The NREL Large-Scale Turbine Inflow and Response Experiment: Preliminary Results

2002 ◽  
Author(s):  
Neil Kelley ◽  
Maureen Hand ◽  
Scott Larwood ◽  
Ed McKenna
Keyword(s):  
Wind Turbine ◽  
Large Scale ◽  
Structural Response ◽  
Technology Center ◽  
Operating Environments ◽  
Sonic Anemometers ◽  
Wide Range ◽  
Scaling Parameters ◽  
Planar Array ◽  
Turbulence Scaling

The accurate numerical dynamic simulation of new large-scale wind turbine designs operating over a wide range of inflow environments is critical because it is usually impractical to test prototypes in a variety of locations. Large turbines operate in a region of the atmospheric boundary layer that currently may not be adequately simulated by present turbulence codes. In this paper, we discuss the development and use of a 42-m (137-ft) planar array of five, high-resolution sonic anemometers upwind of a 600-kW wind turbine at the National Wind Technology Center (NWTC). The objective of this experiment is to obtain simultaneously collected turbulence information from the inflow array and the corresponding structural response of the turbine. The turbulence information will be used for comparison with that predicted by currently available codes and establish any systematic differences. These results will be used to improve the performance of the turbulence simulations. The sensitivities of key elements of the turbine aeroelastic and structural response to a range of turbulence-scaling parameters will be established for comparisons with other turbines and operating environments. In this paper, we present an overview of the experiment, and offer examples of two observed cases of inflow characteristics and turbine response collected under daytime and nighttime conditions, and compare their turbulence properties with predictions.

scholarly journals Research on Zero-Voltage Ride Through Control Strategy of Doubly Fed Wind Turbine

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2287
Author(s):  
Kaina Qin ◽  
Shanshan Wang ◽  
Zhongjian Kang
Keyword(s):  
Wind Turbine ◽  
Wind Power ◽  
Control Strategy ◽  
Large Scale ◽  
Sliding Mode ◽  
Stable Operation ◽  
Wide Range ◽  
Dc Bus ◽  
Doubly Fed ◽  
Zero Voltage

With the rapid increase in the proportion of the installed wind power capacity in the total grid capacity, the state has put forward higher and higher requirements for wind power integration into the grid, among which the most difficult requirement is the zero-voltage ride through (ZVRT) capability of the wind turbine. When the voltage drops deeply, a series of transient processes, such as serious overvoltage, overcurrent, or speed rise, will occur in the motor, which will seriously endanger the safe operation of the wind turbine itself and its control system, and cause large-scale off-grid accident of wind generator. Therefore, it is of great significance to improve the uninterrupted operation ability of the wind turbine. Doubly fed induction generator (DFIG) can achieve the best wind energy tracking control in a wide range of wind speed and has the advantage of flexible power regulation. It is widely used at present, but it is sensitive to the grid voltage. In the current study, the DFIG is taken as the research object. The transient process of the DFIG during a fault is analyzed in detail. The mechanism of the rotor overcurrent and DC bus overvoltage of the DFIG during fault is studied. Additionally, the simulation model is built in DIgSILENT. The active crowbar hardware protection circuit is put into the rotor side of the wind turbine, and the extended state observer and terminal sliding mode control are added to the grid side converter control. Through the cooperative control technology, the rotor overcurrent and DC bus overvoltage can be suppressed to realize the zero-voltage ride-through of the doubly fed wind turbine, and ensure the safe and stable operation of the wind farm. Finally, the simulation results are presented to verify the theoretical analysis and the proposed control strategy.

scholarly journals Super-large-scale flow visualization using natural snowfall for the study of utility-scale wind turbine flows

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Aliza Abraham ◽  
Jiarong Hong
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Complex Dynamic ◽  
Wide Range ◽  
Spatio Temporal ◽  
Large Scale Flow ◽  
Utility Scale ◽  
Fundamental Physical ◽  
Turbine Installation

With the rapid growth of wind turbine installation in recent decades, fundamental physical understanding of the flow around wind turbines and farms is becoming increasingly critical for further efficiency increases. However, the effort to develop this understanding is hindered by the significant challenges involved in modelling such a complex dynamic system with a wide range of relevant scales (blade boundary layer thickness at ∼ 1 mm to atmospheric scales at ∼ 1 km). Additionally, conventional methods used to measure air flow around wind turbines in the field (e.g., lidar) are limited by low spatio-temporal resolutions.

scholarly journals The Analysis of the Aerodynamic Character and Structural Response of Large-Scale Wind Turbine Blades

Energies ◽  
2013 ◽  
Vol 6 (7) ◽  
pp. 3134-3148 ◽  
Author(s):  
Xin Cai ◽  
Pan Pan ◽  
Jie Zhu ◽  
Rongrong Gu
Keyword(s):  
Wind Turbine ◽  
Large Scale ◽  
Turbine Blades ◽  
Structural Response ◽  
Wind Turbine Blades

Low-Emission, Liquid Fuel Combustion System for Conventional and Alternative Fuels Developed by the Scaling Analysis

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
Yonas Niguse ◽  
Ajay Agrawal
Keyword(s):  
Alternative Fuels ◽  
Large Scale ◽  
Small Scale ◽  
Scaling Analysis ◽  
Combustion System ◽  
Low Emission ◽  
Wide Range ◽  
Air Mixing ◽  
Scaling Parameters ◽  
Fine Spray

The objective of this study is to develop a theoretical basis for scalability considerations and design of a large-scale combustor utilizing flow blurring (FB) atomization. FB atomization is a recently discovered twin-fluid atomization concept, reported to produce fine spray of liquids with wide range of viscosities. Previously, we have developed and investigated a small-scale swirl-stabilized combustor of 7-kWth capacity. Spray measurements have shown that the FB injector's atomization capability is superior when compared to other techniques, such as air blast atomization. However, despite these favorable results, scalability of the FB injector and associated combustor design has never been explored for large capacity; for example, for gas turbine applications. In this study, a number of dimensionless scaling parameters that affect the processes of atomization, fuel–air mixing, and combustion are analyzed, and scaling criteria for the different components of the combustion system are selected. Constant velocity criterion is used to scale key geometric components of the system. Scaling of the nonlinear dimensions and complex geometries, such as swirler vanes and internal parts of the injector is undertaken through phenomenological analysis of the flow processes associated with the scaled component. A scaled-up 60-kWth capacity combustor with FB injector is developed and investigated for combustion performance using diesel and vegetable oil (VO) (soybean oil) as fuels. Results show that the scaled-up injector's performance is comparable to the smaller scale system in terms of flame quality, emission levels, and static flame stability. Visual flame images at different atomizing air-to-liquid ratio by mass (ALR) show mainly blue flames, especially for ALR > 2.8. Emission measurements show a general trend of lower CO and NOx levels at higher ALRs, replicating the performance of the small-scale combustion system. Flame liftoff height at different ALRs is similar for both scales. The scaled-up combustor with FB injector preformed robustly with uncompromised stability for the range of firing rates (FRs) above 50% of the design capacity. Experimental results corroborate with the scaling methodology developed in this research.

scholarly journals The effects of blade structural model fidelity on wind turbine load analysis and computation time

2019 ◽  
Author(s):  
Ozan Gozcu ◽  
David Robert Verelst
Keyword(s):  
Wind Turbine ◽  
Structural Model ◽  
Turbine Blades ◽  
Computational Cost ◽  
Structural Response ◽  
Computation Time ◽  
Tip Clearance ◽  
Normal Operation ◽  
Wide Range ◽  
Load Analysis

Abstract. Aero-servo-elastic analyses are required to determine the wind turbine loading for a wide range of load cases as specified in certification standards. The floating reference frame (FRF) formulation can be used to model, with sufficient accuracy, the structural response of long and flexible wind turbine blades. Increasing the number of bodies in the FRF formulation of the blade increases both the fidelity of the structural model as well as the size of the problem. However, the turbine load analysis is a coupled aero-servo-elastic analysis, and computation cost does not only depend on the size of the structural model, but also the aerodynamic solver and the iterations between the solvers. This study presents an investigation of the performance of the different fidelity levels as measured by the computational cost and the turbine response (e.g. blade loads, tip clearance, tower top accelerations). The presented analysis is based on state of the art aeroelastic simulations for normal operation in turbulent inflow load cases as defined in a design standard, and is using two 10 MW reference turbines. The results show that the turbine response quickly approaches the results of the highest fidelity model as the number of bodies increases. The increase in computational costs to account for more bodies can almost entirely be compensated by changing the type of the matrix solver from dense to sparse.

scholarly journals The effects of blade structural model fidelity on wind turbine load analysis and computation time

2020 ◽  
Vol 5 (2) ◽  
pp. 503-517 ◽  
Author(s):  
Ozan Gözcü ◽  
David R. Verelst
Keyword(s):  
Wind Turbine ◽  
Structural Model ◽  
Turbine Blades ◽  
Computational Cost ◽  
Structural Response ◽  
Computation Time ◽  
Tip Clearance ◽  
Normal Operation ◽  
Wide Range ◽  
Load Analysis

Abstract. Aero-servo-elastic analyses are required to determine the wind turbine loading for a wide range of load cases as specified in certification standards. The floating reference frame (FRF) formulation can be used to model the structural response of long and flexible wind turbine blades. Increasing the number of bodies in the FRF formulation of the blade increases both the fidelity of the structural model and the size of the problem. However, the turbine load analysis is a coupled aero-servo-elastic analysis, and computation cost not only depends on the size of the structural model, but also depends on the aerodynamic solver and the number of iterations between the solvers. This study presents an investigation of the performance of the different fidelity levels as measured by the computational cost and the turbine response (e.g., blade loads, tip clearance, tower-top accelerations). The analysis is based on aeroelastic simulations for normal operation in turbulent inflow load cases as defined in a design standard. Two 10 MW reference turbines are used. The results show that the turbine response quickly approaches the results of the highest-fidelity model as the number of bodies increases. The increase in computational costs to account for more bodies can almost entirely be compensated for by changing the type of the matrix solver from dense to sparse.

Inflow and Fatigue Response of the NWTC Advanced Research Turbine

2003 ◽  
Author(s):  
Herbert J. Sutherland ◽  
Neil D. Kelley ◽  
M. Maureen Hand
Keyword(s):  
Test List ◽  
Structural Response ◽  
Synchronous Generator ◽  
Measurement Unit ◽  
Response Data ◽  
Extreme Loads ◽  
Sonic Anemometers ◽  
Planar Array ◽  
Fatigue Loads

The Long-term Inflow and Structural Test (LIST) program is collecting long-term inflow and structural response data to characterize the spectrum of loads on wind turbines. In one of the measurement campaigns being conducted under this program, the 42-m diameter, 600-kW NWTC Advanced Research Turbine (ART) was monitored. The turbine is an upwind, two-bladed teetered-hub machine. It has full span pitch control and a synchronous generator. The inflow was monitored with a planar array of five high-resolution sonic anemometers and supporting meteorological instrumentation located 1.5 diameters upwind of the turbine. The structural response of the turbine was measured using strain gauge circuits and an inertial measurement unit (IMU). The former were used to monitor root bending moments and the low-speed shaft torque, while the latter was used to monitor the motion of the tower and the nacelle. Auxiliary gauges measured blade pitch, rotor teeter, nacelle yaw and generator power. A total of 3299 10-minute records were collected for analysis. From this set, 1044 records are used to examine the influence of various inflow parameters on fatigue loads. Long-term fatigue loads and extreme loads are also examined.

An atmospheric surface layer study: The Idealized horizontal Planar Array experiment for Quantifying Surface Heterogeneity (IPAQS)

2020 ◽  
Author(s):  
Travis Morrison ◽  
Marc Calaf ◽  
Eric Pardyjak ◽  
Marcus Hultmark ◽  
Chad Higgins ◽  
...  
Keyword(s):  
Surface Layer ◽  
Prediction Models ◽  
Weather Prediction ◽  
Surface Heterogeneity ◽  
Internal Boundary ◽  
Valuable Insight ◽  
Sonic Anemometers ◽  
Wide Range ◽  
Planar Array ◽  
Scale Turbulence

<p>Numerical weather prediction models rely heavily on boundary-layer theories, which poorly capture the interactions between the Earth’s heterogeneous surface and the internal boundary layers aloft. Further, in relation to these theories, there remains outstanding questions that still require new understanding, such as the closure of the surface energy balance, advection quantification, and surface-flux interaction. We hypothesize that under certain conditions of unstable and neutral stratification, surface thermal heterogeneities can significantly influence the flow structure and alter momentum and scalar transport. To be able to access this hypothesis, we designed the Idealized horizontal Planar Array experiment for Quantifying Surface heterogeneity (IPAQS). IPAQS took place during the summers of 2018 and 2019 at the Great Salt Lake Desert playa in western Utah at the U.S. Army Dugway Proving Ground’s Surface Layer Turbulence and Environmental Test (SLTEST) facility. The site is characterized by a long uninterrupted fetch with uniform surface roughness and large thermal and moisture heterogeneities covering a wide range of scales. Observations were made with an array of 2-m high, temporally-synchronized, fast-response sonic anemometers, and finewire thermocouples, which were deployed on a coarse grid covering an area of 800 m x 800 m with 200-m spacing. Results provide valuable insight into the spatial and temporal evolution of the flow. Fine-scale turbulence was measured using Nano-Scale Thermal Anemometry Probes (NSTAP). Meanwhile, larger-scale turbulence was captured with Doppler wind LiDARs. Presented is an overview of the experiment and initial results.</p>

scholarly journals Hybrid Pitch Angle Controller Approaches for Stable Wind Turbine Power under Variable Wind Speed

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3622 ◽  
Author(s):  
Md Rasel Sarkar ◽  
Sabariah Julai ◽  
Chong Wen Tong ◽  
Moslem Uddin ◽  
M.F. Romlie ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Output Power ◽  
Pitch Angle ◽  
Pid Controller ◽  
Large Scale ◽  
Wind Speeds ◽  
Wide Range ◽  
Fast Wind ◽  
Simple Implementation

The production of maximum wind energy requires controlling various parts of medium to large-scale wind turbines (WTs). This paper presents a robust pitch angle control system for the rated wind turbine power at a wide range of simulated wind speeds by means of a proportional–integral–derivative (PID) controller. In addition, ant colony optimization (ACO), particle swarm optimization (PSO), and classical Ziegler–Nichols (Z-N) algorithms have been used for tuning the PID controller parameters to obtain within rated stable output power of WTs from fluctuating wind speeds. The proposed system is simulated under fast wind speed variation, and its results are compared with those of the PID-ZN controller and PID-PSO to verify its effeteness. The proposed approach contains several benefits including simple implementation, as well as tolerance of turbine parameters and several nonparametric uncertainties. Robust control of the generator output power with wind-speed variations can also be considered a significant advantage of this strategy. Theoretical analyses, as well as simulation results, indicate that the proposed controller can perform better in a wide range of wind speed compared with the PID-ZN and PID-PSO controllers. The WT model and hybrid controllers (PID-ACO and PID-PSO) have been developed in MATLAB/Simulink with validated controller models. The hybrid PID-ACO controller was found to be the most suitable in comparison to the PID-PSO and conventional PID. The root mean square (RMS) error calculated between the desired power and the WT’s output power with PID-ACO is found to be 0.00036, which is the smallest result among the studied controllers.

Low Emission, Liquid Fuel Combustion System for Conventional and Alternative Fuels Developed by the Scaling Analysis

2015 ◽  
Author(s):  
Yonas G. Niguse ◽  
Ajay K. Agrawal
Keyword(s):  
Alternative Fuels ◽  
Large Scale ◽  
Small Scale ◽  
Scaling Analysis ◽  
Combustion System ◽  
Low Emission ◽  
Wide Range ◽  
Air Mixing ◽  
Scaling Parameters ◽  
Fine Spray

The objective of this study is to develop a theoretical basis for scalability considerations and design of a large scale combustor utilizing flow blurring (FB) atomization. FB atomization is a recently discovered twin-fluid atomization concept, reported to produce fine spray of liquids with wide range of viscosities. Previously, we have developed and investigated a small scale swirl-stabilized combustor of 7-kWth capacity. Spray measurements have shown that the FB injector’s atomization capability is superior when compared to other techniques, such as air blast atomization. However, despite these favorable results, scalability of the FB injector and associated combustor design has never been explored for large capacity, for example, for gas turbine applications. In this study, a number of dimensionless scaling parameters that affect the processes of atomization, fuel-air mixing, and combustion are analyzed, and scaling criteria for the different components of the combustion system are selected. Constant velocity criterion is used to scale key geometric components of the system. Scaling of the nonlinear dimensions and complex geometries, such as swirler vanes and internal parts of the injector is undertaken through phenomenological analysis of the flow processes associated with the scaled component. A scaled up 60-kWth capacity combustor with FB injector is developed and investigated for combustion performance using diesel and vegetable oil (soybean oil) as fuels. Results show that the scaled-up injector’s performance is comparable to the smaller scale system in terms of flame quality, emission levels, and static flame stability. Visual flame images at different air to liquid ratio by mass (ALR) show mainly blue flames, especially for ALR > 2.8. Emission measurements show a general trend of lower CO and NOx levels at higher ALRs, replicating the performance of the small scale combustion system. Flame liftoff height at different ALRs is similar for both scales. The scaled-up combustor with FB injector preformed robustly with uncompromised stability for the range of firing rates above 50% of the design capacity. Experimental results corroborate with the scaling methodology developed in this research.

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