Method for determining temperature of heating element of wind turbine blade

Abstract

A method of determining a temperature of a heating element (210) of a wind turbine blade (200) includes heating the heating element by providing a heating current in the heating element. The method comprises measuring, at a first time, a first value (I1) of the heating current. The method comprises determining a first temperature (T1) of the heating element using a measured first value of the heating current and a known functional correlation (410) between the heating current in the heating element and the temperature of the heating element.

Description

Technical Field

[0001] The present subject matter generally relates to heating elements disposed in one or more rotor blades of a wind turbine, such as for the purpose of de-icing the blades. More specifically, embodiments described herein relate to methods for determining a temperature of a heating element of a wind turbine blade during operation of the heating element. Background Art

[0002] Wind power is considered to be one of the cleanest and most environmentally friendly energy sources currently available, and in this regard, wind turbines have received increasing attention. A modern wind turbine typically includes: a tower, a generator, a gearbox, a nacelle, and a rotor with one or more rotor blades. The rotor blades capture kinetic energy from the wind using the known foil principle and transmit the kinetic energy through rotational energy to rotate a shaft that couples the rotor blades to a gearbox, or directly to a generator if a gearbox is not used. The generator then converts the mechanical energy into electrical energy, which can be deployed to a utility grid.

[0003] During operation of a wind turbine, the rotor blades may experience very cold temperatures. As a result, ice may form on the blades, which may reduce the performance of the wind turbine, or cause failure of some of the wind turbine components. In order to remove ice from wind turbine blades, or to prevent ice formation, the wind turbine blades may include one or more heating elements.

[0004] In order to provide optimal operation of such a heating element, it may be beneficial to monitor the temperature of the heating element as it heats up. The determined temperature may be used to prevent, for example, the heating element from becoming overheated, since excessive temperatures may, for example, reduce the life of the heating element.

[0005] In order to determine the temperature of the heating element, a temperature sensor may be installed in the wind turbine blade. Some sensors may provide an accurate determination of the temperature. However, such sensors may have the disadvantage that they are expensive and that they further complicate the design of the wind turbine blade.

[0006] Therefore, there is a need for an improved method for determining the temperature of a heating element of a wind turbine blade. Summary of the invention

[0007] Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0008] According to one embodiment, a method of determining a temperature of a heating element of a wind turbine blade is provided. The method comprises: heating the heating element by providing a heating current in the heating element. The method comprises: measuring a first value of the heating current at a first time. The method comprises: determining a first temperature of the heating element using the measured first value of the heating current and a known functional dependency between the heating current in the heating element and the temperature of the heating element.

[0009] According to another embodiment, a system for determining a temperature of a heating element of a wind turbine blade is provided. The system includes a current sensor for measuring a first value of a heating current provided in the heating element at a first time. The system includes a controller configured to determine a first temperature of the heating element using the measured first value of the heating current and a known functional correlation between the heating current in the heating element and the temperature of the heating element.

[0010] According to another embodiment, a wind turbine is provided. The wind turbine includes a rotor having wind turbine blades, the wind turbine blades including heating elements. The wind turbine includes a power supply for supplying a heating current to the heating element. The wind turbine includes a system for determining a temperature of a heating element according to embodiments described herein.

[0011] According to another embodiment, a computer program product or non-transitory computer-readable storage medium is provided. The computer program product or non-transitory computer-readable storage medium includes instructions that, when executed by one or more processors of the system, cause the system to determine a first temperature of a heating element using: a measured first value of a heating current provided in the heating element, and a known functional correlation between the heating current in the heating element and the temperature of the heating element. The computer program product or non-transitory computer-readable storage medium may be configured to undertake any (one or more) operations performed by the controller for determining the temperature of the heating element according to the method described herein.

[0012] According to another embodiment, a method for determining a performance degradation characteristic of a heating element of a wind turbine blade is provided. The method includes applying a voltage to the heating element to provide a heating current in the heating element for heating the heating element, wherein the heating current is provided during a heating cycle of the heating element. The method includes performing a cold measurement of the heating current at an initial stage of the heating cycle before the heating current causes the heating element to heat up significantly, wherein the cold measurement produces a measured value of the heating current. The method includes determining a performance degradation characteristic of the heating element using the measured value of the heating current and the applied voltage.

[0013] These and other features, aspects and advantages of the present invention will be further supported and described with reference to the following description and appended claims.The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and together with the description serve to explain the principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] A full and enabling disclosure of the invention is set forth in the specification, which is directed to one of ordinary skill in the art, including the best mode thereof, and which refers to the accompanying drawings, in which: Figure 1 An example of a wind turbine is illustrated; Figure 2-3 A wind turbine blade is shown, the wind turbine blade comprising a heating element; Figure 4 The functional dependence of the heating current in the heating element on the temperature of the heating element is illustrated; Figure 5 shows a test heating element which may be used in a testing phase as described herein; Figure 6 illustrates the collection of measurement data during a test phase for determining a functional dependence between a heating current in a heating element and a temperature of the heating element; and Figure 7 A wind turbine is shown, the wind turbine comprising a current sensor for measuring a heating current in a heating element.

[0015] Individual features depicted in the figures are shown relative to each other and, therefore, are not necessarily shown to scale. Similar or identical elements in the figures are denoted by the same reference numerals even if shown in different embodiments. DETAILED DESCRIPTION

[0016] Reference will now be made in detail to embodiments of the present invention, one or more examples of which are illustrated in the drawings. Each embodiment is provided by way of explanation of the present invention and should not limit the present invention. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made in the present invention without departing from the scope or spirit of the present invention, for example, features illustrated or described as part of one embodiment may be used together with another embodiment to produce yet another embodiment. Therefore, the present invention is intended to cover such modifications and variations within the scope of the appended claims and their equivalents.

[0017] Figure 11 is a perspective view of a portion of an exemplary wind turbine 100. In the exemplary embodiment, wind turbine 100 is a horizontal axis wind turbine. Alternatively, wind turbine 100 may be a vertical axis wind turbine. Wind turbine 100 may include a nacelle 102 that may house a generator ( Figure 1 The nacelle 102 may be mounted on a tower 104 of the wind turbine 100 ( Figure 1 104). Tower 104 may have any suitable height that facilitates operation of wind turbine 100 as described herein. Wind turbine 100 may include rotor 106. Rotor 106 may include three wind turbine blades 108, which may be attached to hub 110. Hub 110 may be a rotating hub. Alternatively, wind turbine 100 includes any number of blades 108 that facilitates operation of wind turbine 100 as described herein. In the exemplary embodiment, wind turbine 100 includes a gearbox ( Figure 1 not shown) and a generator ( Figure 1 ), a gearbox is operatively coupled to the rotor 106 .

[0018] Rotor blades 108 may be spaced about hub 110 to facilitate rotating rotor 106 to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy.

[0019] In one embodiment, rotor blades 108 may have a length ranging from about 15 meters (m) to about 91 m. Alternatively, rotor blades 108 may have any suitable length that enables wind turbine 100 to function as described herein. For example, other non-limiting examples of blade lengths include: 20 m or less, 37 m, 48.7 m, 50.2 m, 52.2 m, or a length greater than 91 m. As wind strikes rotor blades 108 from wind direction 28, rotor 106 rotates about axis of rotation 30. As rotor blades 108 rotate and are subjected to centrifugal forces, rotor blades 108 are also subjected to various forces and moments. Thus, rotor blades 108 may deflect and / or rotate from a neutral position or a non-deflected position to a deflected position.

[0020] Additionally, the pitch angle of rotor blades 108 (i.e., the angle that determines the perspective of rotor blades 108 relative to the wind direction) may be varied by pitch system 109 to control loads and power generated by wind turbine 100 by adjusting the angular position of at least one rotor blade 108 relative to the wind vector. During operation of wind turbine 100, pitch system 109 may vary the pitch angle of rotor blades 108 such that rotor blades 108 move to a feathered position such that the perspective of at least one rotor blade 108 relative to the wind vector provides a minimum surface area of ​​rotor blade 108 oriented toward the wind vector, which facilitates reducing the rotational speed and / or facilitating stalling of rotor 106.

[0021] The blade pitch of each rotor blade 108 may be individually controlled by wind turbine controller 202 or by a pitch control system. Alternatively, the blade pitch for all rotor blades 108 may be controlled simultaneously by the control system.

[0022] Furthermore, in the exemplary embodiment, as wind direction 28 changes, the yaw direction of nacelle 102 may be rotated about yaw axis 38 by yaw system 105 to position rotor 106 relative to wind direction 28. Yaw system 105 may include a yaw drive mechanism provided by nacelle 102. Furthermore, yaw system 105 may also be controlled by wind turbine controller 202.

[0023] In order to properly position the nacelle 102 with respect to the wind direction 28, and to detect wind speed, the nacelle 102 may also include at least one meteorological mast 107, which may include a wind vane and anemometer. The mast 107 may provide information about environmental conditions to the wind turbine controller 202. This may include: wind direction and / or wind speed, as well as ambient temperature, ambient humidity, precipitation type and / or precipitation amount (if any precipitation).

[0024] In the exemplary embodiment, wind turbine controller 202 is shown as being centralized within nacelle 102, however, wind turbine controller 202 may be a distributed system that is distributed throughout wind turbine 100, on the support system ( Figure 1 ), within the wind farm and / or at a remote control center. The wind turbine controller 202 includes a processor and may be configured to perform the methods and / or steps described herein.

[0025] During operation of a wind turbine, the wind turbine (and in particular, the rotor blades) may experience severe weather conditions, such as low temperatures. For example, ice may accumulate on the wind turbine blades. The formation of ice on the rotor blades may be detrimental to the operation of the wind turbine. For example, the power generation of the wind turbine may decrease due to ice.

[0026] In one or more rotor blades of a wind turbine, a heating element or a plurality of heating elements may be provided. The heating element may be used to heat the wind turbine blade or a portion thereof, for example for de-icing the wind turbine blade. De-icing may include removing ice formed on the wind turbine blade and preventing ice from forming on the wind turbine blade. The heating element may be an electrically conductive element which is heated by passing an electric current or a heating current through at least a portion of the heating element.

[0027] Figures 2 to 3 An example of a wind turbine blade 200 (i.e., a rotor blade) is shown, and the wind turbine blade 200 includes a heating element 210. The wind turbine blade 200 may be a rotor blade 108 as described herein. In the example shown, two heating elements 210 are provided, but the present disclosure is not limited thereto. The wind turbine blade 200 may include a single heating element 210, or more than two heating elements 210. The (one or more) heating elements may be at least partially embedded in an inner portion of the wind turbine blade 200. In some embodiments, the heating element 210 may be a thin sheet material, such as a textile material. The heating element 210 may be a heating pad. The heating element 210 may have an elongated shape, which may, for example, extend over a portion of the wind turbine blade 200 along the length direction of the wind turbine blade 200. The heating element 210 (such as a heating pad) may include carbon or be formed of carbon. For example, the heating element may include a carbon fabric layer, or may be a carbon fabric layer.

[0028] The wind turbine may include a power source 220 for supplying current to the heating elements 210. One power source 220 may provide power to multiple heating elements 210 of the same wind turbine blade. Alternatively, several power sources 220 may be provided, and each heating element 210 may receive current from a respective power source 220. The wind turbine blade 200 may include one or more cables 222 connecting the heating elements 210 to the power source 220.

[0029] The power supply 220 for supplying current to the heating element 210 may be arranged, for example, in or near the hub of the wind turbine. The power supply 220 may be arranged in the hub near the proximal end 250 of the wind turbine blade 200. The present disclosure is not limited thereto, and the power supply 220 may be disposed at other locations suitable for providing power to the heating element 210.

[0030] In operation, the power source 220 may apply a voltage to the heating element 210 to provide an electric current or heating current in the heating element 210 for heating the heating element 210, for example, for de-icing at least a portion of the wind turbine blade 200. The heating element 210 may be a resistive element that becomes heated due to the heating current in the heating element 210.

[0031] The heating of the heating element 210 may be a controlled heating controlled by a controller 230 of the wind turbine. Under the control of the controller 230, the magnitude of the heating current in the heating element may be controlled, and thus the temperature of the heating element 210 may be controlled. The controller 230 may be arranged, for example, in the hub of the wind turbine. The present disclosure is not limited thereto, and the controller 230 may be arranged in other locations. The controller 230 may be part of a general wind turbine controller, or may be a separate controller. The controller 230 may be Figure 1 2. The wind turbine controller 202 is shown in FIG.

[0032] It may be beneficial to determine the temperature of the heating element 210 during operation (i.e., the temperature of the heating element caused by the heating current in the heating element). For example, if the temperature of the heating element 210 exceeds a certain upper limit, the operation of the heating element 210 may not be optimal. If the heating element is operated at too high a temperature, the life and / or performance of the heating element 210 may be reduced. In some embodiments, the temperature of the heating element 210 may be facilitated by applying a known voltage to the heating element (e.g., by a power supply 220 as described herein). However, even in such cases, the heating element 210 may experience temperature changes that are unknown a priori, and accurate temperature determination may be beneficial.

[0033] Embodiments described herein provide a method for determining the temperature of a heating element 210, such as a carbon heating pad, during operation of the heating element. Advantageously, embodiments described herein do not require a separate temperature sensor to be installed in the wind turbine blade for determining the temperature of the heating element 210. Instead, the heating element 210 itself is used as a sensor to determine its temperature. According to embodiments described herein, the temperature of the heating element 210 is determined based on a functional correlation between the magnitude of the heating current in the heating element 210 and the temperature of the heating element 210.

[0034] Figure 4An example of a functional correlation 410 between a heating current provided in a heating element 210 and a temperature of the heating element 210 is shown. The temperature of the heating element 210 may, for example, be an average temperature of the heating element 210 associated with a plurality of locations on the heating element 210. The functional correlation 410 may relate the magnitude of the heating current provided in the heating element 210 to the corresponding temperature of the heating element 210. The functional correlation may include a set of possibly continuous points, each point having the form of (T, I), where T is the temperature of the heating element and I is the corresponding heating current in the heating element 210.

[0035] exist Figure 4 In the example shown in FIG. 4 , the functional dependence 410 is a linear dependence. The heating current shown on the vertical axis 402 is a linear function of the temperature of the heating element 210 (shown on the horizontal axis 404). For example, the functional dependence 410 between the heating current I and the temperature T may have the following form: I=I 最小 +α(TT 最小 ), where I 最小 and T 最小 are constants representing the minimum heating current and the corresponding minimum temperature, and α is a constant representing Figure 4 The coefficient of the slope of the linear curve shown in . The present disclosure is not limited in this regard. Functional correlation 410 can be different kinds of correlations, such correlations that are only approximately linear, or correlations that have at least one or more nonlinear parts, etc.

[0036] exist Figure 4 In the example shown in FIG. 4 , the functional dependency 410 is a continuous function, which is the minimum current I 最小 With the maximum current I 最大 Each current between provides a corresponding temperature value - or equivalently, a minimum temperature T 最小 With the maximum temperature T 最大 Each temperature between provides a corresponding value of the heating current. The present disclosure is not limited thereto. Function correlation 410 may be, for example, a discrete function. For example, function correlation 410 may be composed of a set of finite points (T1, I1), ..., (T N ,I N ) each providing a temperature and a corresponding heating current. As another example, the functional correlation 410 may include a combination of a continuous portion and a discrete portion.

[0037] According to the embodiments described herein, the functional dependence 410 is known. The functional dependence 410 may be determined in advance in a test phase, wherein information about the relationship between the heating current and the temperature of the heating element 210 is collected by performing measurements. This will be described in more detail below.

[0038] During operation of the heating element 210, the magnitude (or value) of the heating current in the heating element 210 may be measured. Using the functional correlation 410, the temperature of the heating element 210 corresponding to the magnitude may be determined. Figure 4 According to the linear function correlation 410 shown in FIG. 4 , once the magnitude of the heating current corresponding to the value I1 on the vertical axis 402 has been measured, the corresponding value T1 of the temperature on the horizontal axis 404 can be determined.

[0039] As described above, the embodiments described herein allow the temperature of the heating element 210 to be determined without installing a separate temperature sensor in the wind turbine blade.The heating element 210 itself is used as a sensor to determine the temperature of the heating element.

[0040] Furthermore, the temperature of the heating element 210 may be determined without measuring or otherwise determining the resistance (or impedance) of the heating element. The information provided by the functional correlation between the heating current and the temperature may be sufficient to determine the temperature of the heating element. In particular, it may not be necessary to measure the voltage across the heating element 210 for determining the temperature of the heating element 210. The embodiments described herein allow the temperature of the heating element 210 to be determined based solely on the measurement of the heating current without measuring the voltage or resistance of the heating element.

[0041] In view of the above, according to one embodiment, a method of determining a temperature of a heating element of a wind turbine blade is provided. The method includes: heating the heating element by providing a heating current in the heating element. The method includes: measuring a first value of the heating current at a first time. The method includes: determining a first temperature of the heating element using the measured first value of the heating current and a known functional correlation between the heating current in the heating element and the temperature of the heating element.

[0042] According to embodiments described herein, a first temperature of the heating element is determined without determining a resistance or impedance of the heating element.

[0043] As described herein, a heating element of a wind turbine blade may be electrically conductive. The heating element may include carbon or another conductive material. The heating element may be a thin piece of material, such as a composite material in sheet form. The heating element may be a heating mat of a wind turbine blade, such as a carbon heating mat.

[0044] A heating current as described herein may be understood as an electric current passing through a heating element to heat the heating element. The effect of the heating current is to heat the heating element, for example for de-icing a wind turbine blade, the heating element forming part of the wind turbine blade. By providing a heating current in the heating element, the heating element may be heated by ohmic heating. In other words, the heating element may act as a resistor, which becomes hotter by passing a heating current through the heating element. The method described herein may include applying a voltage to the heating element to provide a heating current in the heating element.

[0045] The first value of the heating current may be measured by a current sensor as described herein.

[0046] A heating element as described herein may be configured for de-icing a wind turbine blade (or at least a portion thereof) in which the heating element is mounted. A heating current in the heating element may be configured to heat the heating element to a temperature sufficient for de-icing the wind turbine blade. For example, the heating current may heat the heating element to a temperature of 5 degrees (Celsius) or more, in particular 10 degrees or more. The heating current may have a magnitude of 40 A (amperes) or more, 50 A or more, for example, such as from 52.5 A to 53.5 A, in particular from 53 A to 53.5 A.

[0047] The concept of functional correlation or functional relationship between the heating current provided in the heating element and the temperature of the heating element can be understood as the relationship between the magnitude of the heating current flowing through the heating element and the temperature of the heating element corresponding to the magnitude of the heating current. For example, the functional correlation may have the form of a function I(T), where T represents the temperature of the heating element, and I represents the corresponding magnitude of the heating current flowing through the heating element at temperature T. Equivalently, the functional correlation may be a function T(I), which represents that the temperature T of the heating element is a function of the magnitude of the heating current I flowing through the heating element. The present disclosure is not limited to the examples mentioned above, and the functional correlation may take other forms.

[0048] The function correlation is "known" in the sense that it has been predetermined and is available for review, for example, by a controller or a portion of a controller and / or by a human operator. For example, the known function correlation may be stored in a memory, such as a memory of a controller of the wind turbine, or another memory external to the wind turbine, and the memory may be read at an appropriate time when the function correlation is needed for determining the temperature of the heating element as described herein.

[0049] The known functional dependence may be at least approximately a linear dependence or a linear relationship between the heating current and the temperature. For example, the function I(T) described above may be a linear function of the temperature T.

[0050] The functional dependence between heating current and temperature can be obtained from the test phase. Figure 5-6 Such testing phases are illustrated.

[0051] Figure 5 A test heating element 210' is shown. The test heating element 210' may be identical to the heating element 210, i.e., may have the same shape, composition, design, functional properties, etc. During the test phase, the test heating element 210' may be part of a wind turbine blade, or may be a separate component that undergoes a test phase in a laboratory or other test area. The test heating element 210' may be connected to a power supply 220' for supplying a test heating current to the test heating element 210' for heating the test heating element 210'. The test heating element 210' may be connected to at least one current sensor 504 for measuring the magnitude of the test heating current in the test heating element 210'. For example, the at least one current sensor 504 may include a Rogowski Coil. The test heating element 210' may be connected to at least one temperature sensor 502 for measuring the temperature of the test heating element 210'. For example, the temperature sensor 502 may include a microintegrated circuit, such as a microintegrated circuit with negligible thermal mass.

[0052] The test phase may include providing a test heating current in the test heating element 210' using the power supply 220' at a plurality of different values ​​of the test heating current and / or at a plurality of external conditions. For example, at different external conditions, each of the different values ​​of the test heating current may be measured by the at least one current sensor 504. By means of the at least one temperature sensor 502, for each of the different values ​​of the test heating current, a corresponding temperature of the test heating element 210' may be measured. Figure 6 An example of experimental data collected during the test phase is shown. Each data point 602 represents a pair of values ​​(T, I), where I is the magnitude of the test heating current as measured by at least one current sensor 504, and T is the corresponding temperature of the test heating element 210' as measured by at least one temperature sensor 502.

[0053] Using the experimental data collected during the test phase, the functional dependence between the heating current and the temperature of the (test) heating element can be determined, for example by fitting a suitable function to the collected data points. Figure 6 , a functional correlation 410 (eg, a linear functional correlation) may be fitted to the data points. Once the functional correlation 410 has been determined, the functional correlation 410 may be stored and used (and reused) for determining the temperature of the heating element 210 in the manner described herein.

[0054] According to embodiments described herein, the test phase may include heating a test heating element of a wind turbine blade or a test heating element for a wind turbine blade by providing a test heating current in the test heating element. The test heating element may be a heating element with similar or even identical properties to the heating element described herein. In particular, the test heating element may be a carbon heating pad. The test heating current may be a current configured for heating the heating element, e.g. for de-icing, similar to the heating current provided in the heating element as described herein.

[0055] The test phase may include: measuring multiple values ​​of the test heating current and corresponding values ​​of the temperature of the test heating element at different times. For each measured value or magnitude of the test heating current, the value of the temperature of the test heating element corresponding to the value of the test heating current may be measured. For example, 10 or more, 50 or more, or even 80 or more values ​​of the test heating current may be measured, as well as corresponding values ​​of the temperature. The test heating current may be measured by one or more first sensors, such as one or more current sensors. One or more first sensors may be connected to the test heating element. One or more second sensors, such as one or more temperature sensors, may be used to measure the temperature of the test heating element. One or more second sensors may be connected to the test heating element.

[0056] The testing phase may include determining a functional correlation between a test heating current provided in the test heating element and a temperature of the test heating element based on a plurality of measured values ​​of the test heating current and a plurality of measured values ​​of the temperature of the test heating element. The functional correlation may be determined by a controller. Determining the functional correlation may include fitting a function or relationship to the plurality of measured values ​​of the test heating current and corresponding measured values ​​of the temperature of the test heating element. For example, a linear function or linear relationship may be fitted to the measurement data.

[0057] Once the functional correlation between the test heating current in the test heating element and the temperature of the test heating element has been determined, the determined functional correlation can then be used as the known functional correlation between the heating current in the heating element and the temperature of the heating element as described herein. That is, the determined functional correlation for the test heating element (e.g., the test heating element 210' shown in the figure) can be a known functional correlation that is used to determine the temperature of the heating element (e.g., the heating element 210 shown in the figure).

[0058] The testing phase may be performed on an offline (not in operation) wind turbine, or even on a test heating element, which is a separate component, which is not installed in the wind turbine or the wind turbine blade.

[0059] Back to Figure 4, refer to the minimum heating current I 最小 and the corresponding minimum temperature T 最小 . Minimum heating current I 最小 Also referred to herein as the cold current value, the cold current value may be the amount of heating current in the heating element 210 before the heating element begins to heat up significantly (e.g., within the first 5-10 seconds of a heating cycle, such as within the first 2 seconds of a heating cycle). 最小 Or the cold temperature is the temperature of the heating element 210 corresponding to the cold current value. For example, the cold temperature may be substantially equal to the ambient temperature of the area surrounding the wind turbine blade.

[0060] Functional dependency 410 may depend on the cold current value I 最小 For example, as described above, the linear function dependency 410 may have the form: I = I 最小 +α(TT 最小 ). ValueI 最小 The determination can be made offline, for example, as part of a test phase described herein, or online, for example, as part of a method for determining the temperature of a heating element according to an embodiment described herein. According to an embodiment described herein, after the value I1 of the heating current in the heating element 210 has been measured, the corresponding value T1 of the temperature of the heating element 210 can be determined from the functional correlation 410 by inputting the measured value of the heating current, the value of the cooling current I 最小 and minimum temperature current value T 最小 , and based on the value, calculate the temperature T.

[0061] According to embodiments described herein, the first temperature of the heating element may be determined using: a measured first value of the heating current, a known functional correlation between the heating current in the heating element and the temperature of the heating element, and a cold current value of the heating current. The cold current value represents the magnitude of the heating current flowing in the heating element at the initial stage (or cold stage) of the heating cycle, before the heating current causes the heating element to heat up significantly, for example when the temperature of the heating element is still below 0 degrees (Celsius), in particular below -5 degrees. For example, the cold current value may be the magnitude of the heating current flowing in the heating element within 5s (seconds) or less, in particular 2s or less, more particularly 1s or less, after the heating cycle has started. The cold current value may be a known, previously determined quantity, for example a quantity obtained as part of a test phase as described herein. Alternatively, the cold current value may be determined as part of the method described herein. For example, the cold current value may be determined in a cold measurement as described herein.

[0062] The measured first value of the heating current may be represented by I1. The cold current value may be represented by I最小 In some embodiments (eg, embodiments in which the heating current I(T) is at least approximately a linear function of the temperature T), the measured first value I1 and the cold current value I of the heating current may be used. 最小 The difference between I1-I 最小 To determine the temperature of the heating element. For example, if the functional dependence as described herein has the form: I = I 最小 +α(TT 最小 ), the temperature can be derived as: T = (II 最小 ) / α+T 最小 , which involves difference II 最小 .

[0063] The methods described herein may include, for example, measuring, at a second time, a second value of the heating current by a current sensor as described herein. In an example, but not limited to, the second time may be before the first time, at which the first value of the heating current is measured. The first time and the second time may belong to the same heating period of the heating element, or the same heating cycle. The second time may be an initial time within the heating cycle, and the first time may be a later time within the same heating cycle.

[0064] As described herein, the first temperature of the heating element may be determined by a controller as described herein, for example, by using a measured first value of the heating current, a measured second value of the heating current, and a known functional correlation between the heating current in the heating element and the temperature of the heating element. The method may include inputting the measured first value and / or the measured second value of the heating current into the known functional correlation, for example using a controller as described herein. The method may include determining or deriving the first temperature from the known functional correlation, in which the measured first value and / or the measured second value have been input. The first temperature may be determined using a controller as described herein.

[0065] The measured first value of the heating current may be represented by I1. The measured second value of the heating current may be represented by I2. In some embodiments (e.g., embodiments in which the heating current I(T) is at least approximately a linear function of the temperature T), the difference I1-I2 between the measured first value I1 of the heating current and the measured second value I2 of the heating current may be used to determine the temperature of the heating element.

[0066] The measurement of the second value of the heating current may be a cold measurement, which is performed at the initial stage (or cold stage) of the heating cycle before the heating current causes the heating element to heat up significantly. In such a case, the second value of the heating current I2 may be the cold current value I as described herein. 最小 .

[0067] Figure 7 A wind turbine according to embodiments described herein is shown. The wind turbine comprises a current sensor 710 for measuring a heating current in the heating element 210. The current sensor 710 may be a current transducer arranged in a hub 110 of the wind turbine.

[0068] According to embodiments described herein, the heating element is part of a wind turbine blade of a wind turbine. The wind turbine may have a hub to which the wind turbine blade is attached. The first value of the heating current and / or the second value of the heating current may be measured by a current sensor, which may be arranged in the hub. The current sensor may be a current transducer, which may be arranged in the hub. The present disclosure is not limited thereto, and other current sensors may be used to measure the heating current. The term "current sensor" as used herein refers to any sensor suitable for measuring the amount of electric current directly or indirectly. For example, the current sensor may be a toroid transducer.

[0069] An advantage of using a current transducer is that such a current transducer may already be installed for normal operation of the heating element, i.e. in the context of the heating function of the heating element, regardless of whether the temperature of the heating element should be determined or not. Using the same current transducer to perform the measurement of the heating current as part of the method for determining the temperature of the heating element means that no additional current sensor needs to be provided.

[0070] As described below, embodiments described herein may include determining a performance degradation characteristic or performance degradation analysis based on a cold measurement of the heating element 210 .

[0071] A method as described herein may include applying a voltage to a heating element to provide a heating current in the heating element, wherein the heating current is provided during a heating cycle of the heating element. The method may include performing a cold measurement of the heating current at an initial stage of the heating cycle, before the heating current causes the heating element to become significantly hot. As described herein, the cold measurement may be performed at a second time. Both the first time and the second time may be within the heating cycle, i.e., within the same heating cycle. The cold measurement may produce a measured value of the heating current. The measured value may be a second value of the measurement of the heating current as described herein. Optionally, the method may include determining a performance degradation characteristic or performance degradation analysis of the heating element using the measured value of the heating current and the applied voltage.

[0072] A performance degradation characteristic or performance degradation analysis of a heating element may be understood as a characteristic or quantity that indicates whether (and more specifically, how much) the heating rate of a heating element has changed or degraded over time. For example, the heating rate may degrade or worsen due to repeated and / or continuous use of the heating element, due to high temperatures generated in the heating element during heating, due to exposure of the heating element to adverse weather conditions such as frost, etc. The performance degradation characteristic may be quantified as to how much the quality of the heating element has degraded due to such factors, which may be known or unknown.

[0073] The performance degradation characteristic may be, or include, a resistance degradation characteristic. The performance degradation characteristic may be, or include, a deviation between the actual resistance of the heating element and a reference resistance of the heating element. As described herein, the actual resistance of the heating element may be the resistance of the heating element at an initial stage or a cold stage of a heating cycle. The actual resistance may be determined based on a cold measurement of the heating current. The reference resistance may be a known quantity. The reference resistance may be the resistance that the heating element is designed to have before the heating element has been put into operation. The reference resistance may be, for example, a factory-defined resistance of the heating element.

[0074] The applied voltage for providing the heating current may be a known voltage, or the method may include measuring the applied voltage. The performance degradation characteristic may be determined using Ohm's law based on the measured value of the heating current and the applied voltage. Determining the performance degradation characteristic may include determining the resistance of the heating element using the measured value of the heating current and the applied voltage. Determining the performance degradation characteristic may include determining a deviation between the determined resistance of the heating element and a reference resistance.

[0075] The determination of the performance degradation characteristic may be part of the method for determining the temperature of a heating element as described herein. The determination of the performance degradation characteristic is an optional part of the temperature determination method, which may be omitted. According to an embodiment, the determination of the performance degradation characteristic as described herein may be a stand-alone method in its own right, that is, regardless of whether the method for determining the temperature of a heating element is performed.

[0076] According to another embodiment, a system is provided for determining a temperature of a heating element of a wind turbine blade. The system includes a current sensor for measuring a first value of a heating current provided in the heating element at a first time. The system includes a controller configured to determine a first temperature of the heating element using the measured first value of the heating current and a known functional correlation between the heating current in the heating element and the temperature of the heating element. The system may be configured to perform any embodiment of the method described herein.

[0077] The controller may be, for example, wind turbine controller 202 or controller 230 shown in the figures.

[0078] The system may be configured to determine the first temperature of the heating element without determining the resistance or impedance of the heating element.

[0079] The controller may be a wind turbine controller or a part thereof. The controller may be a part of the wind turbine. Alternatively, the controller may be a separate controller external to the wind turbine.

[0080] The controller may be connected to the current sensor.The controller may be configured to receive a measured first value of the heating current from the current sensor.

[0081] The controller may be configured to store, read, receive or otherwise obtain a known functional correlation between the heating current in the heating element and the temperature of the heating element. For example, the known functional correlation may be stored in a memory of the controller, may be read by the controller from a memory external to the controller, may be transmitted to the controller via wired or wireless communication, etc. The controller may be configured to input the measured first value into the known functional correlation. The controller may be configured to determine or derive the first temperature from the known functional correlation after the measured first value is input therein.

[0082] The current sensor may be configured to measure a second value of the heating current at a second time. The controller may be configured to determine the temperature of the heating element using the measured first value of the heating current, the measured second value of the heating current, and a known functional correlation between the heating current in the heating element and the temperature of the heating element. The controller may be configured to input the measured first value and the measured second value into the known functional correlation. The controller may be configured to determine or derive the first temperature from the known functional correlation after the measured first value and the measured second value are input therein. The temperature of the heating element may be determined by the controller using the difference between the measured first value and the measured second value of the heating current.

[0083] The current sensor may be part of the wind turbine. As described above, the current sensor may be arranged in a hub of the wind turbine. The current sensor may be a current transducer, for example, a current transducer arranged in the hub.

[0084] According to another embodiment, a wind turbine is provided. The wind turbine includes a rotor having wind turbine blades, the wind turbine blades including heating elements. The wind turbine includes a power supply for supplying a heating current to the heating element. The wind turbine includes a system for determining a temperature of the heating element according to embodiments described herein. The wind turbine may be configured to perform a method according to embodiments described herein.

[0085] According to another embodiment, a computer program product or non-transitory computer-readable storage medium is provided. The computer program product or non-transitory computer-readable storage medium includes instructions that, when executed by one or more processors of a system, cause the system to determine a first temperature of a heating element using a measured first value of a heating current provided in the heating element and a known functional correlation between the heating current in the heating element and the temperature of the heating element. The computer program product or non-transitory computer-readable storage medium may be configured to undertake any (one or more) operations performed by a controller for determining the temperature of a heating element according to the methods described herein.

[0086] According to another embodiment, a method is provided for determining a performance degradation characteristic or performance degradation analysis of a heating element of a wind turbine blade. The method includes applying a voltage to the heating element to provide a heating current in the heating element for heating the heating element, wherein the heating current is provided during a heating cycle of the heating element. The method includes performing a cold measurement of the heating current at an initial stage of the heating cycle before the heating current causes the heating element to heat up significantly, wherein the cold measurement produces a measured value of the heating current. The method includes determining a performance degradation characteristic of the heating element using the measured value of the heating current and the applied voltage.

[0087] The applied voltage may be a known voltage, or the method may include measuring the applied voltage.

[0088] The performance degradation characteristics may be determined using Ohm's law based on the measured values ​​of the heating current and the applied voltage.

[0089] Determining the performance degradation characteristic may include determining a resistance of the heating element using the measured value of the heating current and the applied voltage.Determining the performance degradation characteristic may include determining a deviation between the determined resistance of the heating element and a reference resistance of the heating element.

[0090] According to another embodiment, a system is provided for determining a performance degradation characteristic of a heating element of a wind turbine blade. The system includes a voltage source for applying a voltage to the heating element to provide a heating current in the heating element for heating the heating element, wherein the heating current is provided during a heating cycle of the heating element. The system includes a current sensor for cold measuring the heating current at an initial stage of the heating cycle before the heating current causes the heating element to heat up significantly, wherein the cold measurement produces a measured value of the heating current. The system includes a controller for determining the performance degradation characteristic of the heating element using the measured value of the heating current and the applied voltage.

[0091] The following aspects described under items 1 to 15 are also part of the present disclosure: Item 1. A method of determining a temperature of a heating element (210) of a wind turbine blade (200), comprising: heating the heating element by providing a heating current in the heating element; At a first time, measuring a first value (I1) of the heating current; The first temperature (T1) of the heating element is determined using: a measured first value of the heating current; and A known functional dependence (410) between the heating current in the heating element and the temperature of the heating element.

[0092] Item 2. The method of Item 1, wherein the first temperature of the heating element is determined without determining a resistance of the heating element.

[0093] Item 3. The method of Item 1 or 2, wherein the known functional dependence is at least approximately a linear dependence between the heating current in the heating element and the temperature of the heating element.

[0094] Item 4. The method of any of the preceding items, wherein the known functional dependencies are obtained from a testing phase, wherein the testing phase comprises: heating a test heating element (210') for a wind turbine blade by providing a test heating current in the test heating element; measuring a plurality of values ​​of the test heating current and corresponding values ​​of the temperature of the test heating element at different times; and Based on the plurality of measured values ​​of the test heating current and corresponding measured values ​​of the temperature of the test heating element, a functional correlation between the test heating current in the test heating element and the temperature of the test heating element is determined (410).

[0095] Item 5. The method of any of the preceding items, wherein the wind turbine blade is part of a wind turbine (100), the wind turbine having a hub (110), and wherein the first value of the heating current is measured by a current transducer (710) arranged in the hub.

[0096] Item 6. The method of any of the preceding items, further comprising: At a second time, measuring a second value of the heating current, Therein, the first temperature of the heating element is determined using: a measured first value of the heating current, a measured second value of the heating current, and a known functional correlation between the heating current in the heating element and the temperature of the heating element.

[0097] Item 7. The method of Item 6, wherein the first temperature of the heating element is determined using a difference between the measured first value and the measured second value of the heating current.

[0098] Item 8. The method of item 6 or 7, wherein the measurement of the second value of the heating current is a cold measurement performed at an initial stage of the heating cycle before the heating current causes the heating element to heat up significantly.

[0099] Item 9. The method of any of the preceding items, further comprising: applying a voltage to the heating element to provide a heating current in the heating element, wherein the heating current is provided during a heating cycle of the heating element; Before the heating current causes the heating element to heat up significantly, in an initial phase of the heating cycle, at a second time, a cold measurement of the heating current is performed, wherein the cold measurement produces a measured second value of the heating current (I 最小 );and Using the measured second value of the heating current and the applied voltage, a performance degradation characteristic of the heating element is determined.

[0100] Item 10. The method of any of the preceding items, wherein the heating element is configured for de-icing a wind turbine blade.

[0101] Item 11. The method of any of the preceding items, wherein the heating element is a heating mat of a wind turbine blade, in particular a carbon heating mat.

[0102] Item 12. A system for determining a temperature of a heating element (210) of a wind turbine blade (200), comprising: a current sensor (710) for measuring a first value of a heating current in the heating element at a first time; and A controller (230, 202) configured to determine a first temperature of the heating element using: a measured first value of the heating current; and A known functional dependence (410) between the heating current in the heating element and the temperature of the heating element.

[0103] Item 13. A wind turbine (100), comprising: A rotor having a wind turbine blade (200), the wind turbine blade (200) comprising a heating element (210); a power supply (220) for supplying a heating current to the heating element; A system for determining the temperature of a heating element according to item 12.

[0104] Item 14. A computer program product or non-transitory computer-readable storage medium comprising instructions that, when executed by one or more processors of the system, cause the system to determine a first temperature of a heating element (210) using: a measured first value of a heating current provided in the heating element, and a known functional correlation between the heating current in the heating element and the temperature of the heating element.

[0105] Item 15. A method for determining performance degradation characteristics of a heating element (210) of a wind turbine blade (200), comprising: applying a voltage to the heating element to provide a heating current in the heating element for heating the heating element, wherein the heating current is provided during a heating cycle of the heating element; performing a cold measurement of the heating current at an initial stage of a heating cycle, before the heating current causes the heating element to heat up significantly, wherein the cold measurement produces a measured value of the heating current; and Using the measured values ​​of the heating current and the applied voltage, the performance degradation characteristics of the heating element are determined.

[0106] As used herein, the term "processor" refers not only to what is known in the art as an integrated circuit included in a computer, but also to controllers (e.g., wind turbine controller 202 or controller 230 described herein), microcontrollers, microcomputers, programmable logic controllers (PLCs), application specific integrated circuits, and other programmable circuits. The processor may also be configured to compute advanced control algorithms and communicate with various Ethernet or serial-based protocols (Modbus, OPC, CAN, etc.). In addition, the processor may access (one or more) memory devices, which generally include (one or more) memory elements, including but not limited to computer-readable media (e.g., random access memory (RAM)), computer-readable non-volatile media (e.g., flash memory), floppy disks, compact disk read-only memory (CD-ROM), magneto-optical disks (MOD), digital versatile disks (DVD), and / or other suitable memory elements. Such (one or more) memory devices may generally be configured to store suitable computer-readable instructions, which, when implemented by (one or more) processors, configure the controller to perform various functions as described herein.

[0107] Exemplary embodiments are described above in detail. The systems and methods are not limited to the specific embodiments described herein, but rather components of the systems and / or steps of the methods may be utilized independently and separately from other components and / or steps described herein.

[0108] Although the specific features of various embodiments of the present invention may be shown in some drawings and not in other drawings, this is only for convenience. According to the principles of the present invention, any feature of the drawings may be combined with any feature of any other drawings to be referenced and / or requested for protection.

[0109] Embodiments of the present invention have been described above with reference to methods, apparatus (i.e., systems) and computer program products. It will be understood that each operation of the method and combinations of operations, respectively, may be implemented by various means including computer program instructions. These computer program instructions may be loaded onto a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine such that the instructions executed on the computer or other programmable data processing device create means for implementing the operations of the method.

[0110] These computer program instructions may also be stored in a non-transitory computer readable memory that may instruct a computer or other programmable data processing device to function in a specific manner such that the instructions stored in the computer readable memory produce an article of manufacture that includes computer readable instructions for implementing the functions specified in the flowchart block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing device to cause a series of operational steps to be executed on the computer or other programmable device to produce a computer-implemented process such that the instructions executed on the computer or other programmable device provide steps for implementing the operations included in the method.

[0111] Therefore, the operation of the method supports: a combination of means for performing the specified functions, a combination of steps for performing the specified functions and program instruction means for performing the specified functions. It will also be understood that each operation of the method and the combination of operations can be implemented by: a computer system based on special-purpose hardware that performs the specified functions or steps, or a combination of special-purpose hardware and computer instructions.

[0112] Unless otherwise expressly stated, it is in no way intended that any method described herein be interpreted as requiring that its steps be performed in a specific order. Therefore, in the event that a method claim does not actually recite the order to be followed by its steps, or the claims or specification do not otherwise expressly state that the steps are to be limited to a specific order, no order is intended to be inferred in any way in any respect. This applies to any possible non-express basis for interpretation, including: logical issues regarding the arrangement of steps or operational flows; plain meaning derived from grammatical organization or punctuation; the number or type of embodiments described in the specification.

[0113] This written description uses examples, including the best mode, to disclose the invention, and also enables any person skilled in the art to practice the invention, including making and using any device or system, and performing any incorporated method. Although various specific embodiments have been disclosed above, those skilled in the art will recognize that the spirit and scope of the claims allow for equally effective modifications. In particular, the mutually non-exclusive features of the embodiments described above may be combined with each other. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. For example, a control system for a wind farm may be provided by a centralized controller or by a plurality of interconnected controllers. Such other examples are intended to fall within the scope of the claims if they have structural elements that are not different from the written language of the claims, or if they include equivalent structural elements that are not substantially different from the written language of the claims.

[0114] Reference Mark Wind Direction 28 Axis of rotation 30 Yaw axis 38 Wind Turbine 100 Cabin 102 Tower 104 Yaw system 105 Rotor 106 Mast 107 Rotor blade 108 Pitch system 109 Hub 110 Wind turbine blades 200 Wind turbine controller 202 Heating element 210 Power Supply 220 Cable 222 Controller 230 Near 250 Vertical axis 402 Horizontal axis 404 Function Dependency 410 Temperature sensor 502 Current sensor 504 Data Point 602 Current sensor 710 Testing the heating element 210' Power supply 220'

Claims

1. A method of determining a temperature of a heating element (210) of a wind turbine blade (200), comprising: heating the heating element by providing a heating current in the heating element; At a first time, measuring a first value (I1) of the heating current; The first temperature (T1) of the heating element is determined using: a measured first value of the heating current; and a known functional dependence (410) between the heating current in the heating element and the temperature of the heating element, The method further comprises: At a second time, measuring a second value of the heating current, Therein, the first temperature of the heating element is determined using: a measured first value of the heating current, a measured second value of the heating current, and the known functional correlation between the heating current in the heating element and the temperature of the heating element.

2. The method according to claim 1, wherein: The first temperature of the heating element is determined without determining the resistance of the heating element.

3. The method according to claim 1 or 2, wherein: The known functional dependence is at least approximately a linear dependence between the heating current in the heating element and the temperature of the heating element.

4. A method according to any one of the preceding claims, wherein: The known functional dependencies are obtained from a testing phase, wherein the testing phase includes: heating the test heating element (210') for a wind turbine blade by providing a test heating current in the test heating element; measuring a plurality of values ​​of the test heating current and corresponding values ​​of the temperature of the test heating element at different times; and Based on a plurality of measured values ​​of the test heating current and corresponding measured values ​​of the temperature of the test heating element, a functional correlation between the test heating current in the test heating element and the temperature of the test heating element is determined (410).

5. A method according to any one of the preceding claims, wherein: The wind turbine blade is part of a wind turbine (100) having a hub (110), and wherein the first value of the heating current is measured by a current transducer (710) arranged in the hub.

6. A method according to any one of the preceding claims, wherein: Using a difference between a measured first value of the heating current and a measured second value of the heating current, the first temperature of the heating element is determined.

7. A method according to any one of the preceding claims, wherein: The measurement of the second value of the heating current is a cold measurement, which is performed at an initial stage of a heating cycle, before the heating current causes the heating element to heat up significantly.

8. The method according to any one of the preceding claims, further comprising: applying a voltage to the heating element to provide the heating current in the heating element, wherein the heating current is provided during a heating cycle of the heating element; A cold measurement of the heating current is performed at a second time in an initial phase of the heating cycle, before the heating current causes the heating element to heat up significantly, wherein the cold measurement produces a measured second value (I 最小 );and Using the measured second value of the heating current and the applied voltage, a performance degradation characteristic of the heating element is determined.

9. A method according to any one of the preceding claims, wherein: The heating element is configured to de-ice the wind turbine blade.

10. A method according to any one of the preceding claims, wherein: The heating element is a heating mat of the wind turbine blade, in particular a carbon heating mat.

11. A system for determining a temperature of a heating element (210) of a wind turbine blade (200), comprising: a current sensor (710) for measuring a first value of a heating current in the heating element at a first time and for measuring a second value of the heating current at a second time; and A controller (230, 202) configured to determine a first temperature of the heating element using: a measured first value of the heating current; a measured second value of the heating current; and A known functional dependence (410) between the heating current in the heating element and the temperature of the heating element.

12. A wind turbine (100), comprising: A rotor having a wind turbine blade (200), the wind turbine blade (200) comprising a heating element (210); a power supply (220) for supplying a heating current to the heating element; The system for determining the temperature of the heating element of claim 11.

13. A computer program product or non-transitory computer-readable storage medium comprising instructions which, when executed by one or more processors of a system, cause the system to determine a first temperature of the heating element (210) using: a measured first value of a heating current provided in the heating element, a measured second value of the heating current, and a known functional correlation between the heating current in the heating element and the temperature of the heating element.

14. A method for determining performance degradation characteristics of a heating element (210) of a wind turbine blade (200), comprising: applying a voltage to the heating element to provide a heating current in the heating element for heating the heating element, wherein the heating current is provided during a heating cycle of the heating element; performing a cold measurement of the heating current at an initial stage of the heating cycle, before the heating current causes the heating element to heat up significantly, wherein the cold measurement produces a measured value of the heating current; and Using the measured values ​​of the heating current and the applied voltage, performance degradation characteristics of the heating element are determined.

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