# Technological Advances on Fault Diagnosis in Wind Turbines: A Patent Analysis
## 1 Introduction  
For many decades, the global utilization of energy has increased remarkably, and significant efforts have been made by most developing countries to attenuate and minimize the impacts of climate change by maximizing energy use and minimizing greenhouse gas emissions [1]. Due to current economic and industrial growth, experts have estimated that by 2050, the global energy requirement will be around \(\sim\)30 TW [2], exacerbating the negative impacts related to the use of fossil fuels [3]. The Intergovernmental Panel on Climate Change (IPCC) commented on the future risks emanating from climate change, stating: _\"Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive, and irreversible impacts for people and ecosystems. Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks\"_[4]. Climate change is undoubtedly a major driver of wind power development, and the use of wind energy is an important factor in attenuating the negative effects of global warming. Along with the growing safety concerns surrounding the use of nuclear power,many countries have established important strategies targeting renewable energy with low greenhouse gas and pollutant emissions, including the use of wind energy [5; 6]. Wind energy is a predominant and potentially low-cost renewable energy technology that plays a key role in the transition toward clean energy [7; 8]. Among the current technologies for generating electricity based on renewable sources, the most widely implemented renewable energy in the world is wind power [9]. The energy is collected through conventional wind turbines, converting the kinetic energy of the wind into mechanical energy through the rotation of the blades and then into electrical energy through the use of generators. Depending on their location, wind turbines can be categorized as onshore or offshore wind turbines [10]. In recent decades, the global wind-power-generation capacity has increased from 7.5 GW in 1997 to 743 GW in 2020. Currently, the total world capacity for wind power is about 873 GW, helping the world avoid over 1.2 billion tons of CO\({}_{2}\) annually. China and the U.S. are the two largest wind energy marketplaces in the world. In the United States, installed wind capacity at the end of 2020 was 122,426 MW of onshore wind power and 42 MW of offshore wind power, representing more than USD 20 billion of investment, while in China, the capacity was 272 GW onshore and 9 GW offshore [11]. Experts believe that the global wind energy market will reach over 557 GW of new capacity over the next five years due to current policies. That is more than 110 GW of new installations each year through 2026 [12]. WTs can be categorized according to their location, either onshore or offshore. Onshore wind turbines are located on land, and their systems suffer fewer failures, while offshore turbines, constructed in bodies of water where higher wind speeds are available, generate more electricity due to their larger size and the stronger winds present in the large open spaces where they are located, without restrictions caused by the environment, noise limits, and urban planning [13; 14]. The rapid expansion of wind energy has created novel challenges in turbine control, plant operations, production planning, condition monitoring, and maintenance. Wind turbines (WTs) are exposed to highly variable and severe weather conditions, with rapidly changing ambient temperature, air pressure, and alternating load, including calm winds to gaze force winds, tropical heat, lightning, arctic cold, hail, and snow [15]. Due to these external variances, WTs undergo constantly changing dynamics and local loads, resulting in a large variation in operating conditions that lead to intense mechanical stress [16; 17].