With global warming and the depletion of fossil energy sources, renewable energy is gradually replacing non-renewable energy as the main energy in the future. As one of the fastest growing renewable energy sources, the safety and reliability of wind energy have been paid more and more attention. The size of modern wind turbines is becoming larger and larger. As the main component of wind turbines to capture energy, the blade is often damaged by various complex environments and irregular loads. Therefore, the health monitoring and damage identification of wind turbine blades have become a main research focus. At present, in addition to the overview of various detection methods of wind turbine blades, there is a lack of comprehensive classifications and overviews of the main damage types, damage-generation mechanisms, and basic principles of the damage-detection technology of wind turbine blades. In this paper, firstly, the common fault types of wind turbine blades, such as trailing edge cracking, lightning strike, leading edge corrosion pollution, icing, and delamination, as well as their generation mechanism, are comprehensively analyzed. Then, the basic principles and the latest research progress of the current main detection technologies, such as vision, ultrasonic, thermal imaging, vibration, acoustic emission, and so on, are comprehensively reviewed. The advantages and limitations of the various detection technologies for practical application are summarized. Finally, through a comparative analysis of the various damage-detection technologies, we try to find potential future research directions, and draw conclusions. This paper will provide a reference for understanding the mechanism behind the main damage types and the damage-detection methods of wind turbine blades. It has important reference value for further promoting practical research of wind turbine blade damage-detection technology and grasping this research direction.

Wake effects commonly exist in offshore wind farms, which will cause a 10–20% reduction of whole power production as well as a 5–15% increase of fatigue loading on the wind turbine main structures. Obviously wake interaction between floating offshore wind turbine (FOWT) is more complicated, and needs careful assessment which is a prerequisite for active wake control (AWC). The primary objective of the present research is to investigate in detail how the wake inflow condition, streamwise spacing, turbulence intensity, and wind shear influence the power performance, platform motion dynamic and structural loading of FOWT. FAST.Farm, developed by the National Renewable Energy Laboratory (NREL), was used for simulating two tandem FOWTs in different conditions. Comparisons were made between FOWTs in different conditions on power performance and platform motion dynamic, which were presented through both time and frequency domain analysis. Damage equivalent loads change in FOWTs interference under typical working conditions were discussed and summarized. Half wake inflow would pose many challenges to the downstream FOWT. These research studies can be incorporated into further offshore wind farm wake models, providing applicable AWC strategies to reduce wake interference effects for higher energy production and for the longer life of FOWT.

The wake management of offshore wind farms (OWFs) mainly considers the wake effect. Wake effects commonly occur in offshore wind farms, which cause a 5–10% reduction in power production. Although there have been many studies on wake management, many methods are not accurate enough; for instance, look-up table and static wake model control methods do not consider the time-varying wake state. Dynamic wake management is based on the real-time dynamic wake, so it can increase the energy of the OWFs effectively. For OWFs, dynamic wake control is the main method of dynamic wake management. In this paper, the existing wake model and control progress are discussed, mainly emphasizing the dynamic wake model and the dynamic wake control method, solving the gap of the review for dynamic wake management. This paper presents a digital twins (DT) framework for power and fatigue damage for the first time.. The structure of this paper is as follows: (1) the mechanism of wind farm wake interference is described and then the dynamic wake model is reviewed and summarized; (2) different control methods are analyzed and the dynamic wake management strategies for different control methods are reviewed; (3) in order to solve the problems of dynamic wake detection and real-time effective control, the technology of DT is applied to the dynamic wake control of OWFs. This new DT frame has a promising application prospect in improving power and reducing fatigue damage.

Tidal turbine blades are prone to flow separation in the boundary layer under high speed or high angle of attack, which will reduce energy efficiency and even the stall damage of the blades. This paper proposes introducing the flow control theory of vortex generators (VGs) to tidal turbines and studying the influence of VGs on the hydrodynamic characteristics of the tidal turbine blades. First, a numerical study is performed to investigate the effects of VGS on the hydrodynamic performance of the National Advisory Committee for Aeronautics (NACA) 4418 hydrofoil. The impact of different parameters, such as VG arrangement, spacing, height, and length, on the hydrodynamic performance of hydrofoil is studied by the computational fluid dynamics method. The results show that VGs can effectively suppress the flow separation and improve the maximum lift coefficient of the hydrofoil. The influence of VGs on flow separation characteristics of horizontal axis tidal turbines is studied by the CFD method. The results show that the flow separation of turbine blades mainly occurs at the root part of the suction surface, and the flow separation region expands radially as the flow velocity increases. VGs can effectively reduce the flow separation area on the suction side of turbine blades by suppressing the flow separation effect. Compared with the turbine blades without VGs, the power coefficient of turbine blades with VGs is increased by up to 5%. The flume experiment verifies the accuracy of the simulation results.

The concept behind this research article is advancement towards utilizing renewable energy sources of wind–solar to generate electrical energy for E-bike (electric bike) charging stations. To optimize the design and operation control of the wind–solar E-bike charging station system, the development of modelling this hybrid power generation system, consisting of solar and wind energy combined with battery storage, is proposed and will be studied in this paper. A university campus setting is utilized for the case study by comparing offshore (Huangdao) and onshore (Laoshan) sites. The proposed research will focus on annual energy production (AEP) and system cost analysis. The proposed work’s main objectives are to analyze the wind/solar properties of the installation’s location using the last 20 years’ data, calculate the AEP for wind turbines and solar PV, and estimate how many E-bikes can be charged day/year with reliable operation. We have calculated that the hybrid power available is 27.08 kWh/day offshore and 22 kWh/day onshore. This research study concludes that on average, based on AEP, in the case of offshore, 5110 E-bikes can be charged per year and in the case of onshore, 4015 E-bikes can be charged per year. We have also calculated the COE (cost of energy) for 20 years for the proposed project, which is $0.62/kWh onshore and $0.46/kWh offshore.

The rapid deployment of the offshore wind turbine technology has brought more requirements for remote turbine health monitoring especially for blade health conditions. The trailing edge cracking (TEC) is often the early stage blade health issue which leads to more serious problems and even crash of wind turbine. In response to this cracking issue, this paper presents aero-acoustic noise modeling analysis of the blade airfoil section with and without cracking of typical 3 millimeter (mm) gap in the trailing edge and a comparative study between the simulation and semi-empirical model for the calculation aero acoustic characteristics (AACs) of airfoil TEC noise, and description a new acoustical sensor detection technology of blade TEC. The IEEE P2400 standard will be utilized to complete the acoustical signal calculation for rotating sound source and compared with other existing measured acoustical signals from on-site microphone. Several simulations are presented to test and validate the proposed model and analysis methods, demonstrating this research work cannot only analyze the AACs of the blade TEC detection, but will also contribute the complete wind turbine blade health monitoring technologies.