# Technological Advances on Fault Diagnosis in Wind Turbines: A Patent Analysis
## 3 Results and Discussion  
The use of patents is an interesting and important tool in the assessment of innovative technologies and activities [35]. In the present investigation, a patent search was conducted to evaluate the technology of interest, the systems, methods, and devices for wind turbines. \begin{table}
\begin{tabular}{c c} \hline
**IPC Code** & **Regarding** \\ \hline F03D & Wind Motors \\ G01H & Measurement of Mechanical Vibrations or Ultrasonic, Sonic, or Infrasonic Waves \\ G01M & Testing Static or Dynamic Balance of Machines or Structures; Testing of Structures or Apparatus, Not Otherwise Provided For \\ G01R & Measuring Electric Variables; Measuring Magnetic Variables (Indicating Correct Tuning of Resonant \\ Circuits H03j/12) & Circuits H03j/12) \\  & Measurement of Intensity, Velocity, Spectral Content, Polarization, Phase, or Pulse Characteristics of Infra-Red, \\ G0 IJ & Visible, or Ultra-Violet Light; Colorimetry, Radiation Pyrometry (Light Sources F21, H0 IJ, H01K, H05B; \\ Investigating Properties of Materials by Optical Means G01N) \\ G01K & Measuring Temperature; Measuring Quantity of Heat; Thermally Sensitive Elements Not Otherwise Provided \\  & For (Radiation Pyrometry G01j5/00) \\ \hline \end{tabular}
\end{table} 
Table 1: IPC codes used in the prospecting of current patent technology. In total, 635 were found, with 342 DWPI families. Figure 1 details the annual distribution of patent applications regarding the described technology; the first applications were found in 1982 (Figure 1a). The number of patent document applications showed growth over the analyzed period, indicating a continued strong interest in the development of new technologies for wind energy. Significant growth in the publication year can be observed starting in 2014, followed by a peak in 2021, with 98 documents. The evolution of the number of patent applications may be related to the need to promote technologies aimed at combating extreme climate change caused by global warming, a consequence of exacerbated CO2 emissions. The first patent found was filed in 1982 by the General Electric Company (Boston, Massachusetts, United States) and refers to the diagnosis of undesirable internal changes in an operating turbine by monitoring the dynamic fluid flow pressure and the vibration of the stationary casing's pump frame. The patent describes monitoring using temperature and static pressure data [36]. The consequences of exacerbated CO2 emissions are increasing in both frequency and intensity: floods, wildfires, melting polar ice caps, and extreme seasonal temperature changes--up and down--on all continents. Consequently, the search for strategies to reduce the dependence on fossil fuels for energy production is increasing. One important strategy is the mission of \"net-zero emissions by 2050\", which emerged as a promising strategy to limit global warming and reduce the world temperature to 1.5 \({}^{\circ}\)C in order to significantly reduce the risks and impacts of climate change [37]. The accession of renewable energy and technological innovation provides a viable route to reduce fossil energy use and reduce CO2 emission levels [38,39]. Most of the technologies developed in the patents focused on new methods and/or systems for monitoring wind turbines and rotor blades. The patent filed by [PERSON] et al., 2021, refers to a wind generator failure detection method that collects and processes two different signals obtained from the wind turbine, the first signal coming from the wind turbine generator and the second coming from a vibration sensor attached to the wind turbine. Therefore, it is possible to detect and identify a characteristic signature from a wind turbine bearing failure [40]. [PERSON] et al., 2021 [41] described a blade-handling system and method for conducting tomography (X-ray) scans of wind turbine blades to detect various types of manufacturing defects before blade installation. [PERSON] et al., 2021 [42] described a method  
Figure 1: Time analysis of patent documents. First year of priority.