollers, artificially formed a 2% slope ratio for automatic drainage, and set up every 40 meters in the direction of the left and right banks of the filter material area. A drainage ditch for drainage." Yu Liangsong introduced.
After the rain stopped, the topsoil was removed to quickly resume the filling construction.
Insulation in winter and water release in rainy season.
In this way, the project builders set a precedent for the large-scale continuous construction of soil core walls in winter in the plateau permafrost region, and finally realized that "the dam reached its top one year ahead of schedule, and all units were put into operation half a year ahead of schedule".
Looking at Lianghekou Hydropower Station from the Numbers
●The total filling volume reaches 43 million cubic meters, which can be decomposed into cubes of 1 cubic meter, which can circle the earth more than once.
●The left bank slope is up to 684 meters high, which is about 50 meters higher than the tallest building in China. About 16,000 bundles of anchor cables were used in the construction, and each bundle of anchor cables weighs about 1 ton.
●The factory building is 276 meters long and 29 meters wide, and can park 8 trains of 8 motor cars side by side.
●The total storage capacity is 10.8 billion cubic meters, which is equivalent to the combined water volume of 770 West Lakes, which can generate huge compensation benefits for the middle and lower reaches of the Yalong River, the lower reaches of the Jinsha River and the mainstream of the Yangtze River, and increase the annual power generation during the flat dry period by about 34.2 billion kWh , more than 1/10 of the electricity consumption of the whole society in Sichuan last year.
●The annual power generation of the power station plus the increased power generation from compensation benefits is equivalent to reducing the consumption of raw coal by 13.3 million tons and carbon dioxide emissions by 21.3 million tons each year, which is equivalent to reducing the construction of 4 large coal mines with an annual output of 4 million tons.
Our reporter Wang Zhen