Blade pitch

About: Blade pitch is a research topic. Over the lifetime, 5321 publications have been published within this topic receiving 63134 citations.

Individual Blade Pitch Control for Load Reduction

Abstract: If a pitch-regulated wind turbine has individual pitch actuators for each blade, the possibility arises to send different pitch angle demands to each blade. The possibility of using this as a way of reducing loads has been suggested many times over the years, but the idea has yet to gain full commercial acceptance. There are a number of reasons why this situation may be set to change, and very significant load reductions can result. Copyright © 2002 John Wiley & Sons, Ltd.

Standard and adaptive techniques for maximizing energy capture

Abstract: 1066-033X/06/$20.00©2006IEEE W ind energy is the fastest-growing energy source in the world, with worldwide wind-generation capacity tripling in the five years leading up to 2004 [1]. Because wind turbines are large, flexible structures operating in noisy environments, they present a myriad of control problems that, if solved, could reduce the cost of wind energy. In contrast to constantspeed turbines (see “Wind Turbine Development and Types of Turbines”), variable-speed wind turbines are designed to follow wind-speed variations in low winds to maximize aerodynamic efficiency. Standard control laws [2] require that complex aerodynamic properties be well known so that the variable-speed turbine can maximize energy capture; in practice, uncertainties limit the efficient energy capture of a variable-speed turbine. The turbine used as a model for this article’s research is the Controls Advanced Research Turbine (CART) pictured in Figure 1. CART is located in Golden, Colorado, at the U.S. National Renewable Energy Laboratory’s National Wind Technology Center (see “The National Renewable Energy Laboratory and National Wind Technology Center”). A modern utility-scale wind turbine, as shown in Figure 2, has several levels of control systems. On the uppermost level, a supervisory controller monitors the turbine and wind resource to determine when the wind speed is sufficient to start up the turbine and when, due to high winds, the turbine must be shut down for safety. This type of control is the discrete if-then variety. On the middle level is turbine control, which includes generator torque control, blade pitch control, and yaw control. Generator torque control, performed using the power electronics, determines how much torque is extracted from the turbine, specifically, the high-speed shaft. The extracted torque opposes the aerodynamic torque provided by the wind and, thus, indirectly regulates the turbine speed. Depending on the pitch actuators and type of generator and power electronics, blade pitch control and generator torque control can operate quickly relative to the rotor-speed time constant. STANDARD AND ADAPTIVE TECHNIQUES FOR MAXIMIZING ENERGY CAPTURE

Output power leveling of wind turbine Generator for all operating regions by pitch angle control

Abstract: Wind energy is not constant and windmill output is proportional to the cube of wind speed, which causes the generated power of wind turbine generators (WTGs) to fluctuate. In order to reduce fluctuation, different methods are available to control the pitch angle of blades of windmill. In a previous work, we proposed the pitch angle control using minimum variance control, and output power leveling was achieved. However, it is a controlled output power for only rated wind speed region. This paper presents a control strategy based on average wind speed and standard deviation of wind speed and pitch angle control using a generalized predictive control in all operating regions for a WTG. The simulation results by using actual detailed model for wind power system show the effectiveness of the proposed method.

A tutorial on the dynamics and control of wind turbines and wind farms

Abstract: Wind energy is currently the fastest-growing energy source in the world, with a concurrent growth in demand for the expertise of engineers and researchers in the wind energy field. There are still many unsolved challenges in expanding wind power, and there are numerous problems of interest to systems and control researchers. In this paper, we first review the basic structure of wind turbines and then describe wind turbine control systems and control loops. Of great interest are the generator torque and blade pitch control systems, where significant performance improvements are achievable with more advanced systems and control research. We describe recent developments in advanced controllers for wind turbines and wind farms, and we also outline many open problems in the areas of modeling and control of wind turbines.

Reduction of Wind Turbine Noise using Optimized Airfoils and Trailing-Edge Serrations

Abstract: Acoustic field measurements were carried out on a 94-m-diam three-bladed wind turbine with one standard blade, one blade with trailing-edge serrations, and one blade with an optimized airfoil shape. A large horizontal microphone array, positioned at a distance of about one rotor diameter from the turbine, was used to locate and quantify the noise sources in the rotor plane and on the individual blades. The acoustic source maps show that for an observer at the array position, the dominant source for the baseline blade is trailing-edge noise from the blade outboard region. Because of convective amplification and directivity, practically all of this noise is produced during the downward movement of the blade, which causes the typical swishing noise during the passage of the blades. Both modified blades show a significant trailing-edge noise reduction at low frequencies, which is more prominent for the serrated blade. However, the modified blades also show tip noise at high frequencies, which is mainly radiated during the upward part of the revolution and is most important at low wind speeds due to high tip loading. Nevertheless, average overall noise reductions of 0.5 and 3.2 dB are obtained for the optimized blade and the serrated blade, respectively.