Utilization of wind energy is a promising way to generate power,and wind turbine blades play a key role in collecting the wind energy effectively.This paper attempts to measure the deformation parameter of wind turbin...Utilization of wind energy is a promising way to generate power,and wind turbine blades play a key role in collecting the wind energy effectively.This paper attempts to measure the deformation parameter of wind turbine blades in mechanics experiments using a videometric method. In view that the blades experience small buckling deformation and large integral deformation simultaneously, we proposed a parallel network measurement(PNM) method including the key techniques such as camera network construction,camera calibration,distortion correction,the semi-automatic high-precision extraction of targets,coordinate systems unification,and bundle adjustment,etc. The relatively convenient construction method of the measuring system can provide an abundant measuring content,a wide measuring range and post processing.The experimental results show that the accuracy of the integral deformation measurement is higher than 0.5 mm and that of the buckling deformation measurement higher than 0.1mm.展开更多
The present work is based on the comparative study between “Blade-Element- Momentum” (BEM) analysis and “Computational-Fluid-Dynamics” (CFD) analysis of small-scale horizontal axis wind turbine blade. In this stud...The present work is based on the comparative study between “Blade-Element- Momentum” (BEM) analysis and “Computational-Fluid-Dynamics” (CFD) analysis of small-scale horizontal axis wind turbine blade. In this study, the pitch is considered as fixed and rotor speed is variable. Firstly, the aerodynamic characteristics of three different specialized airfoils were analyzed to get optimum design parameters of wind turbine blade. Then BEM was performed with the application of the open source wind turbine design and performance computation software Q-Blade v0.6. After that, CFD simulation was done by Ansys CFX software. Here, k-ω “Shear-Stress-Transport” (SST) model was conducted for three-dimensional visualization of turbine performance. However, the best coefficient of performance was observed at 6o angle of attack. At this angle of attack, in the case of BEM, the highest coefficient of performance was 0.47 whereby CFD analysis, it was 0.43. Both studies showed good performance prediction which was a positive step to accelerate the continuous revolution in wind energy sector.展开更多
The state-of-art Computational Fluid Dynamics (CFD) codes FLUENT is applied in a fine-scale simulation of the wind field over a complex terrain. Several numerical tests are performed to validate the capability of FL...The state-of-art Computational Fluid Dynamics (CFD) codes FLUENT is applied in a fine-scale simulation of the wind field over a complex terrain. Several numerical tests are performed to validate the capability of FLUENT on describing the wind field details over a complex terrain. The results of the numerical tests show that FLUENT can simulate the wind field over extremely complex terrain, which cannot be simulated by mesoscale models. The reason why FLUENT can cope with extremely complex terrain, which can not be coped with by mesoscale models, relies on some particular techniques adopted by FLUENT, such as computer-aided design (CAD) technique, unstructured grid technique and finite volume method. Compared with mesoscale models, FLUENT can describe terrain in much more accurate details and can provide wind simulation results with higher resolution and more accuracy.展开更多
The spatial distribution of wind speed varies greatly over steep complex terrain, thus the selection of an optimal site in such terrain for wind turbine construction requires great care. We have developed a numerical ...The spatial distribution of wind speed varies greatly over steep complex terrain, thus the selection of an optimal site in such terrain for wind turbine construction requires great care. We have developed a numerical model for simulating unsteady flows called RIAM-COMPACT (Research Institute for Applied Mechanics, Kyushu University, COM putational Prediction of Airflow over Complex Terrain), which is based on the LES (Large-Eddy Simulation) technique. The computational domain of RIAM-COMPACT can be varied from several meters to several kilometers, and the model is able to predict airflow over complex terrain with high accuracy. The present paper discusses the application of RIAM-COMPACT to the micro-siting of wind turbines at sites outside Japan. The results from two case studies will be presented.展开更多
A very large scale wind turbine can be made as a circular large scale stator frame;the frame,which can reach some kilometers in diameter and some hundred meters in height,contains many circular sail trains.The stator ...A very large scale wind turbine can be made as a circular large scale stator frame;the frame,which can reach some kilometers in diameter and some hundred meters in height,contains many circular sail trains.The stator frame can be made using a light-weight tubular design.Wind can almost freely blow through this frame.Train rails are fixed at the outer surface of the frame as horizontal rings.The distance between the rails of one ring can be made to be several meters.As a result,the number of the rings can be ten or more.Each rail ring supports one sail train that is moved with wind power around the frame.The energy of this movement is transformed to electric power and is transmitted to the base of the frame.This design can be realized in a very large scale,which is difficult to achieve using a traditional three-blade turbine.展开更多
This study configures a simple wind tunnel using a blower for generating wind energy, which is equivalent to natural wind, and a test system that measures properties of power. Also, the mechanical and electrical power...This study configures a simple wind tunnel using a blower for generating wind energy, which is equivalent to natural wind, and a test system that measures properties of power. Also, the mechanical and electrical power in a small-scaled wind turbine are empirically measured to analyze the relationship between the mechanical and electrical power.展开更多
With the increasing proportion of wind power integration, the volatility of wind power brings huge challenges to the safe and stable operation of the electric power system. At present, the indexes commonly used to eva...With the increasing proportion of wind power integration, the volatility of wind power brings huge challenges to the safe and stable operation of the electric power system. At present, the indexes commonly used to evaluate the volatility of wind power only consider its overall characteristics, such as the standard deviation of wind power, the average of power variables, etc., while ignoring the detailed volatility of wind power, that is, the features of the frequency distribution of power variables. However, how to accurately describe the detailed volatility of wind power is the key foundation to reduce its adverse influences. To address this, a quantitative method for evaluating the detailed volatility of wind power at multiple temporal-spatial scales is proposed. First, the volatility indexes which can evaluate the detailed fluctuation characteristics of wind power are presented, including the upper confidence limit, lower confidence limit and confidence interval of power variables under the certain confidence level. Then, the actual wind power data from a location in northern China is used to illustrate the application of the proposed indexes at multiple temporal(year–season–month–day) and spatial scales(wind turbine–wind turbines–wind farm–wind farms) using the calculation time windows of 10 min, 30 min, 1 h, and 4 h. Finally, the relationships between wind power forecasting accuracy and its corresponding detailed volatility are analyzed to further verify the effectiveness of the proposed indexes. The results show that the proposed volatility indexes can effectively characterize the detailed fluctuations of wind power at multiple temporal-spatial scales. It is anticipated that the results of this study will serve as an important reference for the reserve capacity planning and optimization dispatch in the electric power system which with a high proportion of renewable energy.展开更多
When a wind turbine is struck by lightning,its blades are usually rotating.The effect of blade rotation on a turbine's ability to trigger a lightning strike is unclear.Therefore,an arching electrode was used in a win...When a wind turbine is struck by lightning,its blades are usually rotating.The effect of blade rotation on a turbine's ability to trigger a lightning strike is unclear.Therefore,an arching electrode was used in a wind turbine lightning discharge test to investigate the difference in lightning triggering ability when blades are rotating and stationary.A negative polarity switching waveform of 250/2500 μs was applied to the arching electrode and the up-and-down method was used to calculate the 50%discharge voltage.Lightning discharge tests of a 1:30 scale wind turbine model with 2,4,and 6 m air gaps were performed and the discharge process was observed.The experimental results demonstrated that when a 2 m air gap was used,the breakdown voltage increased as the blade speed was increased,but when the gap length was 4 m or longer,the trend was reversed and the breakdown voltage decreased.The analysis revealed that the rotation of the blades changes the charge distribution in the blade-tip region,promotes upward leader development on the blade tip,and decreases the breakdown voltage.Thus,the blade rotation of a wind turbine increases its ability to trigger lightning strikes.展开更多
As the proportion of renewable energy increases, the interaction between renewable energy devices and the grid continues to enhance. Therefore, the renewable energy dynamic test in a power system has become more and m...As the proportion of renewable energy increases, the interaction between renewable energy devices and the grid continues to enhance. Therefore, the renewable energy dynamic test in a power system has become more and more important. Traditional dynamic simulation systems and digital-analog hybrid simulation systems are difficult to compromise on the economy, flexibility and accuracy. A multi-time scale test system of doubly fed induction generator based on FPGA+ CPU heterogeneous calculation is proposed in this paper. The proposed test system is based on the ADPSS simulation platform. The power circuit part of the test system is setup up using the EMT(electromagnetic transient simulation) simulation, and the control part uses the actual physical devices. In order to realize the close-loop testing for the physical devices, the power circuit must be simulated in real-time. This paper proposes a multi-time scale simulation algorithm, in which the decoupling component divides the power circuit into a large time scale system and a small time scale system in order to reduce computing effort. This paper also proposes the FPGA+CPU heterogeneous computing architecture for implementing this multitime scale simulation. In FPGA, there is a complete small time-scale EMT engine, which support the flexibly circuit modeling with any topology. Finally, the test system is connected to an DFIG controller based on Labview to verify the feasibility of the test system.展开更多
文摘Utilization of wind energy is a promising way to generate power,and wind turbine blades play a key role in collecting the wind energy effectively.This paper attempts to measure the deformation parameter of wind turbine blades in mechanics experiments using a videometric method. In view that the blades experience small buckling deformation and large integral deformation simultaneously, we proposed a parallel network measurement(PNM) method including the key techniques such as camera network construction,camera calibration,distortion correction,the semi-automatic high-precision extraction of targets,coordinate systems unification,and bundle adjustment,etc. The relatively convenient construction method of the measuring system can provide an abundant measuring content,a wide measuring range and post processing.The experimental results show that the accuracy of the integral deformation measurement is higher than 0.5 mm and that of the buckling deformation measurement higher than 0.1mm.
文摘The present work is based on the comparative study between “Blade-Element- Momentum” (BEM) analysis and “Computational-Fluid-Dynamics” (CFD) analysis of small-scale horizontal axis wind turbine blade. In this study, the pitch is considered as fixed and rotor speed is variable. Firstly, the aerodynamic characteristics of three different specialized airfoils were analyzed to get optimum design parameters of wind turbine blade. Then BEM was performed with the application of the open source wind turbine design and performance computation software Q-Blade v0.6. After that, CFD simulation was done by Ansys CFX software. Here, k-ω “Shear-Stress-Transport” (SST) model was conducted for three-dimensional visualization of turbine performance. However, the best coefficient of performance was observed at 6o angle of attack. At this angle of attack, in the case of BEM, the highest coefficient of performance was 0.47 whereby CFD analysis, it was 0.43. Both studies showed good performance prediction which was a positive step to accelerate the continuous revolution in wind energy sector.
基金supported by the National Natural Science Foundation of China(40805004, 40705039 and 90715031)the "Mini-projecton detailed survey and evaluation of wind energy resources"supported by National Climate Center of Chinese Meteoro-logical Administration (CWERA2010002)
文摘The state-of-art Computational Fluid Dynamics (CFD) codes FLUENT is applied in a fine-scale simulation of the wind field over a complex terrain. Several numerical tests are performed to validate the capability of FLUENT on describing the wind field details over a complex terrain. The results of the numerical tests show that FLUENT can simulate the wind field over extremely complex terrain, which cannot be simulated by mesoscale models. The reason why FLUENT can cope with extremely complex terrain, which can not be coped with by mesoscale models, relies on some particular techniques adopted by FLUENT, such as computer-aided design (CAD) technique, unstructured grid technique and finite volume method. Compared with mesoscale models, FLUENT can describe terrain in much more accurate details and can provide wind simulation results with higher resolution and more accuracy.
文摘The spatial distribution of wind speed varies greatly over steep complex terrain, thus the selection of an optimal site in such terrain for wind turbine construction requires great care. We have developed a numerical model for simulating unsteady flows called RIAM-COMPACT (Research Institute for Applied Mechanics, Kyushu University, COM putational Prediction of Airflow over Complex Terrain), which is based on the LES (Large-Eddy Simulation) technique. The computational domain of RIAM-COMPACT can be varied from several meters to several kilometers, and the model is able to predict airflow over complex terrain with high accuracy. The present paper discusses the application of RIAM-COMPACT to the micro-siting of wind turbines at sites outside Japan. The results from two case studies will be presented.
文摘A very large scale wind turbine can be made as a circular large scale stator frame;the frame,which can reach some kilometers in diameter and some hundred meters in height,contains many circular sail trains.The stator frame can be made using a light-weight tubular design.Wind can almost freely blow through this frame.Train rails are fixed at the outer surface of the frame as horizontal rings.The distance between the rails of one ring can be made to be several meters.As a result,the number of the rings can be ten or more.Each rail ring supports one sail train that is moved with wind power around the frame.The energy of this movement is transformed to electric power and is transmitted to the base of the frame.This design can be realized in a very large scale,which is difficult to achieve using a traditional three-blade turbine.
文摘This study configures a simple wind tunnel using a blower for generating wind energy, which is equivalent to natural wind, and a test system that measures properties of power. Also, the mechanical and electrical power in a small-scaled wind turbine are empirically measured to analyze the relationship between the mechanical and electrical power.
基金supported in part by the National Key R&D Program of China (No.2017YFE0109000)the project of China Datang Corporation Ltd
文摘With the increasing proportion of wind power integration, the volatility of wind power brings huge challenges to the safe and stable operation of the electric power system. At present, the indexes commonly used to evaluate the volatility of wind power only consider its overall characteristics, such as the standard deviation of wind power, the average of power variables, etc., while ignoring the detailed volatility of wind power, that is, the features of the frequency distribution of power variables. However, how to accurately describe the detailed volatility of wind power is the key foundation to reduce its adverse influences. To address this, a quantitative method for evaluating the detailed volatility of wind power at multiple temporal-spatial scales is proposed. First, the volatility indexes which can evaluate the detailed fluctuation characteristics of wind power are presented, including the upper confidence limit, lower confidence limit and confidence interval of power variables under the certain confidence level. Then, the actual wind power data from a location in northern China is used to illustrate the application of the proposed indexes at multiple temporal(year–season–month–day) and spatial scales(wind turbine–wind turbines–wind farm–wind farms) using the calculation time windows of 10 min, 30 min, 1 h, and 4 h. Finally, the relationships between wind power forecasting accuracy and its corresponding detailed volatility are analyzed to further verify the effectiveness of the proposed indexes. The results show that the proposed volatility indexes can effectively characterize the detailed fluctuations of wind power at multiple temporal-spatial scales. It is anticipated that the results of this study will serve as an important reference for the reserve capacity planning and optimization dispatch in the electric power system which with a high proportion of renewable energy.
基金supported by the China State Grid Corp headquarters project in 2015(SGTYHT/14JS-188)
文摘When a wind turbine is struck by lightning,its blades are usually rotating.The effect of blade rotation on a turbine's ability to trigger a lightning strike is unclear.Therefore,an arching electrode was used in a wind turbine lightning discharge test to investigate the difference in lightning triggering ability when blades are rotating and stationary.A negative polarity switching waveform of 250/2500 μs was applied to the arching electrode and the up-and-down method was used to calculate the 50%discharge voltage.Lightning discharge tests of a 1:30 scale wind turbine model with 2,4,and 6 m air gaps were performed and the discharge process was observed.The experimental results demonstrated that when a 2 m air gap was used,the breakdown voltage increased as the blade speed was increased,but when the gap length was 4 m or longer,the trend was reversed and the breakdown voltage decreased.The analysis revealed that the rotation of the blades changes the charge distribution in the blade-tip region,promotes upward leader development on the blade tip,and decreases the breakdown voltage.Thus,the blade rotation of a wind turbine increases its ability to trigger lightning strikes.
基金supported by the State Grid Science and Technology Project (Title: Technology Research On Large Scale EMT Real-time simulation customized platform, FX71-17-001)
文摘As the proportion of renewable energy increases, the interaction between renewable energy devices and the grid continues to enhance. Therefore, the renewable energy dynamic test in a power system has become more and more important. Traditional dynamic simulation systems and digital-analog hybrid simulation systems are difficult to compromise on the economy, flexibility and accuracy. A multi-time scale test system of doubly fed induction generator based on FPGA+ CPU heterogeneous calculation is proposed in this paper. The proposed test system is based on the ADPSS simulation platform. The power circuit part of the test system is setup up using the EMT(electromagnetic transient simulation) simulation, and the control part uses the actual physical devices. In order to realize the close-loop testing for the physical devices, the power circuit must be simulated in real-time. This paper proposes a multi-time scale simulation algorithm, in which the decoupling component divides the power circuit into a large time scale system and a small time scale system in order to reduce computing effort. This paper also proposes the FPGA+CPU heterogeneous computing architecture for implementing this multitime scale simulation. In FPGA, there is a complete small time-scale EMT engine, which support the flexibly circuit modeling with any topology. Finally, the test system is connected to an DFIG controller based on Labview to verify the feasibility of the test system.