Wind-Wave Misalignment Effects on Floating Wind Turbines: Motions and Tower Load Effects

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Erin E. Bachynski ◽  
Marit I. Kvittem ◽  
Chenyu Luan ◽  
Torgeir Moan
Keyword(s):  
Fatigue Damage ◽  
Wind Turbines ◽  
Dynamic Responses ◽  
Wave Direction ◽  
Short Term ◽  
Operational Conditions ◽  
First Order ◽  
Wind Speeds ◽  
Load Effects ◽  
Low Wind Speeds

The dynamic responses of a spar, tension leg platform (TLP), and two semisubmersible floating wind turbines (FWTs) in selected misaligned wind and wave conditions are investigated using numerical simulation with an aero-hydro-servo-elastic computational tool. For a range of representative operational conditions, the platform motions and short-term fatigue damage in the tower base and tower top are examined. Although some misalignment conditions result in increased motions both parallel and perpendicular to the wave direction, aligned wind and waves cause the largest short-term tower base fatigue damage for the studied platforms and conditions. Several factors which lead to larger fatigue damage for certain platforms in particular conditions are identified, such as tower resonance due to the 3p blade passing frequency in low wind speeds; surge and pitch motions, particularly in the wave frequency range; and the variations in first-order hydrodynamic loads due to wave direction. A semisubmersible platform with large displacement suffers the least damage at the base of the tower.

Short-Term Fatigue Analysis of Semi-Submersible Wind Turbine Tower

2011 ◽  
Author(s):  
Marit I. Kvittem ◽  
Torgeir Moan ◽  
Zhen Gao ◽  
Chenyu Luan
Keyword(s):  
Wind Turbine ◽  
Fatigue Damage ◽  
Time Domain ◽  
Narrow Band ◽  
Response Spectra ◽  
Spectral Density Function ◽  
Mean Value ◽  
Short Term ◽  
Wind Speeds ◽  
Low Wind Speeds

Coupled time domain analyses of a semi-submersible wind turbine are performed with the intention to study motions affecting fatigue damage at the base of the tower. The software applied is SIMO/RIFLEX with the extension TDHmill, which gives the wind thrust force and gyro moment on the wind turbine as point loads in the tower top. Short term environmental conditions are chosen from a joint wind and wave distribution for a site in the Northern North Sea. Variance spectra, mean value, standard deviation, kurtosis, skewness and Vanmarcke’s bandwidth parameter are calculated for stresses at the base of the tower. Damage is calculated for each short term condition by two methods; rainflow counting and narrow band approximation. The accuracy of narrow band approximation estimates for fatigue are examined for the structure in question. Time domain simulations are carried out for different sea states and fatigue damage is calculated for each case. Simulations show that turbulent wind dominates the response at low wind speeds and the response spectral density function tends to be very wide-banded. For wave dominated response, spectra have lower bandwidth, and narrow banded approximation for fatigue damage gives estimates 20–50% above rainflow counted damage.

On Short-Term Fatigue Analysis for Wind Turbine Tower of Two Semi-Submersible Wind Turbines Including Effect of Startup and Shutdown Processes

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Chenyu Luan ◽  
Torgeir Moan
Keyword(s):  
Fatigue Damage ◽  
Wind Turbines ◽  
Environmental Conditions ◽  
Limit State ◽  
Offshore Wind ◽  
Short Term ◽  
Design Standards ◽  
Transient Load ◽  
Operational Conditions ◽  
Rule Approach

Abstract Fatigue limit state design check for offshore wind turbines is based on SN curves and the Palmgren–Miner rule approach and focuses normally on stationary processes for which startup and/or shutdown operations induced transient load processes are normally not accounted for. However, large databases of real-time measurements show that the shutdown and startup operations may appear in any operational conditions and the frequency of such operations could be considerable. Although design standards require fatigue design checks for the transient load processes induced by startup and shutdown operations, relevant publications addressing this issue are very limited in particular for floating wind turbines. This paper focuses on analyzing the importance of startup and shutdown induced transient load processes on fatigue damage in the tower of two MW-level horizontal axis semi-submersible wind turbines. The analysis is carried on by comparing short-term fatigue damage in several environmental conditions with and without the startup and shutdown induced transient load processes. It is found that, in many environmental conditions, startup and/or shutdown operations may make an increase in short-term fatigue damage by 10% to 100%, while in some situations, the fatigue damage may be increased by up to 200%. The importance of the transient load processes on long-term fatigue damage is related to the occurrence frequency of startup and shutdown events. Publicly available data indicate that the average time between two consecutive shutdown events might be less than 39 h. However, more data and analysis are needed regarding these issues.

scholarly journals Pengaruh diameter dan jumlah sudu turbin angin savonius tipe L terhadap unjuk kerja yang dihasilkan

2020 ◽  
Vol 1 (2) ◽  
pp. 61-67
Author(s):  
Mohammad Rizqi Saputra ◽  
Nur Kholis ◽  
Mohammad Munib Rosadi
Keyword(s):  
Energy Source ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Mechanical Energy ◽  
Simulation Method ◽  
Wind Speeds ◽  
Turbine Efficiency ◽  
Analysis Technique ◽  
Low Wind Speeds ◽  
Wind Source

Abstract Wind is a renewable mechanical energy source that can be used as an energy source because the energy from the wind can be used to drive wind turbines. Savonius wind turbine type L is a tool to convert wind energy into electricity with a simple construction and can work with low wind speeds. The purpose of this study was to determine the effect of differences in diameter and number of blades on the power produced. The method used is a simulation method with an artificial wind source. With a wind speed of 8 m/s. The data analysis technique used is 2-way ANOVA using the SPSS application. Variations used are 20 cm and 40 cm in diameter and the number of blades 2 and 4 . The result is a wind turbine with a variation of 40 cm and 4 blades capable of producing the best output which produces 350.98 RPM voltage of 11.64 volts current of 0.144 amperes and power of 1,676 watts. As for BHP, torque, and turbine efficiency with a variation of 40 cm and 4 blades capable of producing the best output where the generated BHP is 3.352 watts, torque 0.091 N / m efficiency 2.17. For the results of calculations with SPSS wind turbines with a diameter variation of 40 cm and 4 blades, the biggest power is 1,744 watts and for BHP produces 3.3520 watts and the efficiency reaches 2.17%. Keyword : Diameter, number of blade, Performance Abstrak Angin adalah sumber energi mekanik yang bisa diperbaharui sehingga dapat dimanfaatkan sebagai sumber energi karena dapat digunakan untuk menggerakkan turbin angin. Turbin angin savonius tipe L merupakan alat untuk mengubah energi angin menjadi listrik dengan konstruksi yang sederhana dan dapat bekerja dengan kecepatan angin yang rendah. Tujuan penelitian ini untuk mengetahui pengaruh perbedaan diameter dan jumlah sudu terhadap unjuk kerja yang dihasilkan. Metode yang digunakan adalah metode simulasi dengan sumber angin buatan. Dengan kecepatan angin 8 m/s. Teknik analisis data yang digunakan adalah ANOVA 2 arah dengan menggunakan aplikasi SPSS. Variasi yang digunakan adalah diameter 20 cm dan 40 cm serta jumlah sudu 2 dan 4. Hasilnya turbin angin dengan variasi 40 cm dan 4 sudu mampu menghasilkan output terbaik yang dimana menghasilkan RPM 350,98 tegangan 11,64 volt arus 0,144 ampere dan daya 1,676 watt. Sedangkan untuk BHP, torsi, dan efisensi turbin dengan variasi 40 cm dan 4 sudu mampu menghasilkan output yang terbaik dimana BHP yang dihasilkan adalah 3,352 watt, torsi 0,091 N/m efisisensi 2,17. Untuk hasil perhitungan dengan SPSS turbin angin dengan variasi diameter 40 cm dan 4 sudu menghasilkan daya terbesar yakni 1,744 watt dan untuk BHP menghasilkan 3,3520 watt dan efisiensinya mencapai 2,17 % untuk torsi tertinggi dicapai turbin variasi 40 cm 2 sudu dengan torsi 0,116.   Kata kunci : diameter, jumlah sudu, unjuk kerja

Effect of Slotted Angle on Savonius Wind Turbine Performance

2021 ◽  
Vol 104 ◽  
pp. 83-88
Author(s):  
Rahmat Wahyudi ◽  
Diniar Mungil Kurniawati ◽  
Alfian Djafar
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Electrical Energy ◽  
Speed Ratio ◽  
Angle Variation ◽  
Wind Speeds ◽  
Turbine Performance ◽  
Savonius Wind Turbine ◽  
Low Wind Speeds

The potential of wind energy is very abundant but its utilization is still low. The effort to utilize wind energy is to utilize wind energy into electrical energy using wind turbines. Savonius wind turbines have a very simple shape and construction, are inexpensive, and can be used at low wind speeds. This research aims to determine the effect of the slot angle on the slotted blades configuration on the performance produced by Savonius wind turbines. Slot angle variations used are 5o ,10o , and 15o with slotted blades 30% at wind speeds of 2,23 m/s to 4,7 m/s using wind tunnel. The result showed that a small slot angle variation of 5o produced better wind turbine performance compared to a standard blade at low wind speeds and a low tip speed ratio.

Performance Studies on a Wind Turbine Blade Section for Low Wind Speeds With a Gurney Flap

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
M. Rafiuddin Ahmed ◽  
Epeli Nabolaniwaqa
Keyword(s):  
Wind Turbines ◽  
Lift Coefficient ◽  
Flow Characteristics ◽  
Trailing Edge ◽  
Wind Speeds ◽  
Gurney Flap ◽  
Trailing Edge Flaps ◽  
Blade Section ◽  
Low Wind Speeds ◽  
Lift And Drag

The flow characteristics and the lift and drag behavior of a thick trailing-edged airfoil that was provided with fixed trailing-edge flaps (Gurney flaps) of 1–5% height right at the back of the airfoil were studied both experimentally and numerically at different low Reynolds numbers (Re) and angles of attack for possible applications in wind turbines suitable for the wind speeds of 4–6 m/s. The flap considerably improves the suction on the upper surface of the airfoil resulting in a higher lift coefficient. The drag coefficient also increased; however, the increase was less compared with the increase in the lift coefficient, resulting in a higher lift-to-drag ratio in the angles of attack of interest. The results show that trailing-edge flaps can improve the performance of blades designed for low wind speeds and can be directly applied to small wind turbines that are increasingly being used in remote places or in smaller countries.

scholarly journals Potential of Shrouded Micro Wind Turbine

2017 ◽  
Vol 7 (2 (S)) ◽  
pp. 340
Author(s):  
Kishor Sontakke ◽  
Samir Deshmukh ◽  
Sandip Patil
Keyword(s):  
Renewable Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Renewable Energy Sources ◽  
Turbine Blades ◽  
Weather Conditions ◽  
Power Coefficient ◽  
Solar Panels ◽  
Wind Speeds ◽  
Low Wind Speeds

The growing demand for electrical energy for industrial and domestic use, coupled with the limited amount of available fossil fuel reserves and its negative effects on the environment, have made it necessary to seek alternative and renewable energy sources. The use of renewable energy is promoted worldwide to be less dependent on conventional fuels and nuclear energy. Therefore research in the field is motivated to increase efficiency of renewable energy systems. This study aimed to study potential of micro wind turbine and velocity profile through shroud for low wind speeds. Although there is a greater inclination to use solar panels because of the local weather conditions, there are some practical implications that have place the use of solar panels in certain areas to an end. The biggest problem is panel stealing. Also, in some parts of the country the weather is more appropriate to apply wind turbines. Thus, this study paying attention on the design of a new concept to improve wind turbines to be appropriate for the low wind speeds in India. The concept involves the implementation of a concentrator and diffuser to a wind turbine, to increase the power coefficient. Although the wind turbine was not tested for starting speeds, the realization of the shroud should contribute to improved starting of the wind turbine at lower wind speeds. The configuration were not manufactured, but simulated with the use of a program to obtain the power production of the wind turbine over a range of wind speeds. These values were compared to measured results of an open wind turbine developed. The most important topic at hand when dealing with a shrouded wind turbine is to find out if the overall diameter or the blade diameter of the turbine should be the point of reference. As the wind turbine is situated in a shroud that has a larger diameter than the turbine blades, some researchers believe that the overall diameter should be used to calculate the efficiency. The benefits of shrouded wind turbines are discussed.

scholarly journals Time Series Analysis and Forecasting for Wind Speeds Using Support Vector Regression Coupled with Artificial Intelligent Algorithms

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Ping Jiang ◽  
Shanshan Qin ◽  
Jie Wu ◽  
Beibei Sun
Keyword(s):  
Wind Speed ◽  
Support Vector Regression ◽  
Wind Turbines ◽  
Large Scale ◽  
Wind Farm ◽  
Hybrid Models ◽  
Parameter Determination ◽  
Support Vector ◽  
Short Term ◽  
Wind Speeds

Wind speed/power has received increasing attention around the earth due to its renewable nature as well as environmental friendliness. With the global installed wind power capacity rapidly increasing, wind industry is growing into a large-scale business. Reliable short-term wind speed forecasts play a practical and crucial role in wind energy conversion systems, such as the dynamic control of wind turbines and power system scheduling. In this paper, an intelligent hybrid model for short-term wind speed prediction is examined; the model is based on cross correlation (CC) analysis and a support vector regression (SVR) model that is coupled with brainstorm optimization (BSO) and cuckoo search (CS) algorithms, which are successfully utilized for parameter determination. The proposed hybrid models were used to forecast short-term wind speeds collected from four wind turbines located on a wind farm in China. The forecasting results demonstrate that the intelligent hybrid models outperform single models for short-term wind speed forecasting, which mainly results from the superiority of BSO and CS for parameter optimization.

scholarly journals Dynamic Aeroelastic Response of Stall-Controlled Wind Turbine Rotors in Turbulent Wind Conditions

2021 ◽  
Vol 11 (15) ◽  
pp. 6886
Author(s):  
Sara Jalal ◽  
Fernando Ponta ◽  
Apurva Baruah ◽  
Anurag Rajan
Keyword(s):  
Wind Turbines ◽  
Economies Of Scale ◽  
Control Strategies ◽  
Oscillatory System ◽  
Oscillatory Behavior ◽  
Reduced Order ◽  
Operational Conditions ◽  
Wind Speeds ◽  
Wide Range ◽  
Generating Capacity

With the current global trend of the wind turbines to be commissioned, the next generation of state-of-the-art turbines will have a generating capacity of 20 MW with rotor diameters of 250 m or larger. This systematic increase in rotor size is prompted by economies-of-scale factors, thereby resulting in a continuously decreasing cost per kWh generated. However, such large rotors have larger masses associated with them and necessitate studies in order to better understand their dynamics. The present work regarding the aeroelastic behavior of stall-controlled rotors involves the study of the frequency content and time evolution of their oscillatory behavior. A wide range of experiments were conducted to assess the effects of rapid variations on the rotor’s operational conditions. Various gust conditions were tested at different wind speeds, which are represented by pulses of different intensities, occurring suddenly in an otherwise constant wind regime. This allowed us to observe the pure aero-elasto-inertial dynamics of the rotor’s response. A reduced-order characterization of the rotor’s dynamics as an oscillatory system was obtained on the basis of energy-transfer principles. This is of fundamental interest for researchers and engineers working on developing optimized control strategies for wind turbines. It allows for the critical elements of the rotor’s dynamic behavior to be described as a reduced-order model that can be solved in real time, an essential requirement for determining predictive control actions.

Analytical and experimental study of the integral aerodynamic characteristics of low-speed wind turbines

2014 ◽  
Vol 118 (1209) ◽  
pp. 1229-1244 ◽  
Author(s):  
M. Valiev ◽  
R. Stepanov ◽  
V. Pakhov ◽  
M. Salakhov ◽  
V. Zherekhov ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Power Efficiency ◽  
Wind Farm ◽  
Aerodynamic Characteristics ◽  
Optimal Conditions ◽  
Low Speed ◽  
Wind Speeds ◽  
Horizontal Axis Wind Turbines ◽  
Low Wind Speeds ◽  
Theoretical Results

Abstract This paper proposes a new wind turbine concept suitable for low-speed winds. The design is studied using a combination of wind-tunnel experimentation and aerodynamic theory. After processing the experimental results, and after comparison with theory, the optimal conditions for the operation of the turbine are identified. Experimental and theoretical results suggest that the design offers a realistic alternative to conventional horizontal axis wind turbines. In addition, the proposed turbine has good power efficiency at low wind speeds, and is suitable for deployment in areas not yet favoured by wind farm developers.

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