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Wind energy is a renewable energy with huge resource potential and mature technology. Under the new situation of reducing greenhouse gases and coping with climate change, wind energy has received more and more attention from all countries in the world and has been developed and utilized on a large scale around the world. During the "11th Five-Year Plan" to the "Twelfth Five-Year Plan" period, China's wind power experienced a decade of rapid development, and wind power became the third largest power source after thermal power and hydropower. According to the statistics of the Global Wind Energy Council, in 2017, China's wind power installed capacity reached 19.5GW, and the cumulative installed capacity reached 188.2GW, accounting for 35% of the total installed capacity of wind power in the world. According to the statistics of the China Electricity Council, in 2017, China's wind power installed capacity accounted for 9.2% of the country's total installed power generation, and wind power's annual power generation accounted for 4.8% of the country's total power generation.

China has developed wind power technology research and development for more than 40 years. It started at the same time as Europe and the United States. In the early days, it was mainly researched and trial-produced by scientific research institutions and colleges. During the "Ninth Five-Year Plan" and "Tenth Five-Year Plan" period, China's first batch of wind power The machine manufacturing enterprise initially grasped the overall design technology of the fixed pitch unit, realized large-scale production, and took the first step of industrialization development. Since the "11th Five-Year Plan", as the country has successively formulated relevant laws and support policies to promote the development of renewable energy such as wind power, many domestic and foreign enterprises have invested heavily in China's wind power manufacturing industry, through the introduction of production licenses, joint ventures, and Independent research and development or joint research and development, etc., to develop wind turbine products above the megawatt level. After a certain period of wind turbine technology introduction and industrial production, domestic wind power machine manufacturers have deepened their understanding of the road map, key elements and potential risks of wind power technology development, and developed a number of models with independent intellectual property rights. The capacity is also gradually approaching the international leading level.

China's wind power enterprises have mastered key core technologies through introduction, digestion and re-innovation, and have made breakthroughs in the development of wind turbines adapted to low wind speed conditions and harsh environments. They are in a leading position in the world and are also basic in the development of large-capacity units. Realized synchronization with the world. These achievements not only ensure the sustained and rapid development of China's wind power industry, but also lay a foundation for China's wind power industry to achieve leap-forward development from large to strong.

In order to adapt to the huge low wind speed resources in the central and eastern regions of China, many machine equipment manufacturers have launched high-tower and long-blade programs in recent years. They have borrowed the experience of European manufacturers in the process of technology development, but many of them are China's equipment manufacturers have adapted to local conditions, and some new ideas and methods based on domestic resources and industrial support have shown that China's complete equipment manufacturers have begun to have certain independent innovation capabilities in terms of technical routes.

China's basic research and common technology research in the field of wind turbines is relatively insufficient. Most of the software used in wind turbine design software and load evaluation is European company products. The design standards and concepts are basically in accordance with the wind turbines proposed by DNV.GL. The certification rules and the requirements of the IEC61400 series wind turbine technical standards proposed by the International Electrotechnical Commission (IEC) did not fully take into account the particularities of China's wind energy resources, natural environment and grid acceptance methods. The foreign wind power industry is very active in cross-industry technology integration and results transformation. It has always led the development of mainstream technology and still has a leading edge in basic theory, basic processes and material applications. In the long run, wind power is a capital and technology-intensive industry with very high requirements for equipment reliability. From a global perspective, due to the increase in technology and capital thresholds for the wind turbine industry, industry concentration is also increasing.

Second, the development status of wind turbine technology

(I) Development status of design and manufacturing of large wind turbines

1. Development of large wind turbines

Driven by market demand and competition, China's large-scale wind turbine development technology upgrade and internationalization process has been accelerating. At present, China's 1.5~4MW wind turbines have formed sufficient supply capacity, and some of the unit manufacturers' 5~6MW wind turbine prototypes have also been off the assembly line.

At present, the major foreign machine manufacturers have completed the industrialization of 4~7MW wind turbines, and the 8~10MW wind turbine prototypes have been hung up. The European and American machine design companies have entered the 10MW class design stage. Vestas Wind Technologies (Vestas) and Germany's Senvion have both announced plans to develop a 10MW wind turbine with an impeller diameter of around 200m. In 2018, General Electric announced that it will complete the development of a 12MW offshore wind turbine within three years.

On a global scale, the development of offshore wind power in Europe started at the earliest, with the largest installed capacity. In 2017, the installed capacity of offshore wind power in Europe reached 3 GW, which ushered in a spurt of growth. This shows that European manufacturers have accumulated rich experience in design and engineering through years of practice, and have full confidence in the return on investment and risk control of offshore wind power.

At present, the 6MW offshore wind turbines in Europe have formed industrialization capacity and achieved mass installation. The 8MW offshore wind turbines have entered the prototype trial operation stage, and the larger capacity offshore wind turbines have also begun to design. In terms of the foundation of offshore wind turbines, Europe has the design and manufacturing capabilities of various types of basic forms such as single piles, multiple piles, gravity piles and jackets. In the field of offshore wind power business, the barriers of technology, capital and engineering experience are more significant than that of onshore wind power. The US Siemens and Spain's Gemei Group have formed a huge lead in this field.

A small number of offshore wind farms have been put into operation in China. Due to the lack of demonstration experience of offshore wind farms, the coordination between the design and development of wind turbines and the design of offshore wind power projects has not been fully grasped, resulting in a large proportion of offshore wind power investment costs, lines and The design cost of the substation is difficult to reduce, and the reliability of the unit has not been fully verified. The return on investment of offshore wind power has great uncertainty. Therefore, through the deep customization and research of wind turbine control strategy, blade, tower, and grid-connected characteristics, the overall optimization of wind turbine and offshore wind power engineering design is realized, avoiding the excess design and waste of individual components, and effectively reducing offshore wind power. Electricity costs.

2. Parts and components

In terms of wind turbine components, China's wind power industry has formed a production system for parts including blades, towers, gearboxes, generators, pitch and yaw systems, wheels, and converters. The output of the above-mentioned major components has ranked first in the world. In addition to supporting domestic manufacturers, some parts and components also have a small amount of support for foreign manufacturers. However, in terms of high-performance bearings, greases, sensors, controllers, etc., domestic parts are not yet fully replaceable with imported parts.

China's wind power industry has accumulated a lot of experience in engineering applications, but in the design principle and optimization method, the application of new materials and new processes, multi-physics simulation and full-performance verification test in the development of parts, high There are still shortcomings in the quality control of performance components, and there are still many shortcomings in the research on unit control technology and the correlation between the specific operating performance of the complete machine and parts.

Generally speaking, China's wind power machine and parts supporting industries have different degrees of large but not strong, but not precise, and the research on basic materials and process technology is relatively lacking, in terms of long-term reliability and product consistency. There is still a gap with some imported products. Most component manufacturers pay more attention to themselves when considering design development and engineering applications, and still need to further strengthen their systematic understanding and deep cooperation in the industrial chain.

3. Wind power test platform

Most foreign wind power laboratories cover wind energy resource assessment, wind turbine field test, transmission chain platform test, and wind power grid-connected simulation. For example, the National Renewable Energy Laboratory (NREL) has established research platforms for wind energy resources at different time scales, 7MVA multi-function grid disturbance simulation devices, 5MW wind turbine drive chain test platforms, and other internationally advanced wind/photovoltaic power generation. Test and R&D capabilities of equipment and components; Danish National Renewable Energy Laboratory (DTU/RISØ) research in wind energy including wind energy resource assessment and micro site selection, wind power forecasting, wind power grid and control, offshore wind power, aerodynamics Research and design, structural design and reliability, remote sensing and testing, boundary layer meteorology and turbulence, materials, etc.

At present, only some wind power enterprises in China have their own power test platforms, but the test functions are relatively simple, and they do not have publicity and independence. Most manufacturers carry out research experiments based on their own experience, understanding and product development. Open communication is not enough.

In 2010, China established the National Wind Power Technology Testing and Research Center in Zhangbei. With the help of the public test site, it carried out a series of wind power equipment on-site operation performance and grid adaptability test, which provided China with the improvement of industrial technology capability and accelerated scale development. Effectively assisted. China's suitable area for the development of offshore wind power is concentrated in the southeast coast, with typhoon, salt spray, high temperature, high humidity and other harsh climate characteristics. At present, China's wind power application environment and systematic professional testing technology capabilities have not yet been formed, and it is urgent to strengthen the construction of relevant testing capabilities. In Europe and the United States, a number of testing and research activities have been carried out on the impacts of offshore wind farms on hydrology, power grids, meteorology and biology during construction and operation, and a series of special test equipments have been developed.

(II) Development status of digital wind power technology

With the rapid development of the capacity of the wind power generation market and the equipment industry, the reliability, operational efficiency and working life of wind turbines have begun to attract the attention of experts and scholars. In response to this problem, digital wind power technology has carried out in-depth research and exploration in wind power intelligent monitoring, intelligent operation and maintenance, fault intelligent diagnosis and early warning.

1. Wind power intelligent monitoring

China's wind farm monitoring system mainly has protocols that are not open. Different vendors describe non-uniformity in the protocol information, and cannot achieve interconnection and expansion. These systems use different communication protocols, and the information description is not uniform. It is difficult to achieve interconnection and expansion. Even wind turbines produced by the same manufacturer have different power electronics technology, control technology, stand-alone capacity and software versions. The control methods may also be different, and different operating parameters and control instructions are required, which creates great obstacles for the unified dispatching control and production management of the wind farm.

In order to achieve interconnectivity, interoperability and scalability in wind farms, the International Electrotechnical Commission (IEC) drafted the IEC61400-25 standard. This standard defines the communication principle and information exchange model for building a wind farm monitoring system platform. It is an extension of the power system automation communication protocol IEC61850 standard in the field of wind power generation. China has also carried out the transformation and implementation of the national standard for the IEC61400-25 standard, and basically realized the monitoring operation management of the wind farm.

2. Wind power intelligent operation and maintenance

China's wind power equipment is mostly operated in an environment with difficult natural conditions and poor reachability. The demand for intelligent operation and maintenance is particularly urgent. It is necessary to achieve fixed inspections in consideration of factors such as equipment reliability, maintainability and economy. Reasonable arrangements for maintenance and maintenance, in order to reduce the number of duty personnel, shorten the spare parts supply time and improve operational reliability.

In the intelligent operation and maintenance management system of wind farms, foreign countries started earlier and the level of practicality is relatively high. As a carrier of wind farm control systems, GH-SCADA, RISØ-CleverFarm and other systems have completed traditional data acquisition and analysis. In addition to the functions displayed, it also integrates advanced control functions such as wind farm optimization control, operational data analysis, supply chain services, and information flow management, which has initially embodied the concept of intelligent operation and maintenance of wind farms.

There is a big gap between the level of intelligent operation and maintenance of China's onshore wind farms in terms of refinement and informatization. Offshore wind farms have significant differences in terms of operation and maintenance management restrictions, service equipment, safety requirements and onshore wind farms. European manufacturers have formed a systematic approach to the operation and maintenance of offshore wind farms based on years of experience. The operation and maintenance methods and concepts of offshore wind farms mainly draw on the experience of onshore wind farms, and have not yet formed an operation and maintenance management system that is truly applicable to offshore wind farms.

3. Wind turbine fault intelligent diagnosis and early warning

At present, China has already faced the current situation of a large number of wind turbines in succession. The utilization rate of wind turbines is declining, the performance of components such as transmission systems and blades is degraded, and the shutdown caused by faults is more serious. Some domestic scientific research institutions and machine manufacturers have gradually paid attention to the health status diagnosis technology of wind turbines, and conducted preliminary research with reference to foreign advanced experience. Some state monitoring products have also been developed and applied to wind farms in batches. Some wind energy use developed countries, such as Denmark, Germany, Spain, etc., which have long-term symbiotic and close cooperation in wind power components and complete machine industry chain, and carry out wind turbine operation status evaluation and life cycle assessment based on a large number of on-site collected operational data. Wind energy resources, wind power planning, wind farm assessment, wind turbine equipment operation status and test results, wind farm operation and maintenance, wind farm performance evaluation, etc. are considered together for wind turbine status evaluation, fault diagnosis and economic operation.

With the development of big data technology, all machine manufacturers have established big data centers and carried out research on wind turbine condition monitoring and fault warning. However, domestic wind turbine fault diagnosis technology has weak product analysis and diagnostic functions. The main problem is that the understanding of the operating mechanism and failure mode of the whole machine and parts is not deep enough. At present, the trend judgment and qualitative analysis are the main, lack of quantitative analysis, and the complete evaluation system and accurate judgment and early warning of faults are not available. method.

(III) Status quo of grid-friendly technology development

With the rising proportion of wind power, due to the stable operation of the power grid, China has also put forward new requirements for the grid-connected performance of wind turbines, including low voltage ride through, high voltage ride through, inertia response and primary frequency modulation. At present, low voltage traversal has become a mandatory requirement for wind power equipment in China. The requirements for high voltage ride through, inertia response and primary frequency modulation capability are being further demonstrated, but no clear technical indicators and test methods have been proposed. According to the situation of their own power systems, each country has proposed targeted access standards for wind power equipment. In some countries, the requirements for high and low voltage ride-through and primary frequency performance of wind power are very clear.

Foreign equipment manufacturers have conducted in-depth research on the dynamic characteristics, safety limits, interaction stability of wind turbines and wind farm models, wind turbines and wind farm power quality evaluation of wind turbines in fault traversing and have carried out corresponding research. Tests, domestic manufacturers are more stuck in the function realization, and need to be strengthened in the in-depth exploration and optimization of technology.

Due to the rapid growth of wind power in China in recent years, and the considerable experience and achievements in large-scale grid connection, transmission and operation of wind power, IEC organization will establish the newly established TC8SC8A "large-capacity renewable energy access to the grid" working group The secretariat of the TC8SC8B "Distributed Energy Power System" working group was established in China. Chinese technical experts can participate more in the formulation of international standards and carry out more extensive technical exchanges, greatly improving the wind turbine industry in China. The right to speak in the field of grid access technology.