METHOD FOR OPERATING AT LEAST ONE WIND POWER PLANT AND DEVICE FOR THIS

Description

[0001] The invention relates to the field of wind turbines. Wind turbines are generally known and serve to extract kinetic energy from the wind and convert it into electrical energy in order to feed it into an electrical network.

[0002] These types of wind turbines consist of a generator and an aerodynamic rotor with adjustable rotational speed. The aerodynamic rotor is distinct from an electrodynamic rotor, which is part of the generator. It is known to adjust or change the rotational speed of the aerodynamic rotor by changing the angles of its blades and / or by adjusting the excitation field of a separately excited generator. Therefore, depending on the blade angles or excitation fields, a wind turbine can feed varying amounts of electrical energy into the electrical grid under given constant wind conditions.

[0003] Typically, a wind turbine is operated at an optimal operating point based on the prevailing wind conditions. These prevailing wind conditions primarily refer to the prevailing wind speeds, which, for simplicity, can be considered the sole characteristic of the prevailing wind conditions. In reality, other conditions such as wind gusts or air density would need to be considered, but these can be omitted for the sake of simplicity. Therefore, an optimal operating point can, in principle, be assigned to every wind speed. An optimal operating point is defined as the point at which the wind turbine extracts as much energy as possible from the wind and feeds it into the electrical grid, while simultaneously taking into account boundary conditions such as the stability of the operating point and the load on the turbine, including wear and tear.Such an optimal operating point, which suffices for the following description, is characterized in particular by a correspondingly optimal rotational speed and optimal power output. The power output here refers to the power fed into the electrical grid. The power delivered by the generator may be higher, because losses, for example, must be deducted from it.

[0004] Accordingly, such optimal operating points with an optimal rotational speed are predetermined for basically every wind speed for the respective system, and the wind turbine is operated in such a way that it works at its optimal operating point depending on the wind speed.

[0005] Wind turbines are increasingly tasked with supporting the electrical grid into which they feed. Solutions for this are known from the state of the art, such as frequency-dependent power control. For example, it has been proposed that as the grid frequency increases, the power fed into the grid by the wind turbine is reduced once the grid frequency exceeds a certain threshold. This addresses a grid situation with an energy surplus, which, due to the behavior of large power plants, leads to a frequency increase.

[0006] According to the state of the art, wind turbines are always operated in such a way that they feed as much power as possible into a grid at their optimal operating point, whereby this power can only be reduced to support the grid, i.e., the operation deviates from the optimal operating point.

[0007] To operate a wind turbine with the highest possible yield at any location, a specific structural design is necessary to obtain the standard safety certificate for operation, which is now mandatory for an operating permit. However, to save material and thus reduce the cost of the wind turbines, it is desirable to minimize or even reduce the structural complexity of the design. A standard safety certificate for such wind turbines with structural savings, which are also offered at locations outside their design wind and turbulence class, is only guaranteed if these wind turbines are operated at a reduced capacity. However, this often makes operation uneconomical.Document EP 2 557 311 A1 therefore discloses how to take into account information from the grid operator relating to energy prices when controlling a wind turbine. A further example from the prior art is known from WO2012 / 041327A2.

[0008] In the priority-establishing German patent application, the German Patent and Trademark Office searched the following documents: GB 2 484 266 A, US 2013 / 0 204 447 A1, US 2018 / 0 173 215 A1 and US 2018 / 0 187 648 A1.

[0009] The object of the present invention is therefore to enable the economical operation of a wind turbine with a reduced structural design at sites that lie outside its design wind and turbulence class. At the very least, an alternative to the current operation of a wind turbine is to be proposed.

[0010] The present invention relates, firstly, to the operation of a wind turbine in which a first signal is received that is indicative of the level of remuneration for electrical energy that is currently and / or will be fed into a grid to which the wind turbine is connected. The first signal is indicative of the level of remuneration, i.e., it indicates the amount of remuneration. That is to say, the first signal includes, for example, data from which the level of remuneration can be indirectly derived or which directly indicate the level of remuneration. For example, the first signal includes a figure in euro cents per kilowatt or the like. The remuneration is indicated by the first signal, for example, for the current time and alternatively or additionally for a future period, or a predetermined period extending into the future.Furthermore, according to the invention, a control signal is generated depending on this first signal and the wind turbine is controlled with the control signal in order to generate a power output dependent on the control signal with the wind turbine.

[0011] Thanks to this control system, it is possible to regulate the power output of a wind turbine at a given wind speed, depending on the feed-in tariff. This eliminates the need for control based on wind speed. The invention is based on the following insight: Wind turbines are subject to a certain degree of wear, which increases proportionally with increasing wind speed. This means that the levelized cost of electricity (LCOE) rises with increasing speed, especially when a fixed total lifespan of the wind turbine is assumed. Furthermore, at high wind speeds, due to the high proportion of wind energy fed into the grid, a lower feed-in tariff per kilowatt (kW) is often expected compared to low wind speeds.This means that the profit per kW / h when operating a wind turbine, which is calculated as the feed-in tariff minus the levelized cost of electricity, is significantly lower at high wind speeds than at low wind speeds.

[0012] Operating a wind turbine, for example at reduced capacity during high wind speeds when feed-in tariffs are low (and this is indicated by the initial signal), has a comparatively small impact on the overall profit from operating the turbine. In fact, such reduced operation in these situations can protect the turbine. This has a positive effect on the overall structural stress balance, allowing these reserves to be used in other situations, particularly when high feed-in tariffs are announced. This enables the turbine to be operated at lower stress levels, without power reduction, or even above its optimal operating point, despite its structural design.

[0013] Overall, this approach allows wind turbines that, due to their structural component design, are operated at locations outside their design classes to be operated economically. These turbines can obtain proof of structural stability if it can be demonstrated that they are regularly operated with a load reduction that depends on the initial signal, resulting in an average fatigue load or total service life sufficient to obtain the standard safety certification.

[0014] According to a first embodiment, controlling a wind turbine based on a first signal involves changing the current operating point and operating the turbine at the changed operating point. This applies particularly when the first signal specifies the amount of compensation for electrical energy at a given time. According to the invention, controlling the turbine means setting a schedule with a time-dependent change of the operating point within a predefined period or multiple operating points for times within that predefined period and operating the wind turbine at operating points dependent on the schedule. This applies particularly when the first signal specifies the amount of compensation for electrical energy at several future times, especially for a specific period.Accordingly, operating points can then be set according to a schedule for a predefined period, whereby this period coincides with a period for which the amount of remuneration was received with the first signal, and the wind turbine can be operated during this period according to the schedule.

[0015] An operating point here preferably describes a set of settings or parameters, in particular parameters, that are specified for the wind turbine in order to be operated with these settings. The parameters are, or include, for example, values ​​for adjusting the blade angle and / or values ​​for adjusting the excitation field of a separately excited generator for torque control and / or settings for a converter and / or other components of a wind turbine system for feeding the electrical energy generated by the generator into a grid.

[0016] According to a further embodiment, at least one additional signal is received, which is indicative of at least one factor for determining the current levelized cost of electricity (LCOE) of the wind turbine. Current LCOE thus corresponds to operating-point-dependent LCOE. LCOE represents the costs necessary for the energy conversion performed by the wind turbine. Factors for determining the current LCOE include, for example, fixed and variable operating costs.

[0017] At least one of the factors is preferably a lifetime consumption figure for the wind turbine. This means that the wind turbine is assigned a value, for example, a total lifetime value, from which lifetime consumption during operation is subtracted. It is assumed that when this value has been counted down to zero, the lifetime of the wind turbine has been exhausted. If different lifetime consumption figures are determined or predetermined for different operating points, lifetime consumption can be considered as a factor in the levelized cost of electricity (LCOE).

[0018] For example, if the first signal indicates a particularly high feed-in tariff, but the second signal simultaneously indicates increased lifetime energy consumption, the control system can, despite the high feed-in tariff, reduce the operation of the wind turbine or output less power and generate a corresponding control signal, taking the second signal into account. Lifetime energy consumption is expressed, for example, as lifetime hour equivalents per unit of time or per kilowatt-hour. For instance, a lifetime energy consumption value of 1 represents normal lifetime energy consumption, while a value of 1.3 indicates increased lifetime energy consumption. The unit for this value is, for example, lifetime hour equivalents per hour or lifetime hour equivalents per kilowatt.

[0019] Another factor can be the remaining service life, which can be determined based on condition monitoring or other measurements. Furthermore, the remaining operating time can be a factor, which is determined by permitting status, ongoing project financing, or a planned plant shutdown, for example, due to planned repowering.

[0020] Furthermore, one factor includes, for example, expected wear and tear at different operating points. Additionally, a factor can be considered that includes the costs incurred for grid connection of the wind turbine at different operating points. According to this embodiment, the control signal is then generated depending on the first and second signals. Preferably, for example, a control signal is generated that increases the power output of the wind turbine only when the ratio of the feed-in tariff to the current levelized cost of electricity (LCOE) is as high as possible, and reduces the power output of the wind turbine only when the feed-in tariff is very low relative to the current LCOE.This takes into account that a comparatively higher reduction in the power output of the wind turbine is particularly useful when the current levelized cost of electricity is particularly high, and vice versa.

[0021] Thus, even with a low comparative feed-in tariff, if the levelized cost of electricity (LCOE) is also comparatively low due to the operating point, a power reduction can be avoided. Conversely, if the current operating point results in comparatively high LCOE even with a comparatively high feed-in tariff, a power reduction may be advisable.

[0022] According to a further embodiment, the wind turbine has at least one operating characteristic curve. A control system for the wind turbine then sets operating points that lie on this curve. However, according to this embodiment, at least one section of the operating characteristic curve can be locked. If a section of the operating characteristic curve is locked, operating points cannot be set in that locked section. Therefore, if an operating point is to be set in a locked section of an operating characteristic curve, for example, due to prevailing wind speeds, the control system can only set an operating point below the locked section or, if one exists, above the locked section. Preferably, the operating point set is the one that lies at the edge of the locked section and is closest to the point to be set.The locking and unlocking of at least one area is performed depending on the first signal and preferably also depending on the second signal. Preferably, the locking or unlocking is carried out by the control signal.

[0023] According to a further embodiment, the wind turbine can be operated with at least two different operating characteristics. These operating characteristics are preferably stored within the wind turbine and comprise power-wind speed operating characteristics. That is, if an operating characteristic is a power-wind speed operating characteristic, it preferably has operating points, each corresponding to a specific wind speed, at which the wind turbine generates a certain amount of electrical power. These operating characteristics are preferably selected such that one of them corresponds to an optimal operating characteristic with the optimal operating points.Furthermore, a second operating characteristic curve corresponds to a reduced operation, in which an operation with the operating points at the different wind speeds, for example, generates less energy than the operation with the corresponding operating points on the optimal operating characteristic curve.

[0024] Furthermore, at least one threshold value is stored or predefined, and if the first signal indicates a feed-in tariff at or above the threshold value, a control signal is generated to operate the wind turbine with the first of the two operating curves. If the first signal indicates a feed-in tariff below the threshold value, a control signal is generated to operate the wind turbine with a second of the two operating curves. Preferably, a third or further operating curves can also be stored, which, for example, include operating points that, compared to the first operating curve, generate higher power output at a corresponding wind speed than when operating with the optimal operating curve. This greatly simplifies the control of the wind turbine.

[0025] According to another embodiment, the first and second signals are received by a central control unit. This central control unit is, for example, a control center for several wind turbines or a control system upstream of the wind turbine control center. The central control unit generates control signals for each of the wind turbines and transmits them to the respective turbine to control the turbines in such a way that they generate power dependent on the control signal. A higher authority can therefore determine, based on the prevailing feed-in tariff (which it knows via the first signal), which of the controllable wind turbines should or can be operated at reduced power, and which should continue to operate at its optimal operating point.

[0026] According to a further embodiment, a second signal is generated in each of the wind turbines and transmitted to the central control unit. Alternatively or additionally, at least one factor for determining the current levelized cost of electricity (LCOE) of a wind turbine is transmitted from the wind turbine to the central control unit, in order to generate the second signal for the wind turbine itself using the central control unit.

[0027] According to this embodiment, the central control system can decide which of several wind turbines should be spared, for example, by generating comparatively less power depending on a comparatively low feed-in tariff, and thus operating in a throttled mode. Wind turbines that are nearing the end of their service life and still have sufficient remaining lifespan according to a lifetime consumption indicator can therefore be subjected to greater stress than other wind turbines.

[0028] According to another embodiment, the central control system generates control signals in such a way that a wind turbine with currently low levelized costs of electricity generates a higher power output than another wind turbine.

[0029] According to another embodiment, as an alternative to the previously described reception of the first signal by the central control unit for generating the control signals in the central control unit, the first signal is received by the wind turbine. The second signal is generated by an evaluation circuit of the wind turbine and then used by the wind turbine itself to generate control signals in order to control itself in such a way that it generates power dependent on the respective control signal. A higher-level central control unit is therefore not required.

[0030] According to a further embodiment, the control signal is generated in such a way that an operating point is maintained after a change, preferably for a predefined period of at least one hour, at least 30 minutes, or at least 10 minutes, particularly 15 minutes, even if the initial signal changes within that period. This prevents the operating point of a wind turbine from being constantly changed despite fluctuating feed-in tariffs.

[0031] According to another embodiment, the control signal is generated in such a way that an operating point only changes if the first signal changes by more than a predefined second threshold value. This also takes into account that the operating point of the wind turbine does not need to be constantly changed despite constant wind conditions.

[0032] According to another embodiment, a third signal, indicative of a weather forecast, is received either by the central control system or by the wind turbine itself. A control signal is then generated based on the first, second, and third signals. This ensures that no schedules are set for wind turbines based solely on the first signal, schedules that might not be adhered to, for example, due to prevailing wind conditions.

[0033] The invention further relates to a wind turbine configured to execute a method according to one of the aforementioned embodiments. In particular, the wind turbine is configured to generate or receive a control signal that depends on a first signal. As already explained above, the first signal is indicative of the level of compensation for electrical energy that is currently and / or will be fed into a grid to which the wind turbine can be connected. Furthermore, the wind turbine is configured to generate power that depends on the control signal.

[0034] The invention further relates to a central control unit configured to execute a method according to one of the aforementioned embodiments. In particular, the central control unit serves to generate control signals for several wind turbines according to the aforementioned embodiment. The central control unit receives a first signal that is indicative of the level of compensation for electrical energy that is currently and / or will be fed into a grid to which the wind turbines are connected. The central control unit is also configured to control each wind turbine with a control signal that depends on the first signal.

[0035] Furthermore, the invention comprises a system with a central control unit according to one of the aforementioned embodiments and a wind turbine according to one of the aforementioned embodiments.

[0036] Further embodiments can be seen from the exemplary embodiments explained in more detail in the figures. Fig. 1 shows a wind turbine, Fig. 2 several wind turbines connected to a central control system, Fig. 3 several operating characteristics of a wind turbine, Fig. 4 the control system of a wind turbine, and Fig. 5 the steps of the method according to an exemplary embodiment.

[0037] Fig. 1 Figure 100 shows a schematic representation of a wind turbine according to the invention. The wind turbine 100 has a tower 102 and a nacelle 104 on the tower 102. An aerodynamic rotor 106 with three rotor blades 108 and a spinner 110 is provided on the nacelle 104. During operation of the wind turbine, the aerodynamic rotor 106 is set into rotation by the wind and thus rotates an electrodynamic rotor or rotor of a generator, which is directly or indirectly coupled to the aerodynamic rotor 106. The electric generator is arranged in the nacelle 104 and generates electrical energy. The pitch angles of the rotor blades 108 can be changed by pitch motors at the rotor blade roots of the respective rotor blades 108.

[0038] Fig. 2 Figure 112 shows a wind farm with three exemplary wind turbines 100, which can be identical or different. These three wind turbines 100 are thus representative of essentially any number of wind turbines 100 in a wind farm 112. The wind turbines 100 supply their power, namely the generated electricity, via an electrical park grid 114. The currents or power outputs of the individual wind turbines 100 are added together, and a transformer 116 is usually provided to step up the voltage in the park in order to feed it into the supply grid, or grid 120, at the feed-in point 118, which is also generally referred to as PCC.

[0039] Furthermore, each of the 100 wind turbines is connected to a wind farm controller 22 via a data line 24. Data can be transmitted between the 100 wind turbines and the wind farm controller 22 in both directions via the data line 24, i.e., from the 100 wind turbine to the wind farm controller 22 and from the wind farm controller 22 to the 100 wind turbine. The wind farm controller 22 is in turn connected to a central control unit 26 via another data line 28.

[0040] The central control unit 26 is present in Fig. 2 The central control unit 26 is connected only to the depicted wind farm 112, preferably being connected to and controlling a plurality of wind farms 112. The central control unit 26 can also transmit data to the wind farm controller 22 and vice versa via the additional data line 28, i.e., bidirectionally. The central control unit 26 also has a first input 30 to which one or more first signals 32 are supplied. The first signal 32 indicates the amount of compensation for electrical energy that is currently and / or will be fed into the grid 120, to which the wind turbines 100 are connected. Several first signals 32 serve, for example, to display the respective compensation for the energy when the central control unit 26 controls several wind farms 112 that are connected to different grids 120.Here, each first signal 32 is intended for the wind turbines 100 of the respective wind farm 112.

[0041] Furthermore, the central control unit 26 is configured to receive a second signal 34 from each of the wind turbines 100 of the depicted wind farm 112 via data line 24 and the further data line 28, i.e., forwarded via the wind farm controller 22. This signal is indicative of at least one factor for determining the current levelized cost of electricity (LCOE) of the respective wind turbine 100. The central control unit 26 also has a further input 36 through which a third signal 38 can be received. This third signal 38 is indicative of a weather forecast. Preferably, a third signal 38 contains several weather forecasts for different areas in which several wind farms 112 are located if they are connected to the central control unit 26. However, a separate third signal 38 can also be received for each wind farm 112, depending on its location.As an alternative to the illustrated embodiment, the first input 30 and the further input 36 can also be designed as a single input.

[0042] The central control unit 26, which can also be configured as a control center or as part of the park control system as a decentralized system, is set up to generate and then output a control signal 40 for controlling all wind turbines 100 of the wind farm 112, or each wind turbine 100 separately, depending on the first signal 32, or depending on the first signal 32 and the second signal 34, or depending on the first signal 32 and the second signal 34, or depending on the first signal 32 and the third signal 38. The control signal 40 or signals 40 are then supplied to the respective wind turbine 100, or to one of them at a time, via the additional data line 28 and data line 24, i.e., again via the wind farm controller 22. The control signal 40 serves to control the wind turbine so that the wind turbine generates energy that depends on the control signal.Preferably, the control signal 40 serves to control one or more wind turbines 100 by setting an operating point of the wind turbine(s) 100 that depends on the control signal 40, such that a current operating point of the wind turbine(s) 100 changes to another operating point dependent on the control signal 40. An operating point defines, for example, a blade pitch angle or a blade angle change and / or a control of the excitation voltage of the generator of the wind turbine 100. Thus, depending on the control signal 40, and in particular by changing the operating point, the electrical energy generated by the wind turbine 100 can be changed even with constant wind. The wind turbines 100 of the wind farm 112 are therefore controlled, in particular, depending on the first signal 32, i.e., depending on the level of remuneration.

[0043] In an embodiment not shown here, the aforementioned functions of the central control unit 26 are performed in the wind farm controller 22. For this purpose, the wind farm controller 22 has inputs to receive the first signal 32 and, in particular, the second signal 34, or to generate them itself for the wind turbines 100 controlled by the wind farm controller 22. The wind farm controller 22 then generates control signals 40 for the wind turbines 100 depending on the first signal 32 and preferably depending on the second signal 34.

[0044] Fig. 3 Figure 3 shows three operating characteristic curves 40a, 40b, and 40c. Operating characteristic curves 40a, 40b, and 40c each assign a power output 44 to a wind speed 42. Each of the operating characteristic curves 40a to 40c comprises a multitude of operating points 46. This means that the wind turbine, for example, which is operated with an optimal operating characteristic curve 40a, generates a power output 50 at a wind speed 42, represented by the vertical dashed line 48, as shown by the horizontal dashed line 50.

[0045] Operating point 46, which is shown on the optimal operating characteristic curve 40a, has predefined blade pitch angles and / or excitation field settings. From this operating point 46 on operating characteristic curve 40a, which can also be referred to as the first operating characteristic curve, it is possible, for example, to switch to another operating point 46 on the further or second operating characteristic curve 40b. The operating point 46 on operating characteristic curve 40b has, for example, a different blade pitch angle or a different excitation field setting.

[0046] Thus, depending on the first signal, which indicates the level of remuneration, it is easy to switch between the operating points 46 on the operating characteristic curves 40a to 40c. In the present example, three operating characteristic curves are shown, whereas according to another embodiment, a plurality of operating characteristic curves are stored, each assigned to a remuneration level, and can be selected depending on a remuneration level indicated by the first signal. Alternatively, according to another embodiment not shown here, only at least one operating characteristic curve 40a is stored, whereby higher power ranges of operating characteristic curve 40a can be deactivated or locked, or a power limit can be activated.In this case, not several characteristic curves are stored, but the characteristic curve is divided into several areas, whereby the higher power areas are optional and can be switched on or off or locked and unlocked again depending on the first signal 32.

[0047] Fig. 4 Figure 52 shows a control unit 52 of a wind turbine, which is controlled, for example, independently of a central control unit 26 according to the following procedure. The control unit 52 receives the first signal 32, which indicates the amount of compensation, and optionally the third signal 38, which contains weather forecast data. The control unit 52 also includes an evaluation circuit 54, which generates the second signal 34. Depending on the three signals, a control signal 40 for controlling the wind turbine is then generated by a control signal generation unit 51 of the control unit 52. This control signal 40 can, for example, be used directly in an operating point setting unit 53 of the control unit 42 to control the power output of the wind turbine for a given wind condition, namely by selecting an operating point 46.

[0048] Fig. 5Figure 60 shows the steps of an exemplary embodiment of the method. In step 60, the wind turbine is at a current operating point 46. After a delay time 62, to which a period 64 can be added, a decision step 66 checks whether an applied first signal 32 has changed. If the first signal 32 has not changed, the method returns to step 60 and the wind turbine 100 continues to operate at the current operating point 46. If the first signal 32 has changed, a subsequent decision step 68 checks whether the change in the first signal 32 has exceeded a second threshold value 70. If this is not the case, the wind turbine continues to operate at the current operating point 46.However, if the first signal 32 has changed by more than the second threshold value 70, the wind turbine 100 is controlled in such a way that the wind turbine 100 is operated with a different operating point in step 72.

[0049] Alternatively, a threshold value 74 can be added during the check in step 66. A change in the first signal 32 is only detected if the first signal 32 has changed in such a way that it has exceeded the threshold value 74 at least once, either from a lower value to an upper value or from an upper value to a lower value.

Claims

1. A method of operating at least one wind turbine (100) including the steps: - receiving a first signal (32) which is indicative of a level of a remuneration for electrical energy, which is fed in the future into a grid (120) to which the wind turbine (100) is connected, wherein the first signal indicates the level of remuneration for electrical energy for a plurality of future points in time for a period of time, - producing a control signal (40) dependent on the first signal (32), and - controlling the wind turbine (100) with the control signal (40) for generating power of the wind turbine (100), that is dependent on the control signal (40), wherein the control comprises storing a schedule with a change in respect of time of the operating point (46) for a pre-defined period of time and operating the wind turbine (100) in operating points (46) which are dependent on the schedule, wherein the pre-defined period of time coincides with the period of time, for which the level of remuneration was received.

2. A method as set forth in claim 1 wherein the control includes a change in the current operating point (46) and operating the wind turbine (100) with the changed operating point (46).

3. A method as set forth in claim 1 or claim 2 wherein in addition at least one second signal (34) is received, which is indicative of at least one factor for determining the current electricity generation costs (LCOE) of the wind turbine (100), wherein the at least one factor includes in particular a lifetime consumption, a residual lifetime and / or a residual operating time, of the wind turbine (100), a wear of the wind turbine (100) respectively expected for different operating points (46) and / or costs respectively occurring for different operating points (46) for grid connection power of the wind turbine (100) and producing the control signal (40) in dependence on the first signal (32) and the second signal (34).

4. A method as set forth in one of the preceding claims wherein the wind turbine (100) is operable with at least two different operating characteristics (40a, 40b, 40c), in particular power-wind speed operating characteristics, and at least one threshold value (74) for the wind turbine (100) can be pre-defined, wherein in the situation where the first signal (32) indicates a remuneration at or above the threshold value (74) a control signal (40) is produced to operate the wind turbine (100) with a first (40a) of the two operating characteristics (40a - 40c) and in case where the first signal (32) indicates a remuneration below the threshold value (74) a control signal (40) is produced to operate the wind turbine (100) at a second (40b) of the two operating characteristics (40a - 40c).

5. A method as set forth in one of claims 1 through 3 wherein the wind turbine (100) has at least one operating characteristic (40a) and operating points (46) of the operating characteristic (40a) are set by a control (52), wherein at least one region of the operating characteristic (40a) can be blocked so that in the case of a blockage operating points (46) in the blocked region cannot be set, wherein blocking and re-enablement is effected in dependence on the first signal (32) and preferably in dependence on the second signal (34).

6. A method as set forth in one of the preceding claims wherein the first signal (32) and the second signal (34) are received by a second control (26) and in the central control (26) control signals (40) are respectively produced for one of a plurality of wind turbines (100) and transmitted to the respective ones of the plurality of wind turbines (100) in order to respectively control the plurality of wind turbines (100) with the control signals (40) such that they generate a power dependent on the respective control signal (40).

7. A method as set forth in claim 6 wherein the second signal (34) is produced in the wind turbine (100) and transmitted to the central control (26) or at least one factor for determining the current electricity generation costs of a wind turbine (100) is transmitted from the wind turbine (100) to the central control (26) to produce with the central control (26) the second signal (34) for the wind turbine (100).

8. A method as set forth in claim 6 or claim 7 wherein the control signals (40) are produced in the central control (26) in such a way that a wind turbine (100) with currently lower electricity generation costs in comparison with another wind turbine (100) generates a higher power output than the other wind turbine (100).

9. A method as set forth in one of claims 1 through 5 wherein the first signal (32) is received by means of the wind turbine (100) and the second signal (34) is generated by an evaluation circuit (54) of the wind turbine (100) and the wind turbine (100) produces control signals in order to control itself such that it produces a power output dependent on the respective control signal (40).

10. A method as set forth in one of the preceding claims wherein the control signal (40) is produced in such a way that an operating point (46) is maintained after a change, preferably for a period of time (64) of at least one hour, at least 30 minutes or at least 10 minutes, in particular 15 minutes, even if the first signal (32) changes within the period of time (64).

11. A method as set forth in one of the preceding claims wherein the control signal (40) is produced in such a way that an operating point (46) changes only when the first signal (32) changes by more than a pre-defined second threshold value (70).

12. A method as set forth in one of the preceding claims wherein a third signal (38) is received, which in indicative of a weather forecast, and a control signal (40) is produced in dependence on the first signal (32), the second signal (34) and the third signal (38).

13. A wind turbine for carrying out a method as set forth in one of claims 1 through 12, wherein the wind turbine (100) is adapted to produce or receive a control signal (40) which is dependent on a first signal (32) which is indicative of a level of a remuneration for electrical energy which is fed currently and / or in the future into a grid (120) to which the wind turbine (100) can be connected, wherein the first signal indicates the level of remuneration for electrical energy for a plurality of future points in time for a period of time, and is adapted to generate a power output dependent on the control signal (40) by controlling the wind turbine (100) with the control signal (40) to generate a power output, wherein the control comprises storing a schedule with a change in respect of time of the operating point (46) for a pre-defined period of time and operating the wind turbine (100) in operating points (46) which are dependent on the schedule, wherein the pre-defined period of time coincides with the period of time, for which the level of remuneration was received.

14. A central control, in particular for carrying out a method as set forth in one of claims 1 through 12, for producing control signals (40) for a plurality of wind turbines (100) as set forth in claim 13, wherein with the central control (26) a first signal (32) is received, which is indicative of a level of a remuneration for electrical energy which is fed in the future into a grid (120) to which the wind turbines (100) are respectively connected, wherein the first signal indicates the level of remuneration for electrical energy for a plurality of future points in time for a period of time, and control of the wind turbines (100) with a respective control signal (40) dependent on the first signal (32), wherein the control comprises storing a schedule with a change in respect of time of the operating point (46) for a pre-defined period of time and operating the wind turbine (100) in operating points (46) which are dependent on the schedule, wherein the pre-defined period of time coincides with the period of time, for which the level of remuneration was received.

15. A system comprising a central control (26) as set forth in claim 14 and a plurality of wind turbines (100) as set forth in claim 13.