A Review of Research on Large Scale Modern Vertical Axis Wind Turbines at Uppsala University

Wind energy conversion technologies and engineering approaches to enhancing wind power generation: A review

Nowadays, engineers are toiling away to achieve the maximum possible wind energy harvesting with low costs through enhancing the performances of WECSs in efforts to realize the wind power future forecasts. In fact, achieving this is basically not an easy task due to the intricacies that partly stem from the stochastic nature of wind energy. Further, the efforts in this regard can also be impacted by the ongoing trends in various wind energy conversion-related technologies, and engineering approaches. Hence, the wind power optimization is determined depending on the types of WECS technologies, output power smoothing, and design development approaches that be employed. Currently, the variable speed operations-based WECS technologies are generally opted in wind farm applications. Meanwhile, power management system is the heart of a WECS, where smoothing output power with reducing costs could be implemented. On the other hand, the automated control strategies were reported in literatures to better optimize WECSs’ performances particularly in terms of costs compared to ESS devices. On this basis, MBPC and hybrid control algorithms were commonly presented as the current state-of-the-art for systems modeling, whereas MBD was preferred to be an efficient and cost-saving approach for advanced development of automated control systems. This study aims to conduct comparative analyses on WECS technologies (with different generators, and PECs) based on their energy harvesting capability, cost-effectiveness, and advances in designs. Assessments of the approaches and strategies for smoothing power production are also presented. Finally, the study concludes that trends in PECs, automated control strategies and MBD are the most compelling.

Numerical Prediction on the Dynamic Response of a Helical Floating Vertical Axis Wind Turbine Based on an Aero-Hydro-Mooring-Control Coupled Model

Considering the aero-hydro-mooring-control coupled performance of a floating Vertical Axis Wind Turbine (VAWT), the numerical model of the floating helical VAWT system is established, and the fully coupled simulation program of the floating helical VAWT is developed. The aerodynamic load of the wind turbine system is calculated using the unsteady BEM model, and the hydrodynamic load is calculated using the 3D potential theory. The floating foundation is considered as a rigid body, and the blades and tower are considered as flexible bodies. Based on the Kane method of a multi-body system, the dynamic responses of the VAWT could be solved in the time domain. A variable speed control model considering efficiency and load is established to match the rotating speed with the wind speed, and it could maintain the target output power under the influence of turbulent wind and large-scale movement of the floating foundation. The control strategy of limiting the target speed change rate and low-pass filtering is adopted to ensure the rapid regulation of the wind turbine under low wind speed conditions and stable regulation under high wind speed conditions.

Numerical Analysis and Parameter Optimization of J-Shaped Blade on Offshore Vertical Axis Wind Turbine

In this study, the performance of offshore wind turbines at low tip speed ratio (TSR) is studied using computational fluid dynamics (CFD), and the performance of offshore wind turbines at low tip speed ratio (TSR) is improved by revising the blade structure. First, the parameters of vertical axis offshore wind turbine are designed based on the compactness iteration, a CFD simulation model is established, and the turbulence model is selected through simulation analysis to verify the independence of grid and time step. Compared with previous experimental results, it is shown that the two-dimensional simulation only considers the plane turbulence effect, and the simulation turbulence effect performs more obviously at a high tip ratio, while the three-dimensional simulation turbulence effect has well-fitting performance at high tip ratio. Second, a J-shaped blade with optimized lower surface is proposed. The study showed that the optimized J-shaped blade significantly improved its upwind torque and wind energy capture rate. Finally, the performance of the optimized J-blade offshore wind turbine is analyzed.

Autonomous Fuzzy Controller Design for the Utilization of Hybrid PV-Wind Energy Resources in Demand Side Management Environment

This work describes an optimum utilization of hybrid photovoltaic (PV)—wind energy for residential buildings on its occurrence with a newly proposed autonomous fuzzy controller (AuFuCo). In this regard, a virtual model of a vertical axis wind turbine (VAWT) and PV system (each rated at 2 kW) are constructed in a MATLAB Simulink environment. An autonomous fuzzy inference system is applied to model primary units of the controller such as load forecasting (LF), grid power selection (GPS) switch, renewable energy management system (REMS), and fuzzy load switch (FLS). The residential load consumption pattern (4 kW of connected load) is allowed to consume energy from the grid and hybrid resources located at the demand side and classified as base, priority, short-term, and schedulable loads. The simulation results identify that the proposed controller manages the demand side management (DSM) techniques for peak load shifting and valley filling effectively with renewable sources. Also, energy costs and savings for the home environment are evaluated using the proposed controller. Further, the energy conservation technique is studied by increasing renewable conversion efficiency (18% to 23% for PV and 35% to 45% for the VAWT model), which reduces the spending of 0.5% in energy cost and a 1.25% reduction in grid demand for 24-time units/day of the simulation study. Additionally, the proposed controller is adapted for computing energy cost (considering the same load pattern) for future demand, and it is exposed that the PV-wind energy cost reduced to 6.9% but 30.6% increase of coal energy cost due to its rise in the Indian energy market by 2030.

Performance Analysis of a H-Darrieus Wind Turbine for a Series of 4-Digit NACA Airfoils

The purpose of this paper is to estimate the H-Darrieus wind turbine aerodynamic performance, aerodynamic blade loads, and velocity profiles downstream behind the rotor. The wind turbine model is based on the rotor designed by McDonnell Aircraft Company. The model proposed here consists of three fixed straight blades; in the future, this model is planned to be developed with controlled blades. The study was conducted using the unsteady Reynolds averaged Navier–Stokes (URANS) approach with the k-ω shear stress transport (SST) turbulence model. The numerical two-dimensional model was verified using two other independent aerodynamic approaches: a vortex model and the extended version of the computational fluid dynamics (CFD) code FLOWer. All utilized numerical codes gave similar result of the instantaneous aerodynamic blade loads. In addition, steady-state calculations for the applied airfoils were also made using the same numerical model as for the vertical axis wind turbine (VAWT) to obtain lift and drag coefficients. The obtained values of lift and drag force coefficients, for a Reynolds number of 2.9 million, agree with the predictions of the experiment and XFOIL over a wide range of angle of attack. A maximum rotor power coefficient of 0.5 is obtained, which makes this impeller attractive from the point of view of further research. Research has shown that, if this rotor were to work with fixed blades, it is recommended to use the NACA 1418 airfoil instead of the original NACA 0018.

An Offshore Floating Wind–Solar–Aquaculture System: Concept Design and Extreme Response in Survival Conditions

This study presents a new concept design combining multiple megawatt (MW) vertical-axis wind turbines (VAWTs) and a solar array with a floating steel fish-farming cage. This combined wind–solar–aquaculture (WSA) system is intended to utilize the ocean space and water resources more effectively and more economically, while greatly shortening the payback period of investment in offshore power generation. The details of this WSA design are described, showing that a square-shaped fishing cage serves as a floating foundation for the 7600 m2 solar array and four multi MW VAWTs. The WAMIT program based on potential-flow theory is employed to obtain the WSA’s motion response amplitude operators (RAOs) in sinusoidal waves of varying periods. The motion RAOs indicated that the proposed concept possesses better hydrodynamic seakeeping performances than its OC3Hywind spar and OC4DeepCwind semi-submersible counterparts. A potential site located in the northwest South China Sea is selected to deploy the WSA. Its feasibility is then examined in terms of the hydrodynamic motions and structural dynamic response driven by wind, waves, and current. Fully coupled time-domain simulations are carried out for 50-year survival conditions. The whole structure exhibits outstanding performance for its small motions in random wind and seas. Moreover, under these survival conditions, the top accelerations and tower base stresses of the VAWTs and mooring line tensions readily meet the design requirements. Technically, the WSA has strong competitiveness and wide prospects in the offshore industry for both power exploitation and marine aquaculture in intermediate and deep waters.

Review on the Evolution of Darrieus Vertical Axis Wind Turbine: Large Wind Turbines

The objective of the current review is to present the development of a large vertical axis wind turbine (VAWT) since its naissance to its current applications. The turbines are critically reviewed in terms of performance, blade configuration, tower design, and mode of failure. The early VAWTs mostly failed due to metal fatigue since the composites were not developed. Revisiting those configurations could yield insight into the future development of VAWT. The challenges faced by horizontal axis wind turbine (HAWT), especially in the megawatt capacity, renewed interest in large scale VAWT. VAWT provides a solution for some of the immediate challenges faced by HAWT in the offshore environment in terms of reliability, maintenance, and cost. The current rate of research and development on VAWT could lead to potential and economical alternatives for HAWT. The current summary on VAWT is envisioned to be an information hub about the growth of the Darrieus turbine from the kW capacity to megawatt scale.

Wind Turbines from the Swedish Wind Energy Program and the Subsequent Commercialization Attempts – A Historical Review

This paper summarizes wind turbines of Swedish origin, 50 kW and above. Both the large governmental-funded prototypes from the early 1980s and following attempts to build commercial turbines are covered. After the 1973 oil crisis, a development program for wind turbine technology was initiated in Sweden, culminating in the early 1980s with the 2 and 3-MW machines at Maglarp and Näsudden. However, government interest declined, and Sweden soon lost its position as one of the leading countries regarding wind turbine development. Nevertheless, several attempts to build commercial wind turbines in Sweden were made in the following decades. Most attempts have, like the earlier prototypes, used a two-bladed rotor, which has become synonymous with the Swedish wind turbine development line. The current ongoing Swedish endeavors primarily focus on the niche-concept of vertical axis wind turbines (VAWTs), which is a demonstration of how far from the broad commercial market of Sweden has moved. Thus far, none of the Swedish attempts have been commercially successful, and unlike countries like Denmark or Germany, Sweden currently has no large wind turbine producer. Suggested reasons include early government interventions focusing on two-bladed prototypes and political disinterest, with wind power grants cut in half by 1985, and the domestic industry not being favored in government policies for deploying wind power.