WO2015188835A1 - Perfectionnements apportés à des éoliennes - Google Patents

Perfectionnements apportés à des éoliennes Download PDF

Info

Publication number
WO2015188835A1
WO2015188835A1 PCT/DK2015/050159 DK2015050159W WO2015188835A1 WO 2015188835 A1 WO2015188835 A1 WO 2015188835A1 DK 2015050159 W DK2015050159 W DK 2015050159W WO 2015188835 A1 WO2015188835 A1 WO 2015188835A1
Authority
WO
WIPO (PCT)
Prior art keywords
blade
receiver
deflection
straight
transmitting
Prior art date
Application number
PCT/DK2015/050159
Other languages
English (en)
Inventor
Ib Svend Olesen
Original Assignee
Vestas Wind Systems A/S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vestas Wind Systems A/S filed Critical Vestas Wind Systems A/S
Publication of WO2015188835A1 publication Critical patent/WO2015188835A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0091—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by using electromagnetic excitation or detection
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D17/00—Monitoring or testing of wind motors, e.g. diagnostics
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0016—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings of aircraft wings or blades
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0041—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by determining deflection or stress
    • G01M5/005—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by determining deflection or stress by means of external apparatus, e.g. test benches or portable test systems
    • G01M5/0058—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by determining deflection or stress by means of external apparatus, e.g. test benches or portable test systems of elongated objects, e.g. pipes, masts, towers or railways
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2270/00—Control
    • F05B2270/80—Devices generating input signals, e.g. transducers, sensors, cameras or strain gauges
    • F05B2270/804—Optical devices

Definitions

  • the present invention relates to wind turbine technology and specifically to a system and method for monitoring the deflection of wind turbine blades.
  • FIG 1 shows a typical wind turbine blade 10, which tapers longitudinally from a relatively wide root end 12 towards a relatively narrow tip end 14.
  • a longitudinal axis L of the blade is also shown in Figure 1.
  • the root end 12 of the blade is circular in cross section.
  • the blade has an airfoil profile 16 in cross section.
  • the root of the blade is typically connected to a hub of the rotor via a pitch mechanism, which turns the blade about the longitudinal pitch axis L in order to vary the pitch of the blade.
  • Varying the pitch of a blade varies its angle of attack with respect to the wind. This is used to control the energy capture of the blade, and hence to control the rotor speed so that it remains within operating limits as the wind speed changes. In low to moderate winds it is particularly important to control the pitch of the blades in order to maximise the energy capture of the blades and to maximise the productivity of the wind turbine.
  • Modern wind turbine blades are typically 50-80 metres in length, or longer in some cases, and are generally made from composite materials such as glass-fibre reinforced plastic (GFRP).
  • GFRP glass-fibre reinforced plastic
  • the blades are therefore relatively flexible and inevitably bend and twist to an extent during operation.
  • the relatively narrow outboard part of the blade is particularly susceptible to twisting and bending.
  • the pitch mechanism allows precise control over the angle of the root of the blade, this does not necessarily reflect the angle of the tip of the blade, which is more susceptible to bending and twisting as mentioned above.
  • the present invention provides a method and apparatus for measuring the bending angle of the blade caused by wind loads. These parameters can then be employed in control strategies for the wind turbine. For example, accurate measurements of blade bending angle can be employed in pitch control strategies allowing precise control over the angle of attack of the outboard part of the blade so that the energy capture of the blade can be maximised. These measurements may also be employed in blade load calculations and control strategies for protecting the blades from extreme loads.
  • a first aspect of the invention relates to a wind turbine having at least one rotor blade, comprising a system for determining a parameter indicative of blade deflection.
  • the system comprises an effective source of electro-magnetic (EM) radiation arranged to transmit an EM radiation signal; a receiver arranged to receive the EM radiation signal, the signal having an irradiance, and the receiver being spaced apart from the effective source in a spanwise direction of the blade.
  • the effective source and the receiver are arranged such that deflection of the blade results in a straight-line distance between the effective source and the receiver varying.
  • the system also comprises a processor configured to determine a parameter indicative of blade deflection and/or blade loading on the basis of the irradiance of the EM radiation signal received by the receiver.
  • the "term effective" source refers to the apparent position of an electromagnetic (EM) light source with respect to a point of view, such as from the point of view of a receiver. Consequently, the position of an effective source does not always correlate with the position of a physical EM light source.
  • the presence of optical instruments lying in the optical path between a physical EM light source and a receiver often have the effect of shifting the position of the effective source relative to the position of the physical source, as observed by a receiver. This can be understood by considering the example where a focusing lens is introduced in the optical path between a laser and an optical receiver. With respect to the receiver, the position of the effective source is the point of incidence of the laser beam on the focusing lens.
  • the effective source is the point of incidence of the laser beam on the protective housing, since it appears to the receiver as if the received EM signal has been transmitted from the point of incidence on the protective housing.
  • the position of the effective source may correlate with the location of the physical source, for example, the location of a laser emitting an EM signal.
  • the irradiance is inversely proportional to the square of the distance of separation.
  • the deflection of the blade may be determined on the basis of the measured irradiance. For example, an angle of deflection may be determined.
  • the receiver may be mounted to the rotor blade.
  • the receiver may be mounted to the surface of the rotor blade and the effective source may be located on the surface of the rotor blade; or alternatively, inside the rotor blade. Mounting the receiver and positioning the effective source inside the rotor blade protects the apparatus from external environmental factors that could interfere with their correct operation. Furthermore, the amount of background noise is also reduced, further improving the operation of the apparatus.
  • each one of the wind turbine's rotor blades is associated with a receiver and effective source pair. In this way, the blade deflection of each blade is determinable when the wind turbine is in use.
  • One of the effective source or receiver may be located in the vicinity of the rotor blade tip and the other of the effective source or receiver may be located in the vicinity of the blade root.
  • the effective source may be located in the vicinity of the blade root, and the receiver in the vicinity of the tip of the blade, or vice versa. This configuration improves the accuracy with which the deflection of the blade tip relative to the root is determined.
  • the system may comprise a transmitter, such as an optical transmitter, located on the rotor blade; a physical source of EM radiation located remotely from the transmitter; and a waveguide arranged to connect the transmitter to the physical source.
  • the physical source may relate to any type of EM radiation source, such as a laser emitting an EM wave having a Gaussian beam profile, such as a diode laser for example. Diode lasers are compact and light, and therefore convenient for use with a wind turbine.
  • the optical transmitter may relate to any one or more optical devices, such as an arrangement of optical lenses, arranged to output an EM radiation signal from the waveguide and to focus it on the receiver, and/or any optical instrument located between the transmitter and the receiver.
  • the position of the effective source correlates with the position of the transmitter.
  • the optical transmitter is commonly formed integral to the waveguide.
  • the position of the effective source correlates with the point of incidence of the EM radiation emitted by the transmitter on the one or more optical instruments present in the optical path between the transmitter and the receiver.
  • Non-limiting examples of the aforementioned optical instrument comprise any one or more of an optical lens, a translucent medium, and a transparent medium.
  • the physical source may relate to a conventional light source emitting light in the visible and/or non-visible spectrum, such as infra-red or ultraviolet light for example.
  • the physical EM radiation source may be positioned local to the rotor blade, or remotely therefrom.
  • the physical source may be located in the rotor hub of the wind turbine and may be operatively coupled to a transmitter via a waveguide, such as a fibre optic, as described previously.
  • a waveguide such as a fibre optic
  • One advantage of this arrangement is that a single EM radiation source may be coupled to the transmitters and receivers associated with each one of the wind turbine's rotor blades.
  • Use of a non-electrically conducting waveguide, such as a fibre optic reduces the amount of electrically conducting apparatus present in the wind turbine. This reduces the likelihood of the wind turbine being struck by lightning in adverse weather conditions. This configuration also improves accessibility for maintenance purposes, since the physical EM radiation source is directly accessible via the rotor hub for servicing.
  • each transmitter may be coupled to its own EM radiation source.
  • the processor may be operatively coupled to the receiver and may be positioned local to the receiver. Alternatively, the processor may be located remotely to the receiver. In the latter case, the processor may be located in the wind turbine rotor hub, and operatively coupled to the receiver associated with each rotor blade, thus further reducing the weight of the system.
  • the processor may be operatively coupled to the receiver via an electrically conducting guide arranged to conduct an electrical signal associated with the received EM radiation signal measured by the receiver.
  • the processor may be operatively coupled to the receiver via a waveguide, such as an optical fibre, in which case the received EM radiation signal is guided to the processor where it is measured by a sensor arranged local to the processor.
  • the system comprises first and second receivers arranged such that deflection of the rotor blade results in the straight-line distance between the effective source and one of the receivers increasing, and in the straight-line distance between the effective source and the other receiver decreasing.
  • the processor is configured to determine a magnitude and/or direction of deflection and/or a magnitude and/or direction of blade loading by comparing the irradiance of the EM radiation signal received by the first receiver with the irradiance of the EM radiation signal received by the second receiver. This configuration is advantageous in that it enables both the direction of deflection and/or blade loading and the associated magnitude of deflection and/or blade loading to be determined.
  • the first and second receivers are arranged such that deflection of the blade in a flapwise and/or edgewise direction of the rotor blade results in the straight-line distance between the effective source and one of the receivers increasing, and in the straight-line distance between the effective source and the other receiver decreasing.
  • the first and second receivers may be arranged comprising a straight-line distance of separation having a length component parallel to a thickness of the blade, or in other words, having a component along a line perpendicular to the chordwise direction of the blade. This may be achieved when the first and second receivers are arranged respectively in the vicinity of the suction side and in the vicinity of the pressure side of the rotor blade. This arrangement of receivers enables flapwise blade deflection and/or blade loading, and/or the magnitude of flapwise deflection and/or loading to be determined.
  • first and second receivers may be arranged comprising a straight-line distance of separation having a length component parallel to the chordwise direction of the blade.
  • first and second receivers may be arranged respectively in the vicinity of the leading edge and the trailing edge of the rotor blade. This arrangement of receivers enables edgewise blade deflection and/or blade loading, and/or the magnitude of edgewise deflection and/or loading to be determined.
  • the processor may be arranged to calculate an irradiance ratio on the basis of the irradiances of the EM radiation signals received from the first and second receivers, and to determine direction of magnitude and/or direction of deflection and/or a magnitude and/or direction of blade loading on the basis of the calculated irradiance ratio.
  • the system comprises first and second effective sources configured to transmit first and second EM radiation signals respectively.
  • the first and second EM radiation signals being distinguished from one another by a distinguishing characteristic.
  • the first and second effective sources are arranged such that deflection of the rotor blade results in the straight-line distance between the receiver and one of the effective sources increasing, and in the straight-line distance between the receiver and the other effective source decreasing.
  • the receiver is configured to receive the first and second EM radiation signals
  • the processor is configured to determine a magnitude and/or direction of deflection and/or a magnitude and/or direction of blade loading by comparing the irradiance and/or the distinguishing characteristic of the first and second EM radiation signals received by the receiver.
  • This alternative configuration also enables both the direction of deflection and/or blade loading and the associated magnitude of deflection and/or blade loading to be determined.
  • the first and second effective sources are arranged such that deflection of the rotor blade in a flapwise and/or edgewise direction results in the straight-line distance between the receiver and one of the effective sources increasing, and in the straight-line distance between the receiver and the other effective source decreasing.
  • the first and second effective sources may be arranged comprising a straight-line distance of separation having a length component parallel to a thickness of the blade, or in other words, having a component along a line perpendicular to the chordwise direction of the blade. This may be achieved when the first and second effective sources are arranged respectively in the vicinity of the suction side and in the vicinity of the pressure side of the rotor blade.
  • This arrangement of receivers also enables flapwise blade deflection and/or blade loading, and/or the magnitude of flapwise deflection and/or loading to be determined.
  • first and second effective sources may be arranged comprising a straight- line distance of separation having a length component parallel to the chordwise direction of the blade.
  • first and second effective sources may be arranged respectively in the vicinity of the leading edge and the trailing edge of the rotor blade. This arrangement of receivers also enables edgewise blade deflection and/or blade loading, and/or the magnitude of edgewise deflection and/or loading to be determined.
  • the distinguishing characteristic of the EM radiation signals is selected from any one of: frequency, wavelength, colour, or polarisation.
  • the system comprises a plurality of receivers or effective sources spaced apart in the spanwise direction of the blade, and the processor is configured to determine a parameter indicative of local blade deflection and/or local blade loading at the associated spanwise location of the receivers or effective sources.
  • This configuration enables a more precise determination of blade deflection and/or blade load to be determined along the spanwise direction of the rotor blade. This is particularly useful where the rotor blade is subject to non-uniform loads and/or non-uniform deflection along its length.
  • the system may comprise a plurality of receivers spaced apart along the spanwise direction of the rotor blade, and the processor is configured to determine local blade deflection and/or local blade loading at the associated spanwise location of the receivers.
  • the system may comprise a plurality of effective sources spaced apart in the spanwise direction of the blade.
  • the processor may be configured to determine local blade deflection and/or local blade loading at the associated spanwise location of the effective sources.
  • each one of the EM radiation signals emitted by the plurality of effective sources may comprise a distinguishing characteristic. This enables the different EM radiation signals to be distinguished by the processor.
  • the system may comprise a plurality of pairs of first and second receivers, each pair being spaced apart along the spanwise direction of the rotor blade. The first and second receivers comprised in each pair may be arranged to have an equidistant straight-line distance of separation from the effective source.
  • the first and second receivers comprised in each pair may be located as described previously, respectively in the vicinity of the pressure side of the blade and the suction side of the blade, enabling flapwise deflection and/or load to be determined along the spanwise direction of the blade.
  • the first and second receivers comprised in each pair may be located as described previously, respectively in the vicinity of the leading edge and the trailing edge, enabling edgewise deflection and/or load to be determined along the spanwise direction of the blade.
  • the system may comprise a protective housing comprised of an at least partially translucent material, and the receiver or each receiver is arranged within the protective housing.
  • the surface of the protective housing is the effective source.
  • Use of a protective housing to encase the receiver or each receiver advantageously protects the receivers from environmental pollutants, such as dust which could result in erroneous results. It also reduces the amount of maintenance required.
  • a second aspect of the present invention relates to a method for determining deflection of a rotor blade of a wind turbine.
  • the method comprises the steps of: (a) transmitting an EM radiation signal from a transmitting position; (b) receiving the EM radiation signal at a receiving position, the receiving position and the transmitting position being spaced apart in a spanwise direction of the blade, and being arranged such that deflection of the rotor blade results in a straight-line distance between the transmitting position and the receiving position varying; and (c) determining a parameter indicative of blade deflection and/or blade loading on the basis of the irradiance of the EM radiation signal received at the receiving position.
  • Step (a) of the method may comprise transmitting the EM radiation signal from the vicinity of the rotor blade tip, and step (b) may comprise receiving the transmitted EM radiation signal in the vicinity of the blade root.
  • step (a) of the method may comprise transmitting the EM radiation signal from the vicinity of the blade root, and step (b) comprises receiving the transmitted EM radiation signal in the vicinity of the rotor blade tip.
  • step (b) may comprise receiving the EM radiation signal at a first receiving position and at a second receiving position.
  • step (c) comprises determining a magnitude and/or direction of deflection and/or magnitude and/or direction of blade loading by comparing the irradiance of the EM radiation signal received at the second receiving position.
  • the first receiving position and the second receiving position may be arranged such that deflection of the blade in the flapwise and/or edgewise direction results in the straight- line distance between the transmitting position and one of the first and second receiving positions increasing, and in the straight-line distance between the transmitting position and the other one of the first and second receiving positions decreasing.
  • Step (c) may comprise determining a magnitude of flapwise and/or edgewise bending and/or a magnitude of flapwise and/or edgewise loading.
  • Step (a) may comprise transmitting a first EM radiation signal from a first transmitting position and transmitting a second EM radiation signal from a second transmitting position.
  • the first and second EM radiation signals being distinguishable from one another by a distinguishing characteristic, and the first and second transmitting positions being arranged such that deflection of the blade results in the straight-line distance between one of the first and second transmitting positions and the receiving position increasing, and in the straight-line distance between the other one of the first and second transmitting position and the receiving position decreasing.
  • Step (c) may comprise determining a magnitude and/or direction of deflection and/or magnitude and/or direction of blade loading by comparing the irradiance and/or the distinguishing characteristic of the first and second EM radiation signals received at the receiving position.
  • the first transmitting position and the second transmitting position may be arranged such that deflection of the blade in a flapwise and/or edgewise direction results in the straight- line distance between one of the first and second transmitting positions and the receiving position increasing, and in the straight-line distance between the other one of the first and second transmitting positions and the receiving position decreasing.
  • Step (c) may comprise determining a magnitude of flapwise and/or edgewise bending and/or a magnitude of flapwise and/or edgewise loading.
  • the distinguishing characteristic may be selected from any one of frequency, wavelength, colour and polarisation.
  • Step (c) may then comprise determining a magnitude and/or direction of deflection and/or magnitude and/or direction of blade loading by comparing any one of frequency, wavelength, colour and polarisation of the first and second EM radiation signals received at the receiving position.
  • Step (a) may comprise transmitting a plurality of EM radiation signals each one from a different one of a plurality of transmitting positions spaced apart in a spanwise direction of the blade.
  • Step (b) may comprise receiving the plurality of EM radiation signals; and step (c) may comprise determining a parameter indicative of local blade deflection and/or local blade loading at the associated spanwise location of the plurality of transmitting positions.
  • Step (b) may comprise receiving an EM radiation signal at a plurality of different receiving positions spaced apart in a spanwise direction of the blade; and step (c) may comprise determining a parameter indicative of local blade deflection and/or local blade loading at the associated spanwise location of the plurality of receiving positions.
  • Figure 1 which is a perspective illustration of an exemplary wind turbine blade having a circular cross-section at the root, and an airfoil cross-section profile outboard from the root, has already been described above by way of background to the present invention.
  • Figure 2a is a schematic illustration of the cross-section of the tip of the blade of
  • Figure 1 having a blade tip angle of 0 degrees; whilst Figure 2b illustrates a blade tip angle of ⁇ >0 degrees;
  • Figure 4a is a schematic illustration of a front view of a rotor-hub assembly of a wind turbine, wherein each blade is configured with a single transmitter and receiver in accordance with an embodiment of the invention; whilst Figure 4b illustrates a rotor hub assembly wherein each blade is configured with a single transmitter and two receivers in accordance with an alternative embodiment of the invention;
  • Figure 5a is a schematic illustration showing how both receivers of Figure 4b measure the same irradiance when the blade is undeflected; whilst Figure 5b illustrates how the relative distance of the two receivers with respect to the transmitter varies as the blade is deflected by an angle a, resulting in different irradiances being measured at each receiver;
  • Figure 6a is a schematic illustration showing an undeflected turbine blade configured with two transmitters and a single receiver in accordance with an alternative embodiment of the invention; whilst Figure 6b illustrates how the relative distance between the transmitters and the receiver changes as the blade is deflected, and
  • Figure 7a is a schematic illustration showing an alternative arrangement, wherein two optical receivers are located within a protective housing; and Figure 7b is a magnified plan view of the housing showing how the position of the effective source on the housing varies as the blade is deflected.
  • the tip angle of the blade is defined herein as the angle between the chord line of the blade at the tip and a reference axis in a plane perpendicular to the longitudinal axis L of the blade, as will now be described by way of example with reference to Figures 2a and 2b, in addition to Figure 1.
  • the chord line is the straight line D connecting the leading edge 18 of the blade to the trailing edge 20 of the blade 10.
  • the chordline D is also readily viewable in Figure 1.
  • the pressure side 17 of the blade 10 is the side where a high pressure region is formed as air flows across the airfoil profile of the blade.
  • the suction side 19 is the side where a low pressure region is formed as air flow across the airfoil profile of the blade.
  • the difference in pressure formed at the pressure side 17 and the suction side 19 generates lift.
  • the lift acts on the pressure side 17 and causes the blade to rotate in the direction of the lift.
  • Figures 2a and 2b illustrate a cross-section of the tip of the wind turbine blade 10 in a plane perpendicular to the longitudinal axis L and taken along the line A-A in Figure 1.
  • the blade 10 has a first tip angle
  • the blade 10 has a second tip angle.
  • the tip angle is marked ⁇ in Figures 2a and 2b.
  • the longitudinal axis L is perpendicular to the plane of the page in Figures 2a and 2b.
  • the x-axis in Figures 2a and 2b is generally parallel to a rotor axis about which the blades turn substantially in the L-y plane. It will be appreciated that, in reality, the wind turbine blades of the rotor are arranged to have a certain cone angle to avoid tower strike and the blades bend and flex in use, hence the rotor plane would not strictly coincide with the L-y plane, but this approximation is used to simplify the discussion and understanding of the present invention.
  • the direction of rotation of the rotor about the rotor axis is indicated by R in Figures 2a and 2b.
  • the blade traces a circle in the L-y plane.
  • the wind direction is indicated as W in Figures 2a and 2b.
  • the wind direction is illustrated as being perpendicular to the L-y plane, although in practice the direction of the wind relative to the L-y plane varies, and may be incident at different angles.
  • the blade tip angle ⁇ is arbitrarily defined as 0° degrees when the chordline D is parallel to the x-axis, and therefore perpendicular to the L-y plane.
  • Figure 2b illustrates the blade tip turned through an angle ⁇ with respect to the x-axis.
  • the blade tip angle ⁇ is defined with respect to an arbitrary axis (for example, the x-axis of Figures 2a and 2b) formed generally perpendicular to the plane of rotation (the L-y plane of Figures 2a and 2b) of the blade.
  • the tip angle could be defined relative to another arbitrary reference and so this definition should not be interpreted as limiting the scope of the present invention.
  • Blade tip twisting occurs when the blade tip angle 6 b i ade tip differs from the pitch angle of the blade defined in the vicinity of the root of the blade 12.
  • the twist angle will be denoted ⁇ , and it is to be appreciated that the twisting angle is defined relative to the pitch angle of the root of the blade 12.
  • the total blade tip angle 6 b i ade tip may be considered to be the sum of the blade's pitch angle e roo t defined at its root and the twist angle ⁇ . Blade bending may occur in a so-called 'flapwise' direction or in a so-called 'edgewise' direction.
  • the flapwise direction is perpendicular to the plane containing the longitudinal axis L and the chordwise direction D of the blade, i.e. in the direction £ indicated in Figure 1 , and perpendicular to the L-x plane. Bending in the flapwise direction typically occurs when the wind turbine blade is subjected to large external loads perpendicular to the blade's longitudinal axis L.
  • the edgewise direction is generally in the chordwise direction D (i.e. perpendicular to the L-y plane), and edgewise bending is typically caused by the weight of the blade as the blade rotates. Blade bending may result in significant displacement of the blade tip from the straight longitudinal axis L. Blade tip bending is further explained with respect to Figures 3a and 3b.
  • Figure 3a is a side perspective view of the wind turbine blade 10 taken along the longitudinal axis L, when the blade is straight.
  • Figure 3b shows the blade 10' when bent, e.g. when the outboard part of the blade is subject to wind loads.
  • the blade tip 14 in Figure 3b is deflected by an amount ⁇ perpendicular to the longitudinal axis L.
  • the straight line U in Figure 3b is a line that extends between the deflected tip of the blade and the longitudinal axis L at a point C at the root of the blade, where the blade remains substantially straight.
  • a blade tip bending angle or may be defined as the angle between L' and L.
  • the flapwise direction is perpendicular to the edgewise direction
  • Figures 3a and 3b schematically illustrate either flapwise or edgewise bending depending upon the orientation of the blade.
  • the blade deflection is in a direction comprised in the L-y plane (see Figure 1), in the direction of the straight line £, and Figures 3a and 3b show a side perspective view of the wind turbine blade 10, 10' taken in the L-y plane.
  • Figures 3a and 3b show a side perspective view of the wind turbine blade 10, 10' taken in the L-x plane.
  • FIG 4a schematically illustrates a rotor-hub 22 assembly as featured in a horizontal axis wind turbine.
  • the illustrated rotor-hub assembly 22 comprises three turbine blades 24a, 24b, 24c affixed to a central hub 26 via respective pitch mechanisms (not illustrated).
  • the blades 24a, 24b, 24c have a cross-sectional airfoil profile 16 as illustrated in Figure 1 , and are arranged to cause an anti-clockwise rotation of the rotor- hub, as indicated by the directional arrows 28, when wind is incident on the blades 24a, 24b, 24c in a substantially planar direction perpendicular to and into the plane of the page (i.e. substantially in the direction of the x-axis).
  • Each blade 24a, 24b, 24c of the rotor-hub 22 assembly is configured with at least one optical transmitter 30, which serves as the effective source in this example, and at least one optical receiver 32.
  • the at least one optical transmitter 30 is separated from the at least one optical receiver 32 in the longitudinal direction L of the blade 24a, 24b, 24c. This may interchangeably be referred to as the spanwise direction of the blade.
  • the optical receiver 32 is located substantially in the vicinity of the tip of the blade 24a, 24b, 24c, to enable accurate determination of the bending angle or at the blade tip.
  • the bending angle or may not be constant throughout the blade's length, and therefore positioning the optical receiver 32 substantially in the vicinity of the blade tip ensures that the determined bending angle or is an accurate reflection of the position of the blade tip.
  • the at least one optical transmitter 30 is located substantially in the vicinity of the root 12 of the blade 24a, 24b, 24c. This also improves the accuracy with which the bending angle or is determined. In use the root 12 is unlikely to bend, and therefore provides a convenient reference point with respect to which the bending of the blade tip may be determined.
  • the at least one optical transmitter 30 is configured to emit an eletro-magnetic (EM) signal 24, such as a light signal, which is subsequently received by the optical receiver 32, which is arranged to measure an irradiance value of the received EM-signal 24.
  • EM eletro-magnetic
  • the term irradiance is used to indicate intensity.
  • the irradiance of a light signal is its optical intensity.
  • the bending angle or is determined on the basis of the measured irradiance value.
  • the optical transmitter 30, and the optical receiver 32 are located inside the shell of the turbine blade 24a, 24b, 24c.
  • An example of how the blade tip bending angle or may be determined from the measured irradiance of the received EM-signal is now described.
  • the irradiance value of a received EM-signal, measured by the receiver 32, is compared with a reference irradiance value, and the bending angle or is determined on the basis of this comparison.
  • the reference irradiance value is preferably pre-measured when the blade 24a, 24b, 24c has a known bending angle a.
  • the reference irradiance value may be determined when the bending angle a is zero (i.e. when the blade is undeflected / not under load). This measurement defines a reference irradiance value that may subsequently be used for comparison purposes in order to determine the bending angle a of the blade tip.
  • the measured irradiance / is proportional to the inverse square of the relative radial distance r between the receiver and the transmitter 30 eq.1
  • the position of the optical receiver 32 is displaced relative to the transmitter 30. This displacement results in a variance of the radial distance r (i.e. the straight line distance) between the transmitter 30 and receiver 32, which in turn is associated with a variance in the measured irradiance value.
  • the change in radial distance between the optical receiver 32 and the transmitter 30 is determined, and the bending angle o of the blade tip is determined.
  • the accuracy of the determined bending angle o of the blade tip is improved by positioning the transmitter 30 in closer proximity to the blade tip.
  • the bending angle or may be determined from a reference table configured to associate measured irradiance values with bending angles.
  • a reference table may be generated during a calibration / testing process, where the accurate measurements of bending angle a and measured irradiance values may be carried out in a controlled environment.
  • the irradiance values for a myriad of different bending angles may be measured and populated in the reference table, in order to obtain a range of different bending angles associated with a range of different irradiance values.
  • the range of different bending angles may be generated by applying different loads to the rotor blade. In this way, a known load value is correlated with each bending angle and measured irradiance value.
  • the bending angle or may be calculated from first principles using known trigonometric identities, which are within the common general knowledge of the reader skilled in the art, and for this reason are not discussed herein.
  • FIG 4b schematically illustrates an alternative example of a rotor-hub 22 assembly.
  • each blade 24a, 24b, 24c is configured with at least two optical receivers 32a, 32b.
  • Each blade 24a, 24b, 24c is also configured with an optical transmitter 30, which in this example serves as the effective optical source.
  • a first one of the optical receivers 32a is arranged on the pressure side 17 of the blade 24a, 24b, 24c, and a second one of the optical receivers 30b is arranged on the suction side 19 of the blade 24a, 24b, 24c.
  • the first and second optical receivers 32a, 32b are separated along a thickness of the blade 24a, 24b, 24c in a direction of the straight line £, perpendicular to the chordwise direction of the blade 24a, 24b, 24c, and substantially perpendicular to the longitudinal axis L of the blade.
  • the optical receivers 32a, 32b are located substantially in the vicinity of the tip of the blade 24a, 24b, 24c, to enable accurate determination of the flapwise bending angle or at the blade tip in the L-y plane. It is to be appreciated that the present embodiment functions equally well for any linear separation of the optical receivers 32a, 32b, which comprises a separation component in the direction of the straight line E.
  • the straight line distance of separation between the optical receivers 32a, 32b need not necessarily be parallel to the straight line E. Accordingly, in the present context and going forward separation along the thickness of the blade 24a, 24b, 24c means any separation of the first and second optical receivers 32a, 32b having a separation component in the direction of the straight line E.
  • a third optical receiver (not shown) may be arranged on the leading edge 17 of the blade 24a, 24b, 24c, and a fourth optical receiver (not shown) may be arranged on the trailing edge 20 of the blade 24a, 24b, 24c, in the chordwise direction of the blade (i.e. in the direction of the straight line D).
  • the straight line separation of the third and fourth optical receivers comprise a separation component that is parallel to the chordwise direction (i.e. parallel to the straight line D). Going forward, separation in the chordwise direction means any separation of optical receivers having a separation component parallel to the chordwise direction.
  • FIGS 5a and 5b schematically illustrate how the relative radial distances r A , r B
  • Figure 5a schematically illustrates a blade 10 when it is straight (i.e. not under load).
  • the contour lines Cj, C 2 , C 3 trace lines of equal irradiance.
  • the irradiance measured from the EM-signal emitted by the transmitter 30 is constant.
  • the difference in irradiance measured between the contour lines is inversely proportional to the square of the difference in radial distance between the contour lines, in accordance with equation 1.
  • the transmitter 30 is arranged equidistant (e.g.
  • FIG. 5b schematically illustrates flapwise bending of the blade 10' by a bending angle a.
  • the radial distances r A ', r B ' between each receiver 32a', 32b' and the transmitter 30 are no longer equal, and the receivers 32a', 32b' are no longer equidistant from the transmitter 30.
  • both receivers 32a', 32b' are now located on different intensity contour lines C a -, C b -.
  • the second receiver 32b' is now closer to the transmitter 30 than the first receiver 32b' (e.g. A > B ), and the irradiance ⁇ ⁇ ⁇ measured at the second receiver 32b' is greater than the irradiance ⁇ ⁇ ⁇ measured at the first receiver 32a' (e.g. / ⁇ '> ⁇ -)-
  • the intensity ratio may be defined ⁇ ⁇ ⁇ eq.2
  • Equation 2 shows that the ratio of intensities is proportional to the ratio of the squares of the radial distances.
  • a reference table may be consulted correlating irradiance ratios, and/or radial distance ratios, to bending angles.
  • the reference table is preferably generated in a controlled environment, as described previously.
  • the bending angle or may be defined, as mentioned previously, from first principles using known trigonometric functions.
  • FIGS 6a and 6b schematically illustrate an alternative example comprising a single receiver 38, and two transmitters 36a, 36b.
  • Each one of the transmitters 36a, 36b serves as a different effective source in this example.
  • the receiver 38 is located outboard relative to the two transmitters 36a, 36b in the vicinity of the blade tip.
  • Different wavelengths/frequencies may be used to enable the receiver to distinguish between the EM-signals transmitted from each transmitter 36a, 36b.
  • polarisation may be used to enable the receiver to distinguish between the two emitted EM-signals.
  • the first transmitter 36a may be configured to transmit a circularly polarised EM-signal
  • the second transmitter 36b may be configured to transmit a linearly polarised EM-signal.
  • the receiver may be provided with a filter enabling the two received EM-signals to be distinguished on the basis of their polarisation, and/or wavelength/frequency.
  • the two transmitters may transmit different colours of the visible light spectrum. A relative increase in irradiance of one colour over the other indicates the direction of bending.
  • the blade may be provided with a plurality of pairs of receivers or transmitters, to enable the bending angle o of the blade to be determined along its length. This is convenient where the bending angle a is not constant along the blade's length.
  • Each pair of receivers or transmitters is spaced apart along the blade's length at predetermined intervals, which may be arbitrarily selected, depending on the required accuracy.
  • Each pair of receivers or transmitters enables the bending angle a to be determined at their respective position along the blade's length, in the same way as previously described.
  • the positions of the transmitters and receivers in the previously described examples may be interchanged. In other words, the one or more receivers may be positioned in the vicinity of the blade's root 12, and the one or more transmitters positioned outboard relative to the receivers. In such examples, the bending angle a is determined in the same way as previously described.
  • Figures 7a and 7b illustrate a further example of the present invention.
  • Figure 7a illustrates a blade 10 when it is straight (i.e. not under load), in which the optical receivers 32a, 32b are enclosed in a protective housing 34.
  • the protective housing 34 is preferably comprised of an at least partially translucent material, which enables at least a portion of the light incident on the housing 34 to pass through it. Light which passes through the housing is subsequently measured by the optical receivers 32a, 32b substantially as described in previous embodiments.
  • a translucent material is considered to be a material which allows incident light to pass through it, and wherein some of the light may be scattered on exiting the translucent material.
  • a transparent material is considered to be a special type of translucent material. A transparent material allows light incident on it to pass through it, and does not scatter the incident light when it exits the transparent material. Accordingly, in certain embodiments the protective housing 34 may be comprised of an at least partially transparent material, and in the ensuing description it is to be
  • reference to a translucent material may also relate to an at least partially transparent material.
  • FIG. 7b A magnified view of the housing 34 is illustrated in Figure 7b, in which the position of the effective optical source and the illuminating ray is shown at two different times, as the blade is deflected through a bending angle a.
  • a first ray of light 36 emitted from an optical source 30 is incident on the housing 34, when the blade is straight, at a point 38, where the ray 36 passes through the at least partially translucent material of the housing 34.
  • each optical receiver 32a, 32b measures an optical irradiance.
  • the point of incidence 38 of the incident optical ray 36 appears as an effective source - i.e. with respect to each optical receiver 32a, 32b it appears as if the optical light source 30 is located at the point of incidence 38.
  • the irradiance measured by each one of the optical receivers 32a, 32b is dependent on the radial distances r A , r B of each one of the receivers 32a, 32b with respect to the position of the effective optical source - in other words, with respect to the point of incidence 38.
  • a second optical ray 36' which is emitted at a different time to the first optical ray 36, is incident on the housing 34 at a different point of incidence 38', and with respect to the optical receivers 32a, 32b it appears as if the position of the effective optical source has now moved to the point of incidence 38'.
  • each optical receiver 32a, 32b measures a different optical irradiance as the blade tip bends.
  • the blade tip bending angle a may then be determined as described previously on the basis of the measured optical irradiances.
  • the protective housing 34 is advantageous in that it protects the optical receivers 32a, 32b from environmental pollutants, such as dust which could result in erroneous results.
  • any dust present on the protective housing 34 will have a substantially uniform impact on the measurements of both optical receivers 32a, 32b, and will not adversely affect results.
  • environmental pollutants such as dust present on one of the optical receivers may have an effect on the irradiances measured by the affected optical receiver, which could result in erroneous results, and may lead to inaccurately calculated blade tip bending angles a.
  • Placing the optical receivers 32a, 32b within the same protective housing reduces the effect environmental pollutants have on the calculated blade tip bending angles or, and also reduces the amount of maintenance required to ensure accurate results.
  • the housing 34 may be constructed of any material which is at least partially translucent, such that at least a portion of any incident light passes through the housing.
  • the housing may be constructed of a transparent plastic such as Perspex, or of glass.
  • the housing 32 may be constructed of a scattering material, which is arranged in use to scatter light incident on it through a range of different angles as the incident light propagates through the material. This helps to ensure a more uniform distribution of light within the housing, and is particularly useful where a laser is used as the light source.
  • the present method may be used to calculate the blade bending angle for a wind turbine comprising any number of turbine blades.
  • all herein described embodiments may work with any type of EM radiation source, having any type of propagation wave, including localised Gaussian waves, such as provided by lasers, or alternatively circular waves, as provided by an LED for example.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Combustion & Propulsion (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Electromagnetism (AREA)
  • Sustainable Energy (AREA)
  • Sustainable Development (AREA)
  • Wind Motors (AREA)

Abstract

La présente invention concerne un procédé et un système permettant de déterminer un paramètre indicatif d'une déviation de pale et/ou d'une charge de pale. Une source efficace d'un rayonnement électromagnétique (EM) est agencée pour transmettre un signal de rayonnement EM et un récepteur est agencé pour recevoir le signal de rayonnement EM. Le récepteur est espacé de la source efficace dans le sens de l'envergure de la pale. La source efficace et le récepteur sont agencés de telle sorte que la déviation de la pale entraîne une variation de la distance en ligne droite entre la source efficace et le récepteur. Un paramètre indicatif d'une déviation de pale et/ou d'une charge de pale sur la base de l'éclairement énergétique du signal de rayonnement EM reçu par le récepteur est déterminé.
PCT/DK2015/050159 2014-06-13 2015-06-11 Perfectionnements apportés à des éoliennes WO2015188835A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DKPA201470353 2014-06-13
DKPA201470353 2014-06-13

Publications (1)

Publication Number Publication Date
WO2015188835A1 true WO2015188835A1 (fr) 2015-12-17

Family

ID=53385425

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK2015/050159 WO2015188835A1 (fr) 2014-06-13 2015-06-11 Perfectionnements apportés à des éoliennes

Country Status (1)

Country Link
WO (1) WO2015188835A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112943562A (zh) * 2021-04-12 2021-06-11 上海电气风电集团股份有限公司 风力发电机组的叶片、检测装置及方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110150647A1 (en) * 2009-12-17 2011-06-23 Roland Gierlich Detection of Deformation of a Wind Turbine Blade
US20120132012A1 (en) * 2010-11-25 2012-05-31 Baumer Innotec Ag Means and process for measuring the deformation of a rotor blade under stress
DE102012110477A1 (de) * 2012-11-01 2014-05-08 Bachmann Monitoring GmbH Verfahren und System zur Messung einer Auslenkung eines Hohlbauteils einer Windenergieanlage aus einer Normalposition

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110150647A1 (en) * 2009-12-17 2011-06-23 Roland Gierlich Detection of Deformation of a Wind Turbine Blade
US20120132012A1 (en) * 2010-11-25 2012-05-31 Baumer Innotec Ag Means and process for measuring the deformation of a rotor blade under stress
DE102012110477A1 (de) * 2012-11-01 2014-05-08 Bachmann Monitoring GmbH Verfahren und System zur Messung einer Auslenkung eines Hohlbauteils einer Windenergieanlage aus einer Normalposition

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112943562A (zh) * 2021-04-12 2021-06-11 上海电气风电集团股份有限公司 风力发电机组的叶片、检测装置及方法
CN112943562B (zh) * 2021-04-12 2022-05-31 上海电气风电集团股份有限公司 风力发电机组的叶片、检测装置及方法

Similar Documents

Publication Publication Date Title
US10094359B2 (en) Improvements relating to wind turbines
US10655601B2 (en) Method for the individual pitch control of rotor blades of a wind turbine, and wind turbines
CN203100688U (zh) 一种测量旋转叶片叶尖间隙的光纤传感器
US10422321B2 (en) Method for monitoring a wind turbine, method for identifying ice on a wind turbine, acceleration sensor for a rotor blade, rotor blade comprising an acceleration sensor, and profile for a rotor blade
US8989538B2 (en) Sensor element and method for the production thereof and use thereof
EP2798207B1 (fr) Turbine éolienne et procédé de détermination de la présence et/ou de l'épaisseur d'une couche de glace sur un corps de pale d'une turbine éolienne
US20200132052A1 (en) Strain and vibration measuring system for monitoring rotor blades
US10175167B2 (en) Optical sensor for detecting accumulation of a material
US10697440B2 (en) Method of detecting damage of wind turbine blade, and wind turbine
CN103370802B (zh) 一种半导体发光元件用光接收模块以及半导体发光元件用检测装置
US10816425B2 (en) Fibre-optic pressure sensor having an optical resonator and a method for pressure measurement
WO2015188835A1 (fr) Perfectionnements apportés à des éoliennes
CN110794378A (zh) 用于检测对象的激光雷达设备
CN207487747U (zh) 激光多普勒气体流量计
US8381599B2 (en) Wind energy installation comprising a wind speed measuring system
US10487800B2 (en) Wind turbines
WO2015070870A1 (fr) Perfectionnements apportés à des éoliennes
CN101319917A (zh) 光学式传感器
US20240003676A1 (en) Thz sensor and thz method for measuring an object to be measured
Brostilov et al. Special features of structural design for a fiber-optic microdisplacement transducer
CN116242265A (zh) 检测风力设备转子叶片的至少一个第一扭转的传感器组件
US20160138971A1 (en) Monitoring Apparatus for a Laser Beam
KR20110115710A (ko) 반사형 광온도센서

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 15728402

Country of ref document: EP

Kind code of ref document: A1

122 Ep: pct application non-entry in european phase

Ref document number: 15728402

Country of ref document: EP

Kind code of ref document: A1