Method and control system for operating a wind turbine

Abstract

A method of operating a wind turbine is provided. A wind turbine (100) includes a power generation system (120) configured to generate electrical power from rotating mechanical energy and one or more cables (20) configured to transmit the electrical power generated by the power generation system (120). The one or more cables (20) are associated with a cable temperature threshold for a cable temperature of the one or more cables (20). A measured component operating parameter of a component (122) of a power generation system (120) is obtained. The measured component operating parameter is compared to a component operating parameter threshold, and / or an estimated cable temperature estimated from the measured component operating parameter is compared to a cable temperature threshold. If the comparison indicates that a corresponding threshold is reached or exceeded, a mitigation action is taken to remain stable or reduce the cable temperature.

Description

Technical Field

[0001] This invention relates to a method for operating a wind turbine, a control system for a wind turbine, and a computer program for operating a wind turbine. In particular, it relates to preventing overheating in the cables of the wind turbine. Background Technology

[0002] Significant progress has been made in wind turbine technology over the past few years. Compared to today's standards, wind turbines installed in the past typically had relatively low nominal output power. Therefore, there is a desire to increase the output power of existing wind turbines.

[0003] Increasing the output power of an existing wind turbine can cause several problems. For example, with higher output power, the current in the power cables used to transmit the generated electrical power in the wind turbine increases. This, in turn, can lead to increased temperatures within the cables. Such increased temperatures can cause increased wear on the cable insulation, which could further increase the risk of failure and, in the worst case, the risk of fire. If the risk of cable failure is too high, it may be impossible to increase the power output of the wind turbine.

[0004] To avoid these issues, additional cables can be supplied with the upgrade to allow for higher current carrying capacity. Alternatively, existing cables can be replaced with cables having a higher current capacity. As another alternative, the cables may already be designed to have a higher current rating when the wind turbine is manufactured, providing additional backup margin to allow for future power increases. However, such solutions generally result in a greater workload, are more expensive, and may further expose unused backup capacity.

[0005] Document EP 3 779 181 A1 describes a method for determining control parameters of a turbine for computer implementation. The model calculates losses in components within the transmission system. It employs a thermal model of the generator and / or converter. This model is used to determine parameters of rotating components where sensors are difficult to position. Summary of the Invention

[0006] Therefore, there is a need to mitigate at least some of the drawbacks mentioned above and to provide a solution that allows for increased power output of wind turbines without replacing or supplementing existing cables.

[0007] This requirement is met by the features of the independent claims. The dependent claims describe embodiments of the invention.

[0008] According to one aspect, a method for operating a wind turbine is provided, wherein the wind turbine includes a power generation system configured to generate electrical power from rotational mechanical energy and one or more cables configured to transmit the electrical power generated by the power generation system (e.g., to a load, a collector grid, a power grid, etc.). The one or more cables are associated with a cable temperature threshold. The method includes obtaining measured component operating parameters of components of the power generation system, wherein the measured component operating parameters and the cable temperature are related by a temperature relationship. It also includes comparing the measured component operating parameters with a component operating parameter threshold, wherein the component operating parameter threshold is derived based on the cable temperature threshold and the temperature relationship. Additionally or alternatively, the method includes comparing an estimated cable temperature estimated based on the measured component operating parameters and the temperature relationship with a cable temperature threshold. If the comparison indicates that a corresponding threshold (i.e., correspondingly a component operating parameter threshold or a cable temperature threshold) has been reached or exceeded, mitigation actions are taken to stabilize or reduce the cable temperature.

[0009] This method allows wind turbines to operate at an output power higher than their nominal output power at installation. Specifically, the wind turbine can be an upgraded rated wind turbine, possessing an increased nominal output power compared to its original nominal output power. Furthermore, this method eliminates the need for additional temperature sensors along the cable, as cable overheating is monitored by measuring component operating parameters of the power generation system. Therefore, existing sensors can be used for this measurement, and it can be concluded whether the cable temperature is within limits or exceeds safe operating limits (e.g., cable temperature thresholds). As mentioned above, this can be detected by deriving the threshold or limit of the measured component operating parameters from the cable temperature threshold, or equivalently by estimating the cable temperature from the measured component operating parameters and comparing the estimated cable temperature with the cable temperature threshold. Both methods can be used simultaneously, further improving reliability and consistency. This temperature relationship can be provided at the wind turbine, for example, stored in the wind turbine controller as parameters of a corresponding function, a lookup table, etc. In the former case, it may only be necessary to provide component operating parameter thresholds in the wind turbine, for example, to the wind turbine controller, which can then simply compare the measured component operating parameters with the stored thresholds to detect whether mitigation actions are needed to keep the cable temperature within safe operating limits.

[0010] Therefore, this method, unlike conventional approaches, provides a complex model of the cable and monitors the power flow through it to accurately model cable temperature. Surprisingly, this unusual method has enabled remarkably accurate temperature estimation and efficient protection of the cable from overtemperature conditions. This approach simplifies cable protection and can be easily integrated into existing wind turbine control systems, such as existing overtemperature protection systems. This allows for efficient, cost-effective, and safe upgrading of wind turbine ratings.

[0011] A wind turbine can be an upgraded wind turbine, which includes upgrades to increase energy production. This upgrade may involve adjusting the operating characteristics of the wind turbine, and in particular, may involve increasing the nominal output power of the wind turbine, which can be referred to as "upgrading" (or "capacitating"). This can be achieved, for example, by allowing the wind turbine to operate at higher torque and / or higher rotational speeds of the wind turbine rotor. While this upgrading of the wind turbine results in an increased nominal power output above the previous rated output, it may cause a corresponding increase in the temperature of the power cables transmitting the generated electrical power. With this method, cable temperature can be monitored in a highly efficient manner, requiring no additional sensors and, for example, through a simple software update using existing temperature measurements. Therefore, overtemperature conditions can be detected efficiently and avoided through mitigation actions. This can contribute to increasing the power output of the wind turbine and improve operational safety.

[0012] It should be clear that the components of the power generation system are different from the one or more cables.

[0013] In an alternative embodiment, the component operating parameter is the component temperature. A temperature relationship can correlate the component temperature with the cable temperature. Using this component temperature as the component operating parameter has the advantage that the dynamics of this parameter are likely similar to the dynamics of the cable temperature. Therefore, the component temperature can very accurately reflect the actual cable temperature, enabling effective over-temperature protection for one or more cables through this method. Furthermore, this component temperature may be affected by environmental conditions (e.g., ambient temperature), which are similar to the effects on the actual cable temperature. Therefore, providing over-temperature protection becomes possible without additional consideration of environmental parameters, such as ambient temperature. Other component operating parameters may be used in different embodiments, such as the electrical output power of a power generation system; however, although this output power can indicate the cable temperature, the cable temperature will generally depend on other parameters, such as ambient temperature, the duration of providing output power, etc. Therefore, using the component temperature as the component operating parameter further facilitates the implementation of this method.

[0014] Alternatively, the temperature relationship may be one that is available or has been obtained through any calibration method disclosed herein.

[0015] This method may include obtaining the relationship, for example by receiving the relationship via a communication connection, reading the relationship from a memory (e.g., the memory of a wind turbine controller), etc. The temperature relationship may have been determined before the wind turbine is operated, as explained below, for example during initial calibration. However, it is also conceivable to determine the temperature relationship during operation.

[0016] For example, for different operating conditions of a wind turbine, the temperature relationship can correlate the maximum component temperature with the maximum cable temperature. This relationship can be derived from these maximum values. The corresponding maximum values ​​may have been obtained after the wind turbine has been operating at increased nominal output power for a predetermined amount of time.

[0017] For example, the component may be a component of a generator in a power generation system. It has been found that it is particularly advantageous if the component is a generator winding and the component's operating parameter is winding temperature. Cable temperature can be correlated particularly well with winding temperature, allowing for particularly accurate detection of over-temperature conditions of one or more cables by using the generator's winding temperature as a component operating parameter. For example, the generator winding may be the generator's stator winding and / or rotor winding.

[0018] Cable temperature and cable temperature thresholds can be associated with predetermined locations along the one or more cables. A location refers to a longitudinal position along the cable length. Preferably, the location corresponds to a hot spot where the one or more cables reach their highest temperature during wind turbine operation. By providing over-temperature protection for such locations, the entire cable is protected from over-temperature conditions, which in turn facilitates the implementation of the method. If the protection method ensures mitigation actions are taken when the corresponding temperature threshold is reached or exceeded, such that the cable temperature is controlled and maintained below the cable temperature threshold at the hot spot, then the temperature of the cable along its entire length will remain below the cable temperature threshold. Knowledge of the location of such hot spots can be obtained, for example, during upgrades on a reference wind turbine, or at the respective wind turbine where the method is implemented, for example, by employing temperature sensors positioned at different locations along the cable length.

[0019] As an example, the location may be situated at or near the connection point of the one or more cables to the generator of the power generation system, such as at the corresponding generator terminals. At such a location, it may be difficult to alter the cable arrangement, and the one or more cables may be positioned relatively close to each other, potentially creating a hotspot for cable temperature. This hotspot may refer to the highest temperature.

[0020] In one exemplary embodiment, mitigation may include reducing the active power output of the wind turbine. This reduction decreases the current present in the one or more cables, thereby reducing heat formation in the one or more cables. This mitigation enables efficient cooling of the one or more cables, protecting them from overheating. It should be understood that if mitigation is initiated when a corresponding temperature threshold is reached, the cable temperature may briefly exceed the cable temperature threshold due to the reduced current, and then cool down again to below the cable temperature threshold. The control employed can be a simple binary control, for example, reducing active power output when a temperature threshold is reached, or a more complex control, such as a PI or PID controller, can be used.

[0021] In one embodiment, the wind turbine includes a protection function to mitigate the risk of overheating conditions in components of the power generation system. For example, such a protection function could be a High Temperature Ride-Through (HTRT) function, configured to ensure that components do not overheat during high ambient temperature conditions. This protection function can compare a measured component temperature with a second component temperature threshold associated with that component and can take mitigation actions based on that comparison. This corresponds to the general operation of such a protection function, such as general HTRT operation. A derived component temperature threshold derived for the one or more cables can be provided to the protection function to perform the corresponding comparison and take appropriate mitigation actions based on that comparison. Therefore, this existing protection function for components of the power generation system can also be used to provide overheat protection for the one or more cables. The protection function can specifically monitor a component temperature threshold derived from the cable temperature threshold and a second component temperature threshold for the component itself. Therefore, mitigation actions can be taken when the lower of these two thresholds is reached or exceeded. This further contributes to providing overheat protection because the one or more cables can be protected simply by setting a new temperature threshold for this protection function.

[0022] Preferably, in this method, cable temperature is not measured and / or ambient temperature (e.g., the ambient temperature outside a wind turbine nacelle) is not considered in the corresponding comparison. This comparison may not be based on the measured output power of the power generation system. In other words, deriving component operating parameter thresholds from cable temperature thresholds and / or estimating cable temperature based on measured component operating parameters may not use the actual measured cable temperature, may not utilize any such ambient temperature, and / or may not use the measured output power. Surprisingly, it has been found that by not using complex models to model cable temperature, but rather by using different methods and utilizing only measured component operating parameters, particularly measured component temperatures, it is helpful for temperature protection and can even achieve better results.

[0023] In some wind turbines, the one or more cables may comprise a bundle of cables forming a cable bundle at locations along the bundle. One or more cable separators may be installed at these locations (e.g., shared separators or separate separators). These one or more cable separators may be configured to increase the spacing between the cables at the installation location. The installation location may differ from the location where the comparison of the multiple cables is performed. In particular, the location may differ from the hot spot locations mentioned above along the one or more cables. Therefore, for such locations where the multiple cables form a cable bundle, additional protection against overheating conditions can be achieved.

[0024] For the central cable of such a bundle, heat transfer and therefore cooling may be hindered by the surrounding cables, which also generate heat during operation. Therefore, by installing one or more cable separators, cooling of the central cable can be improved, and temperature rise during operation can be limited, particularly for the central cable. This reduces or avoids wear on the cable insulation, which typically increases with temperature, as well as the risk of failure and fire at such locations. It should be understood that one or more cable separators can be installed at several locations along the length of the plurality of cables, for example, at each location forming a respective cable bundle. A cable bundle can refer to a spatial arrangement of the plurality of cables in which they are physically in contact with each other and / or in which one or more centrally arranged cables are surrounded by other cables. Therefore, additional protection can be achieved for locations where heat may accumulate.

[0025] According to another aspect, a method for calibrating temperature control of one or more cables of a wind turbine is provided. This method determines the relationship between component operating parameters of a wind turbine's power generation system and the cable temperature of the one or more cables. The one or more cables are configured to transmit electrical power generated by the power generation system, for example, to a load, a utility grid, a collection grid, etc. The method includes obtaining measured component operating parameters of the power generation system components, obtaining measured cable temperatures at the locations of the one or more cables, wherein obtaining the measured component operating parameters and obtaining the measured cable temperatures are repeatedly performed for different operating conditions of the wind turbine (e.g., for different operating conditions, both measurements can be obtained (essentially) simultaneously), and the relationship between the component operating parameters and the cable temperatures is derived based on the measured component operating parameters and the measured cable temperatures. This method allows for an accurate estimate of the relationship between component operating parameters and cable temperatures. This method may produce advantages similar to those described above. In particular, deriving this relationship allows for estimation of cable temperatures without measuring the cable temperature, or correspondingly, allows for estimation of component temperature thresholds based on cable temperature thresholds. Therefore, direct measurement of the cable temperature is not required. Thus, this method allows for over-temperature protection of the one or more cables without the installation of sensors. Therefore, equipment can be saved and complexity reduced. In particular, this method can lead to reduced workload and lower costs. This method can also be called a "calibration method" because it provides calibration between actual measured values ​​(component operating parameters, preferably component temperatures) and actual values ​​of unmeasured desired parameters (cable temperatures). For example, different operating conditions can refer to different ambient temperatures, different cabin temperatures, and different wind conditions, etc.

[0026] This method can be performed as part of the operation of a wind turbine. For example, it can be performed as a calibration before the start of wind turbine operation, such as as part of an upgrade of the wind turbine (especially an increase in rating). However, it should be clear that this calibration method can also be performed on different wind turbines, and the derived relationship can be used when operating different wind turbines of the same general type or the same model type with the same type of upgrade (to which the corresponding relationship also applies).

[0027] In one embodiment, the relationship is linear. Determining this relationship may include determining one or more parameters of the corresponding linear function. Preferably, the slope of the linear function and, possibly, the intercept of the linear function, are determined. This linear relationship can further facilitate the calibration method and the operational method because it allows for a relatively simple mapping between the actually measured parameters and the cable temperature. More complex relationships, such as polynomial functions or other suitable types of functions, may be used in different embodiments.

[0028] In one alternative embodiment, the component operating parameter is component temperature, and obtaining the measured component temperature includes obtaining the maximum value of the measured component temperature after operating the wind turbine at increased nominal output power for a predetermined amount of time. Obtaining the measured cable temperature may include obtaining the maximum value of the measured cable temperature after the wind turbine has operated at increased nominal output power for a predetermined amount of time. The maximum values ​​of the measured component temperature and the measured cable temperature can be repeatedly obtained for different operating conditions of the wind turbine. This relationship can be derived specifically from the maximum values ​​of the measured component temperature and the measured cable temperature repeatedly obtained for different operating conditions. Such different operating conditions may also be different ambient temperatures, such as different ambient temperatures outside the wind turbine nacelle, or different temperatures inside the wind turbine nacelle, etc. After the wind turbine has operated at increased nominal output power for this period of time, the maximum values ​​of the measured component temperature and the measured cable temperature can be obtained (substantially) simultaneously. The predetermined amount of time can be selected such that the operation corresponds to (quasi) steady-state operation of the wind turbine at increased nominal output power.

[0029] During such operation, the temperature of the components, and similarly the temperature of one or more cables, may approach a stable temperature value, particularly the highest (critical) temperature. This highest temperature is the temperature with the highest relevance for over-temperature protection. Furthermore, it has been found that the corresponding maximum values ​​of component and cable temperatures exhibit a good correlation. This allows for fairly accurate estimation of reliable relationships based on these obtained maximum values. Therefore, by employing this relationship, accurate component temperature thresholds and / or cable temperature estimates are achieved within the relevant temperature range (i.e., at high temperatures). This is particularly beneficial because mitigation actions are typically only required when approaching the maximum temperature value. The maximum value used may not be a single data point corresponding to the maximum absolute temperature value, but may be an average value over a specific time period, or a value that asymptotically approaches the temperature over time. Increased nominal output power can refer to the actual rated output power of a wind turbine after its original nominal output power has been increased to a higher value (e.g., during a wind turbine upgrade).

[0030] According to another aspect, a method is provided for upgrading a wind turbine using a performance enhancement upgrade. This performance enhancement upgrade is configured to increase the power output of the wind turbine compared to a wind turbine without the upgrade (in other words, the performance enhancement upgrade increases the output power of the wind turbine, and thus results in an increase in nominal output power). The method includes installing the performance enhancement upgrade on the wind turbine and performing calibration according to any calibration method disclosed herein to determine the relationship between component operating parameters of the wind turbine's power generation system and cable temperatures of one or more cables of the wind turbine. This method allows the wind turbine to operate safely at a higher output power without requiring cable replacement or the installation of additional cables during the upgrade. Upgrading the wind turbine can specifically refer to modifying the wind turbine control by enabling over-estimation operation of the wind turbine, during which the electrical power output generated by the wind turbine is higher than the (original) nominal rated power output of the wind turbine before the upgrade. This may involve increasing the nominal rotational speed and / or nominal operating torque of the wind turbine.

[0031] The method may also include operating the wind turbine according to any of the operating methods disclosed herein after calibration. In some embodiments, the calibration method and the operating method may be performed on the same wind turbine. In other embodiments, the calibration method may be performed on an upgraded wind turbine, and different wind turbines may be configured with corresponding upgrades, and subsequently, the calibration relationship can be used for operation without performing the calibration method on that particular wind turbine. Thus, it is possible to provide operation of multiple wind turbines implementing corresponding cable over-temperature protection without requiring a calibration method for each individual wind turbine.

[0032] According to another aspect, a wind turbine control system configured to control the operation of a wind turbine is provided, wherein the wind turbine includes a power generation system configured to generate electrical power from rotational mechanical energy and one or more cables configured to transmit the electrical power generated by the power generation system, wherein the one or more cables are associated with a cable temperature threshold, and wherein the wind turbine control system is configured to perform any of the methods disclosed herein. It should be understood that a control system for operating a wind turbine according to any of the operating methods disclosed herein can be provided, and the same control system or different control systems can be provided to perform any of the calibration methods disclosed herein. This control system may also be referred to as a calibration system when performing calibration, or as an upgrade system when performing an upgrade. Advantages similar to those further outlined above can be achieved through such a control system (or calibration / upgrade system).

[0033] According to another perspective, a wind turbine including such a control system is provided.

[0034] According to another aspect, a computer program is provided for a control system for operating a wind turbine, wherein the wind turbine includes a power generation system configured to generate electrical power from rotational mechanical energy and one or more cables configured to transmit the electrical power generated by the power generation system, wherein the computer program includes control instructions that, when executed by a processing unit of the control system, cause the processing unit to perform any of the methods disclosed herein. The computer program may be provided on a volatile or non-volatile data carrier or storage medium.

[0035] The wind turbine can be an offshore wind turbine, particularly a floating offshore wind turbine, and the method of operating the wind turbine may further include generating electrical power and / or electrical energy from the wind turbine during operation, transmitting at least a portion of the generated electrical power and / or electrical energy to an electrical receiving device, particularly wherein the electrical receiving device is not located in international waters, but on land, and / or within 12 miles of the respective sovereign state under the jurisdiction of the respective country; and supplying at least a portion of the electrical power and / or electrical energy to a public power grid, particularly an onshore public power grid. Using this method, electrical power can be supplied to the onshore site while protecting the one or more cables from overheating conditions.

[0036] It should be understood that the features mentioned above and those explained below can be used not only in the corresponding combinations indicated, but also in other combinations or individually, without departing from the scope of the invention. In particular, features of different aspects and embodiments of the invention can be combined with each other unless otherwise stated.

[0037] The control system may be specifically configured to perform any of the method steps described herein, and the method may be performed by a control system or wind turbine having any of the configurations described herein. Attached Figure Description

[0038] The foregoing and other features and advantages of the invention will become further apparent from the following detailed description, which is taken in conjunction with the accompanying drawings. In the drawings, the same reference numerals denote the same elements.

[0039] Figure 1 This is a schematic diagram showing a wind turbine including a control system according to an embodiment.

[0040] Figure 2 This is a flowchart illustrating a method for calibrating temperature control of one or more cables of a wind turbine according to an embodiment.

[0041] Figure 3 The diagram illustrates the execution. Figure 2 This is a schematic diagram of the temperature measurement results that may be obtained using this method.

[0042] Figure 4 The diagram illustrates the execution. Figure 2 The diagram shows the possible temperature relationships that can be obtained using this method.

[0043] Figure 5 The diagram illustrates the process based on execution. Figure 2 The flowchart uses the temperature relationship obtained during the process to derive the component temperature threshold.

[0044] Figure 6 This is a flowchart illustrating a method for operating a wind turbine according to an embodiment, wherein the method may employ... Figure 2 The temperature relationship obtained from the method and / or Figure 5 The component temperature threshold obtained from the method.

[0045] Figure 7 This is a schematic diagram showing a bundle of cables for a wind turbine.

[0046] Figure 8 This is a schematic diagram illustrating the temperature distribution within a bundle of cables in a wind turbine.

[0047] Figure 9 This is a schematic diagram showing a bundle of cables for a wind turbine according to an embodiment, wherein a cable splitter is installed into one of the cables.

[0048] Figure 10 This is a schematic diagram illustrating the temperature distribution in a bundle of cables of a wind turbine when a cable separator is installed according to an embodiment. Detailed Implementation

[0049] In the following description, embodiments of the invention will be described in detail with reference to the accompanying drawings. It should be understood that the following description of the embodiments is given for illustrative purposes only and should not be construed as limiting. It should be noted that the drawings should be considered as schematic representations only, and the elements in the drawings are not necessarily drawn to scale. Rather, the representation of various elements has been chosen such that their function and general purpose will become apparent to those skilled in the art. As used herein, the singular forms “a,” “an,” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Unless otherwise stated, the terms “comprising,” “having,” “including,” and “containing” will be interpreted as open-ended terms (i.e., meaning “including but not limited to”).

[0050] Figure 1A wind turbine 100 is schematically illustrated, comprising a wind turbine tower 105 on which a nacelle 101 is mounted. The wind turbine 100 includes a wind turbine rotor 110, which includes rotor blades 111. The wind turbine 100 also includes a power generation system 120, which may include a generator 121 mechanically coupled to the rotor 110, for example, directly or via an intermediate gearbox. The power generation system 120 may also include a converter and an optional transformer (not shown). The power generation system 120 may have any known configuration; for example, it may implement a full converter topology or a doubly-fed induction generator (DFIG) topology. The wind turbine 100 may operate in any known manner and may be an onshore or offshore wind turbine.

[0051] Figure 1 A plurality of cables 20 of a wind turbine 100 are schematically illustrated. In this example, these cables are connected to a generator 121 at terminal 22. If a power converter and / or transformer are installed in the nacelle 101 as part of the power generation system 121, the cables 20 may include corresponding cable segments that, for example, connect the generator 121 to the corresponding converter, connect the power converter to the transformer, and / or provide a connection from the transformer to the wind turbine tower 105. At one or more locations along the cables 20, bundles 25 may be formed where the cables are very close to each other and can contact each other, for example at location 32.

[0052] The power generation system 120 includes a component 122, which in this example is the generator winding of the generator 121. It could be another type of component, particularly one with operating parameters related to the output power of the wind turbine, such as component temperature.

[0053] When initially installed, the wind turbine 100 may have a nominal rated power. Therefore, the cable 20 may be sized to transmit electrical power according to the original nominal rated power. The wind turbine 100 also includes a control system 10, which may include a wind turbine controller. The control system 10 may implement one or more protection functions, such as temperature protection functions for components 122 of the power generation system 120. One example is a high-temperature ride-through (HTRT) function for the generator 121. A measurement unit 15 may be provided to measure the temperature of components 122 of the power generation system 120, which may be the windings of the generator 120. The control system 10 may receive the corresponding winding temperature measurement results (corresponding signals) and, if the measurement results indicate that the generator winding temperature is too high, may take mitigation actions. Mitigation actions may include reducing the electrical power production of the wind turbine 100 or may be incorporated therein. For example, the control system 10 may adjust the pitch of the rotor blades 111 to remove them from the wind to reduce power production and thereby lower the temperature of components 122 (e.g., generator windings). This may be particularly advantageous in the following situation: if the wind turbine 100 is rated higher and the generator 121 produces a higher power output than the original nominal power output, this may result in excessive heat generation in the generator winding 122.

[0054] For example, the wind turbine 100 can be upgraded by altering its operating characteristics, according to which the control system 10 controls the operation of the wind turbine 100, for example by allowing a higher rotational speed of the wind turbine rotor 110, allowing a higher torque value, etc. When operating at such an increased output power higher than the original nominal output power, the current transmitted by the cable 20 may be higher than the current intended for its original size setting. This may result in excessive heat generation, for example, at location 31 where the cable 20 connects to the terminal 22 of the generator 121 or at location 32 of the cable bundle 25. As described in further detail below, the control system 10 may be configured, according to embodiments, to reduce the risk of overheating of the cable 20 at these locations and thus provide efficient over-temperature protection.

[0055] The control system 10 may include a processing unit 11 and a memory 12 storing control instructions, which, when executed by the processing unit 11, perform any of the methods disclosed herein, particularly any operating and / or calibration methods. The processing unit 11 may be any type of processor, such as a microprocessor, application-specific integrated circuit, digital signal processor, etc. The memory 12 may include volatile and non-volatile memory, particularly RAM, ROM, EEPROM, FLASH memory, hard disk drive, etc. The control system 10 may also include corresponding input / output interfaces for receiving signals to obtain one or more operating parameters, particularly, for example, temperature measurements via unit 15, and components for controlling the wind turbine. The control system 10 may also include a user interface and other communication interfaces.

[0056] The control system 10 operates during operation to limit the cable temperature at one or more corresponding locations 31, 32 in order to protect the cable 20 from overheating conditions. For this purpose, the control system 10 employs temperature measurement via the measuring unit 15. It has been found that this temperature is related to the cable temperature at the corresponding location through a temperature relationship. This relationship can be obtained through corresponding measurements, as follows regarding… Figure 2 Further description. Based on this relationship and the temperature threshold of the cable temperature, a component temperature threshold for component 122 (e.g., generator winding) corresponding to the cable temperature threshold can be derived. For example, this component temperature threshold can be stored in memory 12 and can be used to provide over-temperature protection for cable 20 during operation. Control system 10 can, for example, compare the measured component temperature with the derived component temperature threshold to detect an over-temperature condition of cable 20 and take appropriate mitigation actions. Alternatively or additionally, the relationship can also be stored in memory 12 and used to derive an estimate of the cable temperature at the corresponding location based on the component temperature measured through unit 15, and then the estimated cable temperature can be compared with the cable temperature threshold. The following is about Figure 6 An exemplary implementation of this method of operation will be described in further detail.

[0057] Figure 2A flowchart illustrating a corresponding calibration method according to an embodiment is shown. In step 41, the wind turbine 100 is upgraded, for example, by modifying its operating characteristics to increase the nominal output power of the wind turbine. In step 42, the wind turbine with the increased rating is operated, and the temperature of the wind turbine component 122 is measured from the measuring unit 15, particularly over a period of time. In step 43, during wind turbine operation, the cable temperature is measured from one or more locations (preferably multiple locations) along the cable. For this purpose, temperature sensors can be placed at different locations along the length of the cable 20, such as at locations 31, 32, and others. The temperature can specifically be the surface temperature of one or more cables 20. Thus, the component temperature and cable temperature measurements can be obtained for the same time period. Other parameters can be measured, particularly the wind turbine's output power and optional ambient temperature (particularly the ambient temperature outside the nacelle). However, the method can also be used without such additional measurements.

[0058] The data obtained from these measurements Figure 3 The diagram in the middle shows, Figure 3 The output power of the wind turbine 100 (curve 61) and the component temperature 62 measured by unit 15 are shown for a 10-hour time period. Further, the measured cable temperature at position 31 (curve 63) and the cable temperature measurements at two other locations along cable 20 (curves 64 and 65) are shown. Curve 66 shows the ambient temperature. When the wind turbine 100 operates at an increased nominal output power of 2,500 kW (right axis) for an extended period, the winding temperature 62 can be seen asymptotically rising to a maximum value between 110°C and 130°C (left axis). As the output power decreases, the winding temperature 62 decreases again. The maximum value of the asymptotically reached winding temperature 62 varies depending on the operating conditions, such as ambient temperature 66.

[0059] A particularly strong correlation has been found between the maximum temperature values ​​of winding temperature 62 and the corresponding maximum temperature value of cable temperature 63, which also asymptotically reaches its maximum value after the wind turbine has operated at increased nominal output power for an extended period. Furthermore, the figure shows that cable 20 reaches its highest cable temperature at location 31. The presence of this hot spot can be identified in step 44. By basing over-temperature protection on the cable temperature at the corresponding location 31 where the highest temperature is reached, efficient over-temperature protection can be achieved for the entire length of cable 20.

[0060] In step 45, a data pair of measured component temperature 62 and measured cable temperature 63 (i.e., for the location of hot spots) is determined based on measurements taken at the time points when component temperature 62 and / or cable temperature 63 (asymptotically) reach their maximum values ​​during wind turbine operation at increased nominal output power. Reaching a maximum value can be understood herein to encompass asymptotically reaching a maximum value, where the maximum value may not be an isolated data point but may be the average of several subsequent data points to reduce noise. Figure 3 The diagram schematically illustrates the first data point 71 and the second data point 72, from which corresponding data pairs can be formed. This is done for different operating conditions, such as different ambient temperatures, resulting in different maximum temperature values.

[0061] Figure 4 This is a schematic diagram illustrating the component temperature T. C A graph showing the corresponding data for (x-axis) and cable temperature 63 (y-axis) against 81. It has been found that the relationship between component temperature and cable temperature 90 can be obtained through, for example... Figure 4 The linear function approximation shown is not included in this text. In addition to showing the corresponding data point for cable temperature 63 at location 31, Figure 4 The figure also illustrates data point 82 for cable temperature 64 and data point 83 for cable temperature 65 measured at different locations. Although a correlation that can be approximated by a linear function exists for these data points, it is easy to see that the correlation is stronger for cable temperature 63 (data point 81).

[0062] In step 46, the temperature relationship 90 is derived from the determined data pair 81. When modeled as a linear function, the slope and optional intercept of the linear function can be determined. Figure 4 The linear function and its parameters for the linear relationship 90 are shown. Given this relationship and the component temperature T... C Accordingly, the corresponding cable temperature at the corresponding cable location can be obtained. Since the highest temperature of cable 20 is achieved when the wind turbine operates at maximum output power for a longer period of time, relation 90 provides a fairly accurate estimate of the cable temperature at this time. Therefore, efficient over-temperature protection can be achieved by using relation 90 without the need to actually measure the cable temperature.

[0063] Figure 2 The method can be used Figure 5The steps continue. In step 47, a cable temperature threshold is determined for the cable temperature of the one or more cables 20. This cable temperature may be specifically related to the surface temperature of the cable. If the cable temperature should be kept below 90°C, then the surface temperature of the cable should, for example, be kept below 84°C, which may be set as the cable temperature threshold. In step 48, the temperature relationship between the component temperature and the cable temperature is obtained. For example, this relationship can be obtained by retrieving it from a memory that stores the parameters of a linear function, or by performing... Figure 2 The method is used to obtain it. In step 49, the component temperature threshold is derived based on the cable temperature threshold and the temperature relationship. Figure 4 For example, the linear relationship is T cable = 0.82* T c -24℃ (rounded down). Therefore, the component temperature threshold can be determined based on the cable temperature threshold. Thresh cable = 84℃, which gives: Thresh c = (84℃ + 24℃) / 0.82 = 132℃ Then, the component temperature threshold Thresh c It can be used to operate wind turbine 100. By keeping the component temperature measured by the measuring unit 15 below the component temperature threshold, mitigation actions can be taken when the cable temperature reaches or exceeds the cable temperature threshold without actually measuring the cable temperature.

[0064] Figure 6 The diagram schematically illustrates a method for operating a wind turbine, employing appropriate component temperature thresholds. Therefore, Figure 2 and Figure 5 The method can be found Figure 6The method is executed prior to obtaining a component temperature threshold. This component temperature threshold may be stored in memory 12 of the control system 10 and may be retrieved from memory 12 during operation. In step 51, the wind turbine is operated to generate electrical power. In step 52, measurements of component temperatures are obtained during wind turbine operation. For example, they may be received from measurement unit 15 as analog or digital signals. In step 53, the measured component temperatures are compared with the component temperature threshold obtained based on derived relationship 90. This comparison may be performed by comparing corresponding analog or digital data values ​​or signals, or may be performed by a controller (e.g., a PI or PID controller). In step 54, it is checked whether the threshold has been reached or exceeded. If the measured component temperature is still below the component temperature threshold, the method continues the operation of the wind turbine in step 51. If the threshold is reached or exceeded in step 54, mitigation actions are taken in step 55. As mentioned above, this may involve the control system 10 reducing the power output of the wind turbine. Power output, as used herein, may specifically refer to active power output. The method then returns to step 51. Therefore, this method can be performed continuously during wind turbine operation, and thus the component temperature can be continuously measured and checked to ensure it remains below the component temperature threshold derived from this relationship, thereby ensuring that the cable temperature remains within safe operating limits. When a mitigation action is taken in step 55 and the temperature drops below the threshold again, the active power output of the wind turbine can be increased again (slowly) until the threshold is reached again in step 54 (e.g., through a ramp-up, etc.). Alternatively, a corresponding controller (e.g., a PID) can use the corresponding component temperature threshold as a target and control the output power to remain as close to that target as possible.

[0065] Figure 2 Methods and Figure 6 This method can be performed by different wind turbines. For example, through... Figure 2 The temperature relationships derived by this method are likely valid for all wind turbines of the same model and their corresponding operating parameter ratings. Therefore, the method can be performed on a reference wind turbine, and the resulting relationships can be stored. While the temperature measurements in steps 42 and 43 are typically performed on the wind turbine, evaluation steps 45 and 46 can also be performed remotely from that wind turbine. Figure 5 The method can also be performed by or away from this reference wind turbine, and the corresponding component temperature thresholds can be stored. When operating the same type of wind turbine, the wind turbine controller can set component temperature thresholds and can adjust accordingly. Figure 6 The method is to operate. Although Figure 2 and Figure 5 The method may therefore be executed only once for a single wind turbine, but Figure 6This method can be performed at multiple different wind turbines. However, it can also be performed for each wind turbine before starting operation on the respective wind turbine. Figure 2 and Figure 5 The corresponding calibration method is thus available. Therefore, a more accurate estimate of the corresponding relationship can be achieved.

[0066] Several steps (such as) Figure 2 Steps 41 and 44 of the method are further optional. Figure 5 The method is also optional and may not form a result. Figure 2 Part of the method. For example, in Figure 2 The relationships determined in the method can be provided to the wind turbine and stored in its controller memory, and Figure 5 and Figure 6 The method can be executed on a wind turbine based on stored temperature relationships. As another example, Figure 5 The steps may not be performed at all. (Through...) Figure 2 The temperature relationship derived by the method can be stored in the memory 12 of the wind turbine control system 10. Instead of using a component temperature threshold, the control system 10 can obtain the temperature measurement result from the measurement unit 15 and use the stored relationship 90 to estimate the cable temperature 63. Then, instead of steps 53 and 54, the estimated cable temperature can be compared with the cable temperature threshold to determine whether to take the mitigation action of step 55. Therefore, several variations of this method are conceivable.

[0067] For example, Figure 6 The method can be achieved by simply adding a component temperature threshold. Thresh c As an (additional) threshold, this is implemented in the High Temperature Ride-Through (HTRT) function of the control system 10. Therefore, efficient over-temperature protection for the one or more cables 20 can be achieved with only minor modifications to the wind turbine control.

[0068] Although relationship 90 can be based on temperature data obtained for location 31 (hot spot) where cable 20 reaches its highest temperature during operation, significant temperature rises may also occur at other locations, such as location 32 where bundle 25 is formed. This temperature rise, due to the increased output power of wind turbine 100, may cause damage to the cable insulation in the long term and, in the event of overheating, lead to dangerous conditions. Figure 7 The diagram illustrates an example of such a bundle 25, in which cables 20 pass through relatively small openings, and therefore cannot be laid out at greater distances between them. Figure 8The diagram illustrates a simulated temperature distribution of this cable bundle 25. As can be seen, overheating occurs in the central cable 26 because heat cannot be efficiently dissipated due to the surrounding cables 20. Therefore, overheating may occur.

[0069] To further ensure that the cable temperature remains within limits throughout the entire length of the cable, one or more cable separators 27 can be installed at position 32 of bundle 25, such as... Figure 9 As shown in the diagram. Installing this cable splitter can form Figure 2 As part of the method, for example, it may be performed after step 41, which increases the rating of the wind turbine. Alternatively, it may be performed in... Figure 6 This is performed before step 51, for example, before starting the operation of a wind turbine to increase its rating.

[0070] exist Figure 9 In the example, the cable splitter is positioned around the central cable 26 and ensures a minimum distance from adjacent cables. This minimum distance can be greater than 1 cm, but is preferably at least 2 cm or 3 cm. Therefore, Figure 9 The cable separator 27 is capable of separating several cables. It comprises two parts assembled around the cables and connected to each other, for example by using cable ties, which facilitates installation. In an alternative embodiment, a separate cable separator 27 may be provided around each cable 20, for example in the form of a ring having a radial extension of its annular section corresponding to the desired minimum distance the cables should be spaced apart. Figure 10 The illustration shows the corresponding temperature distributions of multiple cables 20 separated by respective cable separators. This allows for a very similar temperature distribution for each cable, and by appropriately selecting the distances, it ensures that the maximum desired cable temperature at the cable surface, such as the aforementioned 84°C, is not exceeded during operation. The one or more cable separators 27 can form... Figure 1 It is part of the wind turbine 100 and can be specifically installed at location 32, for example, at the feedthrough between the nacelle 101 and the tower 105.

[0071] The methods and construction described above significantly reduce the risk of cable overheating, while enabling upgraded wind turbines to operate with increased nominal power output. Hot spots in cable 20 can be identified, and temperature relationships and optional component temperature thresholds can be adjusted for a wind turbine during the calibration phase. The possibility of later applying the corresponding parameters to other wind turbines with similar construction further facilitates overheat protection and allows for rapid and relatively easy implementation. In particular, using the above solution, no modifications or installation of additional temperature sensors or even additional cables are required.

[0072] While specific embodiments have been disclosed herein, various changes and modifications may be made without departing from the scope of the invention. The present embodiments should be considered illustrative rather than restrictive in all respects, and all changes falling within the meaning and equivalence of the appended claims are intended to be incorporated herein.

Claims

1. A method of calibrating temperature control of one or more cables (20) of a wind turbine (100), wherein, determining a relationship (90) between a component operating parameter of a component (122) of a power generation system (120) of the wind turbine (100) and a cable temperature of the one or more electrical cables (20), wherein the one or more electrical cables (20) are configured to transport electrical power generated by the power generation system (120), wherein the method comprises: obtaining a measured component operating parameter of the component (122) of the power generation system (120), wherein the component operating parameter is a component temperature, and wherein obtaining a measured component temperature comprises obtaining a maximum value of the measured component temperature after the wind turbine (100) is operated at an increased nominal output power for a predetermined amount of time; obtaining a measured cable temperature measured at a location (31) of the one or more electrical cables (20), wherein obtaining the measured cable temperature comprises obtaining a maximum value of the measured cable temperature after the wind turbine (100) is operated at the increased nominal output power for the predetermined amount of time, wherein obtaining the measured component temperature and obtaining the measured cable temperature are repeatedly performed, including obtaining the maximum values of the measured component temperature and the measured cable temperature, respectively, for different operating conditions of the wind turbine (100); and deriving the relationship (90) between the component temperature and the cable temperature from the measured component temperature and the measured cable temperature.

2. The method of claim 1, wherein, The relationship (90) is a linear relationship, wherein deriving the relationship (90) comprises determining one or more parameters of a respective linear function.

3. A method of operating a wind turbine, wherein, The wind turbine (100) comprises: a power generation system (120) configured to generate electrical power from rotational mechanical energy; and one or more electrical cables (20) configured to transport electrical power generated by the power generation system (120), wherein the one or more electrical cables (20) are associated with a cable temperature threshold of a cable temperature of the one or more electrical cables (20), wherein the method comprises: obtaining a measured component operating parameter of a component (122) of the power generation system (120), wherein the measured component operating parameter and the cable temperature are related by a temperature relationship (90), wherein the component operating parameter is a component temperature (T C ), and wherein the temperature relationship (90) relates the component temperature to the cable temperature; comparing the measured component operating parameter to a component operating parameter threshold, wherein the component operating parameter threshold is derived from the cable temperature threshold and the temperature relationship (90), and / or comparing an estimated cable temperature estimated from the measured component operating parameter and the temperature relationship (90) to the cable temperature threshold; and if the comparison indicates that a respective threshold is reached or exceeded, taking a mitigation action to maintain or reduce the cable temperature.

4. The method of claim 3, wherein, The temperature relationship can be obtained by the method of claim 1 or 2.

5. The method of claim 3 or 4, wherein, The temperature relationship is derived by associating the maximum value of the component temperature with the maximum value of the cable temperature for different operating conditions of the wind turbine. The temperature relationship is derived by associating the maximum value of the component temperature with the maximum value of the cable temperature for different operating conditions of the wind turbine.

6. The method of any one of claims 3 to 5, wherein, The component (122) is a component of a generator (121) of the power generation system (120), wherein preferably the component (122) is a winding of the generator (121) and the component operating parameter is winding temperature.

7. The method of any one of claims 3 to 6, wherein, The cable temperature and the cable temperature threshold are associated with a predetermined location (31) at the one or more cables (20), wherein the location preferably corresponds to a hot spot where the one or more cables (20) reach a highest temperature during operation of the wind turbine (100).

8. The method of any one of claims 3 to 7, wherein, The mitigation action comprises curtailment of active power output of the wind turbine (100).

9. The method of any one of claims 3 to 8, wherein, The wind turbine (100) comprises a protection function for reducing the risk of an over-temperature condition of a component (122) of the power generation system (120), wherein the protection function compares the measured component temperature to a second component temperature threshold associated with the component (122) and takes the mitigation action based on the comparison, wherein a derived component temperature threshold derived for the one or more cables (20) is provided to the protection function to perform the comparison with the respective component temperature threshold and to take the respective mitigation action based on the comparison.

10. The method of any one of claims 3 to 9, wherein, The cable temperature is not measured, and / or wherein the ambient temperature is not considered in the comparison.

11. The method of any one of claims 3 to 10, wherein, The one or more cables (20) comprise a plurality of cables forming a cable bundle (25) at a location (32) along the plurality of cables, wherein one or more cable separators (27) are installed at the location (32) of the cable bundle (25), wherein the one or more cable separators (27) are configured to increase a spacing between the cables (20) at the installed location.

12. A method of upgrading a wind turbine with performance enhancing upgrades, wherein, The performance enhancing upgrade is configured to increase a power output of the wind turbine (100) compared to the wind turbine (100) without the performance enhancing upgrade, wherein the method comprises: installing the performance enhancing upgrade on the wind turbine (100); and performing a calibration according to any one of claims 1 to 2 to determine a relationship (90) between a component operating parameter of a component (122) of a power generation system (120) of the wind turbine (100) and a cable temperature of one or more cables (20) of the wind turbine (100).

13. The method of claim 12, wherein, The method further comprises operating the wind turbine (100) according to any one of claims 3 to 11 after performing the calibration.

14. A wind turbine control system configured to control operation of a wind turbine, wherein, The wind turbine (100) comprises a power generation system (120) configured to generate electrical power from rotational mechanical energy and one or more cables (20) configured to transmit electrical power generated by the power generation system (120), wherein the one or more cables (20) are associated with a cable temperature threshold of a cable temperature of the one or more cables (20), wherein the wind turbine control system (10) is configured to perform the method according to any one of the preceding claims.

15. A computer program for operating a control system of a wind turbine, wherein, The wind turbine (100) comprises a power generation system (120) configured to generate electrical power from rotational mechanical energy and one or more electrical cables (20) configured to transmit the electrical power generated by the power generation system, wherein the computer program comprises control instructions which, when executed by a processing unit (11) of the control system (10), cause the processing unit (11) to perform the method according to any one of claims 1-13.

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