Showing papers on "Blade pitch published in 2015"
TL;DR: In this article, a comparison between ANSYS Workbench and Gambit meshing tools for the numerical modeling is performed to summarize a final numerical sequence for the Darrieus rotor performance.
143 citations
TL;DR: In this paper, a comparative dynamic analysis between full-scale measurements from the floating wind turbine Hywind Demo and corresponding numerical simulations is presented, with the estimated wave elevation time series as input, together measured and further refined statistical parameters of the wind field.
Abstract: A comparative dynamic analysis between full-scale measurements from the floating wind turbine Hywind Demo and corresponding numerical simulations is presented. A description of the main characteristics of the Hywind Demo structure, control system and important measurements are given.
A method for estimation of the incident wave elevation on Hywind Demo is outlined. Comparative dynamic simulations are carried out with the estimated wave elevation time series as input, together measured and further refined statistical parameters of the wind field.
Roll, pitch and yaw motions, tower bending moments, mooring line tensions, power production, rotor speed and blade pitch angle are compared for one case below and one case above the rated wind speed. Overall, good agreement is seen between the measured and simulated responses, and it is believed that the considered analysis tool is well suited for confirming the design of a future optimized floating wind turbine based on the Hywind concept. Copyright © 2014 John Wiley & Sons, Ltd.
94 citations
TL;DR: In this paper, a cooperative wind farm control approach is proposed to improve the power production of a wind farm by using sequential convex programming (SCP) to determine the optimum coordinated control actions for the wind turbines.
83 citations
TL;DR: In this paper, a novel pitch angle control system is proposed to smooth output power and drive-train torque fluctuations for wind turbine, which is characterized by an outer open control loop for enhancing the direct pitching motion and an intrinsic hydro-mechanical position control loop offering the benefit of sensorless pitch control.
58 citations
TL;DR: In this article, a simple and cost-effective vertical axis turbine with flexible foils was designed based on inspiration from hydrodynamic thrust characteristics of aquatic creatures for self-starting in a controlled river environment in Norway.
55 citations
TL;DR: An adaptive sliding mode pump displacement controller and a back-stepping stroke piston controller are designed for the proposed pitch system such that the resulting pitch angle tracks its desired value regardless of external disturbances and uncertainties.
Abstract: A variable-displacement pump controlled pitch system is proposed to mitigate generator power and flap-wise load fluctuations for wind turbines The pitch system mainly consists of a variable-displacement hydraulic pump, a fixed-displacement hydraulic motor and a gear set The hydraulic motor can be accurately regulated by controlling the pump displacement and fluid flows to change the pitch angle through the gear set The detailed mathematical representation and dynamic characteristics of the proposed pitch system are thoroughly analyzed An adaptive sliding mode pump displacement controller and a back-stepping stroke piston controller are designed for the proposed pitch system such that the resulting pitch angle tracks its desired value regardless of external disturbances and uncertainties The effectiveness and control efficiency of the proposed pitch system and controllers have been verified by using realistic dataset of a 750 kW research wind turbine
50 citations
TL;DR: A new electro-hydraulic pitch system is proposed to smooth the output power and drive-train torque fluctuations for wind turbine by employing a servo-valve-controlled hydraulic motor to enhance pitch control performances.
Abstract: A new electro-hydraulic pitch system is proposed to smooth the output power and drive-train torque fluctuations for wind turbine. This new pitch system employs a servo-valve-controlled hydraulic motor to enhance pitch control performances. This pitch system is represented by a state-space model with parametric uncertainties and nonlinearities. An adaptive back-stepping pitch angle controller is synthesised based on this state-space model to accurately achieve the desired pitch angle control regardless of such uncertainties and nonlinearities. This pitch angle controller includes a back-stepping procedure and an adaption law to deal with such uncertainties and nonlinearities and hence to improve the final pitch control performances. The proposed pitch system and the designed pitch angle controller have been validated for achievable and efficient power and torque regulation performances by comparative experimental results under various operating conditions.
44 citations
TL;DR: Subspace predictive repetitive control (RC) is used, which combines online system identification with the continuous implementation of RC to form a fully adaptive control law, which demonstrates the ability to adjust to changes in system dynamics while maintaining a high degree of load alleviation.
Abstract: An increasing number of wind turbines implement individual blade pitch control (IPC) to reduce turbine dynamic loading, and thereby, to reduce the capital and operational costs associated with energy production. The aim of this paper is to demonstrate IPC on a wind turbine prototype, in a model-free data-driven manner and with reduced pitch activity. For this, subspace predictive repetitive control (RC) is used, which combines online system identification with the continuous implementation of RC to form a fully adaptive control law. The controller is tested on a scaled two-bladed wind turbine with active pitchable blades, placed in an open-jet wind tunnel. Substantial load reductions to an extent of 68% are observed, and strict control over actuator signal frequency content is achieved. The control law also demonstrates the ability to adjust to changes in system dynamics while maintaining a high degree of load alleviation.
43 citations
TL;DR: In this paper, the pitch modeling in an advanced BEM code has been exploited to investigate different pitch control strategies for small Darrieus wind turbines, and the prospects of a pitch preset based on both the maximum power and the maximum energy extraction have been evaluated and compared to those connected to a progressive pitch variation with the turbine revolution speed.
43 citations
42 citations
TL;DR: A novel model of large-size tilt-rotor aircraft, which can operate as a helicopter as well as being capable of transition to fixed-wing flight is presented, which includes a switched logic controller based on the finite-time convergent observer to drive the aircraft to implement the mode transition with invariant flying height.
TL;DR: In this article, a 200kW horizontal axis wind turbine (HAWT) blade is designed using an efficient iterative algorithm based on the blade element momentum theory (BEM) on aerodynamic of wind turbines.
TL;DR: In this article, a 2D CFD simulation implementation of a cross-flow tidal turbine, the blades of which have their pitch modified during revolution, is presented, where the pitch motion is obtained through mesh deformation, and the main rotation is implemented through sliding boundaries, with general grid interface model.
TL;DR: In this article, the optimal blade chord and twist angle distributions along the blade span were obtained with a unique aerodynamic mathematical model, and the airfoil profile analysis was integrated in this approach.
TL;DR: In this paper, a flexible rotor is proposed for wind turbine design, in which the blade is purposefully built of a flexible material which can passively adapt its geometry according to local wind conditions.
TL;DR: In this paper, a multi-objective numerical optimization method coupled with the response surface method (RSM) with the genetic algorithm (GA) was employed to obtain desirable blade profiles.
TL;DR: In this article, a proportional integral (PI) control algorithm was proposed to adjust pitch angle of doubly fed induction generator (DFIG)-based wind turbine integrated with two-area-interconnected power system.
Abstract: The impact of wind power with higher size of penetration becomes significant for frequency control problem due to its inconsistent nature and lack of frequency support from the wind turbine units. The frequency can be managed using enhanced control of inertia and droop characteristics. However, at very low and high speeds, the adjustment of pitch angle of wind turbine is necessary so that the aerodynamic power produced remains within the designed limits. This paper discloses the design of proportional integral (PI) control algorithm to adjust pitch angle of doubly fed induction generator (DFIG)-based wind turbine (WT) integrated with two-area-interconnected power system. Here, a heuristic gravitational search algorithm (GSA) is employed to optimize the gains of PI controllers used for pitch angle adjustment and governor speed control of wind turbine, frequency regulation, and tie-line power flow control. The influence of optimal gains by GSA is compared with genetic algorithm (GA) and ant colony o...
01 Jul 2015
TL;DR: For the flow conditions and turbine considered in the case study, wake-redirection control is shown to have a larger potential to improve wind plant energy production than axial-inductionbased control, and causes for the difference in potential are wake expansion and meandering.
Abstract: In recent research, cooperative wind turbine control strategies have been proposed to optimize overall performance of wind plants by taking into account the aerodynamic interaction effects that the wind turbines have on each other through their wakes Wind plant control strategies have different ways of using the control degrees of freedom (DOFs) of the turbine Conventional control DOFs of a wind turbine are the pitch angles of the blades, the generator torque, and the yaw angle of the rotor In most wind plant control approaches in literature, the generator torque and/or blade pitch control DOF is used to affect the wake velocity deficit (referred to as axial-induction-based control) In recent studies, an alternative control method was used, in which the direction of the wake is changed using the yaw DOF such that the overlap of the wake with downstream rotors is avoided or reduced (wake redirection control) In this paper, we present a high-fidelity, computational fluid dynamics simulation case study, in which the potential of both control methods is compared, in terms of their effect on power production of a two-turbine setup For the flow conditions and turbine considered in the case study, wake-redirection control is shown to have a larger potential to improve wind plant energy production than axial-inductionbased control An additional analysis shows that causes for the difference in potential are wake expansion and meandering
TL;DR: In this article, an RANS solver is applied to predict the vapor volume fraction and the pressure in propeller wake for ship propeller E779A with different skew angle.
TL;DR: In this article, a small wind turbine blade was designed and optimized in order to absorb energy with its greatest efficiency, and the main objective of this paper is to optimized blade number and selection of tip speed ratio corresponding to the solidity.
Abstract: A small wind turbine blade was designed and optimized in this research paper. The blade plays an important role, because it is the most important part of the energy absorption system. Consequently, the blade has to be designed carefully to enable to absorb energy with its greatest efficiency. The main objective of this paper is to optimized blade number and selection of tip speed ratio corresponding to the solidity. The power performance of small horizontal axis wind turbines was simulated in detail using blade element momentum methods (BEM). In this paper for wind blade design various factors such as tip loss, hub loss, drag coefficient, and wake were considered. The design process includes the selection of the wind turbine type and the determination of the blade airfoil, twist angle distribution along the radius, and chord length distribution along the radius. A parametric study that will determine if the optimized values of blade twist angle and chord length create the most efficient blade geometry. Th...
TL;DR: In this article, a power summation hybrid transmission is proposed to convert the variable speed of a wind turbine rotor shaft into the constant speed required at a generator shaft for a whole range of wind speeds, thereby eliminating the need for a frequency converter.
TL;DR: In this article, the authors explored heliogyrobot attitude control moment authority with varying sun angles and combinations of pitch profiles, providing critical insight for future development of heliogro attitude control schemes.
Abstract: Heliogyros generate attitude control moments by pitching their sail membrane blades collectively or cyclically, similar to a helicopter. Past work has focused on simple blade pitch profiles with the heliogyro normal to the sun; however, most solar sail missions will require sun angles of at least 35 deg. Furthermore, combination pitch profiles (e.g., cyclic plus collective) are needed for attitude control during all mission segments. The control moments for such situations vary in an unintuitive, nonlinear fashion. This paper explores heliogyro control moment authority with varying sun angles and combinations of pitch profiles, providing critical insight for future development of heliogyro attitude control schemes. Three tactics for generating control moments using various profile combinations are introduced for three-axis attitude control during a variety of practical mission scenarios. These tactics indicate that the heliogyro can generate control moments from any orientation, including edge-on to the s...
TL;DR: In this article, the adaptive neuro fuzzy inference system (ANFIS) was used for variable selection in order to detect the predominant variables affecting the converted wind energy and then it was used to determine how four parameters, blade pitch angle, rotor speed, wind speed and rotor radius, affect the wind turbine power coefficient.
TL;DR: In this paper, a folding actuation mechanism with servo motor and worm-gear reducer was designed for wind turbine rotor control and a servo system with double feedback loops for blade fold angle control was proposed.
TL;DR: In this article, the authors investigated the dynamic responses of land-based and spar-type floating wind turbines (FWTs) during shutdown and simulated the shutdown procedures by pitching one, two, or three blades, and by varying the pitch rate.
Abstract: The shutdown of wind turbines may induce excessive loads on the structures and is an important factor to consider in their design. For pitch-regulated turbines, shutdown calls for blade pitching, and one- or two-blade shutdown may occur during pitch actuator failure. Through coupled analysis, this study investigated the dynamic responses of land-based and spar-type floating wind turbines (FWTs) during shutdown. We simulated the shutdown procedures by pitching one, two, or three blades, and by varying the pitch rate. The nonpitching blades have a fixed pitch angle during the process. Three generator torque conditions were considered: (1) grid loss, (2) mechanical braking, and (3) grid connection. The extreme response values and short-term and annual fatigue damages to the structural components were compared against these values under normal operation and parked conditions. Three-blade shutdown is recommended for both turbines. One- or two-blade shutdown with grid loss may result in a significant rotor overspeed and imbalanced loads acting on the rotor plane. Therefore, unfavorable structural responses are observed. Grid connection or mechanical braking alleviates the situation. The land-based turbine is more sensitive to the pitch rate when considering the tower bottom bending moment, but the blade moments and mooring line loads of the spar-type turbine are affected more.
TL;DR: In this paper, a series of experiments were conducted in a wind tunnel under different installation conditions to investigate the influence of blade pitch angle and axial distance on the performance of the counter-rotating type horizontal-axis tidal turbine (HATT).
TL;DR: In this paper, an innovative pitch regulated blade model with folding outer blade section to control power output was made, which was tested in a low speed wind tunnel to validate the blade effectiveness and found that when the outer blade was folded, decrease of both blade energy conversion efficiency and wind energy contained in the airflow that passes through the rotor leads to power output reduction.
TL;DR: In this paper, a procedure for deriving the Euler-Lagrange equations for both unconstrained and constrained propeller blade-twist optimization is presented, which can be used to optimize other geometric parameters.
Abstract: Propeller optimization by means of calculus of variations is addressed in this paper. A procedure for deriving the Euler–Lagrange equations for both unconstrained and constrained propeller blade-twist optimization is presented. This same procedure can be followed to optimize other geometric parameters, but blade twist is considered here to investigate the feasibility of a variable-twist propeller blade. Results from unconstrained twist optimization show that, regardless of the operating condition (takeoff, climb, or cruise), the maximum efficiency occurs at significantly lower power coefficients than what a propeller will be required to absorb. Constrained optimization supports this observation by showing that, for each operating condition, a power constraint lowers the propeller efficiency. Twist distributions obtained from constrained optimization for each of the three operating conditions differ significantly from one another, but it is shown that the effect on performance is insignificant. This leads ...
DOI•
11 Aug 2015
TL;DR: In this paper, different conventional strategies of pitch angle control are described and validated through simulation results under Matlab\Simulink, and the mathematical model of the system should be known well.
Abstract: . Pitch control is a practical technique for power regulation above the rated wind speed it is considered as the most efficient and popular power control method. As conventional pitch control usually use PI controller, the mathematical model of the system should be known well. This paper deals with the operation and the control of the direct driven permanent magnet synchronous generator (PMSG). Different conventional strategies of pitch angle control are described and validated through simulation results under Matlab\Simulink.
TL;DR: In this article, a new control algorithm for a MW class spar-type floating offshore wind turbine has been developed to improve its performance and to reduce its mechanical load, and the new blade pitch control having two PI control loops applied for different wind speed regions were designed.
Abstract: A new control algorithm for a MW class spar-type floating offshore wind turbine has been developed to improve its performance and to reduce its mechanical load. The new blade pitch control having two PI control loops applied for different wind speed regions were designed. The bandwidth of the controller at near above-rated wind speed region was made lower to keep the vibration mode of the floating platform from being driven, and the bandwidth of the controller at far above-rated wind speed region was made higher to improve the wind turbine performance. Also, a feedback control loop using the angular acceleration information of the nacelle in the fore-aft direction was designed additionally to reduce the tower vibration. To perform modeling and simulation, a commercial multidynamics simulation program widely used for wind turbine design and certification, DNV-GL Bladed was used. The DNV-GL Bladed simulation results for the proposed new control algorithm showed that the output performance is improved and the tower load is reduced in various wind speeds above the rated wind speed.