The Current Situation and Difficulties of Deep Sea Wind Power Generation Technology
2023-11-14
Technical challenges
1. High capacity fan technology
Wind turbines are the core of offshore wind power, and the wind turbines used in offshore wind farms in deep sea areas are generally considered to meet performance requirements such as large capacity and high reliability, while also meeting the requirements of localization and autonomous control.
At present, China has formed a mass production capacity of 4-5 MW offshore wind turbines, and the development capacity of 6-MW wind turbines is basically popularized. The number of wind turbine products with a capacity of 7 MW and above has increased; The first batch of 7-megawatt wind turbines has been put into commercial operation along the coast of Fujian, with the first 8-megawatt wind turbine offline and a 10 megawatt high-capacity wind turbine under development; The impeller diameter can reach a level of 180 meters. At present, the European market is gradually putting 7-8 megawatt wind turbines into large-scale commercial operation; Mitsubishi Vestas 10 MW wind turbine officially launched on the market; General Electric's 12 megawatt wind turbine is expected to install a prototype this year, with an impeller diameter of 220 meters.
2. Long distance transmission technology
The typical technical routes for offshore wind power grid connection include conventional AC transmission, low-frequency AC transmission, and flexible DC transmission.
Conventional AC transmission technology has the characteristics of simple structure, low cost, no need for energy conversion, and rich engineering experience. From the perspective of technology, experience, and cost, AC transmission generally has certain advantages for offshore wind farms with a capacity of less than 70 kilometers and around 500000 kilowatts. However, in the application scenario of large-scale offshore wind power grid connection, the capacitance effect of AC cables will greatly increase reactive power loss and reduce the effective load capacity of the cables. If the conventional AC transmission method is used, it is necessary to add a middle end compensation station in the middle of the submarine cable, which can be compensated through parallel reactors. This will bring difficulties in operation and maintenance, as well as reduced overall economic efficiency.
3. Floating Foundation Technology
Floating structures have become the preferred type of foundation structure for offshore wind farms in deep sea areas. Unlike fixed wind turbines, floating foundations for floating wind turbines have a certain degree of six degrees of freedom of motion under marine environmental loads, and may encounter problems such as tilting and displacement during operation. The wind turbine is located at an altitude of nearly a hundred meters above the sea surface, and the slight movement of the floating foundation can cause severe motion of the wind turbine. It not only requires certain optimization measures such as reinforcement and sealing, but also puts forward high requirements for the design of wind turbine blades, transmission systems, control systems, and other components to adapt to more complex marine environments.
Construction difficulties
At present, the platform foundation manufacturing of floating fans is mainly made of steel materials. However, in recent years, some designs have proposed using prestressed concrete as the main material for floating foundation platforms. The manufacturing process of the entire platform can be carried out at onshore bases such as shipyards, and standardized assembly line operations and large-scale production can significantly reduce manufacturing costs. The foundation weight of floating platforms is mostly over 2000t, and the concrete material can reach over 10000t. Compared to fixed fans, floating fans do not have economic advantages in shallow water areas, but their platform weight is not sensitive to changes in water depth, thus gradually highlighting their cost advantages in deep sea areas.
1. High capacity fan technology
Wind turbines are the core of offshore wind power, and the wind turbines used in offshore wind farms in deep sea areas are generally considered to meet performance requirements such as large capacity and high reliability, while also meeting the requirements of localization and autonomous control.
At present, China has formed a mass production capacity of 4-5 MW offshore wind turbines, and the development capacity of 6-MW wind turbines is basically popularized. The number of wind turbine products with a capacity of 7 MW and above has increased; The first batch of 7-megawatt wind turbines has been put into commercial operation along the coast of Fujian, with the first 8-megawatt wind turbine offline and a 10 megawatt high-capacity wind turbine under development; The impeller diameter can reach a level of 180 meters. At present, the European market is gradually putting 7-8 megawatt wind turbines into large-scale commercial operation; Mitsubishi Vestas 10 MW wind turbine officially launched on the market; General Electric's 12 megawatt wind turbine is expected to install a prototype this year, with an impeller diameter of 220 meters.
2. Long distance transmission technology
The typical technical routes for offshore wind power grid connection include conventional AC transmission, low-frequency AC transmission, and flexible DC transmission.
Conventional AC transmission technology has the characteristics of simple structure, low cost, no need for energy conversion, and rich engineering experience. From the perspective of technology, experience, and cost, AC transmission generally has certain advantages for offshore wind farms with a capacity of less than 70 kilometers and around 500000 kilowatts. However, in the application scenario of large-scale offshore wind power grid connection, the capacitance effect of AC cables will greatly increase reactive power loss and reduce the effective load capacity of the cables. If the conventional AC transmission method is used, it is necessary to add a middle end compensation station in the middle of the submarine cable, which can be compensated through parallel reactors. This will bring difficulties in operation and maintenance, as well as reduced overall economic efficiency.
3. Floating Foundation Technology
Floating structures have become the preferred type of foundation structure for offshore wind farms in deep sea areas. Unlike fixed wind turbines, floating foundations for floating wind turbines have a certain degree of six degrees of freedom of motion under marine environmental loads, and may encounter problems such as tilting and displacement during operation. The wind turbine is located at an altitude of nearly a hundred meters above the sea surface, and the slight movement of the floating foundation can cause severe motion of the wind turbine. It not only requires certain optimization measures such as reinforcement and sealing, but also puts forward high requirements for the design of wind turbine blades, transmission systems, control systems, and other components to adapt to more complex marine environments.
Construction difficulties
At present, the platform foundation manufacturing of floating fans is mainly made of steel materials. However, in recent years, some designs have proposed using prestressed concrete as the main material for floating foundation platforms. The manufacturing process of the entire platform can be carried out at onshore bases such as shipyards, and standardized assembly line operations and large-scale production can significantly reduce manufacturing costs. The foundation weight of floating platforms is mostly over 2000t, and the concrete material can reach over 10000t. Compared to fixed fans, floating fans do not have economic advantages in shallow water areas, but their platform weight is not sensitive to changes in water depth, thus gradually highlighting their cost advantages in deep sea areas.
