Wind turbine control

Abstract

To provide methods and systems for determining reliability or correct functioning of azimuth sensors.SOLUTION: The present disclosure relates to a wind turbine comprising: a wind turbine rotor with a plurality of blades; a generator operatively coupled to the wind turbine rotor for generating electrical power; and a power electronic converter for converting the electrical power generated by the generator to converted AC power of predetermined frequency and voltage. The wind turbine further comprises a wind turbine controller configured to receive values of one or more operational parameter values of the wind turbine from one or more sensors and further configured to temporarily increase the speed of the generator to more than a nominal generator speed if the values of the operational parameters satisfy a potential trip criterion. The present disclosure also relates to methods for controlling wind turbines.SELECTED DRAWING: Figure 3C

Description

Technical Field

[0001] The present disclosure relates to wind turbines, and more particularly to the control of wind turbines. The present disclosure relates in particular to methods and systems for controlling a wind turbine so as to avoid tripping of the wind turbine.

Background Art

[0002] Modern wind turbines are commonly used to supply electricity to the power grid. This type of wind turbine generally comprises a tower and a rotor disposed on the tower. The rotor typically includes a hub and a plurality of blades and rotates under the influence of wind on the blades. This rotation generally generates torque that is transmitted directly or via a gearbox through a rotor shaft to a generator. In this way, the generator generates electricity that can be supplied to the power grid.

[0003] A wind turbine generally further comprises a power electronics converter for converting the power generated by the generator into converted AC ("alternating current") power of a predetermined frequency and voltage. The converted AC power is then supplied to a wind turbine main transformer having a low voltage side and a high voltage side for converting the converted AC power to a higher voltage and bringing this power to the power grid.

[0004] Regarding wind turbine generators and power electronics converters, various topologies are known. One such topology is the DFIG ("doubly-fed induction generator"). In a DFIG configuration, the stator of the generator is directly connected to the power grid. The rotor of the generator comprises a plurality of coils. These coils are electrically connected to the power grid via a power electronics converter comprising a rotor side converter, a DC link, and a grid side converter.

[0005] In another known topology, the generator rotor supports multiple permanent magnets. The rotor stator is connected to the power grid via a so-called "full converter." The full converter includes an equipment-side converter, a DC link, and a power grid-side converter.

[0006] Wind turbines typically also include a wind turbine controller. The wind turbine controller can be configured to determine appropriate actuator setpoints for the wind turbine based on ambient conditions. Examples of actuator setpoints for modern variable-speed wind turbines include generator torque and blade pitch angle. By controlling the blade pitch angle and generator torque, the rotor speed, as well as power output, aerodynamic thrust, and further mechanical loads, can be controlled. The objective of the control system is generally to maximize power output while simultaneously maintaining the load on the wind turbine at an acceptable level.

[0007] The normal or standard operation of a wind turbine can generally follow a predetermined power curve that defines the turbine's operation as a function of ambient wind speed. Normal operation encompasses a range of operating conditions. In the lower wind speed range, the objective is generally to maximize power output. In the higher wind speed range, particularly above the nominal wind speed, the operation of the wind turbine focuses on maintaining power output at a predetermined level while keeping the load under control.

[0008] As mentioned above, the actuator setpoints for torque and pitch (and even other actuators such as yaw) can be changed depending on the situation. Such situations include, for example, average wind speed, turbulence, wind shear, air density, and other meteorological conditions, as well as internal conditions such as vibration, mechanical load, or component temperature. Other situations include specific external requirements for noise reduction, interruptions in operation for maintenance, grid-related situations such as requirements for reduced active power, or grid events such as low voltage events, zero voltage events, and increases in grid frequency.

[0009] A wind turbine controller can be programmed to send signals to various systems (e.g., generators, pitch systems, and yaw systems) to control the operation of the wind turbine, based on a set of measurement variables received from various sensors. Examples of sensors include rotor speed sensors, load sensors (strain gauges or accelerometers), anemometers, wind vanes, and others.

[0010] A wind turbine may trip under various circumstances. In this specification, a trip can be defined as the sudden or immediate shutdown of a wind turbine in response to an exceptional or unexpected event or series of events. Therefore, the operation of the wind turbine is interrupted, and no power is supplied to the grid until the wind turbine restarts.

[0011] High currents, particularly those exceeding a predetermined threshold, and / or currents exceeding that threshold over a specific period, can lead to the converter tripping and, consequently, the wind turbine tripping. [Overview of the project]

[0012] In one embodiment of the present disclosure, a wind turbine is provided, comprising a wind turbine rotor having a plurality of blades supported on a support structure, and a generator operably coupled to the wind turbine rotor for generating electricity. The wind turbine further comprises a power electronics converter for converting the electricity generated by the generator into converted AC power of a predetermined frequency and voltage. The wind turbine further comprises a wind turbine controller configured to receive values ​​of one or more operating parameters of the wind turbine from one or more sensors, the controller further configured to temporarily increase the speed of the generator to a speed above the nominal speed if the value of the operating parameter meets a tripping criterion.

[0013] According to this embodiment, a wind turbine is provided that can delay and / or avoid wind turbine tripping, particularly tripping caused by undesirable events in the power electronics converter. By temporarily increasing the rotational speed of the wind turbine, the current in the equipment-side converter can be reduced, and thus the converter tripping can be avoided or delayed.

[0014] In this specification, a trip criterion can be considered as one or more values ​​of an operating parameter, variable, or actuator setpoint of a wind turbine, which is one or more values ​​that cause a trip of the wind turbine components and / or the wind turbine.

[0015] In this specification, the tripping criterion can be considered as one or more values ​​of an operating parameter, variable, or actuator setpoint of a wind turbine, which, if continued over a period of time, would satisfy the tripping criterion.

[0016] In a further embodiment, a method for controlling a wind turbine is provided. The method includes receiving values ​​of operating parameters of a wind turbine and determining that one or more of the operating parameters satisfy a trip-possibility criterion regarding the possibility of the wind turbine tripping. The method further includes sending a command to a wind turbine actuator to temporarily increase the speed of the wind turbine rotor to a level above the nominal rotor speed and determining that the operating parameters no longer satisfy the trip-possibility criterion. The method then further includes sending a command to the wind turbine actuator to reduce the speed of the wind turbine rotor to the nominal rotor speed.

[0017] This method can be implemented in a wind turbine controller.

[0018] In a further embodiment, a method for operating a wind turbine is provided. This method includes determining one or more of the following operating parameters: current of the equipment-side converter, ambient temperature, and wind speed. This method may include determining whether the operating parameters meet the criteria for changing the operation. This method may further include increasing the generator speed to a level above the nominal generator speed and decreasing the generator speed to or below the nominal generator speed if the operating parameters meet the criteria for returning to the default operation.

[0019] In this specification, a change in operation can be considered as a change in the operating settings of a wind turbine, that is, a change in the actuator setpoint and / or boundary conditions that govern the operation of the wind turbine. [Brief explanation of the drawing]

[0020] [Figure 1] A schematic perspective view of an example of a wind turbine is shown. [Figure 2] Figure 1 shows a simplified internal diagram of an example of a wind turbine nacelle. [Figure 3A] This diagram schematically illustrates the current level generation in the device-side converter at various ambient temperatures. [Figure 3B] This diagram schematically shows the relationship between the generator rotor speed and the current level in the equipment-side converter. [Figure 3C] This shows an example of a method for controlling a wind turbine. [Figure 4] This document provides a schematic overview of standard and modified operation examples of wind turbines. [Figure 5] This provides a schematic example of how to operate a wind turbine. [Modes for carrying out the invention]

[0021] Now, we will refer in detail to embodiments of the present invention, one or more examples of which are shown in the drawings. Each example is provided as an illustration of the present invention, not as a limitation thereof. It will be apparent to those skilled in the art that various modifications and changes can be made to the present invention without departing from the scope or spirit thereof. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield further embodiments. Accordingly, the present invention is intended to embrace modifications and changes that fall within the scope of the appended claims and their equivalents.

[0022] FIG. 1 is a perspective view of an example of a wind turbine 10. In this example, the wind turbine 10 is a horizontal-axis wind turbine. Alternatively, the wind turbine 10 may be a vertical-axis wind turbine. In this example, the wind turbine 10 includes a tower 100 extending from a support system 14 on the ground 12, a nacelle 16 mounted on the tower 100, and a rotor 18 coupled to the nacelle 16. Although FIG. 1 specifically shows an onshore wind turbine, the present disclosure also relates to offshore wind turbines.

[0023] The rotor 18 includes a rotatable hub 20 and at least one rotor blade 22 coupled to the hub 20 and extending outwardly from the hub 20. In this example, the rotor 18 has three rotor blades 22. In alternative embodiments, the rotor 18 includes more or fewer than three rotor blades 22. The tower 100 may be made of tubular steel so as to define a cavity (not shown in FIG. 1) between the support system 14 and the nacelle 16 disposed at the upper end 102 of the tower 100. In alternative embodiments, the tower 100 is any suitable type of tower having any suitable height. According to an alternative form, the tower may be a hybrid tower comprising a concrete portion and a tubular steel portion. Also, the tower may be a partial or complete lattice tower.

[0024] The rotor blades 22 are spaced apart around the hub 20 to facilitate the rotation of the rotor 18, converting kinetic energy from wind into usable mechanical energy, and then into electrical energy. The rotor blades 22 are combined with the hub 20 by coupling the blade root portions 24 to the hub 20 in a plurality of load transmission regions 26. The load transmission regions 26 may have hub load transmission regions and blade load transmission regions (neither of which are shown in Figure 1). The load generated on the rotor blades 22 is transmitted to the hub 20 via the load transmission regions 26.

[0025] In some examples, the rotor blades 22 can have lengths ranging from about 15 meters (m) to about 90 meters or more. The rotor blades 22 can have any suitable length that allows the wind turbine 10 to function as described herein. For example, but not limited to, blade lengths of 20 m or less, 37 m, 48.7 m, 50.2 m, 52.2 m, or more than 91 m. When wind strikes the rotor blades 22 from the wind direction 28, the rotor 18 rotates around the rotor axis 30. As the rotor blades 22 rotate and are subjected to centrifugal force, the rotor blades 22 are also subjected to various forces and moments. Thus, the rotor blades 22 may deflect and / or rotate from a neutral or non-deflected position to a deflected position.

[0026] Furthermore, by changing the pitch angle of the rotor blades 22, i.e., the angle that determines the orientation of the rotor blades 22 with respect to the wind direction, using the pitch system 32, the angular position of at least one rotor blade 22 with respect to the wind vector can be adjusted, thereby controlling the load and the output generated by the wind turbine 10. The pitch axis 34 of the rotor blades 22 is shown. During the operation of the wind turbine 10, the pitch system 32 can change the pitch angle of the rotor blades 22, in particular, to reduce the angle of attack of (a portion of) the rotor blades, thereby facilitating a reduction in rotational speed and / or facilitating stalling of the rotor 18.

[0027] In this example, the blade pitch of each rotor blade 22 is individually controlled by the wind turbine controller 36 or the pitch control system 80. Alternatively, the blade pitch of all rotor blades 22 may be controlled simultaneously by the control system.

[0028] Furthermore, in this example, when the wind direction 28 changes, the yaw direction of the nacelle 16 can be rotated around the yaw axis 38, thereby positioning the rotor blades 22 relative to the wind direction 28.

[0029] In this example, the wind turbine controller 36 is illustrated as a centralized system within the nacelle 16, but the wind turbine controller 36 may be a distributed system located throughout the wind turbine 10, on the support system 14, within the wind power plant, and / or in a remote control center. The wind turbine controller 36 includes a processor 40 configured to perform the methods and / or steps described herein. Furthermore, many of the other components described herein include processors.

[0030] As used herein, the term “processor” is not limited to integrated circuits technically called computers, but broadly refers to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits, and other programmable circuits, and these terms are used interchangeably herein. It should be understood that a processor and / or control system may further include memory, input channels, and / or output channels.

[0031] Figure 2 is an enlarged cross-sectional view of a portion of the wind turbine 10. In this example, the wind turbine 10 includes a nacelle 16 and a rotor 18 rotatably coupled to the nacelle 16. More specifically, the hub 20 of the rotor 18 is rotatably coupled to a generator 42 located within the nacelle 16 by a main shaft 44, a gearbox 46, a high-speed shaft 48, and a coupling 50. In this example, the main shaft 44 is positioned at least partially coaxial with the longitudinal axis (not shown) of the nacelle 16. The rotation of the main shaft 44 drives the gearbox 46, which in turn drives the high-speed shaft 48 by converting the relatively slow rotational motion of the rotor 18 and the main shaft 44 into the relatively fast rotational motion of the high-speed shaft 48. The latter is connected to the generator 42 to generate electrical energy with the help of the coupling 50. Furthermore, a transformer 90 and / or appropriate electronic equipment, switches, and / or inverters may be placed within the nacelle 16 to convert the electrical energy generated by the generator 42, which has a voltage between 400V and 1000V, into electrical energy having a medium voltage (e.g., 10 to 35kV). The electrical energy is then delivered from the nacelle 16 to the tower 100 via power cables 160.

[0032] The gearbox 46, generator 42, and transformer 90 can be supported by a main support structure frame of the nacelle 16, which optionally embodies the main frame 52. The gearbox 46 may include a gearbox housing connected to the main frame 52 by one or more torque arms 103. In this example, the nacelle 16 further includes a main front support bearing 60 and a main rear support bearing 62. Furthermore, the generator 42 can be attached to the main frame 52 by a separation support means 54, in particular to prevent vibrations of the generator 42 from being introduced into the main frame 52 and causing a noise emission source.

[0033] Optionally, the main frame 52 is configured to bear the weight of the components of the rotor 18 and nacelle 16, as well as the entire load caused by the wind and rotational load, and further to introduce these loads into the tower 100 of the wind turbine 10. The rotor shaft 44, generator 42, gearbox 46, high-speed shaft 48, coupling 50, and any related fastening, support, and / or fixing devices such as but not limited to supports 52, front support bearings 60, and rear support bearings 62 may be referred to as the drivetrain 64.

[0034] Furthermore, the nacelle 16 may include a yaw drive mechanism 56 that can be used to rotate the nacelle 16, and by extension the rotor 18, around the yaw axis 38 in order to control the viewpoint of the rotor blades 22 with respect to the wind direction 28.

[0035] To properly position the nacelle 16 with respect to the wind direction 28, the nacelle 16 may further include at least one meteorological measurement system which may include a wind vane and an anemometer. The meteorological measurement system 58 may provide the wind turbine controller 36 with information which may include wind direction 28 and / or wind speed. In this example, the pitch system 32 is at least partially located within the hub 20 as a pitch assembly 66. The pitch assembly 66 includes one or more pitch drive systems 68 and at least one sensor 70. Each pitch drive system 68 is coupled to each rotor blade 22 (shown in Figure 1) to adjust the pitch angle of the rotor blade 22 along the pitch axis 34. Only one of the three pitch drive systems 68 is shown in Figure 2.

[0036] In this example, the pitch assembly 66 includes a hub 20 and at least one pitch bearing 72 coupled to each rotor blade 22 (shown in Figure 1) to rotate each rotor blade 22 around a pitch axis 34. The pitch drive system 68 includes a pitch drive motor 74, a pitch drive gearbox 76, and a pitch drive pinion 78. The pitch drive motor 74 is coupled to the pitch drive gearbox 76 so that the pitch drive motor 74 imparts mechanical force to the pitch drive gearbox 76. The pitch drive gearbox 76 is coupled to the pitch drive pinion 78 so that the pitch drive gearbox 76 rotates the pitch drive pinion 78. The pitch bearing 72 is coupled to the pitch drive pinion 78 so that the rotation of the pitch drive pinion 78 causes the rotation of the pitch bearing 72.

[0037] The pitch drive system 68 is coupled to the wind turbine controller 36 to adjust the pitch angle of the rotor blades 22 upon receiving one or more signals from the wind turbine controller 36. In this example, the pitch drive motor 74 is any suitable motor driven by a power and / or hydraulic system that enables the pitch assembly 66 to function as described herein. Alternatively, the pitch assembly 66 may include any suitable structure, configuration, arrangement, and / or components, but are not limited to, hydraulic cylinders, springs, and / or servo mechanisms. In certain embodiments, the pitch drive motor 74 is driven by energy extracted from a stored energy source (not shown) that supplies the rotational inertia and / or energy of the hub 20 to the components of the wind turbine 10.

[0038] The pitch assembly 66 may further include one or more pitch control systems 80 for controlling the pitch drive system 68 in accordance with a control signal from the wind turbine controller 36 in certain preferential conditions and / or when the rotor 18 is overspeeding. In this example, the pitch assembly 66 includes at least one pitch control system 80 communicably coupled to each pitch drive system 68 in order to control the pitch drive system 68 independently of the wind turbine controller 36. In this example, the pitch control system 80 is coupled to the pitch drive system 68 and the sensor 70. During the normal operation of the wind turbine 10, the wind turbine controller 36 can control the pitch drive system 68 to adjust the pitch angle of the rotor blades 22.

[0039] In one embodiment, a power generator 84, which includes, for example, a battery, an electric capacitor, or a generator driven by the rotation of the hub 20, is located in or within the hub 20 and coupled to the sensor 70, the pitch control system 80, and the pitch drive system 68 to provide a power source to these components. In this example, the power generator 84 provides a continuous power source to the pitch assembly 66 while the wind turbine 10 is operating. In an alternative embodiment, the power generator 84 provides power to the pitch assembly 66 only in the event of a power loss event of the wind turbine 10. Power loss events may include a loss or degrading of the power grid, a malfunction of the wind turbine 10's electrical system, and / or a failure of the wind turbine controller 36. In the event of a power loss event, the power generator 84 operates to provide power to the pitch assembly 66 so that the pitch assembly 66 can operate during the power loss event.

[0040] In this example, the pitch drive system 68, sensor 70, pitch control system 80, cable, and power generator 84 are each located within a cavity 86 defined by the inner surface 88 of the hub 20. In an alternative embodiment, the components are located relative to the outer surface of the hub 20 and can be directly or indirectly coupled to the outer surface.

[0041] Figure 3A schematically illustrates the current levels generated in the equipment-side converter at various ambient temperatures. The y-axis represents the average current (at 10-minute intervals), and the x-axis represents the ambient temperature. The data plotted in Figure 3A corresponds to wind turbines using permanent magnet generators at various locations. Figure 3A shows a tendency for the current level in the equipment-side converter to be higher at higher ambient temperatures. While we do not wish to be bound by any particular theory, this phenomenon is thought to be caused by a decrease in the strength of the magnets in the permanent magnet generator at higher ambient temperatures. To maintain the output level, the torque in the equipment-side converter is increased, which leads to a larger current.

[0042] Naturally, the current level also depends on the operating conditions of the wind turbine, particularly the wind speed. At wind speeds exceeding the nominal wind speed, the output is usually the nominal or "rated" output of the wind turbine. At wind speeds below the nominal wind speed, the output is lower.

[0043] Figure 3A also shows two reference lines. The lower reference line represents the converter's nominal or rated current. This is the level of current expected in the converter at the nominal output. The upper line represents the current level above which the converter's operation may become jeopardized; in other words, the threshold beyond which it cannot continue to operate. The converter's IGBTs, diodes, etc., have operating limits above which they may be damaged. The converter protection threshold is a safety margin above the nominal current level.

[0044] When the current reaches the converter protection threshold, the converter does not necessarily trip immediately. Depending on the converter, various security mechanisms can be implemented. One security mechanism may define a function of both current and time that, when it reaches a certain level, causes the converter to trip. The tripping of the converter leads to the tripping of the wind turbine. One such function is i 2.t is the point at which the threshold is exceeded, i is the current of the device-side converter, and t is the period during which the device-side converter current exceeds the maximum level. Therefore, a high level of current can be maintained for a short period, but not for a long period.

[0045] Figure 3A shows that at higher ambient temperatures, the current may reach levels exceeding the converter protection threshold, which could lead to the wind turbine tripping. It has become clear that in certain locations with higher ambient temperatures, such as above 25°C or even above 30°C, for several hours a day, combined with high wind speeds, this could lead to the wind turbine tripping.

[0046] Figure 3B schematically illustrates the relationship between generator rotor speed and the current level in the equipment-side converter. At a given power level, the generator current and the equipment-side converter current are inversely proportional to the generator rotor speed. The generator rotor speed is directly proportional to the rotational speed of the wind turbine rotor in the case of a directly driven wind turbine, and in the case of a wind turbine with a gearbox having a constant transmission ratio. It has become clear that even a slight increase in RPM of, for example, 1 or 2%, can result in a sufficient decrease in the current level to postpone or avoid equipment-side converter tripping.

[0047] Figure 3C shows an example of a method for controlling a wind turbine. The method for controlling a wind turbine includes receiving values ​​of the wind turbine's operating parameters in block 150. The method further includes determining in block 160 that one or more of the operating parameters meet a trip possibility criterion regarding the possibility of the wind turbine tripping. The method includes sending a command to the wind turbine actuator in block 170 to temporarily increase the speed of the wind turbine rotor to a level above the nominal rotor speed. The method includes determining in block 180 that the operating parameters no longer meet the trip possibility criterion, and sending a command to the wind turbine actuator in block 190 to reduce the speed of the wind turbine rotor to the nominal rotor speed.

[0048] In block 150, the wind turbine controller can receive values ​​of operating parameters from several different sensors. Such sensors may include an ambient temperature sensor, a component temperature sensor, and a sensor indicating the current level. These parameters can indicate the converter temperature and converter current level, and can therefore be used to determine the potential trip condition of the equipment-side converter as described above.

[0049] However, other sensors may also be available, particularly in relation to other potential tripping conditions. Such sensors include strain gauges, vibration sensors, and other sensors for indicating load. Such sensors may be positioned in conjunction with, or can indicate, the operating conditions of, converters, generators, or wind turbine rotors.

[0050] In block 160, it is possible to evaluate whether a specific operating parameter or combination of operating parameters satisfies the tripping criterion, that is, whether the levels of various parameters are sustainable over time, or whether prolonged operation at these levels would lead to a trip of the wind turbine or its components. If the tripping criterion is not met, standard or normal operation can continue. Standard operation in this context can, in particular, refer to operation according to a predetermined power curve that respects both the nominal power of the wind turbine and the nominal speed of the wind turbine rotor or generator rotor.

[0051] In block 160, if it becomes clear that one or more of the predetermined tripping criteria are met, the controller may, in block 170, send a command to temporarily increase the rotor speed of the generator. As previously mentioned, temporarily increasing the rotor speed reduces the current in the equipment-side converter, preventing it from reaching a threshold above which the security of the converter components may be compromised. In another example, such a temporary increase can avoid resonance in a wind turbine. By changing the rotor speed, the excitation frequency of a particular load can be changed, thus avoiding resonance. Thus, potential situations in which the load or vibration reaches a level that would lead to the wind turbine tripping can be avoided.

[0052] In block 170, commands transmitted by the controller may include settings for actuators such as the pitch actuator and / or generator torque. In some examples, two or more operating modes may be predefined in the controller, including a default or standard operating mode and adjusted or modified operating modes. Each of these operating modes may have predetermined rules for adjusting actuator setpoints based on sensor values, such as rotor speed, load, pitch angle, etc. In this example, the modified operating mode can be adjusted in block 170.

[0053] In one example, the operating mode or increased rotational speed can be maintained for a predetermined period. In another example, in block 180, the adjusted operating mode can be maintained until the tripping criterion is no longer met, for example, until the current of the equipment-side converter falls below a predetermined threshold. To avoid hysteresis, a return to the standard operating mode that respects the nominal rotor speed may be performed when the current falls below a predetermined security threshold for a minimum period. In other examples, or in other potential tripping cases, it will be apparent that a return to normal operation may depend on parameters different from the current level.

[0054] In some cases, the tripping criterion for the possibility of a wind turbine tripping may be the same as the tripping criterion for a power electronics converter.

[0055] In some examples, the operating parameters analyzed or considered in assessing the likelihood of tripping include one or more currents within the equipment-side converter. Alternatively, or in addition to these, the operating parameters include ambient temperature and / or the temperature of the wind turbine components.

[0056] In some cases, the level exceeding the nominal rotor speed may be 5% or less above the nominal rotor speed, and in particular, 3% or less above the nominal rotor speed. It has been shown that even a small increase in the nominal rotor speed can sufficiently reduce the current level in the converter, while the potential increase in load is small enough not to affect the lifespan of the wind turbine.

[0057] In some cases, temporarily increasing the speed of a wind turbine rotor to a level exceeding the nominal rotor speed involves maintaining the wind turbine's output at the nominal output.

[0058] In some cases, the speed of the wind turbine rotor can be increased to a level exceeding the nominal rotor speed for 30 minutes or less, and especially 20 minutes or less.

[0059] Figure 4 schematically illustrates examples of standard and modified operation of a wind turbine. According to one aspect of the present disclosure, a wind turbine is provided comprising a wind turbine rotor having a plurality of blades, a generator operably coupled to the wind turbine rotor to generate power, and a power electronics converter for converting the power generated by the generator into converted AC power of a predetermined frequency and voltage. The wind turbine further comprises a wind turbine controller configured to receive values ​​of one or more operating parameters of the wind turbine from one or more sensors, and further configured to temporarily increase the speed of the generator to a speed above the nominal speed if the value of the operating parameter meets a tripping criterion.

[0060] In some examples, the generator may be a DFIG generator. In further examples, the generator may be a permanent magnet generator. This disclosure is not limited to any particular generator and / or converter topology.

[0061] As mentioned above, the level exceeding the nominal rotor speed may be 5% or less above the nominal rotor speed, and in particular, 3% or less above the nominal rotor speed. In some cases, the level exceeding the nominal speed may be approximately 2%.

[0062] As mentioned above, the wind turbine controller can be further configured to maintain the wind turbine's output at its nominal output.

[0063] Referring to Figure 4, two separate power curves are shown. The first power curve shows the effective power of the wind turbine as a function of wind speed in a standard or default operating mode. This power curve can correspond to classic wind turbine control where rotor speed and power increase from a certain wind speed up to a first wind speed (approximately 9 m / s in the example in Figure 4) where the nominal rotor speed is reached. Beyond this wind speed, the rotor speed remains constant at the nominal level until it reaches the nominal wind speed (approximately 12 m / s in the example in Figure 4). Beyond the nominal wind speed, both rotor speed and power are maintained constant. This is typically achieved through the pitch of the wind turbine blades.

[0064] The second power curve shows the effective output of the wind turbine as a function of wind speed in the tuned or modified operating mode. It can be seen that these power curves overlap substantially completely; that is, in the modified operating mode, the output of the wind turbine as a function of wind speed remains unchanged.

[0065] In the same Figure 4, two separate curves show the RPM (revolutions per minute) of the generator in two different operating modes. In this example, at wind speeds of approximately 9 m / s or higher (where the nominal rotor speed is reached), the rotor speed may be higher than the nominal rotor speed.

[0066] When the tripping criterion is met, the wind turbine controller can switch from the default operating mode to a modified operating mode in which the rotor speed exceeds the nominal rotor speed. In some examples, the tripping criterion for the wind turbine may be the same as the tripping criterion for the power electronics converter. In some of these examples, the operating parameters may include one or more currents in the equipment-side converter.

[0067] In a specific example, the trip possibility criterion is i 2 .t may include a threshold value, where i is the current of the device-side converter and t is the period during which the current of the device-side converter exceeds the maximum level.

[0068] In some examples, the wind turbine controller is further configured to reduce the generator speed to the nominal speed if the values ​​of the operating parameters no longer meet the tripping criterion.

[0069] Figure 5 schematically illustrates an example of a method for operating a wind turbine. In one embodiment of the present disclosure, a method for operating a wind turbine is provided, which includes measuring the current of an equipment-side converter in block 250. In block 260, the method may include determining whether the current of the equipment-side converter meets the criteria for changing operation. In block 270, the generator speed may be increased to a level above the nominal generator speed. The method may further include reducing the generator speed to below the nominal generator speed in block 280 if the current of the equipment-side converter meets the criteria for returning to default operation.

[0070] In the example shown in Figure 5, the method may include predefining at least two operating modes in block 230. One of these operating modes may be a default operating mode, and the other may be an adjusted operating mode with a higher rotational speed.

[0071] In block 260, the criteria for making changes to the operation may relate to the protection of the equipment-side converter, as described above. In other examples, other criteria or additional criteria may be used. To evaluate this criterion, the current in the equipment-side converter can be determined. Alternatively, or in addition to this, the ambient temperature may be measured.

[0072] If no change in operation is required, the default operation can continue as shown in block 165. If an operation change is required, the wind turbine can be switched to an alternative operating mode in which the rotor speed may reach levels exceeding the nominal rotor speed.

[0073] In either case, in block 250, the current in the equipment-side converter can be continuously monitored. In block 280, an evaluation can be performed to determine whether the wind turbine can be switched back to the default operating mode. In some examples, the criterion for returning to default operation may include the current in the equipment-side converter falling below a predetermined level for, for example, a minimum period of time. If this is not the case, in block 285, the operating mode with increased generator speed can be continued. If it is possible to return to the default operating mode, the default operating mode can be restarted in block 290.

[0074] According to the examples in this disclosure, it is possible to avoid wind turbine trips in situations where a trip would occur with conventional control methods. According to the examples in this disclosure, the number of wind turbine trips per week, month, or year can be reduced. Improved wind turbine availability can lead to increased annual energy production and potentially reduced component wear. Furthermore, the examples in this disclosure can also reduce the need for cooling of specific components.

[0075] In other examples, a method for operating a wind turbine may include measuring one or more of the following operating parameters in block 250: current of the equipment-side converter, wind speed, and ambient temperature. In block 260, such a method may include determining whether the operating parameters meet the criteria for changing the operation. A single operating parameter, or a combination of operating parameters, may satisfy such criteria. With respect to ambient temperature and wind speed, in some examples, historical values ​​for the last 24, 12, or 6 hours may be taken into account. In such a method, the generator speed may be reduced in block 280 when the operating parameters meet the criteria for returning to default operation.

[0076] The examples of the present disclosure may be particularly suitable for wind turbines operating primarily in high ambient temperature environments to avoid tripping of the equipment-side converter. The examples of the present disclosure may also be useful in environments where high ambient temperatures are rarely reached. In these cases, it may be possible to use components such as converters set near their operating limits, and to temporarily increase rotor speed in exceptional cases where tripping might occur.

[0077] Examples of methods disclosed herein can be implemented in hardware, software, firmware, or combinations thereof. Examples of methods disclosed herein can utilize one or more of the following: virtual machines, cloud computing, and edge computing.

[0078] Those skilled in the art will further understand that the various exemplary logic blocks, modules, circuits, and algorithmic steps described in connection with the disclosure herein can be implemented as electronic hardware, computer software, or a combination of both. To clearly demonstrate this hardware-software compatibility, various exemplary components, blocks, modules, circuits, and steps have been described above in general terms of their function. Whether such functions are implemented as hardware or software depends on the individual application and the design constraints imposed on the overall system. Those skilled in the art can implement the described functions in various ways tailored to each individual application.

[0079] The various exemplary logic blocks, modules, and circuits described in connection with the disclosure herein may be implemented or carried out by one or more general-purpose processors, digital signal processors (DSPs), cloud computing architectures, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. Furthermore, the processor may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors working with a DSP core, or any other such configuration.

[0080] Furthermore, this disclosure relates to a computer program or computer program product that includes instructions (code) that, when executed, perform any of the methods disclosed herein.

[0081] A computer program may be in the form of object code, such as source code, object code, code intermediate source, and partially compiled forms, or in any other form suitable for use in process implementation. A carrier may be any entity or device capable of carrying a computer program.

[0082] When implemented in software / firmware, functions can be stored or transmitted as one or more instructions or codes on a computer-readable medium. Computer-readable medium includes both computer storage media and communication media, including any media that facilitate the transfer of computer programs from one location to another. Storage media may be any available medium accessible by a general-purpose or dedicated computer. Such computer-readable media may include, but are not limited to, RAM, ROM, EEPROM, CD / DVD or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium accessible by a general-purpose or dedicated computer or processor, which can be used to carry or store desired program code means in the form of instructions or data structures. Any connection is also appropriately referred to as computer-readable medium. For example, if software / firmware is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. As used herein, the terms "disk" and "disc" include compact discs (CDs), laser discs, optical discs, digital multipurpose discs (DVDs), floppy disks, and Blu-ray discs, where a disk typically reproduces data magnetically, while a disc reproduces data optically using a laser. Any combination of these should also be included within the scope of computer-readable media.

[0083] This specification discloses the present invention, including preferred embodiments, and uses examples to enable those skilled in the art to practice the invention, including the manufacture and use of any apparatus or system and the execution of any related methods. The patentable scope of the present invention is defined by the claims and may include other examples that a person skilled in the art may conceive. Such other examples are intended to be included in the technical scope of the claims if they have structural elements that are not different from the language of the claims, or if they include equivalent structural elements that do not substantially differ from the language of the claims. A person skilled in the art may construct further embodiments and techniques in accordance with the principles of this application by combining and harmonizing aspects from the various embodiments described above and other known equivalents for each such aspect. Where reference numerals related to the drawings are placed in parentheses in the claims, those reference numerals are merely intended to make the claims more understandable and should not be construed as limiting the technical scope of the claims. [Explanation of symbols]

[0084] 10 Wind Turbines 12 Ground 14 Support System 16 Nacer 18 rotors 20 Hubs 22 rotor blades 24. Blade base 26 Load transfer region 28 Wind direction 30 rotor shaft 32 Pitch System 34 Pitch axis 36 Wind Turbine Controller 38 Yaw axis 40 processors 42 Generators 44 Main shaft, rotor shaft 46 Gearbox 48 High-speed shaft 50 Couplings 52 Main frame, support 54 Separation support means 56 Yaw drive mechanism 58 Weather Measurement Systems 60 Front support bearing 62 Rear support bearing 64 Drivetrain 66 Pitch Assembly 68 Pitch Drive System 70 sensors 72 pitch bearing 74 Pitch drive motor 76 Pitch Drive Gearbox 78 Pitch Drive Pinion 80 Pitch Control System 84 Power Generator 86 Hollow 88 Inner self 90 Transformer 100 Towers 102 Top 103 Torque Arm 160 Power Cables

Claims

1. A wind turbine (10), comprising a wind turbine rotor (18) having a plurality of blades (22), a generator (42) operably coupled to the wind turbine rotor (18) for generating electrical power, a power electronics converter for converting the electrical power generated by the generator (42) into converted AC power of a predetermined frequency and voltage, a wind turbine controller (36) configured to receive values of one or more operating parameters of the wind turbine from one or more sensors and further configured to temporarily increase the speed of the generator (42) above a nominal generator speed when the values of the operating parameters meet a trip probability criterion and the operating parameters include one or more currents in the equipment-side converter, the trip probability criterion regarding the trip probability of the wind turbine (10) is a criterion regarding the trip probability of the power electronics converter, the trip probability criterion includes i2.t exceeding a threshold value, where i is the current in the equipment-side converter and t is the period during which the current in the equipment-side converter exceeds a maximum level, the wind turbine (10).

2. The level above the nominal generator speed is 5% or less above the nominal generator speed, particularly 3% or less above the nominal generator speed, the wind turbine (10) according to claim 1.

3. The wind turbine controller (36) is further configured to maintain the output of the wind turbine (10) at a nominal output, the wind turbine (10) according to claim 1 or 2.

4. The wind turbine controller (36) of claim 1 to 3, further configured to reduce the speed of the generator (42) to the nominal generator speed when the value of the operating parameter no longer meets the trip probability criterion. The wind turbine (10) according to any one of claims 1 to 3.

5. The generator (42) is a DFIG generator or a permanent magnet generator. The wind turbine (10) according to any one of claims 1 to 4.

6. A method for controlling a wind turbine (10), comprising: Receiving (150) a value of an operating parameter of the wind turbine (10), wherein the operating parameter includes one or more currents in the machine-side converter, the step (150); Determining (160) that one or more of the operating parameters meet a trip probability criterion regarding the probability of tripping of the wind turbine (10), wherein the trip probability criterion regarding the probability of tripping of the wind turbine (10) is a criterion regarding the probability of tripping of the power electronics converter, and the trip probability criterion includes that i2.t exceeds a threshold value, where i is the current in the machine-side converter and t is the period during which the current in the machine-side converter exceeds the maximum level. The step (160); Sending a command to the wind turbine actuator to temporarily increase the speed of the wind turbine rotor (18) of the wind turbine (10) to a level above the nominal rotor speed (170); Determining (180) that the operating parameter no longer meets the trip probability criterion; Sending a command to the wind turbine actuator to reduce the speed of the wind turbine rotor (18) to the nominal rotor speed (190); And a method including.

7. The level exceeding the nominal rotor speed is 5% or less, particularly 3% or less, of exceeding the nominal rotor speed, according to the method of claim 6. **Claim 8** Temporarily increasing the speed of the wind turbine rotor (18) of the wind turbine (10) to a level exceeding the nominal rotor speed includes maintaining the output of the wind turbine (10) at the nominal output, according to the method of claim 6. **Claim 9** The operating parameter includes the ambient temperature and / or the temperature in the wind turbine components, according to the method of claim 6. **Claim 10** The speed of the wind turbine rotor (18) of the wind turbine (10) is increased to a level exceeding the nominal rotor speed for 30 minutes or less, particularly 20 minutes or less, according to any one of claims 6 to 9.

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