Method for optimizing rotor blade, rotor blade and wind turbine

Abstract

The invention relates to a method for optimizing a rotor blade of a wind turbine, and to an associated rotor blade and wind turbine, in which the rotor blade extends from a rotor blade connection to a rotor blade tip in the longitudinal direction of the rotor blade by a rotor blade length, the invention relates to a method for designing a rotor blade having an aerodynamic profile extending between a leading edge and a trailing edge, the method having the following steps: designing the rotor blade for design environmental conditions, which comprise at least one design turbulence intensity, the design comprising providing a sound-insulating means in a blade outer region of the rotor blade, the blade outer region is defined as 50% of the length of the rotor blade adjacent to the tip of the rotor blade; providing turbulence intensity at the erection site of the wind turbine; the turbulence intensity is compared with the designed turbulence intensity; and when the turbulence intensity is smaller than the designed turbulence intensity, the induction factor is increased by enlarging the sound insulation mechanism.

Description

Field of the Invention

[0001] The present invention relates to a method for optimizing a rotor blade of a wind energy installation, a rotor blade of a rotor of a wind energy installation, a wind energy installation, and a wind farm. Background Art

[0002] Wind energy installations are generally known and are designed, for example, as in Figure 1 . For example, the design of the rotor blade is an important aspect for the emissions and efficiency of a wind energy installation. The rotor blades of a wind energy installation typically have a suction side and a pressure side. The suction side and the pressure side meet at the trailing edge of the rotor blade (hereinafter simply referred to as the trailing edge). Eddy currents can be generated by the pressure difference between the suction side and the pressure side, and these eddy currents can particularly cause noise emissions and power reduction at the tip of the rotor blade. In addition, when the flow passes around the blade surface, small-scale eddy currents and pressure fluctuations are generated by the friction effects on the pressure side and the suction side, and these eddy currents and pressure fluctuations cause noise emissions when they overflow at the trailing edge of the rotor blade.

[0003] The design of a wind energy installation or its components is carried out according to standardized criteria (such as IEC 61400), which relate to the basic design requirements for ensuring the technical integrity of the wind energy installation. The purpose of these standards is to ensure an appropriate level of protection against damage from risks during the planned service life of the wind energy installation. In this case, standard parameters related to standardized loads but not site-specific are included in the sizing of the wind energy installation. Standard parameters are especially wind shear, the occurrence of turbulence, turbulence intensity, climatic conditions, air density, wind class, and the reference speed of the wind zone. Since the sizing of the wind energy installation is related to standardized loads, the rotor blade has a defined profile with fixed parameters, such as the profile depth together with its associated profile poles, such as lift / drag poles. This defined profile forms the basis for load calculations and annual energy production (AEP) calculations.

[0004] The design of a wind energy installation or the resulting design of the rotor blade is mainly oriented towards standardized sites or standardized loads, and site-specific certifications / loads are also taken into account. Thereby, the subsequent geometric design of the rotor blade is determined. In particular, the rotor blade has a fixed geometry that can no longer be subsequently adjusted in terms of twist or profile depth during the manufacturing process.

[0005] The European Patent Office searched for the documents US2024 / 0011463 A1 and US2020 / 370534 A1 as prior art within the scope of the priority application. Summary of the Invention

[0006] Against this background, the object of the present invention is to achieve a site-specific optimization of the rotor blade without changing the fixed geometry.

[0007] In a first aspect, a method for optimizing a rotor blade of a wind energy installation is provided, wherein the rotor blade extends in the longitudinal direction of the rotor blade from the rotor blade connection to the rotor blade tip over the length of the rotor blade and has an aerodynamic profile extending between a leading edge and a trailing edge therein. Thus, a rotor blade that is basically known is involved, and according to the present invention, the rotor blade can be optimized by the provided method.

[0008] The method has the following steps: designing the rotor blade for design ambient conditions, which include at least one design turbulence intensity, wherein the design includes: arranging a sound insulation mechanism in the outer blade region of the rotor blade, which is defined as 50% of the rotor blade length adjacent to the rotor blade tip.

[0009] Furthermore, the design process of a wind energy installation is known and is described comprehensively in common professional books. In the design conditions on which it is based, such as the design rotational speed and / or the design tip speed ratio, a design of the rotor blade that is as efficient and durable as possible, but also cost-effective, is usually sought.

[0010] The design conditions also include the design ambient conditions, that is to say, these model the environment at the installation site of the wind energy installation under the design conditions. That is to say, the design ambient conditions are theoretical ambient conditions, which are based on the design but do not necessarily also exist at the actual installation site of the wind energy installation. For example, due to the deviation between the design ambient conditions and the environmental conditions at the installation site of the wind energy installation, a performance loss may result. Here, as the most important case, the turbulence intensity below the design turbulence intensity at the installation site is important. For example, the design turbulence intensity can be the standard turbulence intensity, but it can also be other values.

[0011] In another step, according to the present invention, the turbulence intensity at the installation site of the wind energy installation is provided for this purpose. The turbulence intensity can be determined as an average value or an extreme value or other values representing the turbulence intensity at the installation site. For example, the turbulence intensity can be measured or derived from a weather model.

[0012] In another step, according to the present invention, the turbulence intensity is compared with the design turbulence intensity, and in the case where the turbulence intensity is lower than the design turbulence intensity, the induction factor is increased by increasing the sound insulation mechanism.

[0013] That is to say, if a turbulence intensity lower than the design turbulence intensity is obtained at the installation site of the wind energy installation, then according to the present invention, the sound insulation mechanism is increased in order to cause an increase in the induction factor and thus an improvement in performance.

[0014] In the international standard IEC 61400-1, which is important for the design of wind energy devices, there are fixed reference values for the turbulence intensity for different wind classes, namely the design turbulence intensity. The standard presupposes four levels of design turbulence, with A+ as the class with very high turbulence characteristics, followed by A, B, and C with successively decreasing turbulence characteristics. The difference between the respective levels lies in the different values of the reference turbulence intensity I ref . After selecting the corresponding wind class for the desired site, the wind energy device is then designed with the tabulated and fixed values of the reference turbulence intensity I ref .

[0015] However, the inventors of the present invention have recognized that the values set for the respective design turbulence intensities can differ significantly from the actual values at the installation site.

[0016] The knowledge on which the inventors of the present invention base themselves is based on the following: The sound insulation mechanism also increases the effective profile depth, thereby increasing the lift force generated at the location where the sound insulation mechanism is arranged.

[0017] In the case where the turbulence intensity is lower than the design turbulence intensity, two effects result. First, the noise generated is lower, which gives rise to the feasibility of also making compromises in terms of air acoustics, which cause higher noise emissions. In addition, the induction is lower, which results in lower performance and thus explains the reason for the expectation of increased performance.

[0018] In this case, the enlargement of the sound insulation mechanism enables the implementation of site-based optimization of the rotor blade, in particular performance optimization, without changing the geometry of the rotor blade.

[0019] The sound insulation mechanism includes, for example, serrations or robust plate additives arranged at the trailing edge of the rotor blade.

[0020] It is also feasible to arrange a combination of different types of sound insulation mechanisms at the rotor blade.

[0021] The steps of designing, providing, and / or comparing are preferably carried out with the aid of and / or by means of a computer. The step of increasing the induction factor by enlarging the sound insulation mechanism can likewise be carried out by a computer, which determines the value for the enlarged sound insulation mechanism based on the previous method steps. Alternatively or additionally, the step of increasing the induction factor is carried out by enlarging the sound insulation mechanism at the existing rotor blade, for example by adding or changing the sound insulation mechanism.

[0022] In a preferred design, the method further includes obtaining a spectral range of turbulent frequency components based on the turbulence intensity, where the spectral range includes frequencies less than a predefined frequency threshold, in particular 1 Hz. The step of comparing the turbulence intensity with the design turbulence intensity includes comparing the spectral range of the turbulent frequency components with the design turbulence intensity.

[0023] The turbulence intensity results from the superposition of different temporal variations of the wind speed. Here, not only the faster variations of the wind speed, i.e., the higher-frequency portion, but also the slower variations of the wind speed, i.e., the lower-frequency portion, contribute.

[0024] The described embodiment is based on the recognition that turbulence with a certain frequency range is particularly important for the lift generated by the rotor blades and the loads acting on the rotor blades. In particular, it has been recognized that low-frequency turbulence or turbulence portions, in particular low-frequency turbulence or turbulence portions with a frequency less than or equal to 1 Hz, are particularly important for the lift and loads of the rotor blades. In contrast, high-frequency turbulence can be ignored.

[0025] In the described embodiment, if the low-frequency portion has a smaller intensity, the turbulence intensity, here the effective turbulence intensity, is particularly less than the design turbulence intensity. Even if the total intensity of the turbulence is high, with the present invention, the efficiency of the wind energy device can be improved by only considering the portion that significantly affects noise development and loads rather than the total turbulence.

[0026] The design turbulence intensity does not have spectral resolution in terms of frequency according to standardized criteria (such as IEC 61400). The cumulative turbulence intensity of the frequency-specific spectral range (whose frequencies are less than the predefined frequency threshold) is therefore compared with the design turbulence intensity respectively. If the turbulence intensity at least below the frequency threshold is less than the design turbulence intensity, the frequency-specific buffer can be fully utilized by increasing the induction factor due to the sound insulation mechanism, and thus the rotor blades can be optimized.

[0027] In another preferred design, the method includes: obtaining a probability distribution of the turbulence intensity at the installation site of the wind energy device, where the step of comparing the turbulence intensity with the design turbulence intensity includes: comparing the turbulence intensity greater than a turbulence intensity probability threshold with the design turbulence intensity, where the turbulence intensity probability threshold corresponds to a specific percentage of the turbulence intensity probability distribution, in particular 95%.

[0028] Typically, the site-specific turbulence intensity is described as the average of all turbulence intensities measured at the site over a certain period of time. It is also known that the statistical distribution of the turbulence intensity can be approximated by a Weibull distribution (Weibull-Verteilung). In practice, however, the probability distribution at the installation site can deviate significantly from the "standard" Weibull distribution, which, according to the described embodiment, is used to further improve the wind energy device.

[0029] It is now known that, when considering load reserves, it is advantageous for this site-specific turbulence intensity not to use the average value over a certain period of time, but rather a specific sub-region of the distribution, in particular the upper 95 percent. Even if such high turbulence intensities occur relatively rarely, for example less than 5% of the time, their impact on noise and load is particularly significant, thus avoiding the situation where the load reserve determined according to the average value of the turbulence intensity causes an excessive increase in the induction factor, which in turn causes an overloading of the rotor blades in the event of extreme turbulence or, conversely, may not be used for optimizing the rotor blades due to gaps in the probability distribution of the turbulence intensity.

[0030] If the predefined relative threshold is, for example, 95%, this means that 95% of the occurring or measured turbulence intensities are below the threshold. Of course, the threshold is only exemplary and, depending on the application, the upper 10% or upper 1% of the distribution can also be considered.

[0031] In another preferred design, the sound insulation mechanism is configured as a serration having a plurality of teeth arranged side by side in the longitudinal direction of the rotor blade, the teeth being arranged such that a toothed profile forming an effective trailing edge is formed in the region of the sound insulation mechanism, wherein the step of increasing the induction factor includes at least one of a plurality of possible measures for increasing one or more teeth.

[0032] In one design, the method includes increasing one or more of the teeth by geometrically scaling the teeth similarly, wherein the ratio of the length of the teeth to the width of the teeth remains substantially constant.

[0033] In one design, the method includes increasing one or more of the teeth by increasing the length of the teeth while maintaining the width of the teeth.

[0034] In one design, the method includes increasing one or more of the teeth by reducing the share of perforations at the surface of the teeth.

[0035] In one design, the method includes increasing one or more of the teeth by increasing the convexity of the side edges of the teeth.

[0036] In one design, the method includes: increasing one or more teeth in the serrations by changing the triangular shape of the teeth to a polygonal shape.

[0037] The serrations are a sound insulation mechanism of a known type, which is provided at the trailing edge and reshapes the effective profile of the trailing edge, i.e., the outflow edge. Thereby, the acoustic influence of the air turbulence at the trailing edge of the rotor blade is reduced and the wind energy device can operate with lower noise.

[0038] When performing geometrically similar scaling, the ratio of the length to the width of the teeth remains substantially unchanged. In other alternative solutions, it is also possible to only increase the length of the teeth, while the width of the teeth remains unchanged. Combined solutions are also conceivable, for example, where the length is doubled and the width is increased by 50%.

[0039] The serrations typically have a triangular shape, but within the scope of the present invention, polygonal serrations or serrations with concave and / or convex profiles are also considered. In the triangular shape, the teeth occupy 50% of the area outside the trailing edge, i.e., the area of the region with a toothed profile. By changing the edge profile, for example, by convex shaping or by polygonal shaping, the area share of the serrations at the total area outside the trailing edge can be increased, thereby increasing the induction factor.

[0040] Therefore, the increase can consist in either increasing each serration in width or in length. Alternatively or additionally, the increase can also consist in changing the external geometry of the serrations, in such a way that, for example, the edge is shaped convexly or the number of corners is changed, for example, to four, five or seven.

[0041] In a preferred design, the step of increasing the induction factor includes: adjusting the installation angle of the sound insulation mechanism, where the installation angle is defined as the angle between the local chord of the rotor blade and the teeth of the sound insulation mechanism, especially the serrations, and the local chord is determined as the direct connection between the leading edge and the trailing edge at the location of the sound insulation mechanism.

[0042] The serrations change the effective profile depth, and the installation angle of the serrations changes the curvature of the profile accordingly. By adjusting the installation angle in this way, in particular, the curvature of the profile can be changed and the generated lift force can be affected.

[0043] The adjustment of the installation angle can be achieved by: installing the sound insulation mechanism relative to the rotor blade at an installation angle different from the installation angle derived from the design conditions. The installation of the serrations can include laminating the serrations into the rotor blade. In other examples, the installation angle can be adjusted by bending the serrations under the action of mechanical force.

[0044] In particular, the rounded shape of the sound insulation means facing the pressure side of the rotor blade, i.e. the bulge, can increase the lift force and thus increase the induction factor. In the described embodiment, the sound insulation means acts like a flap or a leading edge flap.

[0045] In a preferred embodiment, the method further comprises the steps of: determining the influence of the turbulence intensity on the propagated sound; optimizing the performance taking into account the turbulence intensity and ensuring the sound power level, in particular by increasing the sound insulation means.

[0046] Optimizing the performance in particular includes maximizing the electrical power generated by the wind energy installation. At the same time, an increase in power is not allowed to cause excessive sound emissions.

[0047] Ensuring the sound power level is a measure describing the maximum radiated sound power level of the wind energy installation. In other words: for example, when the electrical power is to be maximized, the control device of the wind energy installation includes the emitted sound level as a boundary condition. In some cases, the operation of the wind energy installation is then limited or restricted by ensuring the sound power level. This may sometimes be the case, for example, at night or for a specific wind direction.

[0048] Another example is to change the angle of the sound insulation means in order to optimize the performance taking into account the turbulence intensity and ensuring the sound power level.

[0049] A lower turbulence intensity is usually associated with a lower sound power, such that there is also a "sound reserve" which can be increased, for example, by additional power. According to the invention, the additional power is not achieved solely by adjusting the operation control, but mainly by increasing the induction in the blade tip region, i.e. by increasing the sound insulation means.

[0050] In a preferred design, the step of increasing the induction factor includes: increasing the extension of the sound insulation means in the longitudinal direction of the rotor blade, in particular increasing the number of teeth of the serrations.

[0051] As an alternative to increasing the number of teeth, the existing number can also be scaled, i.e. the length and / or width of the teeth can be increased. In any case, in the described embodiment, the additional induction caused by the sound insulation means is increased.

[0052] In a preferred design, the step of increasing the induction factor includes: increasing the sound insulation means with a scaling factor varying in the longitudinal direction of the rotor blade.

[0053] The core of this embodiment is that the action of the sound insulation means varies depending on the position along the longitudinal direction of the rotor blade. Thus, according to the invention, the induction can be increased, while for example the additional sound emissions considered here do not exceed a specific limit value.

[0054] In a preferred design, the scaling factor increases from the tip of the rotor blade towards the end of the sound insulation mechanism.

[0055] The described embodiment takes into account the knowledge that, particularly in the vicinity of the tip of the rotor blade, the sound insulation mechanism has a great influence on the generated sound. In order to comply with the sound emission limits, it is accordingly advantageous to design the increase of the sound insulation mechanism to be correspondingly stronger as the distance from the tip of the rotor blade increases.

[0056] In one embodiment, the scaling factor at the tip of the rotor blade is substantially 1. This means that there is no increase in the sound insulation mechanism at the tip of the rotor blade, but the sound insulation mechanism increases correspondingly as the distance from the tip of the rotor blade increases. The increase factor can increase linearly, quadratically, or in other functional relationships with the distance from the tip of the rotor blade.

[0057] On the other hand, there is provided a rotor blade of a wind energy device, wherein the rotor blade extends in the longitudinal direction of the rotor blade from the rotor blade connection to the rotor blade tip by the length of the rotor blade, and has an aerodynamic profile extending between a leading edge and a trailing edge, wherein the rotor blade has a sound insulation mechanism in a blade outer region defined as 50% of the rotor blade length adjacent to the rotor blade tip, wherein the sound insulation mechanism is configured as a serrated portion having a plurality of teeth arranged side by side in the longitudinal direction of the rotor blade, the teeth being arranged such that a toothed profile constituting an effective trailing edge is formed in the region of the sound insulation mechanism, and wherein the following design dimensions are determined for the sound insulation mechanism, and the rotor blade satisfies the guaranteed sound power level when used in the design turbulence intensity.

[0058] According to the invention, in the case where the turbulence intensity is less than the design turbulence intensity, the sound insulation mechanism has a larger size than the design dimensions.

[0059] Accordingly, the rotor blade according to the invention is a direct result of the method according to the invention according to the described aspects of the invention. The preferred design of the described method can also be similarly transferred to the rotor blade, while achieving the same advantages.

[0060] On the other hand, there is proposed a wind energy device having one or more rotor blades according to the invention.

[0061] On the other hand, there is proposed a wind farm having one or more wind energy devices according to the invention.

[0062] On the other hand, a method for retrofitting a rotor blade of a wind energy device is proposed, wherein the rotor blade extends in the longitudinal direction of the rotor blade from the rotor blade connection to the rotor blade tip with a rotor blade length and has an aerodynamic profile extending between a leading edge and a trailing edge, and wherein the method has the following steps: providing the turbulence intensity at the installation site of the wind energy device; comparing the turbulence intensity with a design turbulence intensity; and, in the case where the turbulence intensity is less than the design turbulence intensity, increasing the induction factor of the rotor blade by arranging and / or increasing a sound insulation mechanism in the blade outer region of the rotor blade, the blade outer region being defined as 50% of the rotor blade length adjacent to the rotor blade tip.

[0063] In this context, retrofitting describes that the wind energy device has been operating or is at least in a state where operation is possible before the sound insulation mechanism is increased.

[0064] The detailed description of the method steps of the method according to the first aspect of the invention is correspondingly applied in terms of the method steps of the method for retrofitting a rotor blade according to the invention in this aspect of the invention and also brings corresponding advantages and technical effects.

[0065] Finally, on the other hand, a method for optimizing a wind energy device is proposed, the wind energy device including at least one rotor blade, and wherein the method has the following steps: providing the turbulence intensity at the installation site of the wind energy device; comparing the turbulence intensity with a design turbulence intensity; and, in the case where the turbulence intensity is less than the design turbulence intensity, increasing the generated power of the wind energy device by adjusting the induction factor distribution of at least one rotor blade by means of a structural change of at least one rotor blade.

[0066] Here, the structural change of at least one rotor blade preferably includes adjusting or arranging a sound insulation mechanism, in particular an additional sound insulation mechanism.

[0067] The method according to the invention in this aspect is preferably at least partially implemented by means of a computer and / or on a computer.

[0068] The detailed description of the method steps of the method according to the first aspect of the invention is correspondingly applied in terms of the method steps of the method for optimizing a wind energy device according to the invention in this aspect of the invention and also brings corresponding advantages and technical effects.

[0069] Here, in one embodiment, neither the rotational speed corresponding to the design rotational speed is increased nor the pitch angle corresponding to the design pitch angle is decreased.

[0070] Here, the rotational speed is the rotational speed of the rotor. The pitch angle is the angle of attack of the corresponding rotor blade. The design rotational speed and the design pitch angle are standard parameters based on which the dimensions of the wind energy installation and the rotor blades are designed.

[0071] The wind energy installation according to the invention and the wind farm according to the invention can also achieve the same advantages as the rotor blade according to the invention or the method according to the invention described. Similarly, in the case of obtaining the described advantages, not only the wind energy installation but also the wind farm can be combined with the design variants described as advantageous. Description of the Drawings

[0072] The following describes further advantages and preferred design variants with reference to the drawings. In this case, it is shown:

[0073] Figure 1 A wind energy installation is shown schematically and by way of example;

[0074] Figures 2 to 6 A rotor blade with a sound insulation mechanism is shown schematically and by way of example; and

[0075] Figure 7 A flow chart of a method is shown schematically and by way of example. Detailed Description of the Invention

[0076] Figure 1 A schematic view of a wind energy installation according to the invention is shown. The wind energy installation 100 has a tower 102 and a nacelle 104 on the tower 102. At the nacelle 104, an aerodynamic rotor 106 with three rotor blades 108 and a fairing 110 is provided. The aerodynamic rotor 106 is set in rotational motion by the wind during operation of the wind energy installation and thus also rotates the electric rotor or the rotating member of the generator, which is directly or indirectly coupled to the aerodynamic rotor 106. The generator is arranged in the nacelle 104 and generates electrical energy. The pitch angle of the rotor blades 108 can be changed by a pitch motor at the rotor blade root 109 of the respective rotor blade 108.

[0077] Here, the wind energy installation 100 has a generator 101, which is indicated in the nacelle 104. Electrical power can be generated by means of the generator 101. For feeding in the electrical power, a feeding unit 105 is provided, which can be configured in particular as an inverter. Thereby, a three-phase feeding current and / or a three-phase feeding voltage can be generated according to amplitude, frequency and phase for feeding in at the grid connection point PCC. This can be done directly or also together with other wind energy installations in a wind farm. For controlling the wind energy installation 100 and also for controlling the feeding unit 105, a plant control device 103 is provided. The plant control device 103 can also obtain setpoints from the outside, in particular from a central farm computer.

[0078] Figure 2 Schematically and exemplarily shows the outer blade region 120 of the rotor blade 108. The outer blade region 120 is defined as the outer 50% of the rotor blade 108, which is closer to the blade tip 114 and thus farther from the axis of rotation of the rotor 106. In the outer blade region 120, the rotor blade 108 has a sound insulation mechanism 130 that extends beyond the trailing edge 112. At the trailing edge 112, the suction side and the pressure side of the aerodynamic profile that are separated at the leading edge 110 converge again.

[0079] The sound insulation mechanism 130 is configured as a serrated portion, that is to say, the serrated portion forms a toothed, serrated profile that has alternating tips and recesses, and the serrated portion is connected by an edge that is at an angle to the longitudinal direction of the rotor blade. That is to say, the trailing edge profile is formed by the serrated portion in the region of the sound insulation mechanism 130.

[0080] The serrated portion can be described by its length, width and its mounting angle. The ratio of the length to the width results in an angle with respect to the longitudinal direction of the rotor blade. The mounting angle describes the angle of the serrated portion with respect to the chord line of the rotor blade at the mounting position of the serrated portion, where the chord line is the shortest or direct connection between the leading edge and the trailing edge.

[0081] The present invention relates to a geometric design of the rotor blade 108 in the outer blade region 120 for optimizing the induction factor when the wind energy installation 100 is at a site with low turbulence intensity.

[0082] For reasons of noise reduction, the serrated portion is typically installed in the outer blade region 120. Simulations and experimental studies by the inventors of the present invention clearly show that extending the serrated portion, that is, increasing the length of each tooth beyond the trailing edge 112 (which would exceed the standard length in the absence of the sound insulation mechanism 130), can increase the lift force at the rotor blade 108 and thus increase the induction factor.

[0083] By extending the serrated portion, an effective increase in the local blade depth is obtained, that is, the local spacing between the leading edge 110 and the trailing edge 112, that is, because the serrated portion affects the profile of the trailing edge 112. Thereby, the area that generates the lift force becomes larger.

[0084] Turbulence intensity is a dimensionless number that is defined as the standard deviation of the wind speed within a time interval divided by the average wind speed within that time interval.

[0085] Turbulence intensity has a great influence on the power of the wind, that is, the wind force, where a higher turbulence intensity is accompanied by a higher wind force and thus also by a higher achievable electrical power of the wind energy installation 100.

[0086] The wind energy installation 100 is designed for specific environmental parameters, that is to say, boundary conditions such as the design turbulence intensity are determined during the design process, and then the wind energy installation 100 is optimized for the said design turbulence intensity. For the design turbulence intensity, an optimal operation of the wind energy installation is feasible, and a deviation from the design turbulence intensity causes in principle that the wind energy installation 100 cannot operate at the optimal operating point determined during its design process.

[0087] At the same time, it is not possible to design and test individual wind energy installations for each location, which results in a need for wind energy installations 100 and in particular rotor blades 108 that can be used as widely as possible.

[0088] At locations where the turbulence intensity is significantly lower than the design turbulence intensity in particular, a reduced induction factor generally occurs with standard operation control. The reduced induction factor means that the wind energy installation 100 extracts less energy from the wind and thus the performance of the wind energy installation 100 is reduced.

[0089] The methods used hitherto to improve performance have consisted in adjusting the operation control (for example increasing the rotational speed and / or reducing the pitch angle in order to increase the local angle of attack) in order to balance the induction losses. However, this causes, for example, an increased service life load in the pivoting direction due to the increased rotational speed. The increase in the local angle of attack can also cause flow separation (lower stall margin) on the blade, which can cause increased loads and noise pollution.

[0090] According to the invention, a solution is now proposed which has an increased sound insulation means, in particular an extended serration, wherein the induction factor can be adjusted without having to tolerate higher pivoting loads and a lower stall margin.

[0091] The advantage of the invention described here is that, by using a serration that is longer / larger than the serration designed for standard locations, a significant power increase and thus a significant increase in revenue can be achieved at locations with reduced density.

[0092] Figure 3 The rotor blade 108 is shown schematically and by way of example, wherein Figure 2 the sound insulation means 130 therein is replaced by a sound insulation means 140 which has serrations that are geometrically similar and scaled in size. The serrations of the sound insulation means 140 are scaled geometrically, which means that the aspect ratio of the length to the width of the serration teeth remains constant. Accordingly, the number of teeth is less than in the sound insulation means 130, but the area and thus the influence on the induction is greater.

[0093] The increase in the serrations used can be effected not only by a geometrically similar scaling (where the aspect ratio of the length to the width of the serration teeth remains constant), but also by extending the tooth geometry while maintaining the original width (where the aspect ratio of the serration teeth increases).

[0094] Schematically and by way of example, a second alternative can be seen in the Figure 4 acoustic insulation mechanism 150, where the tooth geometry is extended while maintaining the original width.

[0095] In addition to increasing the serrations, the installation angle (not shown) can also be adjusted in order to further increase the lift force. The installation angle is the angle between the serrations and the chord line of the rotor blade 108. A positive installation angle can be defined towards the pressure side and a negative angle towards the suction side. Adjustment towards the pressure side results in an increase in the lift force due to the increased curvature.

[0096] A particular advantage of the location with reduced density is that, at low turbulence intensities, less sound is propagated by the wind power installation 100. Therefore, at such locations, an air-acoustically optimal serration design is usually no longer mandatory.

[0097] An air-acoustic compromise in favour of performance can be made without exceeding the guaranteed sound power level.

[0098] Figure 5 Schematically and by way of example, another design of the acoustic insulation mechanism 160 is shown. The scaling of the serrations, i.e. Figure 3 the geometrically similar scaling shown in Figure 4 and / or the scaling in the length of the teeth shown in

[0099] does not necessarily have to be carried out identically over the entire radial extent. Rather, different scaling factors can also be applied as a function of the position, compared with the standard density design. Thus, in the regions which are important for air acoustics at the blade tip, for example, an acoustically quite optimal design can be used, while towards the inside of the rotor blade a serration scaling which is optimal for performance is used. Figure 5 This is manifested in

[0100] Figure 6 Schematically and by way of example, another design of the acoustic insulation mechanism 170 is shown. Another possibility for increasing the performance at the location with reduced density is also the extent of the region in which the acoustic insulation mechanism 170 is installed, for example where additional serrations are installed. The additional serrations installed more towards the inside of the rotor blade can effectively increase the induction factor in said region.

[0101] The noise insulation mechanism 170, which is further increased in the longitudinal direction of the rotor blade, can of course also be dimensioned and widened specifically on-site, i.e., in combination with the embodiments shown in Figure 3 , Figure 4 and Figure 5 .

[0102] Figure 7 Schematically and by way of example, the flow of a method 200 for optimizing the rotor blade 108 of a wind energy installation 100 is shown.

[0103] The method 200 includes a step 210 of designing the rotor blade 108 for design environmental conditions, which include at least one design turbulence intensity, wherein the design includes: providing a noise insulation mechanism 130 in an outer blade region of the rotor blade, which outer blade region is defined as 50% of the rotor blade length adjacent to the rotor blade tip.

[0104] Furthermore, the method 200 includes a step 220 of providing the turbulence intensity at the erection site of the wind energy installation 100 and a step 230 of comparing the turbulence intensity with the design turbulence intensity.

[0105] Finally, the method 200 includes a step 240 of increasing the induction factor by increasing the noise insulation mechanism 130, for example up to the noise insulation mechanisms 140, 150, 160 or 170, if the turbulence intensity is less than the design turbulence intensity.

Claims

1. A method (200) for optimizing a rotor blade (108) of a wind energy device (100), wherein the rotor blade (108) extends in a rotor blade longitudinal direction by a rotor blade length from a rotor blade connection (109) to a rotor blade tip (114), and wherein the rotor blade has an aerodynamic profile extending between a leading edge (110) and a trailing edge (112), and wherein the method has the following steps: Design the rotor blade (108) for design environmental conditions (210), the design environmental conditions including at least one design turbulence intensity, wherein the design comprises: Providing a sound insulation mechanism (130, 140, 150, 160, 170) within an outer blade region (120) of the rotor blade (108), the outer blade region being defined as 50% of the rotor blade length adjacent to the rotor blade tip; Providing (220) the turbulence intensity at the installation site of the wind energy device (100); Comparing (230) the turbulence intensity with a design turbulence intensity; And In the case where the turbulence intensity is less than the design turbulence intensity, increasing (240) an induction factor by increasing the sound insulation mechanism (130, 140, 150, 160, 170).

2. The method (200) according to claim 1, the method further comprising: Obtaining a spectral range of turbulence frequency components based on the turbulence intensity, wherein the spectral range includes frequencies less than a predefined frequency threshold, in particular 1 Hz, Wherein the step of comparing (230) the turbulence intensity with the design turbulence intensity comprises: Comparing the spectral range of the turbulence frequency components with the design turbulence intensity.

3. The method according to any one of the above claims, the method further comprising: Obtaining a turbulence intensity probability distribution of the turbulence intensity at the installation site of the wind energy device (100); Wherein the step of comparing (230) the turbulence intensity with the design turbulence intensity comprises: Comparing the turbulence intensity greater than a turbulence intensity probability threshold with the design turbulence intensity, wherein the turbulence intensity probability threshold corresponds to a specific percentage, in particular 95%, of the turbulence intensity probability distribution.

4. The method (200) according to any one of the above claims, wherein the sound insulation mechanism (130, 140, 150, 160, 170) is configured as a serration having a plurality of teeth arranged side by side in the rotor blade longitudinal direction, the teeth being arranged such that a toothed profile forming an effective trailing edge is formed in the region of the sound insulation mechanism, and wherein the step of increasing (240) the induction factor comprises at least one of the following steps: Increasing one or more of the teeth by geometrically scaling the teeth similarly, wherein the ratio of the length of the teeth to the width of the teeth remains substantially constant, Increasing one or more of the teeth by increasing the length of the teeth while maintaining the width of the teeth, Increasing one or more of the teeth by reducing the number of perforations on the surface of the teeth, Increasing one or more of the teeth by increasing the convexity of the side edges of the teeth, One or more teeth among the teeth are enlarged by changing the triangular shape of the teeth into a polygonal shape.

5. The method (200) according to any one of the preceding claims, wherein the step of increasing (240) the induction factor comprises: Adjusting the installation angle of the sound insulation mechanism (130, 140, 150, 160, 170), wherein the installation angle is defined as the angle between the local chord line of the rotor blade and the teeth of the sound insulation mechanism, in particular the teeth of the serrated part, wherein the local chord line is determined as the direct connection between the leading edge (110) and the trailing edge (120) at the location of the sound insulation mechanism (130, 140, 150, 160, 170), and / or Increasing the extension of the sound insulation mechanism (130, 140, 150, 160, 170) in the longitudinal direction of the rotor blade, in particular increasing the number of teeth of the serrated part, and / or Increasing the sound insulation mechanism (130, 140, 150, 160, 170) with a scaling factor that varies in the longitudinal direction of the rotor blade.

6. The method (200) according to any one of the preceding claims, wherein the method further comprises the steps of: Determining the influence of the turbulence intensity on the propagated sound, Optimizing the performance taking into account the turbulence intensity and ensuring the sound power level, in particular by increasing the sound insulation mechanism (130, 140, 150, 160, 170) to optimize the performance.

7. The method (200) according to any one of the preceding claims, wherein the step of increasing (240) the induction factor comprises: Increasing the sound insulation mechanism (130, 140, 150, 160, 170) with a scaling factor that varies in the longitudinal direction of the rotor blade, wherein the scaling factor increases from the rotor blade tip (114) towards the end of the sound insulation mechanism (130, 140, 150, 160, 170).

8. The method (200) according to claim 7, wherein the scaling factor at the rotor blade tip (114) is 1.

9. A rotor blade (108) of a wind energy device (100), wherein the rotor blade (108) extends in the longitudinal direction of the rotor blade from the rotor blade connection part (109) to the rotor blade tip (114) with the rotor blade length, and herein, the rotor blade has an aerodynamic profile extending between the leading edge (110) and the trailing edge (112), wherein the rotor blade (108) has a sound insulation mechanism (130, 140, 150, 160, 170) in the blade outer region (120), and the blade outer region is defined as 50% of the rotor blade length adjacent to the rotor blade tip (114). The sound insulation mechanism (130, 140, 150, 160, 170) is configured as a serrated part, and the serrated part has a plurality of teeth arranged side by side in the longitudinal direction of the rotor blade. The teeth are arranged such that a toothed profile that forms the effective trailing edge (112) is formed in the region of the sound insulation mechanism (130, 140, 150, 160, 170). Design dimensions are determined for the sound insulation mechanism (130, 140, 150, 160, 170), and the rotor blade (108) meets the guaranteed sound power level when used in the design turbulence intensity. It is characterized in that In the case where the turbulence intensity is less than the design turbulence intensity, the size of the sound insulation mechanism (130, 140, 150, 160, 170) is larger than the design size.

10. A wind energy device (100) having one or more rotor blades (108) according to claim 9.

11. A wind farm having one or more wind energy devices (100) according to claim 10.

12. A method for retrofitting a rotor blade of a wind energy device, wherein the rotor blade (108) extends from a rotor blade connection part (109) to a rotor blade tip (114) with a rotor blade length in the longitudinal direction of the rotor blade, and here, the rotor blade has an aerodynamic profile extending between a leading edge (110) and a trailing edge (112). The method includes the following steps: Providing (220) the turbulence intensity at the erection site of the wind energy device (100); Comparing (230) the turbulence intensity with a design turbulence intensity; And In the case where the turbulence intensity is less than the design turbulence intensity, increasing (240) the induction factor of the rotor blade by arranging and / or increasing a sound insulation mechanism (130, 140, 150, 160, 170) in the blade outer region (120) of the rotor blade (108), where the blade outer region is defined as 50% of the rotor blade length adjacent to the rotor blade tip.

13. A method for optimizing a wind energy device, the wind energy device including at least one rotor blade. The method has the following steps: Providing (220) the turbulence intensity at the erection site of the wind energy device (100); Comparing (230) the turbulence intensity with a design turbulence intensity; and In the case where the turbulence intensity is less than the design turbulence intensity, increasing the power generated by the wind energy device by adjusting the induction factor distribution of the at least one rotor blade by means of a structural change of the at least one rotor blade.

14. The method for optimizing a wind energy device according to claim 13, wherein neither the rotational speed corresponding to the design rotational speed is increased nor the pitch angle corresponding to the design pitch angle is decreased.

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