METHOD FOR OPERATING A WIND POWER INSTALLATION, WIND POWER INSTALLATION AND WIND FARM

Abstract

The present disclosure relates to a method for operating a wind power installation, to an associated wind power installation and to a wind farm. The method comprises the following steps: determining at least two, preferably at least three and particularly preferably all the environmental parameters of the environment of the wind power installation selected from the list consisting of: turbulence intensity, air density, air temperature and shear; providing boundary conditions for operating the wind power installation, the boundary conditions containing at least one from a load boundary condition, a noise level boundary condition and a power boundary condition; adapting an operational control, in particular an operating point and/or an operating characteristic, of the wind power installation on the basis of a combination of the changes in the determined environmental parameters taking into consideration the boundary conditions.

Claims

1. A method for operating a wind power installation, the method comprising: determining at least two environmental parameters of an environment of the wind power installation, wherein the at least two environmental parameters are selected from a list consisting of: turbulence intensity, air density, air temperature, shear, and precipitation, providing boundary conditions for operating the wind power installation, the boundary conditions containing at least one boundary condition chosen from a load boundary condition, a noise level boundary condition, and a power boundary condition, and adapting an operational control and/or an operating characteristic of the wind power installation based on a combination of the changes in the at least two environmental parameters taking into consideration the boundary conditions.

2. The method according to claim 1, wherein the adapting the operational control comprises adapting an operating point and further comprises: providing a current operating point of the wind power installation, determining each adaptation of the operational control of the wind power installation based on a change in one of the at least two environmental parameters and on the operating point, and adapting the operational control of the wind power installation based on a combination of the determined adaptations taking into consideration the boundary conditions.

3. The method according to claim 1, wherein the at least two environmental parameters are determined on a recurring basis, wherein the recurring basis is periodically or continuously during an operation of the wind power installation.

4. The method according to claim 1, wherein the adapting operational control comprises adapting an operating point and/or the operating characteristic comprises at least one of the following measures if the taking into consideration of the load boundary condition, a noise level boundary condition and a power boundary condition specifies at least one load reserve, a noise level reserve or a power reserve: reducing a minimum blade angle and reducing a tip-speed-ratio to reduce a distance of the operating point from the operating point with an optimum power coefficient, shifting or changing a characteristic for controlling the pitch angles of the rotor blades, referred to as pitch characteristic, to higher pitch angles for at least part of the operating range, increasing a rotor rotational speed of the wind power installation, and increasing a nominal power of the wind power installation.

5. The method according to claim 1, wherein the determining of the at least two environmental parameters comprises determining the air density, wherein a reduction in the air density leads to an increase of a load reserve and of a noise level reserve and, as a consequence, to adapting the operational control, wherein a rotor rotational speed is increased to compensate for a change in the tip-speed-ratio using the noise level reserve, and/or wherein an operating characteristic and/or a pitch characteristic is adapted using the load reserve.

6. The method according to claim 1, wherein: the determining of the at least two environmental parameters of shear comprises determining a shear coefficient, the shear coefficient is indicative of a change in a vertical direction of a wind speed over a rotor plane of a rotor of the wind power installation, a reduction in the shear coefficient corresponds to a more uniform incident flow with relatively lower alternating loads, the shear coefficient is compared with a predetermined shear threshold value, the predetermined shear threshold value corresponds to the shear coefficient with a minimum of the power output, and wherein the operational control is an operating point and is adapted in accordance with a change in the shear coefficient and a comparison of the shear coefficient with the predetermined shear threshold value.

7. The method according to claim 6, wherein a power reduction range is defined as a value range of the shear coefficient, for which a reduced speed in a lower half of a rotor disc cannot be compensated for by an increased speed in an upper half of the rotor disc and thus a power reduction takes place, wherein a shear coefficient at a lower end of the power reduction range is defined as a design shear coefficient, and wherein the operating point is adapted in accordance with a change in the shear coefficient and a comparison of the shear coefficient with the design shear coefficient.

8. The method according to claim 7, wherein: in the event that a reduction in the shear coefficient occurs in a range below the design shear coefficient, wherein the operating point is adapted in such a manner that an additional load and/or angle of attack reserves for increasing an annual energy production result in an increase in a rotational speed and/or in a more aggressive pitch profile upon individual adjustment of individual rotor blades.

9. The method according to claim 7, wherein in the event that an increase in the shear coefficient occurs in the value range above the design shear coefficient but within the power reduction range, the operating point is adapted in such a manner that, in order to maintain the load and/or angle of attack reserves, at least one of the following adaptations takes place: individually adjusting rotor blades in order to reduce the loads in the upper half of the rotor disc, adjusting a pitch at an earlier point in the upper partial load range in order to reduce the loads, and reducing the rotational speed in order to maintain the load limits.

10. The method according to one of claim 7, wherein in the event that an increase in the shear coefficient occurs in a range above the design shear coefficient and outside the power reduction range, wherein the operating point is adapted in such a manner that, in order to maintain the load and/or angle of attack reserves, at least one of the following adaptations takes place: individually adjusting rotor blades without losses of an annual energy production, adjusting a pitch at an earlier point in the upper partial load range, and reducing the rotational speed in order to reduce the loads.

11. The method according to claim 1, wherein the determining of the at least two environmental parameters comprises determining the turbulence intensity, wherein a reduction in the turbulence intensity brings about an increase in an angle of attack reserve and an increase in a load reserve, and wherein, upon establishing a reduction in the turbulence intensity, the adapting the operational control comprises: a) a tip-speed-ratio and/or a minimum blade angle is reduced in the partial load range in order to increase the power, and b) a pitch characteristic is displaced in the upper partial load range towards higher powers in order to compensate for the load and angle of attack reserves which have arisen, or c) in addition to a) and alternatively to b), a rotor rotational speed of the wind power plant is increased taking into consideration the noise level boundary condition.

12. The method according to claim 1, wherein the determining of the at least two environmental parameters comprises determining the temperature and the air density, wherein a reduction in the temperature with the density remaining the same leads to thermal reserves in an electrical section of the wind power installation, wherein, upon establishing a thermal reserve, the adapting the operational control comprises that a power is increased, either as a temporary power increase or as a permanent nominal power increase, wherein the increasing of the power in accordance with the noise level boundary condition comprises: increasing a rotational speed of a rotor with an existing noise level reserve, or increasing a torque without an existing noise level reserve.

13. The method according to claim 1, wherein the determining of the at least two environmental parameters comprises determining the shear and the turbulence intensity, wherein an influence of the shear and of the turbulence intensity on the load and the angle of attack reserve is calculated, and the adapting the operational control in accordance with the load and angle of attack reserve comprises at least one of the following steps: adapting a pitch characteristic in a partial load range with existing load and angle of attack reserves and reducing a minimum blade angle and/or a tip-speed-ratio; and increasing a nominal power to compensate wind gust.

14. The method according to claim 1, wherein the determining of the at least two environmental parameters comprises determining the air density and the turbulence intensity, wherein, in the event that both the air density and the turbulence intensity increase, a higher annual energy production, higher loads and a higher noise output level follow, wherein, in this case, the adapting the operational control comprises at least one of the following steps: a) changing the pitch characteristic by taking into account decreasing angles of attack due to increased air density and increasing angles of attack due to increased turbulence intensity; b) reducing a rotational speed to reduce loads and a noise output level; and c) increasing an angle of attack reserve in a partial load range by increasing a tip-speed-ratio and/or a minimum blade angle, wherein, in the event that both the air density and the turbulence intensity decrease, at least one of steps a), b) and c) are used in inverted form in order to adapt the operational control.

15. The method according to claim 1, wherein the determining of the at least two environmental parameters comprises determining the air density and the turbulence intensity, wherein, in the event that the air density increases and the turbulence intensity decreases, effects on loads and noise are compensated for, wherein, in this case, the adapting the operational control because of the increased angle of attack limits comprises at least one of the following steps: changing a pitch characteristic to increase an annual energy production; and reducing a rotational speed to compensate for increased loads including load average values.

16. The method according to claim 1, wherein the determining of the at least two environmental parameters comprises determining the air density and the turbulence intensity, wherein, in the event that the air density decreases and the turbulence intensity increases, effects on loads and noise are compensated for, wherein, in this case, the adapting operational control to compensate for decreased angle of attack limits comprises at least one of the following steps: changing a pitch characteristic by adjusting a pitch at an earlier point; and increasing rotational speed.

17. The method according to claim 1, wherein the determining of the at least two environmental parameters comprises determining the air density and the temperature, wherein, in the event that the temperature decreases and the air density increases, in accordance with a noise level boundary condition, the adapting the operational control comprises at least one of the following steps: raising the nominal power while simultaneously reducing the rotational speed to maintain the noise level boundary condition, and, in the event of a noncritical noise level boundary condition, reducing same only as far as maintaining the load boundary condition; and increasing a pitch until the load boundary condition is maintained.

18. A wind power installation comprising: a tower; a nacelle; at least one rotor blade; and a controller, wherein the controller is configured to: determine at least two environmental parameters of an environment of the wind power installation, wherein the at least two environmental parameters are selected from a list consisting of: turbulence intensity, air density, air temperature, shear, and precipitation, provide boundary conditions for operating the wind power installation, the boundary conditions containing at least one boundary condition chosen from a load boundary condition, a noise level boundary condition, and a power boundary condition, and adapt an operational control and/or an operating characteristic of the wind power installation based on a combination of the changes in the at least two environmental parameters taking into consideration the boundary conditions.

19. A wind farm comprising a plurality of wind power installations according to claim 18.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0097] Further advantages and preferred refinements will be described in detail below with reference to the attached figures, in which:

[0098] FIG. 1 shows a wind power installation schematically and by way of example;

[0099] FIG. 2 shows a wind farm schematically and by way of example;

[0100] FIG. 3 shows relationships of noise output level, load level and power for different operational controls schematically and by way of example;

[0101] FIG. 4 shows relationships of annual energy production and shear coefficient schematically and by way of example;

[0102] FIG. 5 shows relationships of noise output level, load level and power for different operational controls schematically and by way of example; and

[0103] FIG. 6 shows relationships of noise output level, load level and power for different operational controls schematically and by way of example.

DETAILED DESCRIPTION

[0104] FIG. 1 shows a schematic illustration of a wind power installation 100. The wind power installation 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 power installation, the aerodynamic rotor 106 is set into a rotary motion by the wind, and thereby also rotates an electro-dynamic rotor of a generator, which is coupled directly or indirectly 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 109 of the respective rotor blades 108.

[0105] The wind power installation 100 here has an electric generator 101 which is indicated in the nacelle 104. Electrical power can be generated by means of the generator 101. In order to feed in electrical power, a feed-in unit 105 is provided which can be designed particularly as an inverter. A three-phase feed-in current and/or a three-phase feed-in voltage can therefore be generated in accordance with amplitude, frequency and phase, for feeding in at a grid connection point PCC. This can be undertaken directly or else together with further wind power installations in a wind farm. An installation controller 103 is provided for controlling the wind power installation 100 and also the feed-in unit 105. The installation controller 103 can also receive default values from externally, in particular from a central farm computer.

[0106] FIG. 2 shows a wind farm 112 with, by way of example, three wind power installations 100, which may be the same or different. The three wind power installations 100 are consequently representative of essentially any number of wind power installations of a wind farm 112. The wind power installations 100 provide their power, to be specific in particular the electricity generated, by way of an electrical farm grid 114. In this case, the electricity or power respectively generated by the individual wind power installations 100 is added together and there is usually a transformer 116, which steps up the voltage in the farm in order then to feed into the supply grid 120 at the feed-in point 118, which is also referred to generally as the PCC. FIG. 2 is just a simplified illustration of a wind farm 112. It is possible for example for the farm grid 114 to be differently designed, in that for example there is also a transformer at the output of each wind power installation 100, to name just one other exemplary embodiment.

[0107] The wind farm 112 additionally has a central farm computer 122, which can synonymously also be referred to as the central park controller. Said central farm computer can be connected to the wind power installations 100 via data lines 124, or in a wireless manner, in order thereby to exchange data with the wind power installations and in particular to acquire measured values from the wind power installations 100 and to transmit control values to the wind power installations 100.

[0108] The requirements of locations are becoming increasingly more complex and individual. The call for an individual mode of operation permitting the setting of the yield from the guarantee data sheet is therefore becoming louder. However, the guarantee data sheet is calculated with standardized ideal values which depict a statistical average of the wind field and of the environmental conditions.

[0109] The individual mode of operation proposes adapting the modes of operation to the parameters of environmental conditions, such as wind field, climate, blade deformation and installation position, that are actually present at the location. Rotational speed (both profile and nominal and desired rotational speed), pitch angle and nominal power can be changed at the installation in order to obtain a maximum yield. The present disclosure proposes a way of how said adjustable parameters can be optimally adjusted or adapted to changing environmental parameters for the yield of the installation.

[0110] The boundary conditions of maximum noise output level, maximum loads, controller stability and generator variables are intended to be maintained here. It should be noted here that certain behavior patterns increase non-linearly.

[0111] For example, a lower turbulence intensity already leads to a reduced noise output level. In this case, because of the lower tendency of the flow to separate at the blade, the trailing edge noise is additionally reduced. Since the loads at locations with lower turbulence also decrease, the margin gained in accordance with the present disclosure can be invested in an increased maximum rotational speed which leads to higher yields while simultaneously maintaining the design loads and noise guarantee.

[0112] In the event of greater stiffening of the blade, because of increased centrifugal forces after an increase in the rotational speed, the elastic deformation of the blade is reduced. This reduces the local angles of attack, and therefore the pitch angles can likewise be reduced, with the angle of attack reserves being simultaneously maintained.

[0113] In the first step, an individual operational control can be configured as a discrete operating characteristic. This is optimally configured to the average wind conditions at the location. It is active throughout the service life of the installation.

[0114] In the second step, a multidimensional parameter space is introduced to the installation controller. The installation sensor continuously measures the wind field, the environmental conditions, the state of the installation and optionally also noise at a defined point of emission.

[0115] The control technology which is implemented in the installation controller 103 preferably ascertains independently and in real time, on the basis of the recorded values, a valid set of parameters of rotational speed and blade angle adjustment in order to achieve the maximum power and to maintain possible sound levels. The boundary conditions of noise output level, loads, controller stability, ranges of inherent frequencies of components, for example rotational speed windows, and generator variables, are intended to be maintained here.

[0116] For example, a power increase is necessary if a lower turbulence intensity, a lower density, a lower shear or a more greatly asymmetric wind distribution prevail (Weibull factor<2). This respectively results in a lower extraction of power from the wind, a lower noise output level, a lower propagation of the noise, lower alternating loads, smaller deformation and in an increased distance from angle of attack reserves in relation to a separation at the blade. Accordingly, a rotational speed can be increased and/or angle of attack reserves can be reduced by a smaller pitch. The maximum possible yield can be obtained as a result.

[0117] In another example, a load reduction is possible in a case in which increased turbulence intensity, an increased density, an increased shear or a greatly symmetrical wind distribution (Weibull factor>2) are present or are determined. The respective result is then a greater extraction of power from the wind, an increased noise output level, a greater propagation of the noise, increased alternating loads, increased deformation loads and a smaller distance from the angle of attack reserves in relation to a separation at the blade. A reduction in the rotational speed or an increase in the angle of attack reserves due to a lower pitch is indicated as the reaction. As a result, the guaranteed yield is maintained, the noise output level is reduced and the alternating loads reduced in order to maintain the maintenance intervals and calculations of the service life.

[0118] The location-specific parameters, which are also referred to as environmental conditions, can be broken down as follows.

[0119] The wind field is determined here from the average and the extreme values for one or more, in particular also all of the following: [0120] a) turbulence intensity [0121] b) shear [0122] c) rotation of the wind speed over height (veer) [0123] d) wind direction (yaw) [0124] e) wind frequency, shape of the Weibull distribution [0125] f) incident flow angle of the rotor surface (flow inclination)

[0126] The climate can be determined from one or more, in particular all of the following values: [0127] a) density [0128] b) temperature [0129] c) humidity [0130] d) precipitation frequency.

[0131] The installation position describes the position in the wind farm 102, i.e., relative to other wind power installations 100 and in the terrain, i.e., relative to orographical characteristics (mountains, valleys, woods).

[0132] The state of the installation is described by one or more, in particular all of the following parameters: [0133] a) angle of attack at the blade [0134] b) the instantaneous load states at the blade [0135] c) the accelerations for bypassing hazardous vibrations from the diverse components.

[0136] The possible measures for reacting to changed environmental parameters comprise one, a plurality or all of the following adaptations of the operating point or of the operational control: [0137] (1) operating the installation more closely to the cp optimum, by reducing the minimum blade angle α.sub.min and reducing the tip-speed-ratio λ, [0138] (2) adjusting the pitch subsequently, i.e., carrying out an increase in the blade angle at higher wind speeds and/or higher power [0139] (3) increasing the rotational speed of the rotor [0140] (4) increasing the nominal power.

[0141] With environmental parameters changed in the opposite direction, an inverted adaptation of the operating point is correspondingly indicated.

[0142] Power should be understood here and throughout the context of the present application preferably as the generated electrical power or as a different measure of the power of the wind power installation. Also suitable for example as a value indicative of the power is the air gap power or a torque as the generator.

[0143] The precise effects of changing environmental parameters are assessed below for the individual environmental parameters and for combinations of environmental parameters.

Influence on a Wind Power Installation 100 by Changed Density; Background Information

[0144] The electrical power is calculated by means of:

P=ρη.sub.elc.sub.pπr.sup.2v.sub.inv.sup.3

and is therefore linear to the density ρ. [0145] At the same time, however, a lower density leads to the wind power installation 100 needing more wind for the same electrical power P, which would lead to a changed λ (TSR, tip-speed-ratio). Although the wind power installation 100 can counteract this, it can do so only in the partial load range since an increase in the rotational speed or in the TSR at the nominal point leads to an increased noise output level. [0146] If the TSR cannot be adapted in the nominal power range, this leads to an aerodynamically poorer Cp or operating point of the wind power installation 100. [0147] However, the exact AEP loss depends on profile series, blade design and possibly used accessory parts, such as vortex generators, serrations and, for example, flaps, and also additional interventions in the pitch control, and can be precisely quantified only from wind power installation 100 to wind power installation 100. This also cannot be considered completely separately from turbulence intensity and shear. [0148] If the density decreases below the design density, yield losses should initially be expected or else the nominal power is reached only later, see above. [0149] At the same time, however, loads and noise also decrease, wherein there is already a known approximate relationship for noise. [0150] It follows from reducing noise that in principle the entire operating characteristic can be scaled with the density (cube root of the density), including the nominal rotational speed of the wind power installation 100. [0151] At the same time, the reduction in the density also reduces the loads, in particular for the average values of the blade loads (My) and the installation thrust or the Ct coefficients. At least for certain installation components (for example tower, flapwise torque, azimuth, pitch), this results in space for a “more aggressive” operational control. This can be configured, for example, by adapting the operating characteristic and/or the pitch characteristic. For example, there can be space here for reducing the angle of attack reserve. [0152] Rotating more rapidly: max. SPL still remains below SPL at design density because of the lower density. Additional load reserves of some components are again used up. Extreme loads are customarily not affected in this case. However, some loads (for example flapwise torque) are increased. In addition, erosion of the leading edge of the blade may be a problem. However, erosion is likewise location-dependent (frequency of rain). When a rain sensor is present, an increased desired rotational speed could be omitted during rain in order to avoid excessive erosion. As a result, the AEP losses which arise virtually inevitably because of the lower density are minimized with very substantially identical loads and conformal noise output levels, as before. [0153] The more rapid rotation (for example at least in the partial load range) maintains angle of attack reserves. If an installation under standard settings has sufficient angle of attack reserves, these can be used up by somewhat more aggressive pitch control. Load reserves would then be used up by a combination of changed operating characteristic and pitch characteristic. However, this would result in an increase in the extreme loads, possibly also in the vibration amplitudes in the flapwise direction. [0154] Depending on the installation, a change in the rotation speed/power characteristic (entirely or only in the partial load range) with/without adaptation of the pitch control can be optimum, depending on the load budget of the wind power installation 100 and possibly on further location parameters, for example turbulence intensity.

[0155] FIG. 3 shows, schematically and by way of example, the relationships of noise output level 310, load level 320 and power 330 in a triaxial diagram 300. The load level 320 substantially corresponds to the inverse of the anticipated service life.

[0156] For standard air density, i.e., the design case, the state 302 is expected. This provides the maximum power 330 under the permissible framework conditions for noise output level 310 and load level 320. When the operational control is maintained, the state 304 is set for an air density which is reduced in relation to the standard air density. It can be seen that a lower power 330 is also achieved with a lower noise output level 310 and lower load level 320.

[0157] By adapting the operational control in accordance with the present disclosure, the state 306 arises. For the state 306, the adaptations comprise in particular a more pronounced adjustment of the pitch in order to reduce the angle of attack reserves and a slight increase in the rotational speed. Like the design state 302, the state 306 meets the requirements imposed on the noise output level 310 and, in comparison to the unchanged operational control in the state 304, leads to an increase in power 330.

[0158] The state 306 continues to provide reserves in the load range, and therefore a further increase in power 330 is achieved by the state 308 by the operational control being further adapted in accordance with the present disclosure. For the state 308, the rotational speed has been greatly increased in relation to the design case in order to exhaust the load reserves.

Influence on a Wind Power Installation 100 by Various Shear Values; Background Information

[0159] The shear coefficient describes the extent to which the wind speed changes over the height of the rotor circular disc.

[0160] FIG. 4 shows, schematically and by way of example, a diagram 400 of the profile of the annual energy production AEP relative to a reference energy production AEPref on the vertical axis over values of the shear coefficient on the horizontal axis: [0161] Low shear coefficients indicate a uniform incident flow with relatively low alternating loads through the wind field. [0162] As the shear coefficient increases, differences in the incident flow speed over the rotor surface and therefore amplitude of the load changes through the wind field and of the angles of attack along the rotor blade increase. [0163] In certain value ranges of the shear coefficient, a reduced speed in the lower rotor disc half cannot be compensated for by an overspeed in the upper rotor disc half, which leads to a power reduction. .fwdarw.Power reduction; in the example of FIG. 4, this corresponds to a range 420 of the shear coefficient of 0.15-0.38. [0164] Above and below the range 420, the reduced speed in the lower rotor disc half is overcompensated for by an overspeed in the upper rotor half, which leads to an increase in power. This relates to the range 410 with a shear coefficient<0.15 and to the range 430 with a shear coefficient>0.38.
Shear Decreases/is Lower than Design Shear (for Example 0.15) and AEP Increases (Range 420 in FIG. 4)

[0165] FIG. 5 shows, schematically and by way of example, the relationships of noise output level 510, load level 520 and power 530 in a triaxial diagram 500 analogously to the illustration in FIG. 3 with decreasing shear or with a shear below the design shear. [0166] If, at a location, the shear of the incident flow is lower than in the design case (second innermost case, state 502), the wind power installation 100 experiences lower amplitudes in the alternating loads and lower fluctuations in the angles of attack (innermost case, state 504). [0167] A change in the noise output level is provided only indirectly via changed angles of attack along the blade and is negligibly small. [0168] The reserves which have arisen in the loads and the angle of attack reserves for further increase of the AEP can be increased (2) by a more aggressive pitch profile. (State 506). [0169] If the location is free of noise restrictions, the load reserves which have arisen can be increased (3) by an additional increase in the rotational speed (state 508). [0170] In each case, for optimum use of the angle of attack reserves, control can be undertaken via IPC.
Shear Increases/is Greater than Design Shear (for Example 0.15) and AEP Decreases (Range 420 in FIG. 4)

[0171] If the shear increases in relation to the design point and the AEP simultaneously decreases, the wind power plant 100 experiences increasing amplitudes in the alternating loads and the angles of attack that cannot be compensated for by increasing the rotational speed and adjusting the pitch subsequently in the upper partial load range. The noise output level increases minimally by increasing the angles of attack.

[0172] In order to be able to continue to maintain the reserves in the angles of attack and loads, the reserve is set for each blade via an IPC (AEP neutral) or an adjustment is made in the pitch at an earlier point in the upper partial load range (AEP-reducing).

[0173] As a load reduction measure, the rotational speed can likewise be reduced (3rd inverse).

Shear Increases/is Greater than Design Shear (for Example 0.15) and AEP Increases (Range 430 in FIG. 4)

[0174] If the shear increases in relation to the design point, the installation experiences further increasing amplitudes in the alternating loads and in the angles of attack. The noise output level increases minimally by increasing the angles of attack.

[0175] Since the AEP increases, this clearance can be used in order to maintain the load limits by reducing the rotational speed. Alternatively, loads can be reduced and angle of attack limits maintained by adjusting the pitch at an earlier point in the upper partial load range (2nd inverse).

[0176] IPC is also suitable for adjusting the angle of attack limits during the revolution of the blade and for reducing the load in particular in the upper rotor disc half.

Influence on a Wind Power Installation 100 by Changed Turbulence (Lower Here); Background Information

[0177] FIG. 6 shows, schematically and by way of example, the relationships of noise output level 610, load level 620 and power 630 in a triaxial diagram 600 analogously to the illustration in FIG. 3 with decreasing turbulence. [0178] If, at a location, the turbulence is lower than for the design case (second innermost state 602), the installation has greater angle of attack reserves and load reserves than necessary, and additional slight acoustic reserves (innermost state 604) because of the decreasing inflow noise portion. [0179] The reserves which have arisen in the angles of attack can be used in order to slightly reduce the tip-speed-ratio in the partial load range and to slightly reduce the α.sub.min, which leads to an improved power (1). At the same time, the reserves in the angles of attack and the loads can be used in order to carry out an adjustment in the pitch at a later point in the high partial load range and thus also to increase the power (2). The greater angles of attack and the thicker boundary layer mean that acoustically slightly higher levels are anticipated which are intended to approximately compensate for the small reserves which have arisen (state 606). Acoustically, the state 606 is identical to the design case. [0180] If the obtained load reserves are intended to be suitable for permitting a slight increase in the maximum rotational speed, in addition to (1) and instead of (2) a rotational speed increase (3) can be implemented (state 608). This measure leads to a greater increase in power than (2), but at the same time also leads to an increase in the noise output level beyond the design case and is therefore possible only for locations without restrictive noise regulation requirements.
Influence on a Wind Power Installation 100 by Changed (Lower Here) Temperature (with the Density Remaining the Same); Background Information

[0181] It is firstly assumed here that only the temperature decreases below the design temperature, but the density remains at the design value (the assumption would be relevant, for example, to a geodetically slightly raised location in the foothills of the Alps). If the temperature at a location is shown to be lower than the design temperature, thermal reserves are produced in the electrical section.

[0182] These could be increased by the nominal power being raised (4) (either as a temporary increase in power or as a permanent nominal power increase).

[0183] Depending on whether there is or there is not a noise boundary condition, the load increase associated therewith can be picked up differently: if the location is noise-critical, the rotational speed has to remain identical, and there remains only the option of increasing the torque in order to arrive at the higher nominal power. This leads to increased average values in the Mx.

[0184] If there are no restrictive noise regulation requirements, as an alternative the torque can be kept constant and the rotation speed slightly increased (3). As a result, the Mx average values remain identical to the design case. While the gradient of the pitch characteristic is maintained as far as the new nominal power, the average values for My and thrust also remain constant. However, the increase in the rotational speed leads to a slight increase in the number of load cycles/collectives for Mx, My and thrust.

Shear Decreases, Turbulence Intensity Increases

[0185] The influence of shear on the yield is non-linear, but in terms of direction/tendency is identical for the entire power range.

[0186] By contrast, turbulence intensity leads to more yield in the partial load range, but to a lesser yield in the range about nominal power.

[0187] Increasing shear and increasing turbulence intensity both lead to increased alternating loads and both lead to an increased SPL, and, in association therewith, both also lead to lower angle of attack reserves.

[0188] Shear and turbulence intensity are generally connected, for example low turbulence intensity and high shear at night (stable layering of the atmosphere), and in the day (days of insolation/sun, high thermals), the turbulence intensity is high, but the shear low.

[0189] Higher turbulence intensity leads to increased loads and lower yield of nominal power. In addition, angle of attack reserves are reduced. [0190] Turbulence intensity leads to increased angles of attack in particular in the blade inner region as far as the blade central region. [0191] Low shear can “protect” angle of attack reserves in the blade outer region and counteract the increase in load.

[0192] In order to compensate for increased turbulence intensity of nominal power, the influence of turbulence intensity and shear can be “calculated,” both for the loads and for the angle of attack reserve, wherein the angle of attack reserves are relevant primarily in the blade outer region.

[0193] If sufficient reserves remain, the pitch can be adjusted more aggressively in the range around nominal power (2) and/or the nominal power can, however, be increased briefly in order to compensate for the gustiness of the wind (4).

[0194] In the partial load range (low wind speed), the wind power installation 100 typically profits from the increased turbulence intensity, and load-increasing measures do not have to be taken in order to increase the power. However, when there is a corresponding reserve—after calculating using the pitch—a reduction of α.sub.min and/or of the tip-speed-ratio is possible (1).

Shear Increases, Turbulence Intensity Decreases

[0195] High shear leads to lower angle of attack reserves and increased alternating loads. At the same time, low turbulence intensity leads to lower loads. Angle of attack reserves and load effects can be calculated in relation to one another.

[0196] Low turbulence intensity means less yield in particular in the partial load range.

[0197] At the same time, if there should still be somewhat more angle of attack reserve in the partial load range, a reduction in the minimum pitch angles and a reduction in the tip-speed-ratio (1) will be taken into consideration if there is still potential for optimization.

[0198] In the nominal power range, the low turbulence intensity has a positive effect, if there are still load and angle of attack reserves, because of the low gustiness, these can readily be increased by a more aggressive adjustment of the pitch (2).

Density and Turbulence Intensity Increase

[0199] If the density and turbulence intensity increase at a location, the AEP, the loads and the noise output level are increased. The latter is caused by the increased inflow noise. In addition, the noise transport through the air is improved, and therefore an increased noise output level is measured at the emission point. However, the angles of attack decrease because of the increased density.

[0200] The margin which has arisen in the AEP can be used to reduce the loads by slower rotation (3rd inverse). This also has the consequence of reducing noise. The effect of the increased density (decreasing angles of attach) and of the increasing turbulence intensity (increasing angles of attack) can be compensated for by greater/weaker adjustment of the pitch (2/2nd inverse), depending on which effect dominates. At the same time, possibly in the partial load range, the angle of attack reserve has to be increased by an increase in the tip-speed-ratio and in the α.sub.min (inverse 1).

Density Increases and Turbulence Intensity Decreases

[0201] If the density increases as the turbulence intensity decreases, the effects for loads and noise are compensated. By means of the increasing density, the loads (average values) increase while the decreasing turbulence intensity has a load-reducing effect (collectives). The same trend is apparent in the noise output level. By means of the lower turbulence intensity, the inflow noise decreases, while the higher density reduces the angles of attack and therefore leads to a lower trailing edge noise. By contrast, the increased noise speed leads to an increased noise output level at the emission point.

[0202] Both when the density is increased and the turbulence intensity is reduced, the angle of attack limits increase. This effect can be used, taking into consideration the load reserves obtained in the collectives, for greater adjustment of the pitch (2) and AEP increases which are associated therewith.

[0203] A reduction in the rotational speed (3rd inverse) can also compensate for the increased loads (average values).

Density Decreases and Turbulence Intensity Increases

[0204] The behavior is inverse to that described in the point “density increases and turbulence intensity decreases.”

[0205] A possible appropriate reaction is adjustment of the pitch at an earlier point (2nd inverse) paired with an increase in the rotational speed (3) in order to take into consideration the decreased angle of attack limits.

Density and Turbulence Intensity Decrease

[0206] The behavior is inverse to “density and turbulence intensity increase.”

[0207] Accordingly, a combination of increase in rotational speed (3) and more aggressive pitch control (2) and a reduction in the angle of attack reserve in the partial load range through (1) is appropriate.

Temperature is Lower and Density is Higher:

[0208] This assumption corresponds to an installation with a great geodetic height on a cool day.

[0209] It follows from the low temperature that there are thermal reserves. It follows from the low density that there are load reserves and also slight noise reserves.

[0210] If noise is critical: It is then appropriate here to increase the nominal power as far as possible (4) and at the same time to increase the rotational speed (3) to such an extent that the noise reserves are exhausted. If further load and angle of attack reserves should be present, these can be realized by a reduction in the pitch (2).

[0211] If noise is non-critical: At a low density, it is highly effective to increase the rotational speed. In this case, in addition to the increase in the nominal power (4), the rotational speed is now intended to be increased if at all possible (3 times greater) and all load reserves are used for this purpose.

[0212] The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.