Abstract: A yaw sensor for a wind turbine comprises a plurality of rotary switches, each configured to be coupled to a yaw drive gearbox of a wind turbine nacelle, the rotary switches each being operable to activate and deactivate respective associated electrical contacts in dependence on an amount of yaw rotation of the nacelle relative to a start position. Each electrical contact is active at a plurality of first yaw rotation ranges with respect to the start position, and inactive at a plurality of second yaw rotation ranges with respect to the start position, the first and second yaw rotation ranges being interleaved.

Abstract: A yaw sensor for a wind turbine is described. The yaw sensor comprises a rotary switch, configured to be coupled to a yaw drive gearbox of a wind turbine nacelle, the rotary switch being operable to activate and deactivate an electrical contact in dependence on an amount of yaw rotation of the nacelle relative to a start position. The electrical contact is active at a plurality of first yaw rotation ranges with respect to the start position, and inactive at a plurality of second yaw rotation ranges with respect to the start position, the first and second yaw rotation ranges being interleaved, at least some of the first yaw rotation ranges having different lengths from each other and/or at least some of the second yaw rotation ranges having different lengths from each other. The electrical contact generates an electrical signal when active.

Abstract: A yaw sensor for a wind turbine is described. The yaw sensor comprises a rotary switch, configured to be coupled to a yaw drive gearbox of a wind turbine nacelle, the rotary switch being operable to activate and deactivate an electrical contact in dependence on an amount of yaw rotation of the nacelle relative to a start position. The electrical contact is active at a plurality of first yaw rotation ranges with respect to the start position, and inactive at a plurality of second yaw rotation ranges with respect to the start position, the first and second yaw rotation ranges being interleaved, at least some of the first yaw rotation ranges having different lengths from each other and/or at least some of the second yaw rotation ranges having different lengths from each other. The electrical contact generates an electrical signal when active.

Abstract: The present invention provides a method of operating a wind turbine. The wind turbine comprises at least one rotatable blade. The method comprises the steps of providing a load sensor configured to generate a load signal representing loading on the blade, generating a first load signal when the blade is in a first position, and generating a second load signal when the blade is in a second position. Additionally, the method comprises steps of detecting a rotational speed of the blade, calculating a weight force on the blade based on the first and the second load signal, and calculating a centrifugal force on the blade based on the first and the second load signal. Subsequently, the weight force is compared with a predetermined weight force, and the centrifugal force is compared with a predetermined centrifugal force at the detected rotational speed. Finally, a risk of ice throw is determined based on the comparisons of the weight force and the centrifugal force with the predetermined forces.

Abstract: A method of determining a twist angle of a wind turbine blade, the method comprising providing first and second transmitters on the wind turbine blade, the first transmitter being spaced apart from a receiver by a first distance, and the second transmitter being spaced 5 apart from the receiver by a second distance, the transmitters being arranged such that twisting of the blade causes an increase in one of the first or second distances and a decrease in the other of the first or second distances; transmitting a blinking signal from each of the first and second transmitters towards the receiver, the blinking signals having a blinking frequency; varying the blinking frequency of the blinking signals; monitoring the 10 amplitude of the blinking signal received by the receiver as the blinking frequency is varied; determining a particular blinking frequency that results in an increased amplitude of the blinking signal received by the receiver; and using the determined particular blinking frequency to calculate th

Abstract: A method of determining torsional deformation in a drivetrain e.g. of a wind turbine. To provide a reliable and simple deformation assessment, the method comprises the step of generating a first signal representing first rotational speed of a low speed shaft, generating a second signal representing the second rotational speed of a high speed shaft, and determining torsional deformation based on changes in the ratio between the first and second signals.

Abstract: Improvements Relating to Wind Turbines A wind turbine apparatus and a method of operating said wind turbine to maintain the load on the rotor blade below a predetermined threshold level is provided. The method comprises: measuring load at a root end of the rotor blade; measuring an acceleration at a location on the rotor blade outboard from the root end, the acceleration being caused by transient loads acting on the rotor blade; and controlling the wind turbine based upon the measured load and the measured acceleration to maintain the load on the rotor blade below a predetermined threshold level.

Abstract: A method of determining a twist angle of a wind turbine blade, the method comprising providing first and second transmitters on the wind turbine blade, the first transmitter being spaced apart from a receiver by a first distance, and the second transmitter being spaced 5 apart from the receiver by a second distance, the transmitters being arranged such that twisting of the blade causes an increase in one of the first or second distances and a decrease in the other of the first or second distances; transmitting a blinking signal from each of the first and second transmitters towards the receiver, the blinking signals having a blinking frequency; varying the blinking frequency of the blinking signals; monitoring the 10 amplitude of the blinking signal received by the receiver as the blinking frequency is varied; determining a particular blinking frequency that results in an increased amplitude of the blinking signal received by the receiver; and using the determined particular blinking frequency to calculate th

Abstract: A yaw sensor for a wind turbine comprises a plurality of rotary switches, each configured to be coupled to a yaw drive gearbox of a wind turbine nacelle, the rotary switches each being operable to activate and deactivate respective associated electrical contacts in dependence on an amount of yaw rotation of the nacelle relative to a start position. Each electrical contact is active at a plurality of first yaw rotation ranges with respect to the start position, and inactive at a plurality of second yaw rotation ranges with respect to the start position, the first and second yaw rotation ranges being interleaved.

Abstract: To identify abnormal behavior in a turbine blade, a failure detection system generates a “fingerprint” for each blade on a turbine. The fingerprint may be a grouping a dynamic, physical characteristics of the blade such as its mass, strain ratio, damping ratio, and the like. While the turbine is operating, the failure detection system receives updated sensor information that is used to determine the current characteristics of the blade. If the current characteristics deviate from the characteristics in the blade's fingerprint, the failure detection system may compare the characteristics of the blade that deviates from the fingerprint to characteristics of another blade on the turbine. If the current characteristics of the blade are different from the characteristics of the other blade, the failure detection system may change the operational mode of the turbine such as disconnecting the turbine from the utility grid or stopping the rotor.

Abstract: The present invention relates to a method and to a wind turbine for determining the tip angle of a blade of a wind turbine rotor during rotation of the rotor. The method comprising: (a) transmitting a light signal from a first blade of the wind turbine rotor towards a second blade of the rotor; (b) receiving the light signal at the second blade of the rotor; and (c) calculating the tip angle of the first or second blade based upon characteristics of the received light signal.

Abstract: Improvements Relating to Wind Turbine Sensors A sensor apparatus for a wind turbine is described. The apparatus comprises a sensor and a heating system. The heating system comprises an optical fibre arranged to transmit electromagnetic radiation from a light source to the sensor. The sensor is irradiated by the electromagnetic radiation thereby heating the sensor and preventing or reducing ice accretion.

Abstract: A method of determining torsional deformation in a drivetrain e.g. of a wind turbine. To provide a reliable and simple deformation assessment, the method comprises the step of generating a first signal representing first rotational speed of a low speed shaft, generating a second signal representing the second rotational speed of a high speed shaft, and determining torsional deformation based on changes in the ratio between the first and second signals.

Abstract: The present invention provides a method of operating a wind turbine. The wind turbine comprises at least one rotatable blade. The method comprises the steps of providing a load sensor configured to generate a load signal representing loading on the blade, generating a first load signal when the blade is in a first position, and generating a second load signal when the blade is in a second position. Additionally, the method comprises steps of detecting a rotational speed of the blade, calculating a weight force on the blade based on the first and the second load signal, and calculating a centrifugal force on the blade based on the first and the second load signal. Subsequently, the weight force is compared with a predetermined weight force, and the centrifugal force is compared with a predetermined centrifugal force at the detected rotational speed. Finally, a risk of ice throw is determined based on the comparisons of the weight force and the centrifugal force with the predetermined forces.

Abstract: A method of determining the shape of at least part of a wind turbine blade during operation of the wind turbine, the method comprising measuring first and second values of acceleration at one or more locations on the blade, the first and second values of acceleration being in substantially mutually perpendicular directions, and determining a shape parameter of the blade based upon the relative magnitudes of the measured first and second values of acceleration at the one or more locations.

Abstract: The rotor blades of a wind turbine each have a plurality of fiber-optic pressure variation sensors which can detect the onset of a stall condition. The output of the stall condition sensors is input to a stall count circuit which increases a stall count signal each time a stall indication is received. The stall count signal is decayed exponentially over time and the current signal is summed with the decayed signal from a previous sampling period to form a value from which a stall margin is determined. An ?:? curve of tip speed to wind speed ratio ? against pitch angle reference ? is then determined from the stall margin.

Abstract: The invention provides a wind turbine blade comprising a first shell, having a first bonding region, and a second shell having a second bonding region, wherein the second bonding region of the second shell is bonded to the first bonding region of the first shell; and a temperature sensor positioned between the first bonding region and the second bonding region. Having a temperature sensor positioned within the turbine blade, in the region at which the two shells of the turbine blade are bonded together, allows for accurate determination and control of the temperature of the critical bonding regions during blade manufacture. The temperature sensor may be used during the service life of the wind turbine blade to detect delamination of the wind turbine blade.

Abstract: The invention provides a method and system of detecting ice or other foreign matter on a wind turbine blade or damage to a wind turbine blade. The method in one aspect comprises: measuring twisting torque on the blade about its longitudinal axis to provide a detected torque signal; comparing a value based on the detected torque signal with a comparison value, the comparison value derived from one or more measured parameters having a predetermined relationship with the twisting torque about the longitudinal axis of the blade when the blade is operating under normal operating conditions; and determining that ice or other foreign matter is on the blade or that the blade is damaged if the value based on the detected torque signal differs from the comparison value by more than a predetermined amount. Wind turbine blades are designed such that any change in the shape of the blade reduces twisting torque on the blades significantly.

Abstract: A sensor system for measuring an operating parameter of a wind turbine component is described. The fiber optic sensor system comprises a light source for outputting light in a predetermined range of wavelengths, and an optical fiber comprising a long Fiber Bragg Grating, extending continuously over a length of the optical fiber to provide a continuous measurement region in the optical fiber. The optical fiber is coupled to the wind turbine component such that the continuous measurement region is located at a region of the wind turbine component to be sensed, and such that the grating period at each location in the continuous measurement period is dependent upon the value of the operating parameter at that location. A light detector receives light from the optical fiber, and provides an output signal to the controller indicating the intensity of the received light; based on the detected light, a value for the operating parameter is determined.

Abstract: A wind energy power plant optical vibration sensor is described, using two light sources 15, 16 that emit light at different respective frequencies. The light from the first light source falls on a surface 44 of the wind energy power plant at a detection site. Movements in the surface result in changes to the phase of the light reflected back from the surface which can be detected by mixing the first light with the light emitted from the second light source. The difference in frequencies between the two light sources results in a beating of the resulting interference signal, whereas movements in the sensor surface result in changes in the phase timing and frequency of the beats.