Title of Invention

METHOD FOR CONTROLLING THE ROTOR BLADES OF A WIND POWER STATION AND WIND POWER STATION COMPRISING A MEASURING SYSTEM FOR CARRYING OUT SAID METHOD

Abstract

The invention relates to a method for controlling and/or inspecting the rotor blades of a wind power station and to a wind power station for carrying out said method, wherein the state of stress or elongation of a rotor blade of the wind power station is detected by means of a fiber-optic and/or piezoelectric method and an alarm signal is triggered depending on the resulting detection signal, and/or the relative position of the rotor blade is controlled. The aim of the invention is to increase the reliability with which alarm signals are produced or the control is carried out. For this purpose, the fiber-optic and/or piezoelectric method is monitored by way of a method based on the comparison of resonance, natural oscillation, passage or reflection signal spectra.

Full Text

FORM 2 THE PATENT ACT 197 0 (39 Of 1970) & The Patents Rules, 2003 COMPLETE SPECIFICATION (See Section 10, and rule 13) 1. TITLE OF INVENTION METHOD FOR CONTROLLING THE ROTOR BLADES OF A WIND POWER STATION AND WIND POWER STATION COMPRISING A MEASURING SYSTEM FOR CARRYING OUT SAID METHOD 2. APPLICANT(S) a) Name b) Nationality c) Address IGUS - INNOVATIVE TECHNISCHE SYSTEME GMBH GERMAN Company ELSE-SANDER-STRASSE 6 01099 DRESDEN GERMANY 3. PREAMBLE TO THE DESCRIPTION The following specification particularly describes the invention and the manner in which it is to be performed : - The invention relates to a method for controlling and/or inspecting the rotor blades of a wind power station, wherein the state of elongation of a rotor blade of the wind power station is detected by means of a fiber-optic and/or piezoelectric method and an alarm signal is triggered depending on the resulting detection signal and/or the relative position of the rotor blade is controlled. The invention also relates to a wind power station with a mast, on which is mounted a rotatable gondola and a rotor connected to the gondola via a shaft, which consists of at least two rotor blades, whereby a first sensor of a first measuring system is located on at least one of the rotor blades, which is composed of a fiber-optic and/or piezoelectric measuring system. Wind power stations for converting wind power into electrical power consist of a mast to which a rotatable gondola is fixed. The gondola houses at least one part of the control electronics and a generator. The generator has a generator shaft, to which the rotor blades are connected. Normally there are three rotor blades for this; however, stations with multiple or two rotor (lades are also common. Rotor blades are among the most heavily burdened components of a wind power station. They have to withstand huge driving and centrifugal forces, winds, turbulence, sunrays, rain and snowfall as well as ice build-up over several years whilst in long-term operation. A long service life is of paramount importance for cost-effective operation of wind power stations. In order to achieve this, a method and device for monitoring the condition of wind power station rotor blades is outlined in DE 100 65 314 Al. The device measures the signal spectra of resonance and natural oscillation or passage and reflection, either after exciter signals are sent, from an internal excitation during operation of a wind power station or from internal noise. The target spectra are determined using previous comparable measurements from either undamaged rotor blades or -2- unusable rotor blades, which characterize either the normal or faulty condition. The measured spectra are then either directly compared with the target spectra or compared using mathematical interim calculations. In accordance with this comparison, a fault signal is triggered that can be further used for evaluation in a different form, when the normal condition is left or when a measured spectrum corresponding to the damaged target spectrum appears. This makes it possible to bond the acceleration sensors directly onto the rotor blades. A computer in either the hub or the gondola carries out an A/D conversion of the sensor signals and transmits these from the hub to the gondola preferably by. Wireless LAN and from the gondola to the base of the tower via Wireless LAN or cable. In the evaluation and communication unit (ECU) located there, the respective conditions of the rotor blades are determined by comparing the actual spectra with the stored target spectra based on a variety qf common normal and fault conditions. All measurement and analysis data are stored on a backup server either at the wind park, with the operator or at a third company. The current conditions of the rotor blades can be shown at any time, for example on the internet via a web browser. With this method, the emergence of cracks, layer separation or bar and scale separation, as well as flaking on the rotor blades can be detected and corrected in good time, before any large-scale damage occurs. Internal damage to the rotor blades can also be detected even if this is not visible from the outside, as can long-term changes such as brittleness, which lead to a change of the elasticity module. This considerably reduces the susceptibility to failure of a wind power station, because it is possible to carry out maintenance repairs in advance when there is little wind. In addition, after a lightening strike it is possible to establish immediately if there has been any damage to the rotor blade that might require intervention. -3- Ice build-up on the rotor blade can be very easily identified and is detected on the rotor blade, not via indirect measurement using the ice sensors on the gondola. Blade breakage and secondary damage from major disasters are prevented, meaning that total loss can essentially be avoided. However, other measuring and inspecting methods are also common, including fiber-optic or piezoelectric measuring methods. One example is a sensor system used in particular for measuring the mechanical voltage and temperature in turbine or propeller rotor blades, as described in EP 0 890 081. It describes the arrangement of optic fibers that create a first and second optic path, which are supplied with a light source. The optical paths alter the light that is emitted from this source or interferences occur during this process. These interferences differentiate from each other through a mechanical alteration of the optical paths, in particular, an extension of these, which occur as a result of elongations. EP 0 640 824 describes a detector system for identifying structural damage using optic fibers. There is also a description of the deformation and damage detector systems mounted on the outer surface for monitoring the structural integrity within the construction of rotor blades. Likewise, EP 0 702 780 describes a fiber-optic measuring system. However, this does not measure the elongation of the connecting systems such as rotor blades, but measures their curve, although not in the elongated part of the connecting system. DE 102 14 984 Al describes an actuator and sensor system for composites, in which the actuators are used as piezoceramic actuators and are designed to measure the reactions of energizations through this array of actuator-fiber-Bragg-grating sensors. This array is intended for active damping of composites and/or form control. -4- The use of actuator and sensor systems for w /id power stations can also be found on the website http://www.smartfibres.com. DE 197 39 162 Al describes a wind power station that has a rotor with rotor blades, which are adjustable in their rotor blade position. A control device for adjusting the rotor blade position is shown, which is an integral part of the control circuit. Targeted adjustment of the rotor blade settings is carried out with the help of momentum calculations, in particular rotation moment, yawing moment or pitching moment. It is also common to control the rotor blade adjustment by measuring the rotor blade deformation. The rotor blade deformation is determined using piezoelectric or fiber-optic measuring. The disadvantage of using piezoelectric or fiber-optic measuring systems, is that they tend to generate faulty signals when rotor blade faults occur like those mentioned above. For example, if a crack forms in the rotor blade but does not necessarily have to go through an optical pat!> of a fiber-optic measuring system, this signals a greater elongation of the blade, as a result of the reduction in strength, although the power (driving power) which normally produces the elongation is not actually present. If, for example, an elongation signal like this is used for controlling the rotor blade adjustment, then a misorientation of the rotor blade automatically occurs, which can lead to loss of efficiency of the wind power station and, at the worst, to further deterioration of the damaged condition. It is therefore the task of the invention, to construct the rotor blade measurements or rotor blade or rotor blade controls that are based on a fiber-optic or piezoelectric elongation measuring method, more reliably in terms of the information they provide and their control function. In terms of the method, the task is solved by the fact that the fiber-optic and/or piezoelectric method is monitored by a method based on resonance, natural -5- oscillation, passage and/ or reflection signal spectra comparison. In particular, the fiber-optic and/or piezoelectric method is monitored by a method in accordance with DE100 65 314 Al. In a cost-effective version of the method, the resonance, natural oscillation, passage and/or reflection signal spectrum of the rotor blade is measured and compared with an appropriate target spectrum. Depending on the size of the toleration of the measured spectrum outside of a permissible area, a fault signal is subsequently generated and when selected signals occur, the control of the rotor blade position is influenced in such a way, that an elongation adjusted to the change is used in the control as a control quantity. It is advantageous here, if an alarm signal is triggered when an adjusted elongation is used as a control quantity. In another version of the method according to the invention, it is planned that when controlling the rotor blade position depending on the detection signal given by the control, the rotor blade is set in a position adjusted to rninimum strain. If a faulty signal is generated through the piezoelectric or fiber-optic method when there is a damaged rotor blade, which would result in an incorrect adjustment of the rotor blade, this could lead to complete destruction of it. In another version it is therefore also planned, that when adjusting the rotor blade position depending on the detection signal given by the control, the wind power station is taken completely out of operation, which can be decided on depending on the extent of the damage. The task is solved on the part of the system, with a wind power station, on which a second sensor from a second measuring system is located, whereby the second measuring system is superior in terms of monitoring to the first measuring system: -6- The second measuring system is made up of a measuring system based on resonance, natural oscillation, passage and/or reflection spectra. This system allows the first system to be monitored by the second system, which also allows the detection signals of the first measuring system to be verified. In a cost-effective version of the wind power system according to the invention, it is planned that the first measuring system has a first output unit and that the second measuring system has a second output unit and that the second output unit is connected with the first output unit. In another version of the invention, it is planned that the first measuring system is an integral part of a control circuit, which includes a control unit that adjusts the rotor blade position and that the second output unit is connected with the control unit. This ensures that if there is a fault signal, the control unit can be appropriately controlled so that the rotor blade can be positioned in such a way, that it bears the least amount of strain possible or that the wind power station is also put out of operation. The invention should subsequently be explained in more detail using an example design. The accompanying diagram shows a control circuit in the design according to the invention. The control system (1) consists of the rotor blade. The first sensors (2) are located on the rotor blade. The sensors belong to a first controller (3). These first sensors (2) are fiber-optic sensors, so that elongations can be measured by an interference measurement in the fiber-optic sensors using the first controller (3). The first controller (3) sets the rotor blade so that a standard tolerance is produced and regulated to zero; this is adjusted through the reference value represented by the maximum elongation. Likewise, second sensors (4) are located on the rotor blade, -7- which record the oscillation spectrum of the rotor blade and compare it with a target spectrum in the evaluation unit (5). As soon as an impermissible deviation for selected conditions is detected using the evaluation unit (5), this affects the first controller (3), so that it sets the rotor blade to produce the least amount of strain possible. Reference List 1 Control system 2 First sensor 3 First controller 4 Second sensor 5 Evaluation unit -8- WE CLAIM : 1. Method for controlling and/or inspecting the rotor blades of a wind power station, wherein the state of stress or elongation of a rotor blade of the wind power station is detected by means of a fiber-optic and/or piezoelectric method and an alarm signal is triggered depending on the resulting detection signal and/or the relative position of the rotor blade is controlled, identified by the fact that the fiber-optic and/or piezoelectric method is monitored by a method based on the comparison of resonance, natural oscillation, passage or reflection signal spectra. 2. Method in accordance with claim 1, identified by the fact that a resonance, natural oscillation, passage or reflection signal spectrum of the rotor blade is measured and compared with an appropriate target spectrum. A fault signal is subsequently generated depending on the size of the tolerance of the measured spectrum outside of the permissible area. When selected fault signals occur, controlling the position of the rotor blade is influenced in such a way, that an elongation adjusted to the change is used in the control as a control quantity. 3. Method in accordance with claim i, identified by the fact that an alarm signal is triggered when using an adjusted elongation as a control quantity. 4. Method in accordance with claim 1, identified by the fact that when adjusting the position of the rotor blade depending on the detection signal given by the control, the rotor blade is set in a position adjusted to produce the least amount of strain. 5. Method in accordance with claim 1, identified by the fact that when adjusting the position of the rotor blade depending on the detection signal given by the control, the wind power station is identified and switched off. -9- 6. Wind power station for implementing the method in accordance with claim 1, with a mast, on which a rotatable gondola is mounted and the rotor is connected to the gondola via a shaft, which consists of at least two rotor blades, whereby on at least one rotor blade, a first sensor of a first measuring system is located, which is made up of a fiber-optic and/or piezoelectric measuring system, identified by the fact that there is also a second sensor of a second measuring system, which is based on the comparison of resonance, natural oscillation, passage and/or reflection signal spectra, and that the second measuring system is superior in monitoring terms to the first measuring system. 7. Wind power station in accordance with claim 6, identified by the fact that the first measuring system has a first output unit and the second measuring system has a second output unit and that the second output unit is connected with the first output unit. 8. Wind power station in accordance with claim 6 or 7, identified by the fact that the first measuring system is an integral part of a control circuit, which includes a control unit to adjust the position of the rotor blade, and that the second output unit is connected with the control unit. Dated this 16th Day of November, 2006 ASEAN SAARC PATENT & TRADE MARK SERVICES AGENT FOR IGUS - INNOVATIVE TECHNISCHE SYSTEME GMBH -10-

Documents:

1406-mumnp-2006 claims (granted) - (6-6-2007).doc

1406-mumnp-2006 form 2 (granted) - (6-6-2007).doc

1406-mumnp-2006-cancelled pages(6-6-2007).pdf

1406-mumnp-2006-claims(granted)-(6-6-2007).pdf

1406-mumnp-2006-claims.doc

1406-mumnp-2006-claims.pdf

1406-mumnp-2006-correspondance-received.pdf

1406-mumnp-2006-correspondence(6-6-2007).pdf

1406-mumnp-2006-correspondence(ipo)-(7-1-2008).pdf

1406-mumnp-2006-description (complete).pdf

1406-mumnp-2006-drawing(6-6-2007).pdf

1406-mumnp-2006-form 1(20-11-2006).pdf

1406-mumnp-2006-form 18(20-11-2006).pdf

1406-mumnp-2006-form 2(granted)-(6-6-2007).pdf

1406-mumnp-2006-form 3(6-6-2007).pdf

1406-mumnp-2006-form 5(20-11-2006).pdf

1406-mumnp-2006-form-1.pdf

1406-mumnp-2006-form-18.pdf

1406-mumnp-2006-form-2.doc

1406-mumnp-2006-form-2.pdf

1406-mumnp-2006-form-3.pdf

1406-mumnp-2006-form-5.pdf

1406-mumnp-2006-form-pct-isa-210.pdf

1406-mumnp-2006-form-pct-isa-2106-6-2007).pdf

1406-mumnp-2006-form-pct-isa-237.pdf

1406-mumnp-2006-granted.pdf

1406-mumnp-2006-power of attorney(6-6-2007).pdf

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