The development of offshore wind power is of great strategic significance, so it should pay high attention and strength support; the development of offshore wind power is facing a serious challenge and it should be scientifically dealt with avoiding impulsive rash advance. To China's offshore wind power development, we must uphold the scientific development philosophy, the rational and orderly development of the high starting point, and the sustainable and leaping development with combination of innovation and unique features.The cost, benefit and risk restric the development of offshore wind. But through the progress of science and technology, mastering the key technology of wind power, and improving the planning and construction ability, we can effectively resolve the major factors that restrict the development to ensure the healthy development of offshore wind power. In view of the sound and rapid development of offshore wind power, to build high-quality and high effective offshore wind farm, some advice was given.
China Three Gorges Corporation (CTGPC) is now undertaking the research of offshore wind farms location, wind turbine operation, maintenance technology development, offshore wind turbine construction, development of special test equipment and other subjects related to research topics, which all belong to the National Key Science and Technology Supporting Program of China for the 11th Five-Year Plan, and CTGPC has built several wind turbines with independent intellectual property right in Jiangsu coastal and intertidal zone. CTGPC is exploring the ways to reduce the cost of offshore wind power development,such as through the research of wind measurement, wind resource assessment, foundation structure, transportation and lifting,O&M, and also by promoting the research and development of the large-scale offshore wind turbine. CTGPC is also looking for a new solution to the problem of wind power consumption, by researching of seawater desalination and application of non-grid wind power.
Offshore wind power is a strategic focus of new energy development. At present, our country's coastal areas are actively engaged in planning large-scale offshore wind power. The offshore wind farm planning and current development situation were first introduced, and the major content of the offshore wind farm planning was summarizied. Finally, the main influencing factors and solutions in the planning of offshore wind farm were analyzed.
The paper presented the principle to offshore wind farm siteselection, the technique to connect with the power grid, the foundation type of high-piled concrete bearing platform with anticollision ability,the analysis method of wind turbine foundation structure, the test means of the pile's bearing capacity, the scheme to high-piled bearing platform construction and wind turbine integral lifting, etc. The above outcomes are achieved by study on some technical issues and certain practice including the site selection, the voltage elevation method employed in the wind farm, the design of foundation type selection, the test of pile foundation, the foundation construction, the erection of wind turbine ,etc.for Shanghai Donghai Bridge Offshore Wind Farm. They are worth recommending for reference for the planning and construction of offshore wind farm in the future.
Manufacture cost and service life of WTGS (wind turbine generator system)are dependent on fatigue load during operation,extreme load and designing standard. Nowadays, most designing standard adopted in China is made on the basis of external condition similar to Europe. When those standards are used for designing WTGS in typhoon area without consideration, project risk or manufacturing cost will rise. Typhoon-resistant WTGS with reasonable cost could not be designed and produced unless understanding meteorological characters of typhoon and its destroying mechanism.
In september 2003, the fan blades of wind turbine were damaged by typhoon "cuckoo" in Shanwei Red Bay wind farm, an offshore hilly land. It can be concluded from the failure modes that the blades flutter have occurred and significantly reversed, which was related to the negative terrain. From this instance of the term, under the same intensity of typhoons, the risk of blade damage of sea wind turbine may be lower than that of coastal ones because of flat sea lack of local change conditions of wind direction. The storm also showed that it was the key for blade loss prevention to keep the wind turbine be paused state of stopping rotation, feathering and yawing.
According to the different of depths and geological conditions,and with the combining of the completed offshore wind farm base forms and construction methods, several forms of gravity, single pile, group piles, set of caisson, open caisson and suction barrel base were introduced. To the different foundation forms,the self-elevating platform, the semi-submersible barge shallow draft, piling barge, lifting the overall floating and other appropriate foundation construction methods were proposed,respectively. According to the types of fan unit,the tower tube and installation of the fans were also introduced.
Offshore wind energy is one of the most attractive sources of renewable energy,however, the economics of offshore wind turbines especially foundations are currently challenges. Because of the difficulties met in conception design of offshore wind turbines foundations, a multi-level and multi-factor fuzzy optimization model has been used in lectotype optimization of foundations. In order to decrease the subjective influences, the multi-level fuzzy optimization has been introduced to cover most of the effect factors, and the prior relation method has been used to determine the membership grade in comprehensive optimization and weight. Considering various 13 factors of optimization objects and 4 design types of pile-style foundation, the method has been successfully used to an offshore wind farm for the lectotype optimization of pile-style foundations. The result shows that the new framework and methodology is scientific, reasonable and easy to use in lectotype optimization of offshore wind turbines foundations.
Based on the feature that offshore wind turbine tower supporting structures are affected by soil foundation and the ocean flow, the paper carries out research on supporting system structure with multi-medium coupling. Based on considering fluid-solid coupling, the paper discusses the effect of seabed soil foundation elastic conditions on tower's dynamic characteristics. The comprehensive analytical result of dynamic characteristics with soil-fluid-solid coupling is given in the end and the change law is got preliminary. The findings will provide an important fundamental basis on the anti-vibration design of offshore wind farms tower supporting structure and further research.
The installation methods used in offshore wind farm around the world were summarized, and the process of split installation, the set necessity and principles of assembly base were analyzed. 8 kinds of typical land-based assembly programs and the assembly technology of main parts were summarized. An installation method was proposed by sitting of the diving boat. The diving installation ship was made by installing a crane, and was located in the seabed during the operation to hoist the turbine components. The installation method is suitable for offshore wind farm construction. The application of the installation method in the test turbine project of Jiangsu Xiangshui offshore wind farm was introduced in the paper finally.
Based on the engineering support requirements of the offshore wind farm construction and operation maintenance, a series of engineering support projects were proposed, including: the series road building project for the zone above the high tide line, the grounded pontoons and the pontoon trestle support projects for the zone between high tide level and the low tide level, the shallow draft jack-up wind power platform and amphibious project during the maintenance period for the zone above 5 m depth of water below low tide level. The adaptability, feasibility and the key techniques of the projects were researched. The projects with series of technique support means can meet the needs of the different requirements of the construction on different tideland zones, and solve the problems effectively of construction engineering support of tideland and the shallow water wind farm.
The classification of offshore wind farm and especially the floating foundations of floating offshore wind farm are introduced in detail. The paper also points out that with the mature of wind power technology, fan capacity maximization, the utilization of vertical-axis wind turbine and non-grid-connected wind power system are regarded as the development trend of floating offshore wind farm.
The state of disastrous weather in China is studied comprehensively, and the characteristics of global climate change, driving factors and trend are analyzed based on the research achievement. Furthermore, the response on extreme weather of China is explored under global climate change. Thus, metrological and hydrological factors that affect offshore wind power are proposed and analyzed, and the issue against the typhoon of offshore wind power station was especially emphasized.
For high cost, hard grid connection and high failure probability of large-scale offshore wind power, a non-grid-connected diverse application system is proposed. Breaking the single on-grid application mode of large-scale offshore wind power, the system directly couples offshore wind power with high-energy consumption industries (such as seawater desalination, hydrogen production by water electrolysis and electrolytic aluminum, etc.) into a new and full one through the necessary technical innovation and integration. It uses offshore wind power and changes power transmission into product transmission ashore, which not only breaks the difficult problem of large-scale, super-large-scale wind power application but also saves the investment of offshore wind farms and increases the utilization efficiency of wind energy. As a result, the system is of great practical and strategic significance.
To deal with the unstable stability of output power and the volatility of voltage in the wind power generation, a wind and hydrogen power electric generating system was put forward in the paper to break though the grid-connected bottleneck. In the system, the controllable output, which corresponds to "valley" of the wind power generation output, is used as the guarantee steady output power for the wind power plant, and the uncontrollable output corresponding to the part between "peak" and "valley" is adopting the peak load shifting mode to balance. In the mode, the "peak" is used for hydrogen generation to "cut the peak" and the "valley" is used for electric power generation by hydrogen to "fill the valley" . What is more, as an example, the Rudongfeng Power Plant was introduced to complete corresponding analysis and computation, and the result showed that the system can guarantee the balance of power output mostly and it can be a feasible and effective way to solve the grid-connection of wind power generation.
In this paper the grid-connected demand of large-scale offshore wind power was analyzed , and a detailed comparation is presented for three kinds of transmission technologies: HVAC(high voltnge alternating current), HVDC(high voltnge direct current) based on line commutated converter(LCC),HVDC based on voltage source converter(VSC). The losses are made numerical analysis for gaining the application scope of various transmission systems.
The power net will be created short in peak and surplus in valley. Supplementing pump storage plant into the ordinary hydropower, the surplus valley power can be changed into the precious peak power. Actually it is equivalent to say that the surplus power may be renewable and it is favorable to the sustainable development.
A rigid module rigid connector(RMRC) model is used to study the dynamic characteristics of connectors of modular offshore platform. It is assumed that the modular offshore platform is a whole structure and the connector loads are simplied as the corresponding section loads is deduced using the Three-Dimensional Potential Theory by means of the assumption—High Encounter Frequency with Low Sailing Speed. 2 sea state cases, 4 structure sizes, and 7 wave angle connectors are calculated gaining the dynamic responses and sea states of connectors,and the regularity and relationship between configuration sizes and wave angles which is useful to design and utilization of connectors.
The paper briefly introduced internal and external situation about the wind power station construction and the newly developing plan for the wind power station construction of our country firstly; and then in detail introduced the general scheme, key techniques, new inventions and realizing methods about the developing subject of QLY2150-full circle slewing and tyre type crane for erecting wind power station which proposed based on the above situation; finally introduced the states of the prototype be used in construction of wind power station , and pointed out some great superiorities of this new crane compared with the other general tyre cranes, tuck cranes and crawler cranes.