Wind Energy Utilization Coefficient Research Articles

Adding Yaw System to Improve Wind Energy Utilization of Offshore Wind Turbines

In wind power generation, the wind energy loss caused by yaw and other factors is as high as 50%, which directly leads to the difficulty of greatly improving The efficiency of wind power generating in producing electricity. The development of yaw control system restricts the progress of wind energy utilization, The purpose of this study is to investigate the application and influence of automatic steering of offshore wind turbines in practice. This paper proposes that the automatic yaw system of offshore wind turbine can improve the efficiency of wind power generation. The outcomes of the experiment demonstrate that the wind resources can be fully utilized and the power generation efficiency of the offshore fan can be improved by enabling the offshore fan to automatically turn according to the wind direction. The research has a certain value for the development of new energy power generation technology. In this paper, the method of Simulink simulation experiment is used to demonstrate that the yaw system can improve the wind energy utilization coefficient of offshore fan.

Sand-Laden Wind Erosion Pair Experimental Analysis of Aerodynamic Performance of the Wind Turbine Blades

In the Inner Mongolia region, sand and dust storms are prevalent throughout the year, with sand erosion having a particularly significant impact on the performance of wind turbine blades. To enhance the performance stability of wind turbines and reduce operation and maintenance costs, this study delves into the specific impact of sand-laden wind erosion on the aerodynamic performance of scaled-down wooden wind turbine blades. The experiment conducts vehicle-mounted tests on scaled models of 1.5 MW wind turbine blades that have been eroded by wind-sand flows from different zones, analyzing the changes in aerodynamic performance of wind turbines caused by the erosion. The results indicate that with an increase in the angle of installation, both the overall power output and the wind energy utilization coefficient of the wind turbines show a declining trend. The power outputs of both the partially eroded group and the fully eroded group are unable to reach the rated power level of 100 W. Compared to the uneroded group, the leading-edge eroded group demonstrated higher power output and wind energy utilization coefficients across most wind speed ranges. This finding verifies the possibility that the drag-reducing effect caused by pits from leading-edge erosion has a positive impact on the aerodynamic performance of the blades. It also provides a new research perspective and strong evidence for the study of erosion effects on wind turbine blades and the optimization of their aerodynamic performance.

A Magnus Wind Turbine Mathematical Model

Wind power units using the Magnus effect are an alternative to conventional blade units in regions having a too low or a high wind potential. A feature of their design is the use of rotating cylinders for producing torque on the wind wheel shaft. The aim of the study was to develop a mathematical model of such unit. Three models of the wind energy utilization coefficient were considered: analytical, regression and correlation. The models were subjected to an analysis, based on which conclusions about their applicability limits were drawn, and their main advantages and disadvantages were highlighted. An alternative simulation aerodynamic model was synthesized using the computational aerodynamics method. The developed model was verified by comparing the unit power output estimated by the simulation model with experimental data obtained on a real unit in the course of field tests. The study results have shown that the developed model based on computational aerodynamics features high accuracy and can be used to simulate a wind power unit based on the Magnus effect under variable wind conditions. In the future, the presented model can be used in the development of algorithms for detecting the maximum power point for this type of wind power units.

Distribution Characteristics of Wind Speed Relative Volatility and Its Influence on Output Power

The stochastic fluctuations of wind speed and wind power curve modeling are complex tasks due to fluctuations in the difference between actual and theoretical power output, leading to a reduction in the accuracy of wind-power curve models. To address this issue, this paper proposes a normal distribution-modeling method based on relative volatility, which extracts the wind-speed variation patterns from the onsite SCADA (Supervisory Control And Data Acquisition) data, analyzes the correlation between wind-speed relative volatility and power relative volatility, and establishes a wind-power volatility-curve model to provide a basis for evaluating the efficiency of wind turbines. First, the definitions of relative volatility and probability vectors are provided, and a probability vector volatility-assessment function is designed to calculate the volatility-assessment index of the probability vector. Then, the relative volatility and probability vectors of wind speed are modeled, and features extracted from the onsite SCADA data, and characteristic parameters such as mean, standard deviation, and confidence interval of wind-speed relative volatility are statistically analyzed, as well as the wide-window coefficient, volatility-assessment index, attribute features (volatility center and volatility boundary), normal distribution features (mean and standard deviation) of the probability vectors of wind-speed relative volatility with different periods. The visualization descriptions of six typical probability vector distributions show that there is a correlation between the volatility assessment index of the probability vector based on relative volatility and the standard deviation of its distribution. Finally, the correlation between wind-speed relative volatility and power relative volatility is analyzed: in the maximum wind-energy tracking area, the derivative of power is linearly related to the derivative of wind speed, while in the constant power area, the derivative of the wind-energy utilization coefficient is linearly related to the derivative of wind speed. The conclusions obtained in this paper will provide a method reference for data processing to mine the parameter variation patterns and interrelationships of wind farm SCADA data and provide a basis for evaluating the power generation efficiency of wind turbines.

Investigation of the influence of the direction of the incoming flow relative to the plane of the three-cylinder rotor on the aerodynamic coefficients

Experiments have been carried out to study the influence of the direction of the incoming flow relative to the rotor plane on the values of the drag coefficient of a multi-blade rotor layout with power elements in the form of rotating cylinders of variable cross-section. It is shown that the drag force of the multipath depends on the Reynolds number, and practically remains constant in the range of Reynolds numbers (16-50)· 104 .According to the results of a series of experimental data, the dependences of the thrust coefficient of the multipath rotor on the Reynolds number and the installation angle of the airflow were also calculated and constructed. It is established that the coefficient of thrust of the rotor decreases with an increase in the Reynolds number. Keywords: rotor, Reynolds number, drag force coefficient, thrust force coefficient, WEUC (wind energy utilization coefficient).

Construction of Power Supply Stability Control Model for Wind Connected Power Grid

There are many problems in the power supply stability control of wind power generation system, such as large fluctuations, poor control effect and so on. Therefore, a new stability control model of wind power grid connected is designed. Determine the DC grid connection mode when the wind farm is connected, convert the DC power into AC power through the converter station, and transmit it to the final AC system to realize the grid connection of wind power and power grid; According to the determined wind power access mode, calculate the mechanical operation power, mechanical torque and wind energy utilization coefficient collected by the wind turbine, complete the best collection of wind energy, and determine the shafting according to the mass block model of the wind turbine and generator, so as to realize the research on the mathematical model of wind power generation. By analyzing the power flow direction of the stator and rotor of the wind turbine generator set, the unstable state of the power supply voltage of the wind turbine generator set after grid connection is determined. The PV curve method is used to calculate the steady-state voltage stability of grid connected wind turbines, and a power supply stability control model based on the voltage stability of grid connected wind turbines is established. The nonlinear objective function method is used to optimize the critical point of power supply stability, calculate the maximum load and maximum power of the system, establish the static power supply and transient power supply stability model after wind power grid connection, and realize the power supply stability control research of grid connected wind power through the analysis of power supply characteristics. The experimental results show that the model is closer to the stability of the actual power supply in the test of improving the stability of the power supply, ensuring the quality of power supply, while the test results of the other two methods have large fluctuations. In the analysis of the change of power supply after grid connection, the experimental results obtained by the model are very close to the actual data values. Therefore, this method can effectively improve the performance of power system.

Influence of airfoil trailing edge on blade design and machining of small wind turbine

In the design of small wind turbine, narrow structure is often produced at the trailing edge of airfoil, which brings great difficulties to production and processing. In this paper, the airfoil sd7080 is modified by removing part of the airfoil trailing edge to meet the processing technology. Through the calculation and analysis of the Q blade software, part of the airfoil trailing edge is removed, and the airfoil and wind-wheel aerodynamic characteristics are changed. Results: Under the same angle of attack, after removing part of the airfoil trailing edge, The lift coefficient CL and drag coefficient Cd of the airfoil are reduced, α<8.6°, the lift-to-drag ratio CL/Cd decreases, α>8.6°, the lift-to-drag ratio Cl/Cd slightly increases; After removing the trailing edge of some airfoils, the wind energy utilization coefficient CP, torque and thrust of the wind turbine are slightly reduced, and the aerodynamic performance meets the use requirements. Finally, this paper introduces the blade modeling method, and processes the blade through 3D printing technology. The research provides reference significance for the initial design and processing of small wind turbine blades.

Wind turbine power prediction based on wind energy utilization coefficient and multivariate polynomial regression

The power curve can reflect the overall generation performance of wind turbines. To avoid the difficulty in input feature selection in power curve modeling, based on power extraction of air streams, the blade tip speed ratio and pitch angle are taken as the input variables of wind energy utilization coefficient modeling. First, by analyzing the characteristic curve of a wind turbine, its working state is divided into three phases: constant power, constant speed, and maximum power point tracking phases. Then, aiming at the limitations of neural network in training time, hyperparameter selection, and model interpretation, a multivariate polynomial segmented power prediction method is proposed. Based on the supervisory control and data acquisition (SCADA) data of a 2 MW wind turbine, the expressions of the wind energy utilization coefficient in three phases are given. In the constant power phase and constant speed phase, the wind energy utilization coefficient is quadratic and quintic polynomial about the blade tip speed ratio and pitch angle, respectively. In the maximum power point tracking phase, the wind energy utilization coefficient is a cubic polynomial of the blade tip speed ratio. The results show that, in the four methods (multivariate polynomial regression and neural network power curve modeling with and without segmentation), the segmented polynomial regression method can not only improve the interpretation ability of the model, but also has high accuracy, and the mean absolute percentage error is 6.29%.

Applied Systems Theory: Wind Turbine Output Power Prediction based on Wind Energy Utilization Coefficient

The output power of a wind turbine is the most critical variable reflecting the operating status of the turbine. To improve the interpretability of the prediction model, a segmented output power method based on wind energy utilization coefficient is established. First, the wind energy conversion system of the wind turbine is given, and the SCADA data of a wind turbine is visually analyzed. Then it is proposed to separate the data into three groups according to different operating regions of wind turbines: the Maximum Power Point Tracking region, the rotator speed control region, and the power control region. In the Maximum Power Point Tracking region, wind energy utilization coefficient is found by a fitted cubic polynomial of the tip speed ratio. In the rotator speed control region, a modeling method for determining wind energy utilization coefficient through dynamic labels is designed. In the power control region, the output power is kept at the rated value. Finally, the 3 models are connected so that time-series data can be handled. The SCADA data of a 2.1MW wind turbine is used to verify the above models. The performance of these models is given in the form of Root Mean Square Error, indicating that the output power predicted by this method has good accuracy.The segmented output power model based on wind energy utilization coefficient can simulate the operation process of wind turbines, and has good accuracy and interpretability.

Analysis of Senegal Type Vertical Axis Wind Turbines Arrangement in Wind Farm

Background: In a wind farm, the wind speed of the downstream wind turbine will be lower than the wind speed of the upstream wind turbine due to the influence of the wake. Therefore, the wake of wind turbines is one of the uncertain factors predicting the annual power generation of the wind farms. The study on the wake can effectively improve the efficiency of power generation. The arrangement of vertical axis wind turbines in wind farms is rarely studied. Therefore, it is important to study the vertical layout of wind turbines under the influence of wakes to obtain the best layout and unit spacing. Objective: The objective of this study is to obtain the optimal layout and unit distance of wind turbines in Senegal wind farms by studying the arrangement of Senegal vertical axis wind turbines in wind farms. Methods: Based on the ANSYS CFX flow field calculation module, the fluid dynamics model of the Senegal fan was established and the flow field simulation analysis was carried out. Based on the Jensen wake model and its improved model, three layout methods for the wind farm wind turbines were proposed: two units were arranged in series, two units were arranged in parallel, and three units were staggered. Through the simulation model, the wind energy utilization coefficient and wind speed of the wind turbine in the wind farm were obtained. Results: The optimal separation distance between the units was analyzed from four different angles: wind energy utilization coefficient, torque analysis, downstream tail flow and wind speed cloud contour. Finally, based on the optimal arrangement and unit distance, a triangular staggered wind farm composed of 10 units was established, and the integrated flow field characteristics of the whole wind farm were simulated and analyzed. The integrated flow field wake characteristics of the wind farm were obtained. Conclusion: In all the three arrangements, the optimum distance between the units must be three times the diameter of the wind turbine. This arrangement ensures that most of the units are unaffected by the wake, the area affected by the low-velocity wake of the wind farm is small, and the area affected by the high-speed wake is large.

Расчет аэродинамических характеристик ветроэнергетической установки с лопастями в виде вращающихся цилиндров

The results of studies on determining the speed of a wind power plant and calculating the wind energy utilization coefficient of a rotating cylinder constant cross-section with a smooth surface are presented. With the help of experimental and theoretical methods, studies of the main aerodynamic characteristics the efficiency of a wind power plant with blades in the form of rotating cylinders were carried out. The changes in the aerodynamic parameters of the flow were 2 m/s and higher. The results showed that the value of the wind energy utilization coefficient decreases with an increase in the speed of the incoming flow. It is experimentally established that the value of the speed a wind power plant decreases with an increase in the Reynolds number.

Design and Performance Analysis of Distributed Equal Angle Spiral Vertical Axis Wind Turbine

Background: The wind turbine is divided into a horizontal axis and a vertical axis depending on the relative positions of the rotating shaft and the ground. The advantage of the choke wind turbine is that the starting torque is large and the starting performance is good. The disadvantage is that the rotation resistance is large, the rotation speed is low, the asymmetric flow occurs when the wind wheel rotates, the lateral thrust is generated, and the wind energy utilization rate is lowered. How to improve the wind energy utilization rate of the resistance wind turbine is an important issue to be solved by the wind power technology. Objective: The nautilus isometric spiral wind turbines studied in this paper have been introduced and analyzed in detail, preparing for the further flow analysis and layout of wind turbines, improving the wind energy utilization rate of wind turbines, introducing patents of other structures and output characteristics of its generator set. Methods: Combined with the flow field analysis of ANSYS CFX software, the numerical simulation of the new wind turbine was carried out, and the aerodynamic performance of the new vertical axis wind turbine was analyzed. The mathematical model and control model of the generator were established by the maximum power control method, and the accuracy of the simulation results was verified by the measured data. Results: The basic parameters of the new wind turbine tip speed ratio, torque coefficient and wind energy utilization coefficient are analyzed. Changes in wind speed, pressure and eddy viscosity were investigated. Three-dimensional distribution results of wake parameters such as wind speed and pressure are obtained. By simulating the natural wind speed, the speed and output current of the generator during normal operation are obtained. Conclusion: By analyzing the wind performance and power generation characteristics of the new wind turbine, the feasibility of the new wind turbine is determined, which provides reference and reference for the optimal design and development of the wind turbine structure.

Research on Effect of Icing Degree on Performance of NACA4412 Airfoil Wind Turbine

In order to study the effect of icing on the wind turbine blade tip speed ratio and wind energy utilization coefficient under working conditions, it is important to better understand the growth characteristics of wind turbine blade icing under natural conditions. In this paper, the icing test of the NACA4412 airfoil wind turbine was carried out using the natural low temperature wind turbine icing test system. An evaluation model of icing degree was established, and the influence of wind speed and icing degree on the performance parameters of wind turbines was compared and analyzed. It is shown that icing is mainly concentrated on the leading edge of the blade and the windward side. The icing on the leeward surface is concentrated near the leading edge of the blade. The amount of icing varies significantly along the direction of blade expansion, with the least amount of ice accumulation at 0.2R, followed by 0.6R, and most at 0.95R. At the beginning of the experiment, the icy thickness at the 0.2R, 0.6R and 0.95R locations increased at a rate of 12.03%, 8.87% and 6.00% respectively, and then the growth rate gradually decreased and stabilized. At the same wind speed, the blade tip speed ratio and wind energy utilization coefficient are inversely related to the change trend of the icing degree. When the blade icing degree is 0.82%, 1.49% and 2.73%, the maximum tip speed ratio is reduced by 7.1%, 14.1% and 21.2% and the maximum wind energy utilization coefficient is reduced by 36.3%, 51.2% and 61.6% respectively.

Reinforcement-Based Robust Variable Pitch Control of Wind Turbines

Due to the influence of wind speed disturbance, there are some uncertain phenomena in the parameters of the nonlinear wind turbine model with time in an actual working environment. In order to mitigate the side effects of uncertainties in speed models of wind turbines, researchers have designed a variety of controllers in recent years. However, traditional control methods require more knowledge of dynamics. Therefore, based on reinforcement learning and system state data, a robust wind turbine controller that adopts adaptive dynamic programming (ADP) is proposed. The ADP algorithm is a combination of Temporal-Difference (TD) algorithm and actor-critic structure, which can guarantee the rotor speed is stable around the rated value to indirectly adjust the wind energy utilization coefficient by changing the pitch angle in the area of high wind speed and achieve online learning in real-time. In addition, the variation of the pitch angle command of the proposed controller is relatively gradual, which can reduce the energy consumption of the variable pitch actuator, and extend the service life of the equipment. Finally, the wind speed model is simulated by combined wind speed based on Weibull distribution, the comprehensive simulation results show that the proposed controller has better control effect than some existing ones.

Optimal control of pitch angle of large wind turbine based on speed differential

In order to improve the power output of wind turbine at low wind speed, this paper studies the aerodynamic performance of wind turbine blades at different installation angles. It is found that the optimal pitch angle of wind turbine can be switched between different installation angles when wind speed changes by introducing wind turbine speed differential feedback signal in PI controller of variable pitch, so as to track the optimal wind energy utilization coefficient The purpose of improving wind turbine power output. In order to verify the reliability of the analysis results, bladed is used to simulate the model of a 1.5MW unit with pitch differential control signal. At the same time, the research results are applied to the actual operation of the unit. The results show that the power curve of the wind turbine unit at low wind speed can be improved and the annual power generation can be increased by 1.24%.

Design and Analysis of Horizontal Axial Flow Motor Shroud

The wind turbine diffuser can increase the wind energy utilization coefficient of the wind turbine, and the addition of the shroud to the horizontal axis wind turbine also plays a role of accelerating the flow of the condensate. First, the structure of the shroud was designed and then modeled in gambit. The fluent software was used to establish the mathematical model for simulation. The length of the shroud and the opening angle of the shroud are analyzed to determine the best shape of the shroud. Then compared the efficiency with or without the shroud, through the simulation and the experiment of the water tank, it is confirmed that the horizontal axis of the shroud can improve the hydrodynamic performance.

Analysis and Simulation of Wind Turbine Optimal Control Considering wind Turbulence Characteristics

A maximum power point tracking (MPPT) algorithm of wind turbines considering wind turbulence characteristics is presented in this paper. The turbulence characteristics of natural wind are analyzed, and the natural wind speed model is established. A MPPT algorithm based on extremum-seeking control (ESC) is proposed, which considers the turbulence characteristics containing in wind speed. The goal of the MPPT algorithm is to keep the wind turbines running at the maximum wind energy utilization coefficient point stably. The algorithm is modeled and analyzed, and the simulation results show that the MPPT algorithm is correct and effective.

Based on the Research of Wind Turbine Vibration Performance and Aerodynamic Performance

Wind turbines is one of the most important components of the wind turbine, design for wind turbines with good wind turbines is the basis of high wind energy utilization coefficient and large economic benefits. Using the theory of Wilson pneumatic designed 100 W horizontal axis wind turbine, in the process of design and design parameters on the vibration performance correction. Finally on rotor vibration modal experiment and pneumatic external characteristic experiment, the experimental results show that the design of the wind turbine at low wind speed can meet the design of the wind energy utilization coefficient, and the wind machine to avoid the resonance region speed at run time, extend the life of the rotor, so as to reduce the design cost.

Aerodynamic Performance Evaluation with a New Method for Darrieus Wind Turbine

The operation condition for darrieus wind turbine is usually complex in urban sites. One of characteristics is unsteady tip speed ratios during the rotor operating, which makes the widely used aerodynamic performance indicator, maximum power coefficient, not so suitable for evaluating vertical axis rotor performance. In this paper, a new method based on the power coefficient values under variable tip speed ratios was developed and the mathematical expression derived by numerical integration measure was presented. Furthermore, a novel wind turbine power performance indicator, average effective wind energy utilization coefficient, has been defined for the rotor performance assessment. A wind tunnel case of darrieus wind turbine with different blade cord length was selected for analyzing. Results demonstrate the proposed method is correct and practical.

On wind turbine blade design optimization

A wind turbine with a horizontal rotation axis is considered in the stationary airflow. A problem of choosing the law of change of the setting angle of the cross section of the wind turbine blade and the value of the angular speed so that the wind energy utilization coefficient is maximal is discussed. Maximization of the respective functional is considered as a variational problem with a priori unknown parameter. Once it is solved numerically or analytically, the optimal value of this parameter is determined, with the sought variables given by rather simple formulas. The results are analyzed on a qualitative level. In particular, the setting angle is found to change monotonically along the blade, which is confirmed by practical wind turbine design. Examples of using the proposed approach to wind turbine blade design are considered.