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Title: Wind turbine speed control by automatic yawing

Abstract

A yaw dynamics analysis was developed for a two-bladed horizontal axis wind turbine with passive cyclic pitch variation achieved by letting the blade pair freely oscillate about a common axis with which the blades formed a small prelag angle. This type of rotor was found capable of high yaw rates without imposing vibratory hub moments and without producing noticeable flapping amplitudes. Experiments were conducted with a tail vane stabilized 7.6-m-diam wind rotor driving a three-phase alternator tuned and loaded to produce a rotor torque proportional to the square of the rotor speed. Two yaw control systems which replaced the usual blade feathering controls were investigated: an active yaw control system using a hydraulic rotor speed governor, and a passive system responding to a combination of rotor thrust and torque. During strong gusts both systems limited rotor speed quite accurately. The passive system appeared to be more promising because of its greater reliability and because of the greater ease of adapting it to larger size wind turbines.

Authors:
;
Publication Date:
Research Org.:
Washington University, St. Louis, Missouri
OSTI Identifier:
6761629
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Energy; (United States); Journal Volume: 7:3
Country of Publication:
United States
Language:
English
Subject:
17 WIND ENERGY; TURBINE BLADES; AERODYNAMICS; TILT MECHANISMS; WIND TURBINES; CONTROL SYSTEMS; AIR FLOW; ALTERNATORS; AMPLITUDES; COMPARATIVE EVALUATIONS; HYDRAULIC CONTROL DEVICES; INCIDENCE ANGLE; OSCILLATIONS; POSITIONING; RELIABILITY; ROTORS; SPEED REGULATORS; TORQUE; CONTROL EQUIPMENT; ELECTRIC GENERATORS; EQUIPMENT; FLUID FLOW; FLUID MECHANICS; GAS FLOW; MACHINERY; MECHANICS; TURBINES; TURBOMACHINERY 170602* -- Wind Energy Engineering-- Turbine Design & Operation

Citation Formats

Hohenemser, K.H., and Swift, A.H.P.. Wind turbine speed control by automatic yawing. United States: N. p., 1983. Web. doi:10.2514/3.62656.
Hohenemser, K.H., & Swift, A.H.P.. Wind turbine speed control by automatic yawing. United States. doi:10.2514/3.62656.
Hohenemser, K.H., and Swift, A.H.P.. 1983. "Wind turbine speed control by automatic yawing". United States. doi:10.2514/3.62656.
@article{osti_6761629,
title = {Wind turbine speed control by automatic yawing},
author = {Hohenemser, K.H. and Swift, A.H.P.},
abstractNote = {A yaw dynamics analysis was developed for a two-bladed horizontal axis wind turbine with passive cyclic pitch variation achieved by letting the blade pair freely oscillate about a common axis with which the blades formed a small prelag angle. This type of rotor was found capable of high yaw rates without imposing vibratory hub moments and without producing noticeable flapping amplitudes. Experiments were conducted with a tail vane stabilized 7.6-m-diam wind rotor driving a three-phase alternator tuned and loaded to produce a rotor torque proportional to the square of the rotor speed. Two yaw control systems which replaced the usual blade feathering controls were investigated: an active yaw control system using a hydraulic rotor speed governor, and a passive system responding to a combination of rotor thrust and torque. During strong gusts both systems limited rotor speed quite accurately. The passive system appeared to be more promising because of its greater reliability and because of the greater ease of adapting it to larger size wind turbines.},
doi = {10.2514/3.62656},
journal = {J. Energy; (United States)},
number = ,
volume = 7:3,
place = {United States},
year = 1983,
month = 5
}
  • A yaw dynamics analysis was developed for a two-bladed horizontal axis wind turbine with passive cyclic pitch variation achieved by letting the blade pair freely oscillate about a common axis with which the blades formed a small prelag angle. This type of rotor was found capable of high yaw rates without imposing vibratory hub moments and without producing noticeable flapping amplitudes. Experiments were conducted with a tail vane stabilized 7.6 m diameter wind rotor driving a three phase alternator tuned and loaded to produce a rotor torque proportional to the square of the rotor speed. Two yaw control systems whichmore » replaced the usual blade feathering controls were investigated: an active yaw control system using a hydraulic rotor speed governor, and a passive system responding to a combination of rotor thrust and torque. Both systems limited during strong gusts rotor speed quite accurately. The passive system appeared to be more promising because of its greater reliability and because of the greater ease of adapting it to larger size wind turbines.« less
  • Variable rotor speed control of a fixed-pitch wind turbine is investigated on a system consisting of a wind turbine which can operate in a wide speed range, from 0 to 38 Rpm. It produces any desired output from the rated (20 kW) to no-load, providing there is wind enough. A special technique is used to determine the operating point of the wind turbine by using the measured rotor speed and power. A difficult problem with this type of wind turbine control is to determine the upper speed limit reasonably high to capture as much energy as possible but still lowmore » enough to avoid power peaks.« less
  • To optimize the power in a wind turbine the speed of the turbine should be able to vary with the wind speed. A simple control is proposed that will allow an induction motor to run a turbine at its maximum power coefficient. The control uses a standard V/Hz converter and controls the frequency to achieve the desired power at a given turbine speed.
  • The accurate modeling of wind turbines is an extremely challenging problem due to the tremendous complexity of the machines and the turbulent and unpredictable conditions in which they operate. Adaptive control techniques are well suited to nonlinear applications, such as wind turbines, which are difficult to accurately model and which have effects from poorly known operating environments. In this paper, we extended the direct model reference adaptive control (DMRAC) approach to track a reference point and to reject persistent disturbances. This approach was then used to design an adaptive collective pitch controller for a high-fidelity simulation of a variable-speed horizontalmore » axis wind turbine. The objective of the adaptive pitch controller was to regulate generator speed in Region 3 and to reject step disturbances. The control objective was accomplished by collectively pitching the turbine blades. The turbine simulation models the controls advanced research turbine (CART) of the National Renewable Energy Laboratory in Golden, Colorado. The CART is a utility-scale wind turbine that has a well-developed and extensively verified simulator. This novel application of adaptive control was compared in simulations with a classical proportional integrator (PI) collective pitch controller. In the simulations, the adaptive pitch controller showed improved speed regulation in Region 3 when compared with the PI pitch controller.« less