The present disclosure generally relates to the field of wind-power units. In particular, the present disclosure is directed to systems for load reduction in a tower of an idled wind-power unit and methods thereof.
Wind-power units (“WPU”s), which generate electrical power from the energy in wind, continue to increase in importance as alternative, or “renewable,” energy sources. In some weather or turbine conditions the WPU must be “idled”, and in some cases fully parked, to limit the loads imposed on the WPU and ensure personnel and equipment safety at all times. For a typical horizontal axis WPU, idling usually entails pitching the blades roughly 90 degrees to a shutdown position, permitting the rotor of the WPU to rotate slowly. In some other examples, a WPU's control logic may call for an additional brake to be applied and for the WPU to be “parked”, with the brake bringing the rotor to a complete stop and essentially locking the rotor from rotating. The WPU may also include a yaw drive that permits an idled or parked rotor to be turned into the wind. Each of these actions, either separately or together, typically reduces the forces the wind exerts on the WPU, thereby reducing the risk of damage to the WPU. However in some cases while the WPU is in an idled or a parked state, off-axis winds interacting with the rotor can result in unsteady and oscillating loads applied to the rotor blades. These oscillating loads can result in dynamic loading of the WPU structure and in the supporting tower that can exceed normal loading conditions and cause equipment damage.
The present disclosure describes exemplary embodiments of methods and apparatus for sensing and responding to dynamic loading conditions that might result in damage to reduce overall loads imposed on the WPU, as well as the WPU's supporting tower and foundation system.
In one implementation, the present disclosure is directed to a system for reducing dynamic loading in a wind power unit in a parked or idled condition, the wind power unit including a turbine, a turbine axle having a longitudinal axis, and a wind power unit brake system including at least one turbine brake. The system includes a sensor adapted to be positioned with the wind power unit and configured to sense at least one parameter indicative of dynamic loading in the wind power unit and produce a dynamic loading signal representative thereof; and a logic circuit in communication with the sensor to receive the dynamic loading signal, the logic circuit being configured to generate a braking signal in response to the dynamic loading signal indicating a level of dynamic loading exceeding a selected value; wherein the brake system is configured to receive the braking signal and execute a reduced torque brake mode in response to the braking signal to reduce the dynamic loading of the wind power unit by permitting intermittent slip of the brake system.
In another implementation, the present disclosure is directed to a method of reducing dynamic loading in an idled wind power unit, the wind power unit including a turbine on a turbine axle and a brake system. The method includes sensing a parameter indicative of dynamic loading of the wind power unit; determining if the sensed parameter is at least at a selected value; and instructing the brake system, when the sensed parameter is at least at the selected value, to execute a reduced torque brake mode to reduce the dynamic loading of the tower.
In still another implementation, the present disclosure is directed to a system for reducing dynamic loading in a tower of a wind power unit. The system includes a sensor configured to detect dynamic loading in the wind power unit and generate a signal indicating the detected loading; and a logic circuit configured to receive the signal and to send a second signal to a turbine brake system in the wind power unit wherein the second signal causes the brake system to execute a reduced torque brake mode to reduce the dynamic loading of the tower.
In yet another implementation, the present disclosure is directed to a system for reducing dynamic loading in a wind power unit in a parked or idled condition, the wind power unit including a turbine, a turbine axle having a longitudinal axis, and a wind power unit brake system including at least one turbine brake. The system includes a sensor adapted to be positioned with the wind power unit and configured to sense at least one parameter indicative of dynamic loading in the wind power unit and produce a signal representative thereof; means, communicating with the sensor to receive the dynamic loading signal, for generating a braking signal in response to the level of dynamic loading exceeding a selected valve and outputting the braking signal to the braking system, wherein the braking signal includes instructions for execution of a reduced torque brake mode to reduce the dynamic loading of the wind power unit by permitting intermittent slip of the parked turbine.
In still yet another implementation, the present disclosure is directed to a system for reducing dynamic loading in a wind power unit in a parked or idled condition, the wind power unit including a turbine, and a turbine axle having a longitudinal axis. The system includes a sensor adapted to be positioned with the wind power unit and configured to sense at least one parameter indicative of dynamic loading in the wind power unit and produce a signal representative thereof, the dynamic loading including at least a component of motion perpendicular to the longitudinal axis of the turbine axle; a processor in communication with the sensor to receive the representative signal, the processor being configured and programmed to determine a level of dynamic loading indicated by the sensed parameter and compare the level to at least one selected value, the processor being further programmed to generate a braking instruction in response to the level of dynamic loading exceeding a selected valve; and a wind power unit brake system including at least one turbine brake, the system configured to receive the braking instruction from the processor, wherein the braking instruction includes a controlled braking and brake-release command for the brake, the controlled braking and brake-release command causing execution by the brake system of a reduced torque brake mode to reduce the dynamic loading of the wind power unit by permitting intermittent slip of the parked turbine.
For the purpose of illustrating the invention, the drawings show aspects of one or more embodiments of the invention. However, it should be understood that the present invention is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:
Disclosed herein are systems and methods for using controlled rotor braking of an idling or a parked WPU so as to reduce dynamic loading that can occur in a WPU tower and foundation under certain environmental conditions. Exemplary manifestations of dynamic loading include, but are not limited to, oscillation, elastic or plastic strain, a bending moment, or other physical or electrical response exhibited by a WPU tower or component that indicate a dynamic load is being experienced by the WPU. The disclosed systems and methods include sensing one or more indicia of dynamic loading within the WPU, determining if the dynamic loading warrants intervention, and then reducing the dynamic loading by modulating excitation factors. As will be appreciated by persons of ordinary skill in the art, systems in accordance with embodiments of the invention may be designed with the control logic executed in digital or analog logic circuits. In one exemplary embodiment, excitation factors may be modulated while the WPU is in a braked and parked state by performing a controlled partial release of the brake to produce a reduced torque brake mode. In such an embodiment, the braking control absorbs energy by allowing a limited, intermittent rotor slip, thereby damping the excitation factors and reducing dynamic loading.
Referring now to the drawings,
WPU 100 also includes a brake system 148, a processor 152 and a sensor 156. Braking system 148 may comprise any appropriate WPU braking system as may be selected by a person of ordinary skill in the art for use with embodiments of the invention as taught herein. Such systems generally include a brake acting on a braking surface, which may be, for example, on the rotor, shaft, a break drum or disk attached to the rotor or shaft, or other appropriate structure. Processor 152, which may comprise a programmable logic controller, may be generally conventional, with the processor additionally configured for control according to embodiments as described herein. Sensor 156 is attached to WPU 100 at a location facilitating the detection of stress, strain, movement, acceleration or other indicia of dynamic loading of WPU 100 in accordance with the particular embodiments as will be appreciated by persons of ordinary skill in the art based on the teachings herein. The location of sensor 156, shown alternatively in dashed lines on tower 104, as well as the type of the sensor, depends on the indicia of dynamic loading to be detected. In one example, if the skilled artisan chooses to detect oscillation in WPU 100 by measuring the elastic strain experienced by tower 104, then sensor 152 may be a strain gauge attached to the tower. The specific location of sensor 156 on tower 104, and even the type of sensor used, are a function of the sensitivity of the sensor, the physical (or electrical) response to be detected, the location that the physical (or electrical) response is expected to occur on the tower or WPU 100, convenience of attachment, and other factors known to those skilled in the art. The use of brake system 148, processor 152, and sensor 156 in the context of the present disclosure will be described in more detail below.
In one example, when WPU 100 is idled, damaging oscillations can occur when, for example, the rotor shaft 136 of turbine 112 is angled between 20° and 40° with respect to the wind.
As further shown in
As also illustrated by
Turning now to
At step 408, motion, force or other parameter detected by sensor 156 as indicative of oscillations are communicated to processor 152. Processor 152 determines whether the indicated oscillations are of sufficient frequency, velocity, amplitude, force, or magnitude to intervene. Part of this determination requires knowledge of the types and degrees of oscillation that are acceptable. For example, WPUs are generally expected to oscillate to some degree and tower 104 is expected to be elastically strained to some degree. This expectation arises because of the natural elasticity in tower 104 construction materials and design, combined with the fact that WPUs are routinely exposed to high winds. Based on the teachings contained herein, persons of ordinary skill in the art will be able to determine appropriate oscillation magnitude for intervention depending on the specific WPU design.
At step 412, once processor 152 determines at step 408 that the oscillations merit intervention, the processor then determines the type of control signal to send to braking system 148 based on the state of WPU 100. If WPU 100 is in an idling condition with the blades pitched to a feathered angle and hub assembly 114 free to slowly rotate, a controlled, partial brake application can be initiated at step 416a. Several methods of controlled braking are feasible to provide the reduced torque brake mode. One example of controlled braking is to apply partial brake pressure, or clamping force, with braking system 148, thereby applying a reduced braking torque to the rotating components. This reduced brake torque state will continue to restrict the movement of turbine 112, while still allowing it to slip periodically depending on wind conditions. Such an operational mode dampens the oscillations by absorbing some of the energy of the oscillations. In another example of controlled braking, a position of a brake-pad (not shown) of braking system 148 is adjusted to decrease the braking force exerted on the turbine as compared to the full force setting of the system. In a further alternative, the brake may be sequentially applied and released in a controlled manner.
However, if WPU 100 is instead in a braked condition as determined at step 412, with the turbine completely locked by full application of braking system 148, then a controlled, partial brake release can be initiated at step 416b by reducing the brake pressure, or clamping force, thereby applying a reduced braking applied torque to the turbine. As in the prior example, the reduced torque brake mode will continue to restrict the movement of turbine 112 while still allowing it to slip periodically depending on wind conditions, again dampening the oscillations by absorbing some of the energy of the oscillations. Any of the reduced torque brake modes mentioned above may be applied.
The effect of this “stick-slip” behavior in terms of reduced bending moment at the base of tower 104 is illustrated in
As mentioned above, the control logic in embodiments of the present invention may be executed in analog logic circuits as well as digital logic circuits, for example implemented in a programmable logic controller as previously described. One example of a suitable analog implementation of a logic circuit 160 is shown in
Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. It will be understood by those skilled in the art that various changes, omissions and additions may be made to that which is specifically disclosed herein without departing from the spirit and scope of the present invention.
This application claims the benefit of priority of U.S. Provisional Patent Application Ser. No. 61/421,479, filed Dec. 9, 2010, and titled “Method and System for Load Reduction in a Tower of an Idled Wind-Power Unit,” which is incorporated by reference herein in its entirety.
Number | Name | Date | Kind |
---|---|---|---|
5289041 | Holley | Feb 1994 | A |
6441507 | Deering et al. | Aug 2002 | B1 |
6888262 | Blakemore | May 2005 | B2 |
7004724 | Pierce et al. | Feb 2006 | B2 |
7075192 | Bywaters et al. | Jul 2006 | B2 |
7175389 | Moroz et al. | Feb 2007 | B2 |
7244100 | Yoshida | Jul 2007 | B2 |
7309930 | Suryanarayanan et al. | Dec 2007 | B2 |
7352075 | Willey et al. | Apr 2008 | B2 |
7418820 | Harvey et al. | Sep 2008 | B2 |
7431567 | Bevington et al. | Oct 2008 | B1 |
7488155 | Barbu et al. | Feb 2009 | B2 |
7602075 | Erdman et al. | Oct 2009 | B2 |
7617741 | Lowe-Wylde | Nov 2009 | B1 |
7763989 | Kinzie et al. | Jul 2010 | B2 |
7939961 | Bonnet | May 2011 | B1 |
8076789 | Miller | Dec 2011 | B2 |
8080891 | Schramm et al. | Dec 2011 | B2 |
8093738 | Stiesdal | Jan 2012 | B2 |
8109722 | Gamble et al. | Feb 2012 | B2 |
8178986 | Vyas et al. | May 2012 | B2 |
8183707 | Siebers et al. | May 2012 | B2 |
8212373 | Wittekind et al. | Jul 2012 | B2 |
8410625 | Stiesdal | Apr 2013 | B2 |
8649911 | Avagliano et al. | Feb 2014 | B2 |
20050169755 | Yoshida | Aug 2005 | A1 |
20060153672 | Davis | Jul 2006 | A1 |
20070166147 | Merswolke et al. | Jul 2007 | A1 |
20070170724 | Calley | Jul 2007 | A1 |
20070187954 | Struve et al. | Aug 2007 | A1 |
20090039651 | Stiesdal | Feb 2009 | A1 |
20090317250 | Gamble et al. | Dec 2009 | A1 |
20100194114 | Pechlivanoglou et al. | Aug 2010 | A1 |
20100215502 | Harrison | Aug 2010 | A1 |
20100329842 | Stiesdal | Dec 2010 | A1 |
20110178771 | Miranda | Jul 2011 | A1 |
20110187108 | Wakasa | Aug 2011 | A1 |
20110299975 | Pechlivanoglou | Dec 2011 | A1 |
20120025528 | Sipil et al. | Feb 2012 | A1 |
20120049520 | Stiesdal | Mar 2012 | A1 |
20120074712 | Bursal | Mar 2012 | A1 |
20120139248 | Bertolotti | Jun 2012 | A1 |
20120263601 | Baker et al. | Oct 2012 | A1 |
20130099497 | Bowyer et al. | Apr 2013 | A1 |
20130272877 | Andersen et al. | Oct 2013 | A1 |
20140003939 | Adams et al. | Jan 2014 | A1 |
20140037448 | Fu et al. | Feb 2014 | A1 |
Number | Date | Country |
---|---|---|
0020207 | Dec 1980 | EP |
2133563 | Dec 2008 | EP |
2306005 | Apr 2011 | EP |
2007043895 | Apr 2007 | WO |
2008049426 | May 2008 | WO |
2009068035 | Jun 2009 | WO |
2010084131 | Jul 2010 | WO |
2011157342 | Dec 2011 | WO |
Entry |
---|
J.M. Jonkman, Dynamics Modeling and Loads Analysis of an Offshore Floating Wind Turbine, National Renewable Energy Laboratory, Technical Report; NREL/TP-500-41958; Nov. 2007; Table of Contents and Chapter 6, pp. 102-122. |
“Spinner Anemometry—an Innovative Wind Measurement Concept,” by T.F. Pedersen et al.,www.metek.de/.../usonic-1-spinner.html?...Spinner%20Anemometry . . . ; pp. 1-8; 2009. |
U.S. Appl. No. 13/746,123, filed Jan. 21, 2013. |
PCT International Search Report dated Apr. 24, 2012 for related PCT/US2011/064231 entitled “Systems for Load Reduction in a Tower of an Idled Wind-Power Unit and Methods Thereof,” Garrett Bywaters, et al. |
Office Action (Non-Final) dated Apr. 18, 2014 related to U.S. Appl. No. 13/746,123, filed Jan. 21, 2013, Lynch. |
Spinner Anemometry—An Innovative Wind Measurement Concept; TF Pedersen*), N Sørensen, HA Madsen, R Møller, M Courtney, Risø National Laboratory, 8 pages, 2009. |
Number | Date | Country | |
---|---|---|---|
20120146333 A1 | Jun 2012 | US |
Number | Date | Country | |
---|---|---|---|
61421479 | Dec 2010 | US |