Showing papers on "Blade pitch published in 2017"
TL;DR: In this article, the authors investigated the variations in loads and moments on the turbine as well as the experienced angle of attack, shed vorticity and boundary layer events (leading edge and trailing edge separation, laminar-to-turbulent transition) as a function of pitch angle.
262 citations
TL;DR: In this paper, an intelligent pitch angle controller using a multilayer perceptron artificial neural network (MLP-ANN) was proposed for the Darrieus vertical axis wind turbine (H-type VAWT).
101 citations
TL;DR: In this paper, the authors investigated the aerodynamic and performance of a scale OF-VAWT in pitch motion using the computational fluid dynamics (CFD) method with the turbulence model of improved delayed detached eddy simulation (IDDES) and the overset mesh technique.
65 citations
TL;DR: In this article, the authors employed the novel advanced MOTs for enhancing the dynamic behavior of the wind power plant for the optimal tuning of the blade pitch control (BPC) system parameters.
Abstract: Wind energy (WE) as an environment-friendly resource is green, clean, and innovative solution for the globe energy dilemma For the blade pitch control (BPC) of the WE, the gain scheduling of the BPC becomes important to cope with the wind intermittency The innovative idea of this study is to employ the novel advanced MOTs for enhancing the dynamic behaviour of the wind power plant For this purpose, the genetic algorithm (GA), artificial bee colony (ABC) algorithm and grey Wolf optimiser (GWO) are used for the optimal tuning of the BPC system parameters A comprehensive comparative study is presented to verify the effectiveness of the proposed MOTs over different conventional methods such as the conventional Zeigler–Nichols, and the simplex algorithm) This comparative analysis is based on the time response specifications such as maximum overshoot, settling time and steady-state error The proportional-integral-differential (PID) controller is applied to the multivariable BPC for a wind turbine generating system connected to a large power system The simulation results show that the GWO-PID is more effective than the ABC, GA and the conventional methods Moreover,the GWO-PID controller robustness is verified in the presence of system parameter variations, an abrupt change in the mechanical torque and the wind speed variation
62 citations
TL;DR: In this article, the influence of the platform surge motion on the behaviors of the power output and rotor thrust of a typical Spar-type OFWT were investigated using Free Vortex Method (FVM).
60 citations
25 Feb 2017
TL;DR: In this paper, a numerical prediction method to determine small-scale propeller performance is presented using the commercially available computational fluid dynamics (CFD) solver, FLUENT.
Abstract: The current work presents the numerical prediction method to determine small-scale propeller performance. The study is implemented using the commercially available computational fluid dynamics (CFD) solver, FLUENT. Numerical results are compared with the available experimental data for an advanced precision composites (APC) Slow Flyer propeller blade to determine the discrepancy of the thrust coefficient, power coefficient, and efficiencies. The study utilized unstructured tetrahedron meshing throughout the analysis, with a standard k-ω turbulence model. The Multiple Reference Frame model was also used to consider the rotation of the propeller toward its local reference frame at 3008 revolutions per minute (RPM). Results show reliable thrust coefficient, power coefficient, and efficiency data for the case of low advance ratio and an advance ratio less than the negative thrust conditions.
51 citations
TL;DR: In this article, the Triple Spar floater, a hybrid between a spar buoy and a semi submersible tri-floater, is tested with active blade pitch control.
45 citations
TL;DR: In this paper, the influence of wind turbine blade pitch and generator control on the global response of a floating wind turbine is investigated, and the results from platform pitch free-decay tests as well as a simultaneous dynamic wind and irregular sea state condition are used to understand the controllers' influence on floating turbine dynamic behavior.
44 citations
TL;DR: In this paper, the impact of individual pitch and trailing edge flaps on the levelised cost of energy of wind turbine blades has been evaluated using the NREL 5MW reference turbine as an initial point.
42 citations
TL;DR: In this article, the effects of varying the blade pitch angle of the upstream turbine on its wake characteristics, as well as the combined power of the two, were investigated, and the effect of turbulence intensity of the inflow on the efficacy of this method was found.
Abstract: The reduction in power output associated with complex turbine-wake interactions in wind farms necessitates the development of effective wake mitigation strategies. One approach to this end entails the downregulation of individual turbines from its maximum power point with the objective of optimizing the overall wind farm productivity. Downregulation via blade pitch offset has been of interest as a potential strategy, though the viability of this method is still not clear, especially in regard to its sensitivity to ambient turbulence. In this study, large-eddy simulations of a two-turbine arrangement, with the second turbine in the full wake of the first, were performed. The effects of varying the blade pitch angle of the upstream turbine on its wake characteristics, as well as the combined power of the two, were investigated. Of specific interest was the effect of turbulence intensity of the inflow on the efficacy of this method. Results showed enhanced wake recovery associated with pitching to stall, as opposed to pitching to feather, which delayed wake recovery. The increased wake recovery resulted in a noticeable increase in the power of the two-turbine configuration, only in conditions characterized by low turbulence in the incoming flow. Nevertheless, the low turbulence scenarios where the use of this method is favorable, are expected in realistic wind farms, suggesting its possible application for improved power generation.
41 citations
TL;DR: In this paper, a high-fidelity simulation framework is presented to investigate wind turbine aero-servo-elastic behavior, coupling dynamic overset computational fluid dynamics (CFD) and multibody dynamics (MBD) approaches.
TL;DR: The coaxial rotor has distinct advantages in hover performance and forward flight compared to a conventional isolated rotor as discussed by the authors, and the viscous vortex particle approach based on the Lagrangian formulation.
Abstract: The coaxial rotor has distinct advantages in hover performance and forward flight compared to a conventional isolated rotor. The viscous vortex particle approach based on the Lagrangian formulation...
TL;DR: In this paper, a survey of recently emerged methods for wind turbine control is presented, focusing on blade pitch control, which is considered one of the key elements in facilitating load reduction while maintaining power capture performance.
TL;DR: In this paper, the effects of wind shear and tower shadow on power output in terms of power fluctuation and power loss to estimate the capacity and quality of the power generated by a wind turbine were investigated.
Abstract: The magnitude and stability of power output are two key indices of wind turbines. This study investigates the effects of wind shear and tower shadow on power output in terms of power fluctuation and power loss to estimate the capacity and quality of the power generated by a wind turbine. First, wind speed models, particularly the wind shear model and the tower shadow model, are described in detail. The widely accepted tower shadow model is modified in view of the cone-shaped towers of modern large-scale wind turbines. Power fluctuation and power loss due to wind shear and tower shadow are analyzed by performing theoretical calculations and case analysis within the framework of a modified version of blade element momentum theory. Results indicate that power fluctuation is mainly caused by tower shadow, whereas power loss is primarily induced by wind shear. Under steady wind conditions, power loss can be divided into wind farm loss and rotor loss. Wind farm loss is constant at 3α(3α–1)R2/(8H2). By contrast, rotor loss is strongly influenced by the wind turbine control strategies and wind speed. That is, when the wind speed is measured in a region where a variable-speed controller works, the rotor loss stabilizes around zero, but when the wind speed is measured in a region where the blade pitch controller works, the rotor loss increases as the wind speed intensifies. The results of this study can serve as a reference for accurate power estimation and strategy development to mitigate the fluctuations in aerodynamic loads and power output due to wind shear and tower shadow.
TL;DR: Wang et al. as discussed by the authors used FLUENT to calculate propeller hydrodynamic performance and exciting force in oblique flow and applied sliding grid technique to simulate the propeller rotation.
Abstract: CFD commercial software FLUENT, based on solving RANS equations, was used to calculate propeller hydrodynamic performance and exciting force. Sliding grid technique was applied to simulate the propeller rotation. Different advance coefficients and oblique inflow angles were set as different working conditions through adjusting inflow magnitude and direction. DTMB4679 propeller as the research object, hydrodynamic performance of this propeller in oblique flow was first calculated, and agreed well with test results. It verifies the accuracy of calculation method. The time-domain data of propeller exciting force under different working conditions was monitored, and then spectrum curve was obtained through fast Fourier transform. The results show that propeller load in oblique flow will aggravate, and transverse velocity component of oblique flow will cause great transverse force generated by propeller. Moreover, the smaller advance coefficient causes the greater peak of propeller fluctuating pressure. Additionally, oblique flow angle has a greater influence on unsteady bearing force than fluctuating pressure.
TL;DR: In this article, an approach for multiple-feedback control of generator power and nacelle fore-aft speed employing blade pitch and generator torque manipulations was developed for a spar-type floating offshore wind turbine-generator system.
IAC1
TL;DR: In this article, the bearing loads developed by the propellers of a twin screw model during quasi-steady conditions is extended to transient maneuvers, and the analysis shows that the overall degradation of the propeller performance may occur also at kinematic conditions weaker than those usually considered as the most critical ones (in general, tight maneuvers); therefore, these conditions should be accounted for also in early design phases.
TL;DR: In this article, the performance of a 5m diameter Darrieus vertical axis wind turbine was predicted using both a double multiple streamtube model and a two-dimensional unsteady Reynolds-averaged Navier-Stokes comp...
Abstract: The performance of a 5-m diameter Darrieus vertical axis wind turbine was predicted using both a double multiple streamtube model and a two-dimensional unsteady Reynolds-averaged Navier–Stokes comp...
TL;DR: The developed blade-pitch controller is proven to function throughout the test campaign, which also proves the reliability of the simplified simulation model for controller design.
TL;DR: In this article, an individual blade pitch control law is designed using multivariable linear parameter-varying control techniques to reduce the structural loads both on the rotating and non-rotating parts of the turbine.
Abstract: The increasing size of modern wind turbines also increases the structural loads caused by effects such as turbulence or asymmetries in the inflowing wind field. Consequently, the use of advanced control algorithms for active load reduction has become a relevant part of current wind turbine control systems. In this paper, an individual blade pitch control law is designed using multivariable linear parameter-varying control techniques. It reduces the structural loads both on the rotating and non-rotating parts of the turbine. Classical individual blade pitch control strategies rely on single-control loops with low bandwidth. The proposed approach makes it possible to use a higher bandwidth since it accounts for coupling at higher frequencies. A controller is designed for the utility-scale 2.5 MW Liberty research turbine operated by the University of Minnesota. Stability and performance are verified using the high-fidelity nonlinear simulation and baseline controllers that were directly obtained from the manufacturer. Copyright © 2017 John Wiley & Sons, Ltd.
TL;DR: Considering the estimation error of the wake model, a solution to implement the optimized pitch angle and tip speed ratio is proposed, which is to generate the optimal control curves for each individual wind turbine off-line.
Abstract: In modern wind farms, maximum power point tracking (MPPT) is widely implemented. Using the MPPT method, each individual wind turbine is controlled by its pitch angle and tip speed ratio to generate the maximum active power. In a wind farm, the upstream wind turbine may cause power loss to its downstream wind turbines due to the wake effect. According to the wake model, downstream power loss is also determined by the pitch angle and tip speed ratio of the upstream wind turbine. By optimizing the pitch angle and tip speed ratio of each wind turbine, the total active power of the wind farm can be increased. In this paper, the optimal pitch angle and tip speed ratio are selected for each wind turbine by the exhausted search. Considering the estimation error of the wake model, a solution to implement the optimized pitch angle and tip speed ratio is proposed, which is to generate the optimal control curves for each individual wind turbine off-line. In typical wind farms with regular layout, based on the detailed analysis of the influence of pitch angle and tip speed ratio on the total active power of the wind farm by the exhausted search, the optimization is simplified with the reduced computation complexity. By using the optimized control curves, the annual energy production (AEP) is increased by 1.03% compared to using the MPPT method in a case-study of a typical eighty-turbine wind farm.
TL;DR: In this article, a laser-Doppler velocimetry (LDV) system is used to measure the axial flow velocity distributions produced by the seven-cycle wake screen in the water tunnel.
TL;DR: Intelligent control methods are applied to control the blade pitch angle of doubly-fed induction generator (DFIG) WTS and adaptive neuro-fuzzy inference systems controller revealed better performance to maintain the aerodynamic power and rotor speed at the rated value.
Abstract: Blade pitch angle control, as an indispensable part of wind turbine, plays a part in getting the desired power. In this regard, several pitch angle control methods have been proposed in order to li...
TL;DR: In this paper, the effect of hydrodynamic load on the propeller blade is compared with the structural dynamics of the blade and its effect on the hydrodynamics loading.
Patent•
30 Mar 2017TL;DR: In this paper, a method of controlling a wind turbine comprising a wind direction sensor, a yawing system, and a control system for the wind turbine rotor relative to the wind is described.
Abstract: The invention relates to a method of controlling a wind turbine comprising a wind direction sensor, a yawing system, and a control system for yawing the wind turbine rotor relative to the wind. The method comprises obtaining an estimate for a wind power parameter as a function of a relative wind direction, where the wind power parameter is determined as one of a power, a torque, a blade load, or a blade pitch angle of the wind turbine. At time intervals, a data set is established comprising a wind power parameter and a wind direction parameter as measured by the wind direction sensor. Over time a group of data sets is then obtained for a number of pre-defined wind direction intervals, and a wind direction offset is determined for each interval by comparing the average wind power parameter for that interval with the estimate of the wind power parameter. The wind direction offsets of the different wind direction intervals are used to adjust the wind direction parameter, and applied in the controlling of the wind turbine. The invention further relates to a control system for a wind turbine for performing a control method as mentioned above.
02 May 2017
TL;DR: In this article, the results of torque measurements under load are presented and compared to results obtained using different calculation models, indicating the various sources of friction that should be taken into account for a reliable calculation model.
Abstract: . Pitch bearings of wind turbines are large, grease-lubricated
rolling bearings that connect the rotor blades with the rotor hub. They are
used to turn the rotor blades to control the power output and/or structural
loads of the turbine. Common actuators turning the blades are hydraulic
cylinders or electrical motor–gearbox combinations. In order to design pitch
actuator systems that are able to turn the blades reliably without imposing
an excessive power demand, it is necessary to predict the friction torque of
pitch bearings for different operating conditions. In this paper, the results
of torque measurements under load are presented and compared to results
obtained using different calculation models. The results of this comparison
indicate the various sources of friction that should be taken into account
for a reliable calculation model.
TL;DR: In this paper, the effect of extreme typhoon on the aerodynamic performance of a 5MW OC3-Hywind floating offshore wind turbine (FOWT) system has been investigated, based on the Aero-Hydro-Servo-Elastic FAST code.
TL;DR: In this paper, the use of rapid pitch control for handling short-term variations in wind conditions and load fluctuations within one cycle of rotation, with special attention to the prognosis of the aeroelastic response of the rotor.
01 May 2017
TL;DR: This paper presents a method to compute the movable range of an offshore wind turbine with a semi-submersible floating platform in still water under uniform wind field using a 5MW baseline system.
Abstract: This paper presents a method to compute the movable range of an offshore wind turbine with a semi-submersible floating platform in still water under uniform wind field. The movable range is the set of X-Y positions of the platform where equilibria can be achieved while constraints on power, generator torque and generator speed are fulfilled. Within the computed movable range, a static feedforward controller combined with generator speed feedback is designed to accomplish a specified position transfer by only passively utilizing the aerodynamic force through the manipulation of the nacelle yaw angle and the rotor blade pitch angle. Simulation results on the proposed movable range computation and platform position control using a 5MW baseline system are presented.