Analysis on patent application situation of the ho

Analysis of patent application situation of wind turbine pitch system

statistical analysis shows that Chinese enterprises still have a large gap with foreign countries in the patent application of wind turbine pitch technology, and their ability to grasp technology hotspots is also weak. Especially in the research and development of independent pitch technology, which is the future development trend of pitch system, domestic enterprises need to cooperate with major universities to strengthen the research of basic disciplines

in the wind turbine, the main functions of the pitch system include: automatically adjusting the angle between the blade and the wind direction according to the wind speed, so as to achieve a constant speed of the wind turbine; Using the principle of aerodynamics, the blade can be feathered 90 degrees, parallel to the wind direction, and the unit can be shut down. The working principle of the pitch system is to control the speed of the wind turbine by controlling the angle of the blades, so as to control the output power of the unit, and make the unit stop safely by understanding the aerodynamic braking. During the normal operation of the wind turbine, when the wind speed exceeds the rated wind speed, the rotating speed of the wind turbine is kept constant by controlling the angle of the blades. Any shutdown caused by any condition will make the blades feathering to the 90 degree position. The pitch system mainly includes: pitch bearing, and the blade (root) of the unit is connected with the hub through the pitch bearing; The pitch motor is meshed and linked with the internal teeth of the pitch bearing through a pinion. In addition, the pitch system sometimes needs to be powered by backup battery for pitch operation. Therefore, the pitch system must be equipped with backup battery to ensure safe shutdown in case of serious failure or major accident of the unit; A redundant limit switch is also required to ensure the safe braking of the pitch motor when the main limit switch fails

this paper analyzes the patent application of the pitch system from two aspects: the global patent application situation and the Chinese patent application situation, so as to compare the gap between domestic and foreign technologies. The samples of global patent application situation analysis are from the world patent index (WPI) database, and the samples of Chinese patent application situation analysis are from the China Patent Database (CPRs)

analysis of global patent application situation of pitch system

in order to analyze the global patent application situation of pitch system, this section focuses on the global patent application trend and the ranking of important applicants

I. application trend

Figure 1 shows the trend of global patent applications for wind turbine pitch system, which can be roughly divided into three stages:

(I) technology accumulation period (1970-2005)

in 1970, the first patent application for pitch system appeared, but from 1970 to 2005, the number of applications generally grew slowly. From 1978 to 1988, the number of applications reached a small peak, thanks to the wind energy policy act passed by the U.S. House of Representatives and Senate in 1978, which determined the 1978-1988 national wind energy development plan. During this period, a large number of patent applications were filed by American enterprises, which made the number of patent applications peak during this period. However, during the ten years from 1988 to 1999, the application of pitch system not only did not increase, but fell slightly. From 2000 to 2005, the pitch system began to get attention again, and the number of patent applications also increased slightly

(II) rapid development period (2006-2011)

since 2006, pitch system technology has developed rapidly, especially during 2006-2011, the number of applications has increased several times. This is mainly due to the implementation of the renewable energy law in China on January 1st, 2006. The State encourages and supports renewable energy and power generation, which has led to a blowout growth in China's applications. During this period, Chinese applicants submitted a large number of relevant applications

(III) technology stability period (since 2012)

after experiencing a rapid development period, after 2012, the wind turbine market appeared short-term saturation, and the number of patent applications also fell slightly, but it still maintained a high level of applications every year. However, the application volume data after 2014 is affected by the public lag, and can not accurately reflect the real application volume

II. Ranking of major applicants

Figure 2 shows the ranking of global applicants for wind turbine pitch system patents. Among the top ten applicants in the field of pitch system patents, Chinese enterprises account for only three seats, and the total number of applications is far behind foreign enterprises. This shows that Chinese enterprises have made some achievements in the research and development and protection of wind power pitch system, but there is still a big gap compared with leading enterprises in the world. In addition, general electric and Vestas ranked first and second respectively, keeping pace with each other in the number of applications, and the number of applications of these two enterprises is far more than that of other enterprises; Siemens and Mitsubishi Heavy Industries ranked third and fourth. The top ten applicants are all companies, and the rest are companies or research institutions, and there are basically no individual applications. It can be seen that pitch system is a field with high technical level requirements and industrialization, which is difficult for individuals to enter

analysis of Chinese patent application situation of pitch system

in order to analyze the Chinese patent application situation of pitch system, this section focuses on three aspects: the trend of Chinese patent application of pitch system, the distribution of applied technology, and the comparison of domestic and foreign technology

I. application trend

Figure 3 shows the development trend of Chinese patent applications in the field of wind turbine pitch system

in 1990, the first patent application for pitch system appeared in China. However, from 1990 to 2005, the number of applications was generally in a state of slow growth, with only 26 applications in 15 years. In these 15 years, the overall research and development level of the pitch system is low, with few achievements. After 2006, the number of applications increased rapidly, especially reaching the peak of more than 200 patent applications in 2011 and 2012, and maintaining more than 100 applications in the following years. This is also mainly due to the renewable energy law implemented by China on January 1st, 2006. After 2012, this trend has slowed down. From 2013 to 2015, there was a certain decline in the number of applications

II. Technology distribution

2 is the implementation of industrial scope

Figure 4 shows the technology distribution and application volume trend of Chinese patent applications for pitch system. It can be seen from the figure that among the patents of pitch system applied for in China, the majority are pitch device assembly and pitch control method, accounting for 29% and 25% respectively, followed by pitch electronic control structure, safety and reliability. From the perspective of the trend of application volume, the application volume of major technology branches was relatively small in 2004 and before. Most of the early applications involved the pitch device assembly, and since 2005, the application volume of pitch device assembly and pitch control method has increased rapidly. However, after reaching the peak in 2011, the application volume of pitch device assembly fell sharply, while the application volume of pitch control method still maintained a high level; The number of patent applications for pitch electric control structure and pitch bearing gear began to increase in 2009, and has remained stable since then; There were a few patent applications involving safety and reliability in the early stage, but the blowout began in 2007. In 2011, the electronic universal experimental machine: the electronic universal experimental machine is a new generation of double space microcomputer controlled electronic universal experimental machine specially designed for colleges and universities and scientific research institutes. It has become one of the key technical branches since then

III. comparison of technical distribution of domestic and foreign cleaning test bench

Figure 5 shows the radar diagram of technical distribution comparison of domestic and foreign patent applications for pitch system, in which the amount of applications is calculated in percentage. It can be seen from the figure that among the seven technical branches of pitch system, the most concerned technical points at home and abroad are different. First, domestic applicants pay more attention to the pitch device assembly, accounting for 26% of the total applications; Foreign applicants pay much more attention to pitch control methods than other technical branches, accounting for 43% of the total applications. After further detailed analysis of these applications, it can be seen that the above domestic applications mainly involve the improvement of the overall structure of the pitch device, while foreign applications pay more attention to the independent pitch control method, the method of executing pitch control according to the signal, etc. Secondly, foreign applications pay great attention to the improvement of pitch system in terms of safety and reliability, and the proportion of applications involving this aspect is very large, reaching 21%; However, China pays less attention to this aspect, accounting for only 6% of the total number of applications. On the other hand, there are few foreign applications for electric control and hydraulic pitch systems that domestic applicants are more concerned about

to sum up, we believe that there is still a certain gap between domestic and foreign patent applications. Through the analysis of the technology distribution trend of the patent application of the pitch system, it can be seen that the hot spot of the pitch system at present is the pitch control method, safety and reliability. Foreign applicants have grasped the hot spots and attached great importance to the application of these two technical branches. However, domestic applicants pay too much attention to the improvement of the structure of the pitch device and pay insufficient attention to the above-mentioned technical hotspots, especially in terms of safety and reliability. Domestic applicants' patent applications for these technical branches are far behind foreign countries

analysis of patent application for independent pitch technology

with the development of wind power technology, the unit capacity is getting larger and larger, and the diameter of wind turbine also continues to increase. Due to wind shear, turbulence, disturbance effect, tower shadow effect of the tower, gravity and centrifugal force of the blades and other factors, the influence of irregular changes in blade load is also intensified, and the fatigue load of blades, hubs, spindles, towers and other components increases, reducing the life of these components and the reliability of the unit. On the other hand, with the development of load measurement sensor technology, the load on the unit can be measured reliably for a long time. It is more economical to reduce the fatigue load of major components of large-scale wind turbine through independent pitch control than to improve the reliability and life of equipment by increasing the strength of mechanical structure. After 2005, the number of patent applications for independent pitch technology has increased significantly. This section selects General Electric, Vestas, Siemens and Mitsubishi Heavy Industries, which rank among the top four in the number of patent applications for pitch system in the world, to analyze their independent pitch technology patent applications in detail

as can be seen from Figure 6, these four companies have applied for independent pitch technology patents. In particular, Vestas, as a company dedicated to wind energy utilization research, is far ahead of other companies with 32 patent applications related to independent pitch technology. This is mainly due to the fact that most of the products supplied by Vestas are large-scale wind turbines with a single unit capacity of more than MW, and at present, the vast majority of large-scale units adopt independent pitch technology

Figure 7 shows the technology branches of independent pitch patent applications of the four major companies. Through comparative analysis, it is found that these applications mainly involve three aspects:

1 Load calculation. The main function of the technology is to reduce the fatigue load of each component of the unit during operation on the premise of ensuring the power output. Therefore, the measurement and calculation (or estimation) of the load of each component is the basis of independent pitch technology. General Electric, Vestas and Siemens have 9 applications related to load calculation, which shows that these companies attach great importance to the protection of patents in this regard

2. Environmental monitoring. The difference of wind speed and direction of each blade is the main cause of load imbalance