3. Methods for operating a wind turbine

Abstract

Method for operating a wind turbine, wherein the wind turbine includes a rotor, wherein the rotor has at least one rotor blade, wherein the rotor is set up to rotate at an optimal speed, wherein the optimal speed enables the theoretically maximum possible power gain to be delivered, wherein the method comprises: a Determining a turbulence parameter; and b Operating the wind turbine at a rotor speed that is increased by a speed deviation amount compared to the optimal speed; where the speed deviation amount depends on the turbulence parameter.

Description

BACKGROUND OF THE INVENTION

[0001] The subject matter described herein relates generally to methods and systems for operating a wind turbine and, in particular, to methods and systems for operating a wind turbine below its rated power. The subject matter further relates to a control device for operating a wind turbine and to a wind turbine itself.

[0002] In general, a wind turbine consists of a turbine with a rotor that has a rotating hub assembly with multiple blades. The blades convert wind energy into mechanical torque, which, via the rotor, drives one or more generators. The generators are sometimes, but not always, rotatably connected to the rotor via a gearbox. The gearbox increases the inherently low rotational speed of the rotor so that the generator can efficiently convert the mechanical rotational energy into electrical energy, which is fed into a power grid via at least one electrical connection. Gearless direct-drive wind turbines also exist. The rotor, generator, gearbox, and other components are typically mounted within a housing or nacelle, which is positioned atop a base that can be a lattice girder or a tubular tower.

[0003] Some wind turbine configurations incorporate doubly fed induction generators (DFIGs). Such configurations may also include power converters (current converters) used to transform the frequency of a generated electrical current into a frequency substantially similar to that of the grid. In addition, these converters, in conjunction with the DFIG, transfer electrical power between the grid and the generator and also transfer generator excitation power to a wound generator rotor from one of the connections to the grid connection. Alternatively, some wind turbine configurations, but not limited to, incorporate alternative types of induction generators, permanent magnet (PM) excited synchronous generators, electrically excited synchronous generators, and switched reluctance generators.These alternative configurations may also include power converters, which are used to convert frequencies and transfer electrical power between the supply network and the generator, as described above.

[0004] Familiar wind turbines have several mechanical and electrical components. Each electrical and / or mechanical component may have independent or different operating limits, such as current, voltage, power, and / or temperature limits. Furthermore, wind turbines are typically designed and / or built with predefined rated power limits.

[0005] A wind turbine can only extract a certain percentage of the energy associated with the wind, up to the so-called "Betz limit" of 59%. This percentage is described as the power coefficient. The value of the power coefficient depends on the shape, wind speed, rotational speed (or RPM), and tilt of the specific wind turbine. Assuming all operational variables are constant, this coefficient has only one maximum point at a fixed wind speed when the rotational speed is varied. It is therefore known to adjust the rotational speed of the turbine rotor to this maximum value, referred to here as the "optimal rotational speed" or "optimal RPM," in order to extract the maximum possible energy from the wind.

[0006] The characteristics of the power coefficient are normally expressed using the high-speed number A, which is defined as follows: λ=vpv=Ω⋅Rv where v p where R is the circumferential speed at the tip of one or more turbine blades, R is the radius of the turbine rotor, Ω is the angular velocity of the rotating turbine, and v is the wind speed.

[0007] In Fig. 3 is the power coefficient C for an exemplary wind turbine. P The power coefficient is graphically represented as a function of the speed-of-flight ratio λ. As can be seen from the diagram, the power coefficient is a function of the speed-of-flight ratio and has only a single maximum value. Therefore, known wind turbines are operated at a rotational speed that corresponds to the speed in the diagram. Fig. 3 as λ max This corresponds to the designated high-speed number. This makes it possible to extract as much energy from the wind as theoretically possible.

[0008] In modern wind turbines, even small improvements in energy yield can lead to a significant increase in the return on investment. Therefore, there is a constant drive to further increase the annual energy production (AEP) of the wind turbine. The inventors of the present disclosure have invented a method to achieve this, which can be applied in particular when the wind turbine is operated below its rated power.

[0009] It is therefore an object of the invention to provide a method for operating a wind turbine below its rated power. This object is achieved by the present invention. BRIEF DESCRIPTION OF THE INVENTION

[0010] In one embodiment, a method for operating a wind turbine is provided. The wind turbine has a rotor that is set up to rotate at an optimal speed. The method includes determining a turbulence parameter and operating the wind turbine at a speed that is increased by a certain amount compared to the optimal speed. The amount of the speed deviation depends on the turbulence parameter.

[0011] In a further embodiment, a method for operating a wind turbine is provided. The wind turbine has a rotatable rotor that is set to rotate at an optimal speed. The method includes measuring the turbulence intensity and setting the rotor speed to a specific value. The speed is the sum of the optimal speed and a speed deviation value, and the wind turbine is operated at this specified speed. The speed deviation value depends on the turbulence intensity.

[0012] In a further embodiment, a wind turbine is provided. The wind turbine has a rotor with at least one rotor blade. The rotor is configured to rotate at an optimal speed. The wind turbine also has a control device for controlling the wind turbine. The control device is configured to partially or completely execute the methods described herein. In particular, the control device can be configured to determine a turbulence parameter and to operate the wind turbine at a speed that is increased by a certain amount compared to the optimal rotor speed. The amount of the speed deviation depends on the turbulence parameter.

[0013] Further aspects, advantages and features of the present invention are obvious from the dependent claims, the description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] A complete and enabling disclosure, including its best manner of execution, is given in particular in the remainder of the description, and it refers to the accompanying figures, which show: Fig. 1 a perspective view of a section of an exemplary wind turbine; Fig. 2 A schematic view of an exemplary electrical and control system for use in the Fig. 1 illustrated wind turbine is suitable; Fig. 3 a schematic representation of the power coefficient as a function of the high-speed number; Fig. 4 and Fig. 6 methods for operating a wind energy plant as known in the art; Fig. 5 and Fig. 7. Methods for operating a wind energy plant according to the embodiments described herein. DETAILED DESCRIPTION OF THE INVENTION

[0015] The various embodiments will now be described in detail, one or more examples of which are illustrated in each figure. Each example is provided within the context of an explanation of the invention and is not intended as a limitation. For example, features shown or described as part of one embodiment can be used in or in combination with other embodiments to give further embodiments. It is intended that the present invention includes such modifications and variations.

[0016] The embodiments described herein feature a wind turbine system that operates with increased efficiency with respect to annual energy production (AEP). Specifically, the wind turbine, as described herein, can be operated particularly in locations and / or environments with high turbulence levels. Furthermore, the positive effects of the operating procedure as described apply especially to the energy yield when operating below the rated power of the wind turbine.

[0017] As used herein, the term "power" shall denote the energy produced by the wind turbine per unit of time. Typically, power is measured in the physical unit watt [W]. As used herein, the term "blade" shall denote any device that produces a reaction force when in motion relative to a surrounding fluid. As described herein, the term "wind turbine" shall denote any device that generates rotational energy from wind energy and, in particular, converts the kinetic energy of the wind into mechanical energy and typically further into electrical energy.

[0018] The term "turbulence parameter," as used herein, is intended to encompass any parameter that characterizes the turbulence intensity of the wind at the wind turbine installation site. In particular, the turbulence parameter could be based on or influenced by turbulence in wind speed and / or wind direction. It typically refers to short-term changes and may specifically refer to short-term changes in wind speed and / or wind direction. The term "short-term" in this context is to be understood as lasting up to one minute or even just half a minute.

[0019] The expression "optimal operation of a wind turbine" or "operation of a wind turbine at the optimal rotational speed" is intended to describe the operation of the wind turbine at a rotational speed or rotor speed that enables it to deliver the theoretically maximum possible power gain, i.e., at a rotational speed where the tip speed ratio A theoretically has its maximum power coefficient, as exemplified above with regard to Fig. 3 explained. Similarly, the terms “optimal speed”, “optimal tip speed”, “optimal rotational speed”, “optimal rotational speed”, or “optimal tip speed ratio” are intended to characterize a rotor speed for a given wind such that the power coefficient is theoretically at its maximum, as referenced in Fig. 3 illustrated.

[0020] The present embodiments could include a determination of the optimal speed, such as the optimal rotational speed or the optimal tip speed. The term "determination of the optimal speed" is intended to specifically include a calculation of the optimal speed and / or a query of the optimal speed from a memory, such as a database or the like. The optimal speed can also be queried from a remote system, such as a remote control center for the wind turbine. According to some embodiments, the optimal speed is not explicitly calculated, but rather the wind turbine is operated at the optimal speed. This is described in more detail below.The term "speed deviation amount," or synonymously "rotational speed deviation amount" or "rotational speed deviation amount," as used herein, is intended to denote the additional rotational speed / rotational speed compared to the optimal speed / rotational speed. The speed deviation amount can be expressed as a percentage or in a unit of speed, such as, but not limited to, m / s, km / h, mph, 1 / s, Hz, and the like. Although, for the sake of simplicity, the following description usually refers to the speed deviation amount in terms of rotational speed / rotational speed, it should be understood that other ways of expressing rotor speed, such as tip speed or tip speed, can be used equivalently. The rotational speed deviation amount can, for example, be expressed as...The speed deviation can be determined by means of the control device, which may be configured to calculate it. According to other embodiments, the speed deviation is not explicitly calculated, but rather the settings of the wind turbine, in particular the generator, are adjusted so that the wind turbine operates at the optimal speed plus the speed deviation.

[0021] Experience shows that in practice, the wind is almost never constant. This means that wind speed and / or wind direction typically change within short time intervals. Generally, the wind turbine's operation attempts to adapt to these changes and operate optimally. For example, if the wind turbine is operating optimally at a given wind speed and a gust hits, it might adjust its settings, such as the angle of attack or the generator torque. Known wind turbines adjust these settings in such a way that, under wind conditions caused by a gust, the tipping ratio returns to its maximum power coefficient. Almost the same principle applies when the wind suddenly decreases, such as during a period of calm.At least theoretically, this can achieve optimal energy yield. In practice, however, it takes some time for the settings to adjust and for the adjusted settings to take effect. Therefore, wind turbines are often operated with a lag error in practice. The lag error corresponds to the fact that the control system lags behind the current environmental conditions.

[0022] According to the present disclosure, however, the wind turbine is operated at a higher tip circumferential speed than the optimal tip circumferential speed. In this regard, it should be emphasized that for a given wind turbine, the tip circumferential speed is directly and uniquely correlated with the rotational speed. If l is the length of one or more rotor blades of the wind turbine, then the tip circumferential speed is defined as 2πl times the rotational speed. Furthermore, the tip speed ratio for a given wind is directly and uniquely correlated with both the rotational speed and the tip circumferential speed.Therefore, the terms "circumferential speed at the tip," "optimal circumferential speed at the tip," and "rotational speed," "optimal rotational speed," and "optimal rotational speed" can be used synonymously here. In particular, the expression "the wind turbine is operated at a specific tip speed" can be used synonymously with "the wind turbine is operated at a specific rotational speed" or "the wind turbine is operated at a specific circumferential speed at the tip," since the specific tip speed, the specific rotational speed, and the specific circumferential speed at the tip are unambiguously equivalent.

[0023] The inventors discovered that, despite selecting a rotational speed that is theoretically suboptimal, it is possible to increase the total annual energy yield (AEP). According to the present disclosure, the turbulence intensity at the wind turbine's installation site is taken into account to determine the magnitude of the rotational speed deviation. The inventors of the present disclosure found that it is more tolerable to react to gusts of wind than to periods of calm. In other words, by operating the wind turbine at a higher than optimal peak rotational speed, the turbine is able to quickly regain the optimal peak rotational speed when a gust of wind occurs.This is because, given a certain aerodynamic torque of the rotor blades and a given wind speed, the wind turbine rotates faster the higher the optimal tip speed ratio. Therefore, if the wind speed increases, the wind turbine must increase its rotational speed to operate the turbine at its optimal operating point.

[0024] Having discovered this, the inventors also realized that operating the wind turbine at a higher speed than optimal means the turbine takes longer to reduce its rotor speed when the wind decreases, such as in calm conditions. Consequently, when wind is calm, the power output of the operating method disclosed herein can be expected to be lower than that of the operating method known in the art, i.e., at the optimal rotational speed instead of the increased rotational speed.

[0025] Nevertheless, experimental results from the inventors show that the overall energy yield of a wind turbine operated according to the disclosed methods is increased compared to known operating methods. This is because the maximum power that can be generated by the wind turbine is proportional to the cube of the wind speed. Thus, an improvement in power output at higher wind speeds outweighs a decrease in power output at lower wind speeds.

[0026] Thus, under turbulent conditions, which include a series of gusts and periods of calm, the combined gains from the gusts outweigh both the losses due to periods of calm and the losses from periods of constant wind speed if the turbine were operated at its optimum, assuming it were optimally controlled as is known in the art. According to embodiments that can be combined with all other embodiments described herein, the method described herein for operating a wind turbine is therefore only used when the gusts and periods of calm dominate the wind, i.e., when a minimum turbulence threshold is exceeded.

[0027] As turbulence intensity increases, operating the turbine at a higher rotational speed than the optimal speed typically results in a more positive effect than at lower turbulence intensities. According to some embodiments, the magnitude of the speed deviation from the optimal speed is thus increased when turbulence intensity increases. Additionally or alternatively, according to some embodiments, the magnitude of the speed deviation from the optimal rotational speed is decreased when turbulence intensity decreases.

[0028] A wind turbine typically includes a closed-loop speed control device designed to compensate for, for example, turbulence intensity characterized by a turbulence parameter. When high turbulence is present (corresponding to a first turbulence parameter), the control device operates the wind turbine at a higher speed deviation compared to the optimal speed than during periods of lower turbulence (corresponding to a second turbulence parameter, which is smaller than the first).

[0029] According to some embodiments described herein, the method for operating a wind turbine includes a calculation of the optimal speed and / or a calculation of the magnitude of the speed deviation. Accordingly, the control device, as described herein, may be configured to calculate the optimal speed and / or the magnitude of the speed deviation. Consequently, any information about the wind speed should be as accurate as possible. With these values ​​available, the turbine settings can be adjusted as described, so that, in particular, the speed can be set to the speed plus the magnitude of the speed deviation.

[0030] The control device could provide the optimal rotational speed. According to the embodiments, the control device determines the value of the optimal rotational speed or rotational speed. For example, the control device could query values ​​from a lookup table, a data memory, or the like (see description of the Fig. 2 (regarding examples). Alternatively, the control device and / or another suitable processing unit operationally connected to the control device could calculate the optimal rotational speed. An operation of the wind turbine that includes a calculation or determination of the optimal speed and / or the amount of the speed deviation shall be referred to as an “explicit operating procedure”.

[0031] According to many wind turbine designs and methods for operating wind turbines, the exact instantaneous wind speed is unknown to the wind turbine's control device because it cannot be measured accurately enough at the turbine. With such poor-quality information about the wind speed, the present designs can, instead of explicitly calculating the optimal speed, utilize the following implicit control law. If the optimal tip speed ratio and the corresponding power coefficient for the turbine are known, for example, by being stored in a data memory within the control device or the wind turbine, then a value k can be calculated such that the control law M g =k*ω 2 is fulfilled, where M gwhere k is the controllable torque of the generator and ω is the rotational speed of the rotor. Note that k is also referred to as the "speed-up factor" and depends on several values, including air density, to determine the optimal speed-up factor λ. max and the associated optimal power coefficient C pmax (cf.) Fig. 3) is dependent. This implicit control law will then lead to the operation of the wind turbine at the optimal speed, without the need to actually know the current wind speed and tip speed ratio. Thus, in summary, it can be said that with the implicit operating method, the wind turbine is operated without an explicit calculation of the optimal rotational speed and / or the deviation of the speed at the desired speed.

[0032] Known wind turbines are operated according to their optimal rotational speed. The present disclosure proposes that the control device operates the wind turbine at a rotor speed increased compared to the optimal rotational speed. The magnitude of the speed deviation, i.e., the value by which the rotational speed is increased compared to the optimal rotational speed, typically depends on the measured or estimated turbulence intensity, which may be represented by a turbulence parameter. A predetermined transfer function or relationship for determining the magnitude of the speed deviation as a function of the turbulence intensity can be used to enable the control device according to the present disclosure to dynamically change the rotor speed.

[0033] According to embodiments, the operation of the wind turbine described herein can exhibit a speed deviation or a tip speed deviation of at least 5% or even at least 10%. For example, in low turbulence, the wind turbine is operated at a rotational speed (or tip speed) that exhibits a small speed deviation from the optimal rotational speed (or tip speed deviation), e.g., a deviation of at most 8% or even at most 5%, and usually at least 1% or 2% of the optimal rotational speed (or tip speed).As understood herein, any deviation in speed or speed-to-speed ratio from the optimal rotational speed or speed-to-speed ratio shall be understood as an intentional deviation, as disclosed herein. A deviation from the optimal rotational speed or speed-to-speed ratio shall not be misinterpreted as a deviation due to changing wind conditions, although the wind turbine's control system is designed to prevent any such deviation. In higher turbulence conditions, the wind turbine will be operated with a significant deviation from the optimal rotational speed or speed-to-speed ratio, for example, a deviation of at least 5%, 10%, or even 15%.

[0034] For example, the optimal rotational speed at a given time for a given wind turbine may be such that the tip speed ratio is λ=8.0. A known wind turbine would be operated in such a way that the control device would attempt to adjust all parameters, in particular the generator torque, so that the tip speed ratio is indeed λ=8.0. However, since high turbulence is detected, e.g., by measurement or estimation, the control device according to the present disclosure attempts to operate the wind turbine at a higher rotational speed, e.g., at a rotational speed corresponding to a tip speed ratio of A=8.8 or even λ=9.0.

[0035] Turbulence intensity is typically characterized by the turbulence parameter. The turbulence parameter can be a scalar quantity, a vector quantity, or a matrix. The turbulence parameter can be one or more values ​​of average wind speed, wind speed range, wind speed standard deviation, average wind direction, wind direction range, or wind direction standard deviation. The wind speed standard deviation and / or the wind direction standard deviation can be normalized by dividing the calculated standard deviation by the corresponding average value, i.e., the average wind speed and / or the average wind direction. Here, and in accordance with the literature, the standard deviation will be denoted by σ.It can refer in particular to the normalized standard deviation of wind speed, the normalized standard deviation of wind direction, and / or a combination of these. Typical normalized standard deviations of wind speed range up to approximately 30% at wind turbine sites with high turbulence levels and up to approximately 15% at wind turbine sites with low turbulence levels.

[0036] In general, and not limited to any particular embodiment, determining the turbulence parameter involves at least either calculating an average value and / or calculating a standard deviation. Typically, the measured values ​​are taken over a time interval of at least 5 minutes. Determining the turbulence parameter could involve measuring deviations in the angle of attack of at least one rotor blade and / or deviations in the output power of the wind turbine.

[0037] The relationship (e.g., a numerical function) between the value of the velocity deviation from the optimal rotational speed and the turbulence parameter can be stored in the wind turbine so that the control device can retrieve it whenever necessary. The relationship typically increases steadily; that is, the higher the turbulence parameter, the greater the magnitude of the velocity deviation. Thus, in general, and not limited to any embodiment described herein, at the same wind speed, the control of the wind turbine depends on the turbulence intensity. In particular, it is possible for the turbulence intensity to fall below a selectable threshold, so that the turbulence mode, as described herein—i.e., the operation of the wind turbine at an increased speed—is completely deactivated.

[0038] For example, if the turbulence parameter is the normalized standard deviation of the wind speed σ, then the value of the speed deviation d could be calculated, for example, as σ times f, where f denotes a multiplication factor that can be chosen between 0.1 and 3, typically between 0.5 and 2. The multiplication factor is typically selectable and can depend on the installation location, in particular on the frequency of gusts and calm periods. For example, let the turbulence parameter σ = 10% and the optimal tip speed ratio λ for the given wind speed be... opt =7.8. In this example, if the multiplication factor f is chosen to be 1.5, then the deviation d is calculated as 10% * 1.5 = 15%. Consequently, the turbine is operated with a velocity deviation of λ. opt *d=7.8*0.15=1.17 away from the optimal tip speed of 7.8, i.e. the turbine is operated at a tip speed of A = λ opt + 1.17 = 8.97 operated.

[0039] According to certain embodiments, changes in environmental conditions, such as temperature and atmospheric density, are taken into account when determining the operating rotational speed. The torque generated at a given wind speed is typically a function of atmospheric density and thus of temperature. In the implicit control law described above, this means that the tip speed factor k must be adjusted depending on the density and / or temperature. In the explicit formulation, the environmental conditions can be considered when determining the instantaneous wind speed.

[0040] The control of the method disclosed herein is typically dynamic. That is, the control is typically based on actual values ​​of the parameters at the installation site, such as, but not limited to, temperature, density, wind direction, and / or wind speed. The parameters of the installation site can be measured directly or determined indirectly, for example, by measuring another parameter that allows a conclusion to be drawn about them.

[0041] According to embodiments, operation is controlled by varying the generator torque to change the rotor's rotational speed. Furthermore, according to embodiments, the present method is only applied at wind speeds below the rated wind speed (i.e., at the wind speed corresponding to the rated power of the wind turbine). Additionally, according to embodiments, the present operating method keeps the angle of attack constant as long as the wind speed remains below the rated wind speed.

[0042] Fig. Figure 1 shows a perspective view of a section of an exemplary wind turbine 100. The wind turbine 100 has a nacelle 102 which contains a (in Fig. 1 (not shown) generator. The nacelle 102 is mounted on a tower 104 (with a section of the tower 104 in Fig. (as shown in Figure 1). The tower 104 can have any suitable height that enables the operation of the wind turbine 100 as described herein. The wind turbine 100 further comprises a rotor 106 having three blades or wings 108 mounted on a rotating hub 110. Alternatively, the wind turbine 100 can have any number of wings 108 that enables the operation of the wind turbine 100 as described herein. In the exemplary embodiment, the wind turbine 100 comprises (in Figure 1) a rotor 106 having three blades or wings 108 mounted on a rotating hub 110. Fig. 1 (not shown) gearbox, which is connected to the rotor 106 and a (in Fig. 1 (not shown) generator is operationally connected.

[0043] Fig. Figure 2 shows a schematic representation of an exemplary electrical and control system 200 that can be used in the wind turbine 100. The rotor 106 has blades 108 coupled to the hub 110. The rotor 106 also has a low-speed shaft 112 that is rotationally fixed to the hub 110. The low-speed shaft 112 is connected to a high-ratio gearbox 114, which is configured to increase the rotational speed of the low-speed shaft 112 and transmit this speed to a high-speed shaft 116. In the exemplary embodiment, the gearbox 114 has a gear ratio of approximately 70:1.For example, a low-speed shaft 112 rotating at approximately 20 revolutions per minute (rpm), when coupled to the gearbox 114 with a gear ratio of approximately 70:1, generates a speed of approximately 1400 rpm for the high-speed shaft 116. Alternatively, the gearbox 114 has any suitable gear ratio that enables the operation of the wind turbine 100 as described herein. As a further alternative, the wind turbine 100 has a direct-drive generator that is rotationally fixed to the rotor 106 without an intervening gearbox.

[0044] The high-speed shaft 116 is rotationally fixed to the generator 118. In the exemplary embodiment, the generator 118 is a three-phase, doubly fed (induction generator) asynchronous generator (DFIG) with a wound rotor, comprising a generator stator 120 that is magnetically coupled to a generator rotor 122. In an alternative embodiment, the generator rotor 122 has several permanent magnets instead of rotor windings.

[0045] The electrical and control system 200 includes a wind turbine control device 202, or simply a "controller" 202. The wind turbine control device 202 includes at least one processor and memory, at least one processor input channel, at least one processor output channel, and may include at least one computer (none of which are in Fig. 2 is shown). The term computer, as used herein, is not limited to integrated circuits which are referred to as computers in engineering, but refers broadly to a processor, a microcontroller, a microcomputer, a programmable logic controller (PLC), application-specific integrated circuits and other programmable circuits (none of which are shown in Figure 2). Fig. 2 is shown), and these terms are used interchangeably herein. In the exemplary embodiment, the memory may, but is not limited to, be a computer-readable medium, e.g., random-access memory (RAM) (in Fig. 2 none / none shown). Alternatively, one or more storage devices, e.g., a floppy disk drive, a CD-ROM drive, a magneto-optical disk drive (MOD), and / or a DVD drive, may be used (none of which are shown in Fig. 2 is shown). Likewise, in the exemplary embodiment (in Fig. 2 additional input channels (not shown) may be computer peripherals, without being limited thereto, wherein the computer peripherals may be associated with a user interface, such as a mouse and keyboard (none of which are shown in Fig. 2 is shown). Furthermore, in the exemplary embodiment, additional output channels, a (in Fig. 2 (not shown) operator interface monitors, but are not limited to them.

[0046] Processors for the wind turbine control device 202 process information transmitted by several electrical and electronic devices, which may include, but are not limited to, voltage or current transformers. The RAM and / or memory devices store and transmit information and instructions to be executed by the processor. The RAM and / or memory devices may also be used to store and provide temporary variables, static (i.e., unchanging) information and instructions, or other intermediate information to the processors during instruction execution. The instructions executed include, but are not limited to, resident conversion and / or comparison algorithms. The execution of instruction sequences is not restricted to any specific combination of hardware circuits and software instructions.

[0047] The generator stator 120 is electrically coupled to a stator synchronization switch 206 via a stator bus 208. To enable a DFIG configuration, in an exemplary embodiment the generator rotor 122 is electrically coupled to a bidirectional power converter or inverter arrangement 210 via a rotor bus 212. Alternatively, the generator rotor 122 is electrically coupled to the rotor bus 212 via any other device that enables the operation of the electrical and control system 200 described herein. As a further alternative, the electrical and control system 200 is configured as a (not shown) full-power inverter system that includes a (in Fig. The device comprises two full-power converter arrangements (not shown), which are similar in design and operation to the power converter arrangement 210 and are electrically coupled to the generator stator 120. The full-power converter arrangement enables the transmission of electrical power between the generator stator 120 and an electrical power transmission and distribution network (not shown). In this exemplary embodiment, the stator bus 208 transmits three-phase power from the generator stator 120 to the stator synchronization switch 206. The rotor bus 212 transmits three-phase power from the generator rotor 122 to the power converter arrangement 210. In this exemplary embodiment, the stator synchronization switch 206 is electrically coupled to a main transformer disconnect switch 214 via a system bus 216.In an alternative embodiment, one or more fuses (not shown) are used instead of the main transformer disconnect switch 214. In a further embodiment, neither fuses nor a main transformer disconnect switch 214 are used.

[0048] The power converter arrangement 210 has a rotor-side filter 218, which is electrically coupled to the generator rotor 122 via the rotor bus 212. A rotor filter bus 219 electrically couples the rotor filter 218 to a rotor-side power converter 220, and the rotor-side power converter 220 is electrically coupled to a grid-side power converter 222. The rotor-side power converter 220 and the grid-side power converter 222 are power converter bridges containing (not shown) power semiconductors. In the exemplary embodiment, the rotor-side power converter 220 and the grid-side power converter 222 are configured in a three-phase pulse-width modulation (PWM) configuration, which (in Fig. The power converter assembly 210 comprises two switching devices (not shown) with insulated-gate bipolar transistors (IGBTs) operating in a manner known in the art. Alternatively, the rotor-side power converter 220 and the grid-side power converter 222 have any configuration with any switching devices that enable the operation of the electrical and control system 200 as described herein. The power converter assembly 210 is in an electronic data communication link with the wind turbine control device 202 to control the operation of the rotor-side power converter 220 and the grid-side power converter 222.

[0049] In the exemplary embodiment, a grid-side power converter bus line 223 electrically couples the grid-side power converter 222 to a grid filter 224. Likewise, a grid bus 225 electrically couples the grid filter 224 to a grid contactor 226. Furthermore, the grid contactor 226 is electrically coupled to a converter grid disconnect switch 228 via a converter grid disconnect switch bus line 230. Additionally, the converter disconnect switch 228 is electrically coupled to the main transformer grid disconnect switch 214 via a system bus 216 and a connecting bus line 232. Alternatively, the mains filter 224 is electrically coupled directly to the system bus 216 via the connecting bus line 232 and includes any (not shown) suitable safeguarding device designed to accommodate the removal of the mains contactor 226 and the inverter disconnect switch 228 from the electrical and control system 200.The main transformer network disconnector 214 is electrically coupled to a main power transformer 234 via a generator-side bus line 236. The main transformer 234 is electrically coupled to a supply network disconnector 238 via a disconnector-side bus 240. The supply network disconnector 238 is connected to the electrical power transmission and distribution network via a network bus line 242. In an alternative embodiment, the main transformer 234 is electrically coupled to one or more fuses (not shown) via the disconnector-side bus line 240 instead of the supply network disconnector 238. In a further embodiment, neither fuses nor a supply network disconnector 238 are used, so that the main transformer 234 is instead coupled to the power transmission and distribution network via the disconnector-side bus line 240 and the network bus 242.

[0050] In the exemplary embodiment, the rotor-side power converter 220 is electrically connected to the grid-side power converter 222 via a single direct current (DC) connection 244. Alternatively, the rotor-side power converter 220 and the grid-side power converter 222 are connected via (in Fig. Two separate direct current (DC) connections (not shown) are electrically coupled. The DC connection 244 has a positive rail 246, a negative rail 248, and at least one capacitor 250 connected between the positive rail 246 and the negative rail 248. Alternatively, the capacitor 250 includes one or more capacitors arranged in series and / or parallel to each other between the positive rail 246 and the negative rail 248.

[0051] The wind turbine control device 202 is configured to receive multiple voltage and electrical current measurement signals from a first set of voltage and electrical current sensors 252. Furthermore, the wind turbine control device 202 is configured to monitor and control at least some of the operating variables associated with the wind turbine 100. In the exemplary embodiment, each of the three voltage and electrical current sensors 252 is electrically connected to one of the three phases of the network bus line 242. Alternatively, the voltage and electrical current sensors 252 are electrically connected to the system bus line 216. As a further alternative, the voltage and electrical current sensors 252 are electrically connected to each part of the electrical and control system 200 that enables the operation of the electrical and control system 200 as described herein.As yet another alternative, the wind turbine control device 202 is configured to receive any number of voltage and electrical current signals from any number of voltage and electrical current sensors 252, including, but not limited to, a single voltage and electrical current signal from a single signal transmitter.

[0052] As in Fig. As shown in Figure 2, the electrical and control system 200 further comprises a converter control device 262, which is configured to receive multiple voltage and electrical current measurement signals. For example, in one embodiment, the converter control device 262 receives voltage and electrical current measurement signals from a second set of voltage and electrical current sensors 254, which are in an electronic data communication link with the stator bus line 208. The converter control device 262 receives a third set of voltage and electrical current measurement signals from a third set of voltage and electrical current sensors 256, which are in an electronic data communication link with the rotor bus line 212.The inverter control device 262 further receives a fourth set of voltage and electrical current measurement signals from a fourth set of voltage and electrical current sensors 264, which are in electronic data communication connection with the inverter disconnect switch bus line 230. The second set of voltage and electrical current sensors 254 is essentially similar to the first set of voltage and electrical current sensors 252, and the fourth set of voltage and electrical current sensors 264 is essentially similar to the third set of voltage and electrical current sensors 256. The inverter control device 262 is essentially similar to the wind turbine control device 202 and is in electronic data communication connection with the wind turbine control device 202.Furthermore, in the exemplary embodiment, the inverter control device 262 is physically integrated within the power inverter arrangement 210. Alternatively, the inverter control device 262 has any configuration that enables the operation of the electrical and control system 200 as described herein.

[0053] During operation, wind strikes the blades 108, which convert wind energy into mechanical torque that, via the hub 110, drives the low-speed shaft 112. The low-speed shaft 112 drives the gearbox 114, which further translates the low rotational speed of the low-speed shaft 112 to drive the high-speed shaft 116 at an increased rotational speed. The high-speed shaft 116 drives the generator rotor 122. A rotating magnetic field is induced by the generator rotor 122, and a voltage is induced within the generator stator 120, which is magnetically coupled to the generator rotor 122. The generator 118 converts the mechanical rotational energy into a sinusoidal, three-phase alternating current (AC) energy signal in the generator stator 120.The associated electrical power is transmitted to the main transformer 234 via the stator bus line 208, the stator synchronization switch 206, the system bus line 216, the main transformer network disconnect switch 214, and the generator-side bus line 236. The main transformer 234 increases the voltage amplitude of the electrical power, and the converted electrical power is further transmitted to a supply network via the disconnect switch-side bus line 240, the supply network disconnect switch 238, and the network bus line 242.

[0054] In the exemplary embodiment, a second electrical power transmission path is created. The three-phase, sinusoidal alternating current (AC) power is generated within the generator rotor 122 and transmitted via the rotor bus line 212 to the power converter assembly 210. Within the power converter assembly 210, the electrical power is transmitted to the rotor filter 218, and the electrical power is modified for the rate of change of the PWM signals assigned to the rotor-side power converter 220. The rotor-side power converter 220 acts as a rectifier and rectifies the sinusoidal, three-phase AC power into DC power. The DC power is transmitted to the DC connection 244.The capacitor 250 enables the attenuation of voltage amplitude fluctuations on the DC connection 244 by attenuating the DC ripple associated with the AC rectification.

[0055] The DC power is subsequently transmitted from the DC connection 244 to the grid-side power converter 222, which acts as an inverter configured to convert the DC power from the DC connection 244 into three-phase, sinusoidal AC power with predetermined voltages, currents, and frequencies. This conversion is monitored and controlled by the converter control device 262. The converted AC power is transmitted from the grid-side power converter 222 via the grid-side power converter bus line 223 and the grid bus line 225, the grid contactor 226, the converter grid disconnect switch bus line 230, the converter grid disconnect switch 228, and the connection bus line 232 to the system bus line 216.The line filter 224 compensates or balances harmonic currents in the electrical power transmitted by the line-side power converter 222. The stator synchronization switch 206 is configured to close to allow the three-phase power from the generator stator 120 to be connected to the three-phase power from the power converter assembly 210.

[0056] The inverter network disconnect switch 228, the main transformer network disconnect switch 214, and the supply network disconnect switch 238 are designed to interrupt the corresponding bus lines if, for example, an overcurrent flow could damage the components of the electrical and control system 200. Additional protective components are also provided, including a network contactor 226, which can be controlled to interrupt the bus lines by opening a (in Fig. 2 (not shown) to create an interruption to each line of the line bus 225 associated with a switch.

[0057] When changes occur, for example in the wind speed at the hub 110 and the blades 108, the power converter arrangement 210 compensates for or adjusts the frequency of the three-phase power from the generator rotor 122. Therefore, in this way, the mechanical and electrical rotor frequencies are decoupled from the stator frequency.

[0058] Under certain conditions, the bidirectional properties of the power converter assembly 210, and in particular the bidirectional properties of the rotor-side power converter 220 and the grid-side power converter 222, allow at least a portion of the generated electrical power to be fed back to the generator rotor 122. Specifically, electrical power is transferred from the system bus line 216 to the connection bus line 232 and then through the converter network disconnect switch 228 and the converter network disconnect switch bus line 230 into the power converter assembly 210. Within the power converter assembly 210, the electrical power is transferred through the network contactor 226, the network bus line 225, and the grid-side power converter bus line 223 into the grid-side power converter 222. The grid-side power converter 222 acts as a rectifier and converts the sinusoidal, three-phase AC power into DC power.The DC power is transferred to the DC connection 244. The capacitor 250 enables a reduction of the voltage amplitude fluctuations at the DC connection 244 by attenuating the DC ripple sometimes associated with three-phase AC rectification.

[0059] The DC power is then transmitted from the DC link 244 to the rotor-side power converter 220, which acts as an inverter configured to convert the DC power transmitted from the DC link 244 into three-phase, sinusoidal AC power with predetermined voltages, currents, and frequencies. This conversion is monitored and controlled by the converter control device 262. The converted AC power is transmitted from the rotor-side power converter 220 via the rotor filter bus line 219 to the rotor filter 218 and subsequently via the rotor bus line 212 to the generator rotor 122, thus enabling subsynchronous operation.

[0060] The power converter assembly 210 is configured to receive control signals from the wind turbine control device 202. These control signals are based on detected conditions or operating characteristics of the wind turbine 100 and the electrical and control system 200. The control signals are received by the wind turbine control device 202 and used to control the operation of the power converter assembly 210. Feedback from one or more sensors of the electrical and control system 200 can be used to control the power converter assembly 210 via the converter control device 262, for example, by...The converter network disconnect switch bus line 230, the voltage or current feedback from the stator bus line and the rotor bus line can be obtained by means of the second set of voltage and current sensors 254, the third set of voltage and current sensors 256, and the fourth set of voltage and current sensors 264. By using this feedback information and, for example, the switching control signals, control signals for the stator synchronization switch and control signals (tripping signals) for the system line disconnect switch can be generated in any conventional way. For example, for a transient network voltage with predefined characteristics, the converter control device 262 will, at least temporarily, essentially disconnect the IGBTs on a line within the network-side power converter 222.Such exclusion from the operation of the grid-side power converter 222 will essentially reduce the electrical power conducted by the power converter arrangement 210 to approximately zero.

[0061] Fig. Point 3 was explained in the background section and describes the well-known dependence of the power coefficient on the tip speed ratio. As far as the inventors are aware, almost every textbook on wind turbines contains this relationship, along with the further finding that wind turbines should be designed to maximize energy yield at λ. max should be operated.

[0062] Fig. Figure 4 illustrates the known control system of a wind turbine in an exemplary situation when a gust of wind affects the turbine. The diagram shows the optimal rotational speed v. p optThe rotor blade, marked by line 400, over time t. As is evident in the example, the optimal rotational speed 420 increases from a first value to a second value that is higher than the first. Due to the generally known relationship of the optimal tip speed, which is also related to Fig. As explained in section 3, if otherwise constant conditions prevail, the increase in the optimal rotation speed 420 is caused by a sudden increase in wind speed.

[0063] Accordingly, the familiar control system of a wind turbine attempts to operate the turbine at its optimal rotational speed, which corresponds to the optimal tipping ratio. This is illustrated by the dashed line 410. If the wind suddenly changes, it is impossible for a real wind turbine to follow it quickly enough. Instead, and as shown in Fig. As illustrated in Figure 4, it takes some time for one or more operating parameters of the wind turbine to reset and for the reset to take effect, in order to return to the optimal circumferential speed at the tip (right part of the dashed line 410). The hatched area 420 is intended to illustrate the time during which the actual rotational speed v p of the wind turbine from the optimal circumferential speed at the tip v p opt deviates. Consequently, the turbine generates less energy during this time than would theoretically be possible.

[0064] Fig. Figure 5 is intended to illustrate the method disclosed herein for operating a wind turbine. The optimal rotational speed v p opt , which is marked by line 400, is identical to the optimal rotational speed in Fig. 4. That is, both Fig. 4 and Fig. 5 describe the same environmental situation, namely that an identical sudden increase in wind speed occurs.

[0065] According to the method disclosed herein, the control system of the wind turbine attempts to operate the wind turbine outside its optimal rotational speed, namely at a rotational speed increased compared to the optimal rotational speed. This is illustrated by the dashed line 510, which shows that initially, despite the constant wind condition for short periods t, the actual rotational speed v p The rotation speed is set above the optimal speed. For example, the rotation speed could be set 10% higher than the optimal speed. Consequently, power generation during this time is not optimal, as illustrated by the hatched area 520 in the diagram.

[0066] When a gust of wind catches the wind turbine and the wind speed suddenly increases, the optimal rotational speed also rises. The control device attempts to follow this trend, as shown by the dashed line 510, and manages to adjust the wind turbine control device significantly earlier than with a conventional control system, as described in reference to Fig. As described in section 4, the goal is to bring the wind turbine to its optimal rotational speed. That is, the hatched area 510, which represents the time during which the control device operates the wind turbine in a suboptimal manner, is significantly smaller than the hatched area 420. Fig. 4.

[0067] In this respect, it is very important to note that the power generated increases with the cube of the wind speed. In other words, a 1% increase in power generated at wind speed v1 yields eight times the total power generated as a 1% increase at half the wind speed, i.e., at wind speed v1 / 2. This is why a reduction of the hatched area 510, i.e., a reduction in the time the wind turbine operates suboptimally at higher wind speeds (in Fig. 5 as illustrated by the hatched area 530) is much more valuable in terms of annual energy yield (AEP) than the suboptimal time when the wind turbine is operated in a suboptimal manner at low wind speeds (in Fig. 5 as illustrated by the hatched area 520).

[0068] As in Fig. Figure 5 illustrates that, according to embodiments that can be combined with other embodiments described herein, the wind turbine control device sets the actual rotational speed to the optimal rotational speed at higher wind speeds. This is only one embodiment, and depending on the actual wind speed, it may be possible that the control device attempts to operate the wind turbine at a higher rotational speed than the optimal rotational speed, even at higher wind speeds.

[0069] However, according to the embodiments described herein, the deviation from the optimal rotational speed depends on the absolute wind speed. For example, at wind speeds very close to the rated wind speed, e.g., a maximum of 20% below the rated wind speed, it is possible to select a smaller deviation from the optimal rotational speed than at times with lower wind speeds.

[0070] Additionally or alternatively, the turbulence parameter may, alone or among other things, characterize a range of wind variations around the average value (i.e., a maximum positive and / or negative deviation from the average value, e.g., the average wind speed). For example, wind measurements might indicate that the average wind speed is 5 m / s, with a measured maximum positive deviation of 4 m / s. Thus, the wind speed during the period of interest would obviously never have exceeded 9 m / s. Furthermore, it is generally possible for the turbulence parameter to characterize a weighted range, meaning that each deviation is assigned a statistical probability of occurrence.For example, with an average wind speed of 5 m / s and a maximum deviation of up to 9 m / s, the wind speed between 8 m / s and 9 m / s could have a probability of occurrence of less than 0.05.

[0071] The turbulence parameter is used for the operation of the wind turbine. For example, if the in Fig. If the higher optimal circumferential speed of 400 shown in Figure 5 corresponds to a peak wind speed with a low probability of occurrence, e.g., below 0.1, then the control device could consequently be configured to set the rotational speed to the optimal rotational speed for wind speeds whose probability of occurrence is below a selectable threshold, which is not limited to the embodiment shown. This is the reason why in the Fig. Figure 5 illustrates an exemplary embodiment in which, after increasing the optimal rotational speed 400, the rotational speed 510 is not above the optimal rotational speed 400, but coincides with it.

[0072] Fig. 6 and Fig. Figure 7 illustrates a situation in which a calm period approaches the wind turbine and, as a result, the wind speed suddenly decreases. Thus, as illustrated by line 600, the general power coefficient, as it relates to Fig. Figure 3 illustrates that the optimal rotational speed v p opt is decreasing. Fig. Figure 6 illustrates a method for operating a wind turbine, as known in engineering, which means that the wind turbine's control device attempts to follow the optimal rotational speed. This could theoretically work for constant wind speeds, as shown in Fig. 6. This is evident for lower time values; however, if a sudden decrease in wind speed occurs, the settings of the wind turbine cannot be adjusted quickly enough, so there is a period of time during which the actual rotational speed v p the wind turbine, which is located 610 in Fig. The area marked 6 deviates from the optimal wind speed of 600. During this period, power generation is not optimal, as illustrated by the hatched area 620.

[0073] Fig. Figure 7 illustrates the identical environmental situation with the same calm conditions (600) as in the situation after... Fig. 6. However, according to the embodiments disclosed herein, the wind turbine could operate with a rotational speed v p The system is operated at a speed marked 710, which is higher than the optimal rotational speed. When calm winds arrive, the control device attempts to adapt to the changed situation and reduces the rotational speed. As shown in the illustration of the Fig. As can be seen in Figure 7, the hatched area 720, which is intended to illustrate the suboptimal operation of the wind turbine, is larger than the hatched area 620 in Figure 7. Fig. 6.

[0074] Thus, the comparison of Fig. 6 and Fig. 7, that the method proposed here usually leads to an energy yield from the wind turbine that is worse than the energy yield obtained when the wind turbine is operated using known methods that attempt to follow the optimal rotational speed during periods of suddenly decreasing wind speed.

[0075] Nevertheless, the increase in energy yield during periods of sudden increases in wind speed, such as during gusts, far outweighs this negative impact on the annual energy yield. In other words, since power output is proportional to the cube of wind speed, it is more profitable to respond to gusts than to calm periods. In reality, the wind frequently consists of local gusts and periods of calm. And the control device must constantly react to these changes by causing the rotor to accelerate or decelerate. However, current methods for operating a wind turbine do not take into account the turbulence at the installation site when determining the most profitable tip speed.

[0076] For example, let's say the wind speed is 10 m / s. With a given modern wind turbine, a gust of 11 m / s will result in a power increase of 1331 kW (33%), and a decrease in wind speed to 9 m / s will result in a power decrease of 729 kW (27%). If the wind turbine is operated as described here, the rotor can accelerate more quickly to respond to the change in wind speed from 11 m / s than in a conventional wind turbine. Conversely, the rotor takes longer to decelerate in response to the reduced wind speed of 9 m / s than in a conventional wind turbine. In other words, the optimal speed for wind gusts is regained more quickly than for calm conditions.

[0077] Because the power output is proportional to the cube of the wind speed, the gain at the higher wind speed of 11 m / s will more than compensate for the loss at the lower wind speed of 9 m / s. Consequently, the method described herein operates the wind turbine at a higher rotor speed compared to the optimal rotor speed. This method will be particularly effective for sites with higher turbulence (e.g., wind turbine sites on or near mountains or hills), where the positive effects on the annual energy yield are usually more pronounced than at sites with lower turbulence (e.g., wind turbine sites on flat land or offshore wind turbines).

[0078] One of the main advantages of the present disclosure is the higher energy yield from the available energy, particularly in winds below the rated operating speed of the wind turbine. The inventors were able to demonstrate through simulations that this idea can achieve an increase in annual energy yield of up to approximately 0.5%, especially at wind turbine sites exposed to greater wind turbulence.

[0079] An example of the effects of operating a wind turbine at a higher rotational speed, as disclosed herein, is given below. For an increase in the average rotational speed of 5-8%, an increase in the noise level of 1-1.5 dB should be expected. At the same time, the inventors found that an increase in the annual energy yield of 0.4-0.6% can be expected. This applies particularly to sites with higher turbulence (e.g., Class A sites according to IEC 61400-1). However, the increase in energy yield can still be relevant at sites with lower turbulence (e.g., Class B sites according to IEC 61400-1).

[0080] The disclosed method is usually operated in the manner of a closed control loop. According to the described embodiment, and as is generally applicable, the turbulence parameter is determined online. In this context, "online" determination should be understood as a determination of the turbulence intensity based on actual wind values, normally including historical values ​​of up to a maximum of 24 hours, typically 12 hours, or even more typically 6 hours or one hour, and even more typically a maximum of 30 minutes or 15 minutes. In particular, according to many embodiments, the actual turbulence intensity is continuously determined and used to adjust the desired rotational speed.

[0081] The desired rotational speed can be set, in particular, by changing the generator's torque, for example, by varying the voltage applied to the generator magnets. For instance, if an increase in rotational speed is desired (e.g., in situations such as those encountered in the Fig. 4 and Fig. 5 are illustrated), the generator torque (i.e. the generator torque) can be reduced by reducing the applied voltage.

[0082] Turbulence is characterized by a turbulence parameter, which can be a scalar value, such as a standard deviation, or a vector containing various turbulence-related information, such as an average wind speed, a standard deviation of the wind speed, information about wind speed maxima, possibly including their probabilities of occurrence, etc. The turbulence parameter can be determined by measurement. For example, it is possible to measure the wind speed and / or wind direction and calculate the turbulence parameter from this data. It is also possible to determine the turbulence parameter indirectly, for example, by analyzing values ​​related to changes in the angle of attack and / or generator torque. It is generally typical to use historical values, especially from the last hour or half hour, for this determination.

[0083] Based on the changing turbulence situation, characterized by the turbulence parameter, the circumferential speed at the tip is typically varied dynamically. This is particularly useful for increasing the annual energy yield at installation sites where seasonal changes in turbulence occur, or for wind turbines in coastal regions where the wind direction changes very frequently.

[0084] It is possible to combine the described embodiments for operating a wind turbine with a method for operating wind turbines with reduced noise emissions (in so-called "noise-reduced operation," "NRO"), such as at night. Depending on the specific situation, the method described herein can be permanently or only temporarily suspended by the noise-reduced operation during these times when noise emissions must be limited. According to the embodiments, however, the method described herein can always be used for controlling the wind turbine if the resulting noise generation complies with noise-related regulations.It can be verified as part of the procedure, and / or the wind turbine's control device can be programmed to check whether operation according to the embodiments described herein conflicts with or complies with the noise reduction regulations. In the case of compliance, the wind turbine is operated according to the embodiments described herein. In the case of conflict, the control device could regulate the operation of the wind turbine based on the noise-reducing setpoints.

[0085] The method and apparatus described herein also produce a further advantageous effect with regard to the aging of the rotor blades, e.g., soiling, abrasion, deterioration, etc. In general, despite aging of the rotor blades, which is usually unknown to the control device, the control device commands the same torque to the generator as if the blades were new and did not exhibit any deterioration in their aerodynamic properties. That is to say, with reference to the Fig. The illustrated curve diagram shows that the control device causes the turbine to run slower than desired, i.e., slightly to the left of the maximum. Fig. 3. In embodiments of the present invention, the wind turbine control device, for example, commands a lower torque at the generator in order to operate the wind turbine at a higher speed. That is, with reference to the c p-λ-curve according to Fig. 3. The turbine is typically located on the right side of the maximum of c. p -λ-curve operated. Although this operating point might not be theoretically optimal in the case of unaged rotor blades, the operating point could shift towards the operating point that corresponds to the actual optimal operating point of the aged rotor blades in the case of deteriorated blades.

[0086] Exemplary embodiments of systems and methods for operating a wind turbine are described in detail above. The systems and methods are not limited to the specific embodiments described herein; rather, components of the systems and / or steps of the methods can be used independently and separately from other components and / or steps described herein. In fact, the exemplary embodiment can be implemented and used in conjunction with many other rotor blade applications. Furthermore, it should be understood that the described method can be part of a computer program for operating a wind turbine. The computer program is typically run on a PLC-type controller. It can typically be, for example, in an executable version on a computer-readable medium, e.g.,stored on a hard disk drive, a CD or DVD, a data storage stick, or the like.

[0087] Although specific features of different embodiments of the invention may be illustrated in some drawings but not in others, this is solely for the sake of simplicity. According to the principles of the invention, any feature of one drawing can be referenced and / or claimed in conjunction with any feature of any other drawing.

[0088] This written description uses examples to disclose the invention, including the best embodiment, and also to enable anyone skilled in the art to put the invention into practice, including creating and using any devices or systems and carrying out any methods contained therein. While various specific embodiments are disclosed above, those skilled in the art will recognize that the scope and extent of the claims permit equally effective modifications. In particular, non-mutually exclusive features of the embodiments as described above may be combined. The patentable scope of the invention is defined by the claims and may include further examples that may occur to a person skilled in the art.It is intended that such further examples should fall within the scope of the claims if they have structural elements that do not differ from the literal meaning of the claims, or if they have equivalent structural elements with differences that are insignificant compared to the literal meaning of the claims.

[0089] A method for operating a wind turbine has been provided. The wind turbine includes a rotor configured to rotate at an optimal speed. The method involves determining a turbulence parameter and operating the wind turbine at a speed increased by a specified velocity deviation compared to the optimal speed. The velocity deviation depends on the turbulence parameter. A wind turbine 100, comprising a control device 202 for controlling the wind turbine according to the disclosed method, has also been provided.

Claims

[1] Method for operating a wind turbine, wherein the wind turbine includes a rotor, wherein the rotor has at least one rotor blade, wherein the rotor is set up to rotate at an optimal speed, wherein the optimal speed enables the theoretically maximum possible power gain to be delivered, wherein the method comprises: a Determining a turbulence parameter; and b Operating the wind turbine at a rotor speed that is increased by a speed deviation amount compared to the optimal speed; where the speed deviation amount depends on the turbulence parameter. [2] Method according to claim 1, wherein determining the turbulence parameter includes at least one of measuring the wind speed, measuring the wind direction, measuring the power generated and determining the angle of attack of the rotor blade. [3] Method according to any of the preceding claims, comprising at least either an increase and / or a decrease of the generator torque. [4] Method according to any of the preceding claims, wherein determining the turbulence parameter includes calculating at least either an average value and / or a standard deviation. [5] Method according to claim 4, wherein the mean value and the standard deviation are calculated on the basis of measured values. [6] Method according to claim 5, wherein the measured values ​​are measured over a time interval of at least 5 minutes. [7] Method according to any of the preceding claims, wherein the speed is either a rotational speed or a circumferential speed of the tip or a top speed number. [8] Method according to any of the preceding claims, wherein the wind turbine is operated at a speed that is at least 5% higher than the optimal speed. [9] Method according to any of the preceding claims, wherein at least either the velocity deviation amount is increased when the turbulence parameter increases, and / or the velocity deviation amount is decreased when the turbulence parameter decreases. [10] Method according to one of the preceding claims, wherein determining the turbulence parameter comprises measuring deviations of the angle of attack of at least one rotor blade. [11] Method according to one of the preceding claims, wherein determining the turbulence parameter comprises measuring deviations in the output power of the wind turbine. [12] Method for operating a wind turbine, wherein the wind turbine has a rotatable rotor which is set up to rotate at an optimal speed, wherein the optimal rotational speed enables the theoretically maximum possible power gain to be delivered, wherein the method comprises: a. Measuring turbulence intensity; b Setting the rotor speed to a speed equal to the sum of the optimal speed and a speed deviation amount, where the speed deviation amount depends on the turbulence intensity; and c Operating the wind turbine at the specified speed. [13] Method according to claim 12, wherein the turbulence intensity is characterized by one or more of the following: an average wind speed, a range of wind speed, a standard deviation of wind speed, an average wind direction, a range of wind direction, a standard deviation of wind direction. [14] Method according to claim 12 or 13, wherein the wind turbine is operated at a speed that is at least 5% higher than the optimal speed. [15] Method according to any one of claims 12 to 14, wherein the speed is set to the optimal speed for wind speeds whose probability of occurrence is below a selectable threshold. [16] Wind turbine which features: a rotor comprising at least one rotor blade, wherein the rotor is configured to rotate at an optimal speed, the optimal rotational speed enabling the theoretically maximum possible power gain to be delivered; b a control device for controlling the wind turbine, wherein the control device is configured: i) to determine a turbulence parameter; and ii) to operate the wind turbine at a speed which is increased by a speed deviation amount compared to the optimal speed of the rotor; wherein the speed deviation amount depends on the turbulence parameter. [17] Wind energy system according to claim 16, which further comprises at least either a wind vane and / or an anemometer, wherein the determination of the turbulence parameter includes at least either a measurement of the wind speed using the anemometer and / or a measurement of the wind direction using the wind vane. [18] Wind turbine according to claim 16 or 17, wherein the wind turbine is configured to operate at a speed that is at least 5% higher than the optimal speed. [19] Wind turbine according to one of claims 16 to 18, wherein the control device is configured to at least either increase the amount of speed deviation when the turbulence parameter increases, and / or decrease the amount of speed deviation when the turbulence parameter decreases. [20] Wind turbine according to one of claims 16 to 19, wherein the control device is configured to adjust the speed to the optimal speed for wind speeds whose probability of occurrence is below a selectable threshold.

Images