# Technological Advances on Fault Diagnosis in Wind Turbines: A Patent Analysis
## 3 Results and Discussion
The company supplies power to a population of more than 1.1 billion across 26 provinces, autonomous regions, and municipalities, covering 88% of China's national territory [67]. General Electric, in third place with 16 documents, is an American multinational company with 125 years of experience; it is known for its efforts in the power, renewable energy, aviation, and healthcare industries. In 2021, the company had 52k wind turbines installed in more than 35 countries, the first position in the United States in terms of wind installations [68]. It can be seen from Figure 2a that not only do companies appear between the main applicants but also research institutes and universities. This reflects the possibility of patent applications not only by companies but also by research and development institutions. Among the patents that can be cited is the Inner Mongolia University of Technology (Inner Mongolia-Hohhot, China), which is the publication applied for in 2021. The invention concerns a process related to a new device and method for measuring the dynamic noise of wind turbines. Figure 2b shows the top ten inventors of the prospected technologies, most of whom are associated with the companies and universities found. The main countries and regions that produce this type of technology are demonstrated in Figure 3. By analyzing the main countries that deposited those technologies, it is possible to observe that China and the United States are the main countries, with 373 and 45 documents, respectively. China plays an important role in the development and export of technologies involving renewable energies [69; 70]. The country has made a commitment to achieving peak carbon by 2030 and carbon neutrality by 2060, and wind power has become a practical alternative [71]. The electricity created in China by wind power was 467 billion kWh in 2020, accounting for more than 20% of the total renewable energy generated [72]. In order to encourage the sustainable development of the wind power industry, China's Government has provided support through political measures [73]. Such policies might include clarifying the goal of large-scale wind power development, raising the amount of wind power in the electricity supply, and sharing the operating costs of wind power generation through some political actions such as taxation, financial subsidies, and feed-in tariff adjustments [74; 75]. In 2010, China became the leading wind power market in the world, both annually and cumulatively, in terms of market size. The country usually establishes a Five-Year Plan (FYP), which takes five years as a stage to undertake the development planning of social  
Figure 2: Analysis of the main (**a**) applicants and (**b**) inventors of the prospected technologies. economy and energy. The most current FYP is the 14 th Five-Year Plan (FYP) on Renewable Energy Development (2021-2025), released in June of 2022 [76]. The plan aims for a 50% increase in renewable energy generation (from 2.2 trillion kWh in 2020 to 3.3 trillion kWh in 2025), establishes a 33% share of renewable electricity consumption by 2025, and mandates that 50% of the increase in electricity and energy consumption nationally must come from renewable sources in the period 2021-2025. Achieving the objectives, China will reduce up to 2.6 gigatons of carbon emissions annually [77]. The development history of wind power in China can be divided into four main stages: the initial pilot stage (1986-1995), the experimental development stage (1995-2006), the comprehensive expansion stage (2006-2010), and the stable development stage (since 2010) [78]. In the initial stage, the Chinese government imported small off-grid wind turbines to be used in remote areas, and the country initiated the application and construction of wind farms [79,80]. During the experimental stage, China built small wind farms with foreign grants and loans, and the government provided support to companies to license and start the production of wind turbines and all relevant technology [81,82].