• Energy Research

Abstract The use of wind generators has grown exponentially in recent decades to meet the increasing demand for electricity. With both generator design and generation capability growing, the resulting increases in the size of generators require them to withstand multiple and intense dynamic loads. These loads cause greater stresses, fatigue, torsions, deflections, and vibrations, among others, leading to greater failures during a generator's life cycle. These issues are of great significance to the research and technological development involved in improving the design, manufacturing process, and installation of wind turbine towers. This work presents a detailed review of the most notable aspects involved in the analysis and design of towers. These aspects include loads and actuating forces, types of structural analysis, used software, and types of experiments used for validating the aspects themselves. In addition, different perspectives regarding the types of supports for onshore and offshore wind turbines are discussed. Likewise, the proposals for new designs and construction materials are also analyzed. The present review integrates the most relevant aspects and recent developments in the design, manufacture, and installation of wind turbine towers. This has been carried out with the objective of providing a contemporary frame of reference that will facilitate the future research and project development related to wind turbine towers.

Mexico has more than 40 years of researching, investing, and obtaining electric power through wind energy. Within the country, there are highly windy areas, such as the Isthmus of Tehuantepec or the state of Tamaulipas, and there are about 2500 MW installed and 70,000 MW tested, all onshore. There are still no offshore wind farms in Mexico, despite having two main coasts, the East and the West, with the Gulf of Mexico and the Pacific Ocean, respectively. Although the Mexican coastal states of the Gulf of Mexico are Tamaulipas, Veracruz, Tabasco, Campeche, and Yucatán, this work focuses on the study and feasibility of offshore wind energy use on the coasts of the states of Tabasco, Campeche, and Yucatán. This is because of the availability of data in that region; however, sustainability criteria that can be used in other regions are also presented. MERRA-2 and ERA5 data were used employing WAsP and Windographer software. It was found that the capacity factor in the area of Tabasco, Campeche, and Yucatán is 32%, 37%, and 46%. It can be noted that, in the WF100% scenario, each of the wind farms could contribute more than 35% of the region’s electricity consumption; those of Campeche and Yucatán stand out with contributions of more than 70%.

This paper proposes the development of an active control system to control the power output of a low-power horizontal-axis wind turbine (HAWT) when operating at wind speeds above the rated wind speed. The system is composed of an active articulated vane (AAV) in charge of the orientation of the wind turbine, which is driven by an electric actuator that changes the angle of the AAV to maintain a constant power output. Compared with the passive power regulation systems most often used in low-power HAWTs, active systems allow for better control and, therefore, greater stability of the delivered power, which reduces the structural stresses and allows for controlled braking in any wind condition or during system failures. The control system was designed and simulated using MATLAB R2022b software, and then built and evaluated under laboratory conditions. For the control design, the transfer function (TF) between the pulse width modulation (PWM) and the AAV angle (θ) was determined via laboratory tests using MATLAB’s PIDTurner tool. For the simulation, the relationship between the power output and the AAV angle was determined using the vector decomposition of the wind speed and wind rotor area. Wind speed step and ramp response tests were performed for proportional–integral–derivative (PID) control. The results obtained demonstrate the technical feasibility of this type of control, obtaining settling times (ts) of 6.7 s in the step response and 2.8 s in the ramp response.

This paper presents an analysis of sound pressure levels through theoretical modeling and experimental validation in a 1 kW small wind turbine. The models used in the theoretical analysis are BPM (Brooks, Pope, and Marcolini) and BM (Brooks and Marcolini), where wind turbine blades are divided in sections, and each section has its own contribution with respect to the total emitted sound pressure level. The noise propagation study and its experimental validation were accomplished within the requirements of the standard IEC 61400-11 Ed.3 and the standard NOM-081-SEMARNAT-1994. The comparative study of theoretical and experimental results showed that the BPM and BM methods have a maximum error of 5.5% corresponding to the rated wind speed of 10 m/s. However, at low wind speeds, the theoretical models fit well to experimental data, for example, in the range from 5 to 8 m/s. The experimental data showed that the rotor’s aerodynamic noise is more evident at low wind speed, because under these conditions, environmental noise is much less than wind turbine noise. Finally, to prevent possible negative effects on people’s health, there is a recommended minimum and suitable distance between small wind turbine installations and buildings.

A methodology for the optimization of renewable hybrid low power generation systems (RHLPS) is presented, analyzing its performance under different control strategies and thus reducing the costs of power generation using the existing equipment, and varying only the configuration of the factory settings. The above is achieved through the use of software tools for simulations and sensitivity analysis. In the first instance, a description of the different control strategies that have been applied to the RHLPSs is made. Secondly, a RHLPS optimization methodology is developed by means of control strategies. As a third and last point, the methodology is applied to a system in operation, where, through simulations, the optimal values are obtained and those allow to analyze the operation of the system under different control strategies. The results show that an appropriate control strategy allows a better performance and operation of the systems, and therefore it is important to perform an optimization and operational analysis to the existing systems, to make a better use of the equipment, as well as the available renewable resources.

This study introduces a metrological approach to measure the aerodynamic shape and the twist of a wind turbine blade. The optical profilometer measurement technique used is laser triangulation. A camera records the image of a line projected onto a section of the blade and, by reconstructing the airfoil shape, the twist angular position of the profile with respect to the axial line of the blade is determined. This methodology is applied to test different sections of a Wortmann FX 63-137 airfoil with a length of 1700 mm. The results of the aerodynamic shape and twist angle are quantitatively verified by comparing them with the ideal or design values. The reconstruction process achieved a resolution of 0.06 mm, and measurement errors in the twist angular position were less than 0.1°. The presented method is efficient, accurate, and low cost to evaluate the blade profiles of low-power wind turbines. However, due to its easy implementation, it is expected to be able to measure any full-scale wind blade profile up to several meters in length.

Abstract The heat transfer and entropy generation in a magnetohydrodynamic flow of Al 2 O 3 –water nanofluid through a porous vertical microchannel with nonlinear radiative heat flux were investigated numerically. Then, combined effects of nanoparticle volume fraction, hydrodynamic slip, magnetic field, suction/injection and thermal radiation on heat transfer and entropy generation were studied. The dimensionless governing equations were solved numerically by applying Runge–Kutta integration method together with shooting technique. In this study, the accuracy of the numerical results was verified by comparing its predictions with exact solutions of model without both radiation effects and buoyancy force. Here, different from previous literature, heat transfer subject to nonlinear thermal radiation, Joule heating and viscous dissipation was solved and analyzed using conjugate convective-radiative heat transfer on the boundary surfaces. Moreover, influences of pertinent parameters on nanofluid velocity, temperature, local and global entropy generation and Nusselt number were discussed in detail and illustrated graphically. Based on the numerical results, it was proved that the global entropy generation decreased with both nanoparticle volume fraction and suction/injection Reynolds number while it increased with Grashof number (Buoyancy force intensity), radiation parameter and conduction-radiation parameter. In addition, it was possible to determine optimum values of slip flow with minimum values of global entropy generation rate. The Nusselt number was also calculated and explored for different conditions. In this way, optimum values of Grashof number with maximum heat transfer on the heated left plate were derived.