The principle of offshore wind power and ordinary wind power generation is the same, is the use of the wind at sea to drive the windmill blade rotation, the kinetic energy of the sea wind into mechanical kinetic energy, and then through the speed booster will rotate the speed, the mechanical energy into electric kinetic energy, prompting the generator to generate electricity.
In recent years, Chinese rapid development of offshore wind power, the installed capacity continues to maintain the world's first. With the accelerated layout of offshore wind power projects and the continuous exploration of the sea environment, the offshore wind power industry gradually to high-power, deep-sea advance, has formed a complete wind power industry chain and supply chain with leading levels and global competitiveness. At present, 60% of wind power equipment in the global market is from China.
About offshore wind power
1.Offshore wind turbine foundation development
Offshore wind turbine foundation is subject to strong winds, waves, currents and other alternating loads coupled with strong corrosive environment, large foundation size, high construction equipment requirements, and complex processes. Wind turbine foundation design, the factors that affect the selection of wind turbine foundation include: the geological conditions of the seabed, offshore distance, water depth, the role of external loads such as wind, wave and current ice, and the impact of the ecological environment, etc., of which the geological conditions of the seabed and water depth conditions are the main influencing factors.
2.Chinese offshore wind power construction equipment resources status
Domestic offshore wind farm engineering construction construction field, after gradual exploration and engineering practice, has formed a set of economic and effective construction programs and ship supporting equipment. At present, the domestic offshore wind power construction development trend for ship specialization, that is, for different processes, the use of different ships for construction, while different types of ships in dealing with a variety of different construction processes, but also has the characteristics of flexibility, adaptability, safety and efficiency.
3.Main construction vessel
Wind turbine monopile foundation construction equipment requirements are the highest, the main construction vessel for the floating crane ship. At present, the most mature single pile foundation sinking pile construction process, for the first set up reusable special stable pile platform, using floating crane ship for sinking pile construction; offshore wind turbine installation to use jack-up crane ship for split installation, so the current domestic offshore wind power construction of the main construction vessel for the floating crane ship and jack-up platform ship two major types of engineering vessels.
4.Offshore wind turbine foundation structure form
(1) Monopile: the most widely used, the share of the European waters up to 81%, for the water depth of 0-30m sea.
Advantages: mature technology, good economy, adaptability; disadvantages: structural stiffness is small, easy to deformation, the impact of sea bed scouring.
(2) Multi-pile bearing platform: commonly used reinforced concrete mechanism, is a common structure of coastal pier and bridge pier foundation, suitable for 0-30m near-shore sea.
Advantages: mature construction technology, good anti-collision, good adaptability to soft ground; disadvantages: long construction time at sea, complicated procedures, not suitable for deep water sea.
(3) Gravity type: is one of the main forms of offshore wind turbine foundation structure, applicable conditions: water depth of 0-30m sea.
Advantages: simple structure, good stability, small on-site installation workload; disadvantages: high requirements for seabed geological conditions, the need for deeper, better concealed conditions of prefabricated docks and water conditions.
4) Multi-legged type: divided into three-legged and multi-legged foundation, taking tripod as an example, using the standard three-legged support structure, applicable conditions: water depth 0-30m sea area.
Advantages: not high requirements for equipment, cost between monopile foundation and conduit frame foundation, easy to collide with vessels.
About CRRC’s Offshore Wind Power
The offshore wind turbine developed by CRRC achieves full coverage of power class 8-12MW, impeller diameter reaches 225m, and its wind-sweeping area is about 40,000 square meters, equivalent to about 5.6 standard soccer fields. The platform product can carry out regional customized development configuration according to the specific conditions of different sea areas to achieve the best customer yield and the lowest whole life cycle cost of electricity.
The unit has high efficiency in power generation, with 22 kWh of electricity generated per revolution at rated wind speed, and a single unit can output about 50 million kWh of clean electricity per year. It has significant energy saving and emission reduction benefits. The unit adopts a series of advanced technologies and cost-optimal design concepts such as highly efficient blade design for power generation, lightweight semi-direct drive structure, highly fault-tolerant electrical system, top-mounted box transformer, integrated hoisting, and in-cabin orbital inspection robot.
Technical characteristics of wind power transmission systems
1.Highly integrated system
The transmission system adopts super compact and integrated structure with integrated design of gearbox and generator, which reduces the weight of generator and greatly shortens the axial dimension of generator and gearbox, making the transmission system more compact and the system integration higher.
2.High system matching
The parameters of the converter, generator and gearbox are highly matched, and the mutual compatibility between the internal parts of the system is fully considered at the beginning of the design. Through multi-body dynamics analysis, multi-physical field coupling simulation analysis, and multiple iterations of optimization, the whole transmission system is highly matched and has low vibration; it is more "friendly" to the power grid.
3.High reliability
It adopts reliable insulation system to adapt to the high voltage change rate and spike voltage of the converter; the magnetic pole structure adopts a fully sealed structure, and has passed the wet heat, salt spray, mold, high and low temperature impact tests to improve the operational reliability in offshore conditions; it adopts a special anti-corrosion system to meet the "harsh" requirements of the offshore operating environment.
4.Low temperature rise
The patented technology of high efficiency cooling, innovative design of low wind resistance air guide structure, reduce wind pressure loss, optimize the temperature distribution gradient of water cooling system, improve the utilization rate of cooling system, and overcome the problem of temperature rise of domestic 10MW class transmission system
5.Low vibration
Through transmission system dynamics simulation analysis, the generator electromagnetic and structure, gearbox structure and other optimization, the use of special slot design, through the optimization of the rotor pole structure size, reduce the harmonic content, improve the power quality, reduce the torque pulsation, the vibration and noise to achieve the lowest, good adaptability to the marine environment.
Strength of CRRC
As one of the earliest Chinese companies to enter the wind power industry, CRRC has extended the advanced technologies accumulated in the rail transportation industry to the new energy industry, and successfully applied the key core technologies of rail transportation, such as system integration, converter and control, to wind power, photovoltaic and comprehensive energy business in a flat manner. In 2021, the wind power generator sales ranked first in China, the blade sales ranked second in China, the tower sales ranked third in China ,the newly installed onshore wind power machine ranks fourth in China.
CRRC onshore wind turbine covers 1.5MW, 2.xMW, 2.5xMW, 3.xMW, 4.xMW, 5.xMW, 6.xMW, 7.xMW, 8.xMW and other power levels, realizing the wind power product type spectrum. And has developed 40-100 meters level blade, is promoting the development of more than 100 meters blade, the main products are 146 series blade, 155 series blade, 16X series blade, 17X series blade, 18X series blade, 19X column blade.
CRRC has also introduced the international cutting-edge rail traction motor technology accumulated for more than 60 years into the whole process of wind turbine development, and become the leader of wind turbine technology. The self-developed products cover 1.2MW-14MW direct-drive permanent magnet wind turbine, 2MW-16MW semi-direct-drive permanent magnet wind turbine, 750kw-6MW double-fed asynchronous wind turbine, and wind power transformers such as large-capacity main transformer, medium-sized oil transformer, small oil transformer and distribution transformer. In terms of wind power tower manufacturing, CRRC can meet the production of 5MW-16MW high-power wind turbine towers, and has the annual production capacity of 600 sets of wind power tower equipment.
The advantages of offshore wind power
1.High wind speed, low wind shear: Because the seawater surface is very smooth, the roughness is small, the friction is small. Therefore, the wind speed is larger, wind speed, wind direction changes are smaller, wind shear (i.e., wind speed changes with height) is also smaller, so that you do not need a very high tower, can reduce the cost of wind turbine components.
2.Low turbulence: offshore wind turbulence intensity is low, with a stable dominant wind direction, the unit is subjected to low fatigue load, the turbine life longer.
3.High output: offshore wind farms allow a single turbine with a larger capacity, the higher up to 5MW ~ 10MW, due to the lower noise requirements, through higher rotation speed and voltage, can obtain higher energy output. At present, China's offshore wind energy resources can be developed is three times more than onshore wind energy resources.
4.Save land area and reduce the impact on residents and the environment. Giant wind turbines installed near residential areas can produce visual and auditory pollution, and the shadows and noise generated by continuous rotation can have a significant impact on residents. Onshore wind turbines can also cause slight damage to the natural environment during the construction and transportation process, and some research institutions have shown that wind power plants can also have an impact on natural life. Offshore wind power largely avoids these old problems of onshore wind power.
5.The rapid development of the offshore wind power industry will significantly drive the global offshore wind power professional ship industry.
Offshore wind power has the advantages of high efficiency of power generation and utilization, does not occupy land resources, suitable for large-scale development, and convenient waterway transportation of wind turbines; therefore, the wind blowing from the sea will also become the new direction of China's future clean energy.
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