PROCEDURE FOR OPERATING A WIND POWER PLANT

Abstract

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

Description

[0001] The present disclosure relates to a method for operating a wind turbine, an associated wind turbine and a wind farm.

[0002] It is known to perform yield calculations for wind turbines using site-specific parameters. However, it has been found that the subsequently determined yields deviate due to the actual site conditions.

[0003] Against this background, one objective of this disclosure was to compensate for potential performance losses due to site conditions through operational management and to improve the individual operational management of the wind turbine depending on the location. Adapting operational management to sites with extreme environmental or wind conditions must simultaneously ensure compliance with load and sound power levels in order to enable optimal settings even for more complex sites.

[0004] The following terms and common abbreviations are assumed to be familiar for the description below. AEP: Annual Energy Production; Annual energy yield α min / Minimum blade angle: This corresponds to the blade angle, i.e., the angle of incidence of a rotor blade, at which the wind turbine is operated at a minimum in a partial load range. Increases in the blade angle are possible, for example, due to load, power, and / or noise requirements. Operating characteristic curve: Relationship between rotational speed n of the rotor and generated electrical power P el, to which the wind turbine regulates during operation. Operating point: Discrete point on the operating characteristic curve and a defined pitch angle of the rotor blades, which is reached at a wind speed. C p : Power coefficient of the wind turbine, which indicates how much power the wind turbine can harvest in relation to the available wind power. C t :Thrust coefficient of the wind turbine, which indicates how much thrust (force perpendicular to the rotor plane) the wind turbine generates in relation to a closed circular area. λ / TSR: Tip speed ratio. This is the ratio of the speed of the rotor blade at the tip to the wind speed. Load reserve: Difference between the instantaneous load or the stationary load conditions and the design load case. Power reserve: Difference between electrical power and possible electrical power. Sound level reserve: Difference between the generated sound level and the permissible sound level. M x : Blade moment in the direction of rotation M y : Leaf moment in the direction of travel IPC: Individual Pitch Control, individual blade angle control, the pitch angles of the individual rotor blades can be controlled independently of each other - in addition to a collective control.

[0005] In one aspect of the present disclosure, a method for operating a wind energy plant is proposed, the method comprising the following steps: Determine at least two, preferably at least three, and particularly preferably all, of the environmental parameters of the environment of the wind turbine selected from the list consisting of: turbulence intensity, air density, air temperature, shear, and precipitation; provide boundary conditions for operating the wind turbine, the boundary conditions comprising at least one load boundary condition, one sound level boundary condition, and one power boundary condition; adapt an operating mode, in particular an operating point and / or an operating characteristic curve, of the wind turbine based on a combination of changes in the determined environmental parameters, taking into account the boundary conditions.

[0006] The environmental parameters can be determined in advance, i.e., before commissioning or even before the wind turbine is erected. Preferably, the environmental parameters are determined alternatively or additionally during the operation of the wind turbine. Suitable sensors are preferably provided on or in the vicinity of the wind turbine for determining the environmental parameters. The type and design of the sensors for determining the environmental parameters are not restricted, as long as they are suitable for determining one or more of the environmental parameters: turbulence intensity, air density, air temperature, shear, and precipitation.

[0007] The load boundary condition can, for example, be a permissible load according to the design case. The sound level boundary condition can, for example, include a permissible sound level. The power boundary condition can, for example, include a possible electrical power and / or a maximum grid-side power, whereby other boundary conditions indicative of the power, such as torque limits, etc., are also conceivable.

[0008] Preferably, an additional environmental parameter based on wind speed is provided. This can be, for example, the wind speed itself, a wind direction, but especially also a mean annual wind speed relevant for considering the loads, or a distribution of wind speeds and / or directions.

[0009] The operating characteristic curve is preferably the speed-power curve commonly used in wind turbines, which specifies a power output (more precisely: an indicative value for the power output) for various rotor speeds n, such as the electrical power Pel, the air gap power to be provided by the rotor, or a torque at the generator. Other characteristic curves can also be understood as operating characteristics within the meaning of the disclosure; for example, a characteristic curve designated as a pitch curve, which specifies the pitch angle of the rotor blades for a certain wind speed and / or electrical power and / or air gap power, is conceivable. Other characteristic curves are also conceivable as operating characteristics.

[0010] According to this perspective, increasing the maximum possible output by individually adjusting the operating characteristic curve or the operating point, e.g., the pitch settings, can contribute to increasing the annual energy yield. In particular, boundary conditions such as load and noise level conditions can be exploited to utilize reserves compared to the design operating loads by individually adjusting the operating characteristic curve and pitch settings to optimize the annual energy yield.

[0011] Preferably, adjusting the operating point includes the following steps: Providing the current operating point of the wind turbine, determining one adjustment to the operation of the wind turbine based on a change in one of the defined environmental parameters and the current operating point, and adjusting the operation of the wind turbine based on a combination of the defined adjustments, taking into account the boundary conditions.

[0012] According to this explanation, an individual adjustment of the operational management is determined based on an individual change in one of the environmental parameters.

[0013] These adjustments can – depending on the case – reinforce each other or even contradict each other. The final adjustment then only occurs after combining the specific individual adjustments, taking the boundary conditions into account. This allows for optimal adaptation of the operational management even when multiple environmental parameters are changing.

[0014] For example, the adjustment for a change to one of the specified environmental parameters can be selected from a list of possible adjustments. Preferably, the selection from the list of possible adjustments is made by considering all changes to the environmental parameters. In other words, one or more adjustment candidates can be selected from the list of possible adjustments for each environmental parameter, and the final adjustment can be chosen from the one or more selected candidates, taking all the specified environmental parameters into account. In this case, an optimal selection of the appropriate measure or adjustment for the combination of environmental parameters is possible without requiring an unnecessary restriction to a specific adjustment for the individual environmental parameters.

[0015] Preferably, the environmental parameters are determined repeatedly, in particular periodically and especially preferably continuously during the operation of the wind turbine.

[0016] The environmental parameter(s) are determined, for example, by means of measurement. Alternatively or additionally, the environmental parameters are calculated and / or approximated.

[0017] Accordingly, adjustments to operational management are particularly preferred to be made on a recurring basis, especially periodically or continuously.

[0018] Preferably, the adjustment of the operating point and / or the operating characteristic curve includes at least one of the following measures, if the consideration of the load boundary condition, a sound level boundary condition and a power boundary condition provides at least one load reserve, one sound level reserve or one power reserve: Adjustment, in particular lowering, of a minimum blade angle and adjustment, in particular lowering, of the tip speed ratio to reduce the distance of the operating point to the operating point with optimal power coefficient, shifting or changing a characteristic curve for controlling the pitch angles of the rotor blades, called pitch characteristic curve, towards higher pitch angles for at least part of the operating range, increasing a rotor speed of the wind turbine, raising a rated power of the wind turbine.

[0019] Preferably, the adaptation includes at least two of the aforementioned measures; more preferably, the adaptation includes at least three and, in particular, all of the aforementioned measures.

[0020] Preferably, determining the environmental parameters includes determining the air density, wherein a reduction in air density leads to an increase in a load reserve and a sound level reserve, and consequently, to adapt the operating control, a rotor speed is adjusted, in particular increased, to compensate for a change in the speed ratio by utilizing the sound level reserve, and / or an operating characteristic and / or a pitch characteristic is adjusted by utilizing the load reserve.

[0021] This adjustment can at least partially compensate for a reduction in power output caused by lower density and the associated lower air mass flow. Depending on the wind turbine, a change in the speed-power characteristic curve, either completely or only in a partial load range (i.e., a range below rated or full power), with or without adjusting the pitch control, may be optimal. This depends primarily on the load balance of the wind turbine as well as other environmental parameters, such as turbulence intensity.

[0022] Preferably, determining the environmental parameter of shear comprises determining a shear coefficient, wherein the shear coefficient is indicative of a change in the vertical direction of a wind speed over a rotor plane of a rotor of the wind turbine, a reduction of the shear coefficient corresponds to a more uniform flow with relatively lower alternating loads, the shear coefficient is compared with a predetermined shear threshold, the predetermined shear threshold corresponds to the shear coefficient with a minimum power output, and the adjustment of the operating point is carried out depending on a change in the shear coefficient and the comparison of the shear coefficient with the predetermined shear threshold.

[0023] To determine the shear threshold, for example, the wind speed is measured at at least two different heights z and a shear coefficient α is derived or fitted from the difference according to the logarithmic and / or potential law, for example according to IEC 61400-1: u z = u z 0 z z 0 α

[0024] Alternative methods for determining the shear threshold, for example based on acoustic measurements, especially according to IEC 61400-11, are also conceivable.

[0025] For example, α = 0.5 can be set as the upper limit or as the annual average, although higher values ​​are possible for shorter periods. It is also possible to have multiple shear thresholds for short-term, medium-term, and / or long-term smoothing, allowing for particularly precise alignment with the prevailing shear forces. In other cases, locations with negative shear coefficients α are also possible.

[0026] Different shear coefficients can be set, for example, on a daily, weekly, or monthly basis, depending on requirements, without being limited to this.

[0027] A design shear coefficient of preferably between 0.15 and 0.2 is used, which has proven suitable for a typical German coastal location. Preferably, the design shear coefficient is chosen at which the annual energy yield reaches a minimum. In other words, in both cases, yield increases can be achieved if the shear deviates from the design shear coefficient, provided that the other boundary conditions allow for appropriate control of the wind turbine.

[0028] Preferably, the shear coefficients are determined in advance, i.e., before the wind turbine is erected, using measuring masts that conduct wind measurements at the turbine site. For this purpose, the wind speed is preferably determined at at least two heights, and particularly preferably at more than two heights. A different determination method, for example during operation, is also possible.

[0029] Preferably, a power reduction range is defined as a range of values ​​of the shear coefficient for which a reduced speed in the lower half of the rotor disk cannot be compensated for by an increased speed in the upper half of the rotor disk, and thus a power reduction occurs, wherein a shear coefficient at a lower end of the power reduction range is defined as the design shear coefficient, and wherein the adjustment of the operating point depends on a change in the shear coefficient and the comparison of the shear coefficient with the design shear coefficient.

[0030] In contrast to the previously described preferred embodiment, the design shear coefficient, rather than the minimum power output, is used here as the evaluation criterion for adjusting the operating point according to the invention. In this case, the design shear coefficient is defined as lying at the lower end of the power reduction range.

[0031] Preferably, in the event that a reduction in the shear coefficient occurs in the range below the design shear coefficient, the operating point is adjusted in such a way that the additional load and / or angle of attack reserves for increasing the annual energy yield result in an increase in rotational speed and / or a more aggressive pitch profile, especially in the case of individual pitch control (IPC) of individual rotor blades.

[0032] Here, the terms pitch curve and pitch characteristic curve are used synonymously.

[0033] Preferably, in the event that an increase in the shear coefficient occurs in the range above the design shear coefficient but within the power reduction range, the operating point is adjusted such that at least one of the following adjustments is made to maintain the necessary load and / or angle of attack reserves: a) individual adjustment of the individual rotor blades to reduce the loads, especially in the upper half of the rotor disk, b) earlier pitching in the upper partial load range to reduce the loads, and c) reduction of the rotational speed to comply with the load limits.

[0034] Preferably, in the event of an increase in the shear coefficient in the range above the design shear coefficient and outside the power reduction range, the operating point is adjusted such that at least one of the following adjustments is made to maintain the necessary load and / or angle of attack reserves: a) individual adjustment of the individual rotor blades without loss of annual energy yield, b) earlier pitching in the upper partial load range and c) reduction of the rotational speed to reduce the loads.

[0035] The different preferred configurations regarding the shear coefficient thus enable a concrete response to all possible changes in environmental parameters in order to achieve optimized control of the wind turbine.

[0036] Preferably, determining the environmental parameters includes determining the turbulence intensity, wherein a reduction in turbulence intensity results in an increase in angle of attack reserve and an increase in load reserve, and wherein, upon detecting a reduction in turbulence intensity, adjusting the operational control includes ensuring that a) a speed ratio and / or a minimum blade angle in the partial load range is reduced to increase power output, and b) the pitch characteristic curve in the upper partial load range is shifted towards higher power outputs to compensate for the resulting load and angle-of-attack reserves, or c) in addition to a) and alternatively to b), a rotor speed of the wind turbine is increased taking into account the noise level boundary condition.

[0037] This design therefore enables the control system of the wind turbine to react optimally to changes in turbulence intensity.

[0038] Preferably, determining the environmental parameters includes determining the temperature and air density, wherein a reduction in temperature at constant density leads to thermal reserves in an electrical string of the wind turbine, wherein, upon detection of a thermal reserve, adjusting the operating mode includes increasing the power output, either as a temporary power increase or as a permanent rated power increase, wherein the power increase depends on the sound level boundary condition. a) increasing the rotational speed of the rotor with an existing noise level reserve and / or b) increasing the torque without an existing noise level reserve.

[0039] This explanation therefore reveals how optimal control of the wind turbine is achieved for a changing temperature at the same air density.

[0040] Preferably, determining the environmental parameters includes determining the shear and turbulence intensity, taking into account the influence of shear and turbulence intensity on the load and angle-of-attack reserves, and adapting the operational management depending on the load and angle-of-attack reserves includes at least one of the following measures. a) Adjusting the pitch curve, especially in the partial load range with available load and angle-of-attack reserves, by reducing the minimum blade angle and / or the tip speed ratio; and b) Short-term increase of the rated power to compensate for the gustiness of the wind.

[0041] This explanation therefore reveals how optimal control of the wind turbine is achieved for a combination of the parameters shear and turbulence intensity.

[0042] In one embodiment, the minimum blade angle is a blade angle that is fixed to the same value for all blades and remains constant throughout the entire rotor revolution. In a preferred embodiment, a minimum blade angle is defined individually for each rotor blade. Alternatively or additionally, in a particularly preferred embodiment, a minimum blade angle is defined as a function of the blade's angular position. For example, a sinusoidal or other variation around a specific blade angle with the period of one rotor revolution can be defined.

[0043] Preferably, determining the environmental parameters includes determining the air density and the turbulence intensity, wherein, in the case that both the air density and the turbulence intensity increase, a higher annual energy yield, higher loads and a higher sound power level follow, wherein in this case, adjusting the operating management includes at least one of the following measures. a) Modifying the pitch curve by balancing the decreasing angles of attack due to increased air density and the increasing angles of attack due to increased turbulence intensity; b) Reducing the rotational speed to reduce loads and sound power levels; and c) Increasing an angle-of-attack reserve in the partial load range by increasing the tip speed ratio and / or the minimum blade angle.

[0044] Preferably, in the case that both the air density and the turbulence intensity decrease, at least one, at least both and especially preferably all, of the measures a), b) and c) are inverted to adjust the operational management.

[0045] In this version and the two versions described below, the control for all possible combinations of the environmental parameters density and turbulence intensity is described.

[0046] Preferably, determining the environmental parameters includes determining the air density and the turbulence intensity, wherein, in the case that the air density increases and the turbulence intensity decreases, the effects on loads and noise are compensated, wherein in this case the adjustment of the operating conditions due to the increased angle-of-attack limits includes at least one of the following measures. a) Changing the pitch curve to increase the annual energy yield; b) Reducing the rotational speed to compensate for increased loads, especially average load values.

[0047] Preferably, determining the environmental parameters includes determining the air density and the turbulence intensity, wherein, in the case that the air density decreases and the turbulence intensity increases, the effects on loads and noise are compensated for, wherein in this case, adjusting the operating parameters to compensate for the reduced angle-of-attack limits includes at least one of the following measures. a) Change in the pitch characteristic curve by earlier pitching; b) Increasing the rotational speed.

[0048] In one embodiment, determining the environmental parameters includes determining the air density and the temperature, whereby, in the case that the temperature decreases and the air density increases, depending in particular on the sound level boundary condition, the adjustment of the operating mode includes at least one of the following measures. a) Increasing the rated power while simultaneously reducing the speed to comply with the sound level boundary condition; if the sound level boundary condition is non-critical, reducing only until the load boundary condition is met; b) If necessary, increasing the pitch until the load boundary condition is met.

[0049] In this version, the control system is optimized for combined changes in air density and temperature. This allows thermal reserves from lower temperatures, lower load reserves, and lower noise reserves from higher densities to be combined.

[0050] In another aspect, a wind turbine with a control system is proposed, wherein the control system is designed to control the wind turbine according to a method as disclosed.

[0051] The wind turbine enables the same advantages to be achieved as described in connection with the method according to the disclosure. In particular, the control system of the wind turbine can be designed to implement one, several, or all of the embodiments described as preferred and achieve the associated optimized control.

[0052] Furthermore, a wind farm with several wind turbines is proposed in accordance with the disclosure.

[0053] The wind farm also enables the same advantages to be achieved as described in connection with the method according to the disclosure. In particular, the control of the multiple wind turbines of the wind farm can be designed to implement one, several, or all of the embodiments described as preferred and thus achieve the associated optimized control.

[0054] Further advantages and preferred configurations are described in detail below with reference to the attached figures. These show: Fig. 1 schematically and by way of example a wind turbine; Fig. 2 schematically and by way of example a wind farm; Fig. 3 schematically and by way of example relationships between sound power level, load level and power for different operating conditions; Fig. 4 schematically and by way of example relationships between annual energy yield and shear coefficient; Fig. 5 schematically and by way of example relationships between sound power level, load level and power for different operating conditions; and Fig. 6 schematically and by way of example relationships between sound power level, load level and power for different operating conditions.

[0055] Fig. 1Figure 1 shows a schematic representation of a wind turbine 100. 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 mounted on the nacelle 104. During operation of the wind turbine, the aerodynamic rotor 106 is set into rotation by the wind and thus also rotates an electrodynamic rotor or generator rotor, which is directly or indirectly coupled to the aerodynamic rotor 106. The electric generator is located 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.

[0056] The wind turbine 100 has an electric generator 101, which is indicated in the nacelle 104. Electrical power can be generated by means of the generator 101. A feed-in unit 105 is provided for feeding electrical power into the grid; this unit can be specifically designed as an inverter. This allows a three-phase feed-in current and / or a three-phase feed-in voltage with amplitude, frequency, and phase to be generated for feeding into a grid connection point (PCC). This can be done directly or in conjunction with other wind turbines in a wind farm. A plant control unit 103 is provided for controlling the wind turbine 100 and the feed-in unit 105. The plant control unit 103 can also receive setpoint values ​​from external sources, in particular from a central park computer.

[0057] Figure 2Figure 112 shows a wind farm with three exemplary wind turbines 100, which can be identical or different. The three wind turbines 100 thus represent, in principle, any number of wind turbines 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 120 at the feed-in point 118, which is also generally referred to as PCC. Fig. 2 This is only a simplified representation of a wind farm 112. For example, the park network 114 can be designed differently, for instance by including a transformer at the output of each wind turbine 100, to name just one other embodiment.

[0058] Wind farm 112 also has a central park computer 122, which can also be referred to as a central park control unit. This can be connected to the wind turbines 100 via data lines 124 or wirelessly, in order to exchange data with the wind turbines and, in particular, to receive measured values ​​from the wind turbines 100 and to transmit control values ​​to the wind turbines 100.

[0059] Sites are becoming increasingly complex and individual in their requirements. Therefore, the call for a customized operating method that allows for adjusting the yield based on the guaranteed data sheet is growing louder. However, the guaranteed data sheet is calculated using standardized ideal values ​​that represent a statistical average of the wind field and environmental conditions.

[0060] Individual operating modes propose adapting the operating modes to the actual parameters present at the site, derived from environmental conditions such as wind field, climate, blade deformation, and turbine position. The turbine's rotational speed (both the speed profile and the rated and set speeds), pitch angle, and rated power can be modified to achieve maximum yield. This disclosure proposes a method for optimally adjusting these adjustable parameters to changing environmental conditions and thus maximizing turbine yield.

[0061] The boundary conditions, including maximum sound power level, maximum loads, controller stability, and generator characteristics, must be adhered to. It should be noted that certain behaviors are amplified non-linearly.

[0062] For example, lower turbulence intensity already leads to a reduced sound power level. In this case, the reduced tendency for flow separation at the blade also reduces trailing edge noise. Since loads also decrease at locations with lower turbulence, the resulting margin can be invested, according to the present disclosure, in an increased maximum rotational speed, leading to higher yields while simultaneously complying with the design loads and the noise guarantee.

[0063] With increased blade stiffness due to higher centrifugal forces following a speed increase, the elastic deformation of the blade decreases. This reduces the local angles of attack, which in turn allows for a reduction in pitch angles while maintaining the available angle-of-attack reserves.

[0064] As a first step, an individual operating control can be designed as a discrete operating characteristic curve. This is optimally tailored to the average wind conditions at the site. It remains active throughout the entire lifespan of the system.

[0065] In the second step, a multidimensional parameter space is fed into the system's control system. The system's sensors continuously measure the wind field, ambient conditions, the system's status, and, if necessary, sound at a defined point of impact.

[0066] The control technology implemented in the plant control unit 103 preferably determines a valid parameter set of rotational speed and blade angle setting independently and in real time, based on the recorded values, in order to achieve maximum performance while adhering to any noise levels. The boundary conditions, including sound power level, loads, controller stability, component natural frequency ranges (e.g., speed windows), and generator characteristics, must be observed.

[0067] For example, increased performance is necessary when turbulence intensity, density, shear, or a more asymmetrical wind distribution prevails (Weibull factor < 2). This leads, respectively, to lower power extraction from the wind, a lower sound power level, reduced sound propagation, lower alternating loads, less deformation, and a greater margin to the angle-of-attack reserves compared to blade separation. Therefore, the rotational speed can be increased and / or the angle-of-attack reserves reduced by decreasing the pitch. As a result, the maximum possible energy yield can be achieved.

[0068] In another example, load reduction is possible in cases where increased turbulence intensity, increased density, increased shear, or a highly symmetrical wind distribution (Weibull factor > 2) is present or determined. This results in, respectively, greater power extraction from the wind, an increased sound power level, stronger sound propagation, increased alternating loads, increased deformation loads, and a smaller margin to the angle-of-attack reserves compared to blade separation. As a response, a reduction in rotational speed or an increase in the angle-of-attack reserves through a lower pitch is indicated. This maintains the guaranteed yield, reduces the sound power level, and decreases the alternating loads to comply with maintenance intervals and service life calculations.

[0069] The site-specific parameters, also referred to as environmental conditions, can be categorized as follows.

[0070] The wind field is determined from the averaged and extreme values ​​for one or more, in particular also all, from a) Turbulence intensity b) Shear c) Rotation of wind speed over height (Veer) d) Wind direction (Yaw) e) Wind frequency, shape of the Weibull distribution f) Flow inclination of the rotor surface

[0071] The climate can be determined from one or more, in particular all, of the values. a) Density b) Temperature c) Humidity d) Precipitation frequency.

[0072] The plant position describes the position in the wind farm 102, i.e. relative to other wind turbines 100, as well as in the terrain, i.e. relative to orographic features (mountains, valleys, forests).

[0073] The condition of the system is described by one or more, in particular all, of the parameters. a) Angle of attack on the blade b) the instantaneous load conditions on the blade c) the accelerations to avoid dangerous vibrations from the various components.

[0074] Possible measures to respond to changing environmental parameters include one, several, or all of the following adjustments to the operating point or operational management: (1) Operate the system closer to the cp optimum by lowering the minimum blade angle amins and the tip speed ratio λ. (2) Pitch later, i.e., increase the blade angle at higher wind speeds and / or higher power. (3) Increase the rotor speed. (4) Increase the rated power.

[0075] If environmental parameters change in the opposite direction, a corresponding adjustment of the operating point is indicated.

[0076] In this context and throughout the entire application, "power" preferably refers to the generated electrical power or another measure of the power output of the wind turbine. For example, the air gap power or the torque of the generator is also suitable as an indicative value for power.

[0077] The exact effects of changing environmental parameters are evaluated below for the individual environmental parameters as well as combinations of environmental parameters. Impact of changed density on a wind turbine 100; background information

[0078] Electrical power is calculated using P = ρη el c p π r 2 v inv 3 and is therefore linear to the density p. However, a lower density means that the wind turbine 100 requires more wind for the same electrical power P, which would lead to a change in λ (TSR, tip speed ratio). The wind turbine 100 can counteract this, but only in the partial load range, since increasing the rotational speed or TSR at the rated operating point leads to an increased sound power level. If the TSR cannot be adjusted in the range below rated power, this results in a less aerodynamically efficient Cp or operating point for the wind turbine 100. The exact AEP loss depends on the airfoil series, blade design, and any add-on components such as vortex generators, serrations, and flaps, as well as any additional modifications to the pitch control, and can only be precisely quantified for each individual wind turbine 100. Furthermore, it cannot be considered completely independently of turbulence intensity and shear.If the density falls below the design density, yield losses are to be expected initially, and the rated power output will also be reached later (see above). At the same time, however, loads and noise also decrease, and there is already a known approximate relationship for noise. The reduction in noise implies that, in principle, the entire operating characteristic curve can be scaled with the density (cube root of the density), including the rated rotational speed of the wind turbine at 100 rpm. Simultaneously, the reduction in density also results in a reduction in loads, particularly for the mean values ​​of the blade loads (µ) and the turbine thrust or the Ct coefficient. This provides scope for a more "aggressive" operating mode, at least for certain turbine components (e.g., tower, impact moment, azimuth, pitch). This can be achieved, for example, by adjusting the operating characteristic curve and / or the pitch characteristic curve. For instance, there might be room to reduce the angle-of-attack reserve.Increased rotation speed: Due to the lower density, the maximum SPL remains below the SPL at design density. Additional load reserves of some components are again consumed. Extreme loads are typically unaffected. However, some loads (e.g., impact torque) are increased. Additionally, erosion of the blade leading edge can be a problem. However, erosion is also site-dependent (rain frequency). If a rain sensor is present, an increased target rotation speed could be avoided during rain to prevent excessive erosion. As a result, the AEP losses, which are virtually unavoidable due to the lower density, are minimized under largely identical loads and still compliant sound power levels. The faster rotation speed (e.g., at least in the partial load range) maintains angle-of-attack reserves.If a system has sufficient pitch angle reserves under standard settings, these can be used up by a slightly more aggressive pitch control. Load reserves would then be used up by a combination of a modified operating characteristic and pitch characteristic. However, this would lead to an increase in extreme loads, and possibly also in vibration amplitudes in the direction of the stroke. Depending on the system, a change in the speed-power characteristic (completely or only in the partial load range) with / without adjusting the pitch control may be optimal, depending on the load balance of the wind turbine and possibly other site parameters such as turbulence intensity.

[0079] Fig. 3 The diagram schematically and exemplarily shows the relationships between sound power level 310, load level 320 and power 330 in a three-axis diagram 300. The load level 320 essentially corresponds to the inverse of the expected service life.

[0080] For standard air density, i.e., the design case, state 302 is expected. Under the permissible conditions, this offers a maximum power output of 330 for a sound power level of 310 and a load level of 320. If the operating conditions remain unchanged, state 304 is reached for a reduced air density compared to standard air density. It can be seen that with a lower sound power level of 310 and a lower load level of 320, a lower power output of 330 is also achieved.

[0081] By adjusting the operating parameters according to the present disclosure, state 306 is achieved. The adjustments for state 306 include, in particular, a sharper pitch control to reduce the angle-of-attack reserves and a slight increase in rotational speed. State 306, like design state 302, meets the requirements for the sound power level 310 and results in a power gain 330 compared to the unchanged operating parameters in state 304.

[0082] State 306 still offers reserves in the load range, so a further increase in power 330 is achieved by state 308 by further adjusting the operating parameters according to the present disclosure. For state 308, the rotational speed was significantly increased compared to the design case in order to fully utilize the load reserves. Influence of different shear values ​​on a wind turbine 100; background information

[0083] The shear coefficient describes how much the wind speed changes over the height of the rotor disc.

[0084] Fig. 4 Diagram 400 schematically and exemplarily shows the course of the annual energy yield AEP relative to a reference energy yield AEPref on the vertical axis over values ​​of the shear coefficient on the horizontal axis: Low shear coefficients mean uniform airflow with relatively low alternating loads from the wind field. As the shear coefficient increases, differences in airflow velocity across the rotor area increase, and thus the amplitude of the load changes from the wind field and the angle of attack along the rotor blade also increase. In certain shear coefficient ranges, a reduced velocity in the lower half of the rotor disc cannot be compensated for by an increased velocity in the upper half, leading to a reduction in power output. → Power reduction; In the example of the Fig. 4This corresponds to a shear coefficient range of 0.15–0.38 (range 420). Above and below range 420, the reduced speed in the lower half of the rotor disk is more than compensated for by the increased speed in the upper half, resulting in a power increase. This applies to range 410 with a shear coefficient < 0.15 and range 430 with a shear coefficient > 0.38. Shear decreases / is lower than design shear (e.g. 0.15) and AEP increases (range 420 in Fig. 4)

[0085] Fig. 5 schematically and exemplarily shows the relationships between sound power level 510, load level 520 and power 530 in a three-axis diagram 500 analogous to the representation in Fig. 3 in the case of decreasing shear or shear below the design shear. If the wind shear at a given location is lower than in the design case (second innermost case, state 502), the wind turbine experiences 100 times lower amplitudes in the alternating loads and smaller fluctuations in the angles of attack (innermost case, state 504). Changes in sound power levels are only indirectly related to altered angles of attack along the blade and are negligible. The resulting load and angle-of-attack reserves for further increasing the AEP can be utilized by a more aggressive pitch profile (2) (state 506). If the location is free of noise restrictions, the resulting load reserves can be further increased by an additional increase in rotational speed (3) (state 508). In any case, IPC control can be used to optimally utilize the angle-of-attack reserves. Shear increases / is greater than design shear (e.g. 0.15) and AEP decreases (range 420 in Fig. 4)

[0086] If the shear increases relative to the design point and the AEP decreases simultaneously, the wind turbine experiences 100% increasing amplitudes in the alternating loads and angles of attack, which cannot be compensated for by increasing the rotational speed and later pitching in the upper part-load range. Increasing the angle of attack results in a minimal increase in the sound power level. To maintain the reserves in the angles of attack and loads, the reserve for each blade is set via an IPC (AEP-neutral) or the pitch is initiated earlier in the upper part-load range (AEP-reducing). The rotational speed can also be reduced as a load reduction measure (3 inverse). Shear increases / is greater than design shear (e.g. 0.15) and AEP increases (area 430 in Fig. 4)

[0087] If the shear increases relative to the design point, the system experiences further increasing amplitudes in the alternating loads and angles of attack. Due to the increased angles of attack, the sound power level rises slightly. Since the AEP (Accelerated Elevation Power) increases, this margin can be used to comply with the load limits by reducing the rotational speed. Alternatively, loads can be reduced and angle-of-attack limits complied with by earlier pitch adjustment in the upper partial load range (2 inverse). IPC (Integrated Pitch Control) is also suitable for adjusting the angle-of-attack limits during blade rotation and for load reduction, particularly in the upper half of the rotor disk. Impact of altered turbulence on a wind turbine (lower here); background information

[0088] Fig. 6 schematically and exemplarily shows the relationships between sound power level 610, load level 620 and power 630 in a three-axis diagram 600 analogous to the representation in Fig. 3 as turbulence decreases. If the turbulence at a given location is lower than for the design case (second innermost state 602), the system has larger angle-of-attack and load reserves than necessary, as well as additional slight acoustic reserves due to the decreasing inflow noise component (innermost state 604). The resulting angle-of-attack reserves can be used to slightly reduce the tip speed ratio and the minimum α in the partial load range, leading to improved performance (1). Simultaneously, the angle-of-attack and load reserves can be used to delay pitching in the high partial load range, thus also increasing performance (2). Acoustically, slightly higher levels are expected due to the higher angles of attack and the thicker boundary layer, which should roughly compensate for the small reserves gained (state 606). Acoustically, state 606 is identical to the design case.Should the gained load reserves be sufficient to allow a slight increase in the maximum speed, a speed increase (3) can be implemented in addition to (1) and instead of (2) (state 608). This measure leads to a greater increase in power than (2), but also results in an increase in sound power levels beyond the design case and is therefore only possible for locations without restrictive noise regulations. Impact of a changed (here lower) temperature (with constant density) on a wind turbine 100; background information

[0089] First, it is assumed here that only the temperature falls below the design temperature, while the density remains at the design value (this assumption would apply, for example, to a slightly elevated geodetic location in the Alpine foothills). If the temperature at a location is lower than the design temperature, thermal reserves arise in the electrical circuit. These could be utilized by increasing the rated power (4) (either as a temporary power increase or as a permanent increase in rated power). Depending on whether a noise boundary condition exists or not, the associated load increase can be accommodated differently: If the location is noise-sensitive, the rotational speed must remain the same, and the only option is to increase the torque to achieve the higher rated power. This leads to increased mean values ​​in the Mx.If there are no restrictive noise regulations, the torque can alternatively be kept constant and the rotational speed slightly increased (3). This keeps the mean Mx values ​​identical to the design case. Furthermore, by maintaining the gradient of the pitch characteristic curve up to the new rated power, the mean values ​​for My and thrust also remain constant. However, the increase in rotational speed leads to a slight increase in the number of load cycles / collectives for Mx, My, and thrust. Shear decreases, turbulence intensity increases.

[0090] The influence of shear on yield is non-linear, but the direction / tendency is identical across the entire power range. Turbulence intensity, on the other hand, leads to higher yield at partial load, but lower yield around rated power. Increasing shear and increasing turbulence intensity both lead to increased alternating loads and both to increased SPL (sequence propagation power), which in turn both lead to lower angle-of-attack reserves. Shear and turbulence intensity are usually linked, e.g., at night (stable atmospheric stratification) low turbulence intensity and high shear, during the day (radiation / sunny days, strong thermals) high turbulence intensity but low shear. Higher turbulence intensity leads to increased loads and lower yield before rated power. It also reduces angle-of-attack reserves. Turbulence intensity leads to increased angles of attack, especially in the inner and middle sections of the blade.Low shear can conserve angle-of-attack reserves in the outer blade area and counteract the load increase. To compensate for increased turbulence intensity before rated power, the influence of turbulence intensity and shear can be factored in, both for the loads and the angle-of-attack reserve, with the angle-of-attack reserves being primarily relevant in the outer blade area. If sufficient reserves remain, more aggressive pitching can be applied in the range around rated power (2) and / or the rated power can be increased in the short term to compensate for wind gusts (4). In the partial load range (low wind speed), the 100-watt wind turbine typically benefits from the increased turbulence intensity; load-increasing measures do not need to be taken to increase power output. With sufficient reserves – after factoring in pitch – a reduction in α min and / or the tip speed ratio is possible (1). Shear increases, turbulence intensity decreases

[0091] High shear leads to lower angle-of-attack reserves and increased alternating loads. Simultaneously, low turbulence intensity results in lower loads. Angle-of-attack reserves and load effects can be offset against each other. Low turbulence intensity means less power output, especially in the partial load range. At the same time, a slightly larger angle-of-attack reserve should be available in the partial load range; lowering the minimum pitch angle and the top-up speed (1) will be considered if further optimization potential exists. In the range below rated power, the low turbulence intensity has a positive effect; if load and angle-of-attack reserves are still available, these can be effectively utilized by more aggressive pitch control (2) due to the low turbulence. Density and turbulence intensity increase

[0092] If the density and turbulence intensity increase at a location, the AEP (airspeed indicator), loads, and sound power level also increase. The latter is caused by the increased inflow noise. Additionally, sound transmission through the air improves, resulting in a higher sound power level being measured at the point of immission. However, the increased density reduces the angle of attack. The resulting margin in the AEP can be used to reduce loads by slowing down the rotation (3 inverse). This also results in a reduction in noise. The effect of the increased density (decreasing angles of attack) and the increasing turbulence intensity (increasing angles of attack) can be compensated for by increasing / decreasing the pitch (2 / 2 inverse), depending on which effect is dominant. Simultaneously, the angle of attack reserve may need to be increased in the partial-load range by increasing the tip speed ratio and the α min (inverse 1). Density increases and turbulence intensity decreases.

[0093] As density increases with decreasing turbulence intensity, the effects on loads and noise cancel each other out. The increasing density leads to higher loads (average values), while the decreasing turbulence intensity reduces loads (collectives). The same trend is reflected in the sound power level. Lower turbulence intensity reduces inflow noise, while higher density lowers the angle of attack, resulting in less trailing-edge noise. Conversely, the increased speed of sound leads to a higher sound power level at the point of immission. Both increased density and reduced turbulence intensity increase the angle-of-attack limits. This effect, taking into account the increased load reserves in the collectives, can be used to achieve sharper pitch control (2) and the associated AEP slopes. A reduction in rotational speed (3 inversely) can also compensate for the increased loads (average values). Density decreases and turbulence intensity increases.

[0094] This behavior is the inverse of that described under point "Density increases and turbulence intensity decreases". A possible response is earlier pitching (2 inverse), coupled with an increase in engine speed (3), to account for the reduced angle-of-attack limits. Density and turbulence intensity decrease

[0095] The behavior is the inverse of "density and turbulence intensity increase". Accordingly, a combination of increased engine speed (3) and more aggressive pitch control (2) and reduction of the angle of attack reserve in the partial load range by (1) is recommended. Temperature is lower and density is higher:

[0096] This assumption corresponds to a facility at a high geodetic altitude on a cool day. The low temperature implies the presence of thermal reserves. The low density implies the presence of load reserves and also slight noise reserves. The case of sound is critical.Here, it is advisable to increase the rated power as much as possible (4) and simultaneously increase the rotational speed (3) to the point where the noise reserves are fully utilized. If further load and angle-of-attack reserves are available, these can be achieved by reducing the pitch (2). The case of sound is not critical At low density, increasing the rotational speed is very effective. In this case, in addition to increasing the rated power (4), the rotational speed should be increased as much as possible (3 more), utilizing all available load reserves.

Claims

1. A method for operating a wind turbine, comprising the following steps: - Determining at least two, preferably at least three, and particularly preferably all, of the environmental parameters of the environment of the wind turbine selected from the list consisting of: turbulence intensity, air density, air temperature, shear, and precipitation; - Providing boundary conditions for operating the wind turbine, the boundary conditions comprising at least one of a load boundary condition, a sound level boundary condition, and a power boundary condition; - Adapting an operating mode, in particular an operating point and / or an operating characteristic curve, of the wind turbine based on a combination of changes in the determined environmental parameters, taking into account the boundary conditions.

2. The method of claim 1, wherein the adjustment of the operating point comprises the following steps: - providing the current operating point of the wind turbine, - determining one adjustment of the operation of the wind turbine based on a change in one of the determined environmental parameters and the current operating point, - adjusting the operation of the wind turbine based on a combination of the determined adjustments taking into account the boundary conditions.

3. Method according to one of the preceding claims, wherein the environmental parameters are determined repeatedly, in particular periodically and especially preferably continuously during the operation of the wind turbine.

4. A method according to any of the preceding claims, wherein the adjustment of the operating point and / or the operating characteristic curve comprises at least one of the following measures, where consideration of the load boundary condition, a sound level boundary condition and a power boundary condition specifies at least one load reserve, a sound level reserve or a power reserve: - Adjustment, in particular reduction, of a minimum blade angle and adjustment, in particular reduction, of the tip speed ratio to reduce the distance of the operating point to the operating point with optimal power coefficient, - Shifting or changing a characteristic curve for controlling the pitch angles of the rotor blades, called the pitch characteristic curve, towards higher pitch angles for at least part of the operating range, - Increasing a rotor speed of the wind turbine, - Increasing a rated power of the wind turbine.

5. Method according to one of the preceding claims, wherein determining the environmental parameters includes determining the air density, wherein a reduction in air density leads to an increase in a load reserve and a sound level reserve and, as a consequence, to adapt the operating management, a rotor speed is adjusted, in particular increased, to compensate for a change in the speed ratio by utilizing the sound level reserve, and / or an operating characteristic and / or a pitch characteristic is adjusted by utilizing the load reserve.

6. A method according to one of the preceding claims, wherein determining the environmental parameters of the shear comprises determining a shear coefficient, the shear coefficient being indicative of a change in the vertical direction of a wind speed over a rotor plane of a rotor of the wind turbine, a reduction of the shear coefficient corresponding to a more uniform flow with relatively lower alternating loads, the shear coefficient being compared with a predetermined shear threshold, the predetermined shear threshold corresponding to the shear coefficient with a minimum power output, and the adjustment of the operating point depending on a change in the shear coefficient and the comparison of the shear coefficient with the predetermined shear threshold.

7. Method according to claim 6, wherein a power reduction range is defined as a range of values ​​of the shear coefficient for which a reduced speed in the lower half of the rotor disk cannot be compensated for by an increased speed in the upper half of the rotor disk and thereby a power reduction occurs, wherein a shear coefficient at a lower end of the power reduction range is defined as the design shear coefficient, and wherein the adjustment of the operating point is dependent on a change in the shear coefficient and the comparison of the shear coefficient with the design shear coefficient.

8. Method according to claim 7, wherein, in the event that a reduction of the shear coefficient occurs in the range below the design shear coefficient, the operating point is adjusted such that the additional load and / or angle of attack reserves for increasing the annual energy yield result in an increase in rotational speed and / or a more aggressive pitch profile, particularly in the case of individual pitch control (IPC) of individual rotor blades.

9. Method according to claim 7 or 8, wherein, in the event that an increase in the shear coefficient occurs in the range above the design shear coefficient but within the power reduction range, the operating point is adjusted such that, in order to maintain the necessary load and / or angle of attack reserves, at least one of the following adjustments is made: a) individual adjustment of the individual rotor blades to reduce the loads, particularly in the upper half of the rotor disk, b) earlier pitching in the upper partial load range to reduce the loads, and c) reduction of the rotational speed to comply with the load limits.

10. Method according to one of claims 7 to 9, wherein, in the event of an increase in the shear coefficient in the range above the design shear coefficient and outside the power reduction range, the operating point is adjusted such that, in order to maintain the necessary load and / or angle of attack reserves, at least one of the following adjustments is made: a) individual adjustment of the individual rotor blades without loss of the annual energy yield, b) earlier pitching in the upper partial load range, and c) reduction of the rotational speed to reduce the loads.

11. A method according to one of the preceding claims, wherein determining the environmental parameters includes determining the turbulence intensity, wherein a reduction in turbulence intensity results in an increase in an angle of attack reserve and an increase in a load reserve, and wherein, upon detection of a reduction in turbulence intensity, adjusting the operating parameters includes a) lowering a tip speed ratio and / or a minimum blade angle in the partial load range to increase power output, and b) shifting the pitch characteristic curve in the upper partial load range towards higher power outputs to compensate for the resulting load and angle of attack reserves, or c) in addition to a) and alternatively to b), increasing the rotor speed of the wind turbine, taking into account the noise level boundary condition.

12. Method according to one of the preceding claims, wherein determining the environmental parameters includes determining the temperature and the air density, wherein a reduction in temperature at constant density leads to thermal reserves in an electrical train of the wind turbine, wherein, upon detection of a thermal reserve, adjusting the operating mode includes increasing the power output, either as a temporary power increase or as a permanent rated power increase, wherein increasing the power output, depending on the sound level boundary condition, includes a) increasing the rotational speed of the rotor if a sound level reserve is available or b) increasing the torque without a sound level reserve being available.

13. A method according to any of the preceding claims, wherein determining the environmental parameters includes determining the shear and turbulence intensity, wherein the influence of the shear and turbulence intensity on the load and angle-of-attack reserves is taken into account, and wherein adjusting the operating parameters as a function of the load and angle-of-attack reserves comprises at least one of the following measures: a) adjusting the pitch characteristic, particularly in the partial load range with available load and angle-of-attack reserves; reducing the minimum blade angle and / or the tip speed ratio; and b) briefly increasing the rated power to compensate for wind gusts.

14. A method according to any of the preceding claims, wherein determining the environmental parameters includes determining the air density and the turbulence intensity, wherein, in the case that both the air density and the turbulence intensity increase, a higher annual energy yield, higher loads and a higher sound power level result, wherein in this case, adjusting the operating parameters includes at least one of the following measures: a) changing the pitch characteristic curve, taking into account the decreasing angles of attack due to increased air density and the increasing angles of attack due to increased turbulence intensity; b) reducing the rotational speed to reduce the loads and the sound power level;and c) increasing an angle-of-attack reserve in the partial load range by increasing the tip speed ratio and / or the minimum blade angle, and wherein, in the case that both the air density and the turbulence intensity decrease, at least one, preferably at least both and particularly preferably all, of the measures a), b) and c) are inverted to adapt the operating conditions.; 15. A method according to one of the preceding claims, wherein determining the environmental parameters includes determining the air density and the turbulence intensity, wherein, in the case that the air density increases and the turbulence intensity decreases, the effects on loads and noise are compensated, wherein in this case the adjustment of the operating mode due to the increased angle of attack limits includes at least one of the following measures: a) changing the pitch characteristic curve to increase the annual energy yield; b) reducing the rotational speed to compensate for the increased loads, in particular the average load values.

16. A method according to any of the preceding claims, wherein determining the environmental parameters includes determining the air density and the turbulence intensity, wherein, in the case that the air density decreases and the turbulence intensity increases, the effects on loads and noise are compensated, wherein in this case, adjusting the operating procedure to compensate for the reduced angle-of-attack limits includes at least one of the following measures: a) changing the pitch characteristic by earlier pitching; b) increasing the rotational speed.

17. Method according to one of the preceding claims, wherein determining the environmental parameters includes determining the air density and the temperature, wherein, in the case that the temperature decreases and the air density increases, depending in particular on the sound level boundary condition, adjusting the operating mode includes at least one of the following measures: a) increasing the rated power while simultaneously reducing the rotational speed to comply with the sound level boundary condition, in the case of an uncritical sound level boundary condition, reducing only until the load boundary condition is met; b) If necessary, increasing the pitch until the load boundary condition is met.

18. Wind turbine with a control system, wherein the control system is configured to control the wind turbine according to a method of the preceding claims.

19. Wind farm with multiple wind turbines according to claim 18.