Customized blade efficiency enhancement method based on safety margin for low-speed wind farms

Abstract

The present invention discloses a method for customized blade efficiency enhancement based on safety margin for low-speed wind farms, comprising the following steps: performing load calculation based on wind resource simulation results and constructing a whole machine load model; obtaining the safety margin of the unit based on the design load of the unit, and designing customized blade efficiency enhancement; simulating the whole machine using the blade efficiency enhancement design; based on the simulation results, checking the load of the whole machine using the blade efficiency enhancement design and performing prototype testing and verification. The present invention is suitable for promotion in wind farms where the actual annual average wind speed is far lower than the feasible wind speed. According to the customized blade efficiency enhancement system design based on the effective utilization of the safety margin and the wind turbine optimization efficiency enhancement technology based on the effective utilization of the safety margin, customized design optimization is performed for the machine model to meet the needs of different machine models.

Description

Technical Field

[0001] The present invention relates to the technical field of wind farms, and in particular to a method for enhancing the efficiency of blades customized based on safety margins in low-speed wind farms. Background Art

[0002] In anticipation of a decline in the benchmark wind power price, a large number of wind power projects were launched in a relatively short period of time. However, some projects lacked sufficient wind resource data during the investigation stage and no complete and scientific wind resource assessment was conducted. This resulted in the actual local wind resource situation not being fully reflected during the investigation stage, causing the actual operating wind speed of these wind farms after construction to be far lower than the designed wind speed, and the actual annual power generation hours to be generally lower than the investigation design level.

[0003] In response to this situation, wind turbine manufacturers usually recommend increasing the tower height and blade length of wind turbines in low wind speed areas. However, simply increasing the tower height from 80 meters to 100 meters, and simply increasing the blade length from the original 87-meter blade to a 93-meter blade, both have extremely high total project prices, with an average investment of more than 2 million per wind turbine. Therefore, adopting this solution will have a significant impact on the wind farm economically, and the power loss caused by the construction period is huge, and it will take many years to recover the investment and capital cost, which is unacceptable for a wind turbine with a service life of 20 years. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above existing problems, the present invention is proposed.

[0006] Therefore, the present invention provides a blade efficiency enhancement method for a low-speed wind farm based on a safety margin customization to solve the blade optimization problem of a low-speed wind farm whose actual annual power generation hours are generally lower than the survey design level.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] Calculate the load based on the wind resource simulation results and build the whole machine load model;

[0009] Based on the design load of the unit, the unit's safety margin is obtained, and the blade efficiency enhancement customization is designed;

[0010] Simulate the whole machine with blade efficiency enhancement design;

[0011] Based on the simulation results, the load of the whole machine with blade efficiency enhancement design is checked and prototype tests are carried out for verification.

[0012] As a preferred solution of the method for enhancing the efficiency of low-speed wind farms based on customized blades with safety margin described in the present invention, the wind resource simulation results are based on historical data obtained from wind measurement towers at each position of the wind farm and a topographic map of the location of the wind farm, a simulation model is established, and the wind resources at each position are estimated based on the historical data.

[0013] As a preferred solution of the method for customized blade efficiency enhancement based on safety margin for low-speed wind farms described in the present invention, the historical operation data includes the 10-minute average wind speed, the 10-minute average generator speed, the 10-minute average generator power, and the unit power generation data with a sampling interval of 10 minutes, the duration of which is 1 full year, the statistical values ​​of wind speed data for each machine position with a sampling interval of 10 seconds, air density, turbulence intensity, annual average wind speed and maximum wind speed.

[0014] As a preferred solution of the method for customized blade efficiency enhancement based on safety margin for low-speed wind farms described in the present invention, the safety margin is based on wind resource simulation and a correction method for the wind resource calculation results of each machine position. A wind wheel model is established at each machine point, load simulation is performed, and the load simulation results are compared one by one with the simulation results of the corresponding prototype machine in the standard wind zone. Based on a comprehensive evaluation of each component, the safety margin between the whole machine load at each machine position and the standard design load is obtained.

[0015] As a preferred solution of the method for enhancing the efficiency of low-speed wind farms based on customized blades with safety margin described in the present invention, the correction method is to derive the correction factor under different wind speeds based on the ratio of the actual power curve of each machine position to the theoretical power curve, and bring this correction factor into the theoretical power curve after enhancement for correction.

[0016] As a preferred solution of the method for enhancing the efficiency of low-speed wind farms based on customized blades with safety margin described in the present invention, the method for obtaining the theoretical power curve after enhancement is to sample the historical operation data of each machine position, calculate and obtain the average wind speed and average power of the data, calculate the power value of the wind speed point with an interval of 0.5m / s between 0-20m / s, and use this to draw the power curves of each machine position in the actual operation of the wind farm, establish a wind wheel model based on the power curves of each machine position, and obtain the theoretical power curve after enhancement after simulation.

[0017] As a preferred solution of the method for customized blade efficiency enhancement based on safety margin for low-speed wind farms described in the present invention, the sampling method of the historical operation data is as follows: the wind speed is divided into ranges, with 0.5m / s as the center and continuous intervals divided by 0.25m / s on the left and right, and the average power of each interval is calculated respectively, and the sampling data in the interval of (μ-1.96σ, μ+1.96σ) is selected to calculate and obtain the average wind speed and average power of the sampling data.

[0018] As a preferred solution of the method for enhancing the efficiency of low-speed wind farms based on customized blades with safety margin according to the present invention, the prototype test and verification divides the entire wind farm into three types of units according to low, medium and high wind speeds, and arranges the units at a machine point corresponding to low, medium and high wind speeds, respectively, and compares the obtained power curve with the actual power curve of the unit previously located at the machine position.

[0019] As a preferred solution of the method for customized blade efficiency enhancement based on safety margin for low-speed wind farms described in the present invention, wherein: the blade efficiency enhancement is customized and designed, the torsion angle of the blade tip chord remains unchanged, the smaller the value of the root chord installation angle, that is, the more the leading edge of the root chord points to the inside of the main blade, the greater the power coefficient of the middle and tip of the main blade, and the power coefficient of the tip winglet itself is slightly reduced.

[0020] As a preferred solution of the method for customized blade efficiency enhancement based on safety margin for low-speed wind farms described in the present invention, wherein: the load calculation is performed according to the wind resource simulation results to construct the whole machine load model, and the wind resource data analysis utilizes the sector analysis method to derive the conduction function between adjacent machine positions, and combines the wind speed and power data of each machine position in the corresponding time period to correct the corresponding nacelle anemometer wind speed, and finally obtains a relatively accurate wind speed, turbulence intensity and wake effect of each machine position.

[0021] Beneficial effects of the invention: Under the premise of ensuring the safety of the whole machine, the invention effectively utilizes the safety margin of the unit, customizes the design of blade efficiency, and maximizes the wind capture capacity of the blade. At the same time, it develops safe, reliable, and cost-effective quality improvement and efficiency enhancement technology for inefficient units, which can significantly improve the unit utilization efficiency of low wind speed wind farms, increase the power generation of the units, and realize the turnaround of loss-making units in low wind speed areas, thereby improving the economic benefits of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0023] Figure 1A basic flow chart of a method for enhancing the efficiency of low-speed wind farm blades based on safety margin customization provided by one embodiment of the present invention;

[0024] Figure 2 A symmetric view of the flow around the blades of a method for enhancing blade efficiency based on safety margin customization in a low-speed wind farm provided by one embodiment of the present invention;

[0025] Figure 3 A parameter angle view of a blade tip winglet design for a safety margin customized blade efficiency enhancement method for a low-speed wind farm provided by an embodiment of the present invention;

[0026] Figure 4 A structural diagram of wind turbine main blade airfoils and NACA airfoils with the same size parameters selected by a method for customized blade efficiency enhancement based on safety margin for a low-speed wind farm provided by an embodiment of the present invention;

[0027] Figure 5 A lift-to-drag ratio curve diagram of two airfoils for a low-speed wind farm based on a safety margin customized blade efficiency enhancement method provided by an embodiment of the present invention;

[0028] Figure 6 A diagram showing the relationship between a high lift-to-drag ratio airfoil and lift in a method for enhancing blade efficiency based on a safety margin customization for a low-speed wind farm provided by an embodiment of the present invention;

[0029] Figure 7 A relationship diagram showing the influence of blade tip winglets at different heights and inclination angles on blade power coefficients in a method for enhancing blade efficiency based on safety margin customization for a low-speed wind farm provided by an embodiment of the present invention; DETAILED DESCRIPTION

[0030] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0033] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0034] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0035] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] Example 1

[0037] Reference Figure 1 , which is an embodiment of the present invention, provides a method for enhancing the efficiency of low-speed wind farm blades based on safety margin customization, such as Figure 1 As shown, the following steps are included:

[0038] S1: Calculate the load based on the wind resource simulation results and build the whole machine load model;

[0039] Furthermore, the wind resource simulation results are based on the historical data obtained from the wind towers at each machine position of the wind farm, as well as the topographic map of the location of the wind farm. A simulation model is established, and the wind resources at each machine position are estimated based on the historical data.

[0040] Furthermore, the historical operation data include the 10-minute average wind speed, the 10-minute average generator speed, the 10-minute average generator power, and the unit power generation data with a sampling interval of 10 minutes, the duration of which is one full year, the statistical values ​​of wind speed data at each machine position with a sampling interval of 10 seconds, air density, turbulence intensity, annual average wind speed and extreme wind speed.

[0041] Furthermore, the sampling method of historical operation data divides the range by wind speed, with 0.5m / s as the center and 0.25m / s on each side as the continuous interval, calculates the average power of each interval, selects the sampling data in the interval (μ-1.96σ,μ+1.96σ), and calculates and obtains the average wind speed and average power of the sampling data.

[0042] S2: Based on the design load of the unit, obtain the unit's safety margin and design the blade efficiency enhancement customization;

[0043] Furthermore, the safety margin is based on wind resource simulation and a correction method for the calculated wind resource results at each machine position. A wind rotor model is established at each machine point, load simulation is performed, and the load simulation results are compared one by one with the simulation results under the corresponding prototype machine standard wind zone. Based on a comprehensive evaluation of each component, the safety margin between the whole machine load at each machine position and the standard design load is obtained.

[0044] Furthermore, the correction method is to obtain the correction factor under different wind speeds based on the ratio of the actual power curve and the theoretical power curve of each position, and bring this correction factor into the theoretical power curve after efficiency enhancement for correction.

[0045] Furthermore, a method for obtaining the theoretical power curve after efficiency improvement is to sample the historical operating data of each machine position, calculate and obtain the average wind speed and average power of the data, calculate the power value of the wind speed point with an interval of 0.5m / s from 0-20m / s, and use this to draw the power curve of each machine position in the actual operation of the wind farm. Based on the power curve of each machine position, a wind rotor model is established, and the theoretical power curve after efficiency improvement is obtained after simulation.

[0046] S3: Simulate the whole machine with blade efficiency enhancement design;

[0047] S4: Based on the simulation results, the load of the whole machine with blade efficiency enhancement design is checked and prototype testing is carried out for verification.

[0048] Furthermore, the prototype test verified that the entire wind farm was divided into three types of units according to low, medium and high wind speeds, and the units were arranged at a machine point corresponding to low, medium and high wind speeds respectively. The power curve obtained was compared with the actual power curve of the unit previously located at the machine position.

[0049] The prototype verification time for each position shall be no less than 6 months, preferably 1 year;

[0050] Comparing the actual calculated power generation with the historical data of the corresponding position before the blade efficiency enhancement design, the improvement effect is no less than 10%.

[0051] Example 2

[0052] In order to facilitate those skilled in the art to clearly and fully understand the technical solution of the present invention, this embodiment further explains the wind resource simulation of S1.

[0053] The low-speed wind farm model is a CFD (computational fluid dynamics) simulation model established according to the wind farm topographic map. The historical data obtained by the wind towers at each machine point in the wind farm are used to infer the wind resources and wake effects at each machine position.

[0054] Wind resource data analysis uses sector analysis methods to derive the conduction function between adjacent aircraft positions, and combines the wind speed and power data of each aircraft position in the corresponding time period to correct the corresponding cabin anemometer wind speed, and finally obtain more accurate wind speed, turbulence intensity and wake impact of each aircraft position.

[0055] In order to facilitate those skilled in the art to clearly and fully understand the technical solution of the present invention, this embodiment further explains the whole machine load model and load calculation in S2.

[0056] Taking the CWT1500-87 wind turbine as an example, according to the CFD wind resource analysis and correction results, a wind rotor (Bladed) model is established for each unit, and load simulation is carried out. According to the design loads of the unit foundation, tower, blades, main bearings, and main shaft components, the load safety margin of the wind rotor model is analyzed, and the blade efficiency enhancement customized design is carried out under the premise of ensuring that the load safety margin is within a certain range.

[0057] In order to facilitate those skilled in the art to clearly and fully understand the technical solution of the present invention, this embodiment further explains S3.

[0058] The average power is calculated as follows:

[0059]

[0060] The interval of 0.25 m / s on each side is taken as a sample, and n represents the total number of samples.

[0061] To improve the reliability of the sample, calculate the sample standard deviation of the standardized data:

[0062]

[0063] Select sampling points in the interval of (μ-1.96σ,μ+1.96σ), that is, 95% of the sampling data, and then calculate the average wind speed and average power of these data. Finally, use the interpolation method to calculate the power value of the wind speed point with an interval of 0.5m / s between 0-20m / s, and draw the power curve of each position in the actual operation of the wind farm.

[0064] Based on the above results, the power generation, i.e. the integral of the product function of the wind frequency distribution function multiplied by the wind power curve over wind speed and time, satisfies the following formula:

[0065]

[0066] Among them, AEP is the annual power generation; N is the wind power curve fitting function of the group number; Vi is the standardized and average wind speed of group i; Pi is the standardized and average output power of group i. By fitting the power generation before and after the efficiency enhancement, the annual power generation efficiency enhancement ratio can be obtained.

[0067] Among them, blade efficiency enhancement includes optimizing blades;

[0068] Based on the wind turbine capture calculation formula Increase the impeller radius R or capacity of the wind turbine.

[0069] Specifically, blade optimization includes: extending the blade tip; extending the blade root; bonding vortex generators to the blade surface; installing Green flaps; and active flow control. All of the above measures are aimed at increasing the absorbed power.

[0070] Tip extension: This means increasing the effective length of the blade to increase the output, but this method increases the load on the blade body, especially the root. Therefore, when this method is used, the strength of the bolts at the root of the blade must be checked. At the same time, as the blade is extended, the linear speed at the tip is faster, and the connection construction process requirements for the extended part must be more stringent.

[0071] Blade root extension section: This is to extend the blade by adding a cylindrical flange at the root of the original blade. However, the cylindrical flange is not beneficial to the aerodynamics of the blade root. This method extends the blade outward in disguise, thereby increasing the tip speed ratio.

[0072] Vortex generators bonded to the blade surface: that is, by bonding vortex generators to the blade surface, the generation of separation flow near the leading edge is delayed, thereby improving the wind energy utilization coefficient CP.

[0073] Install Green flaps: In order to control the flow conditions at the trailing edge of the airfoil, Green flaps are installed on the blades to reduce flow separation on the trailing edge surface of the blades, improve the lift-to-drag ratio, and the aerodynamic performance of the unit.

[0074] Active flow control: Active means are used to reduce the separation of the blade boundary layer and improve CP. For example, air holes can be added at the leading edge of the blade root to actively inhale airflow through the air pump inside the blade.

[0075] Blade efficiency improvement also includes software optimization: upgrading unit control software, adjusting unit control strategy, and adjusting unit control parameters.

[0076] The table lookup method and PI algorithm used by old wind turbines can no longer meet the requirements of existing motors. Therefore, targeted models are optimized and upgraded through wind turbine manufacturers to adapt to the wind resources of wind farms. For example, relevant parameters such as unit yaw, pitch, speed, torque, vibration, temperature, etc. are corrected one by one, and control strategies are updated and optimized.

[0077] In addition, upgrading the main controller, optimizing the main control strategy and increasing the cut-out wind speed are comprehensive optimizations of wind turbines through updating and upgrading the main control program. The main controller upgrade includes PLC upgrade; adjusting the unit control strategy is mainly updating and optimizing; adjusting the unit control parameters, including pitch angle, impeller speed, correcting wind direction parameters and cabin yaw control.

[0078] In general, optimization can be performed through the hardware part, software part and comprehensive part.

[0079] The technical solution of the present application is suitable for the promotion of wind farms where the actual annual average wind speed is far lower than the feasible wind speed. According to the customized blade efficiency enhancement system design based on the effective utilization of the safety margin and the wind turbine optimization efficiency enhancement technology based on the effective utilization of the safety margin, customized design optimization is carried out for the machine models to meet the needs of different machine models.

[0080] On the premise of ensuring the safety of the entire machine, we effectively utilize the safety margin of the unit, customize the design of blade efficiency improvement, maximize the blade's wind capture capacity, and at the same time develop safe, reliable, and cost-effective technology to improve the quality and efficiency of inefficient units. This technology can significantly improve the unit utilization efficiency of low wind speed wind farms, increase the unit's power generation, and achieve the turnaround of loss-making units in low wind speed areas, thereby improving the company's economic benefits.

[0081] Example 3

[0082] To further illustrate the customization of blade efficiency enhancement, a specific design method is provided in this embodiment.

[0083] The design principle is: without changing the main structure of the blade, by optimizing the aerodynamic shape of the unit blade, reducing the tip turbulence loss, improving the wind energy utilization coefficient and the swept area, the wind capture ability of the blade is improved.

[0084] The fluid control equations for simulation calculation are based on the Reynolds averaged NS equations, the k-ω two-equation turbulence model is used for turbulence simulation, and the moving coordinate system method is used to simulate the blade rotation motion. The structured grid is used to discretize the calculation space.

[0085] like Figure 2 As shown, according to the symmetry of the flow around the blade, one-third of the flow field is used in the calculation area, and the velocity inlet, pressure outlet, no-slip blade surface and periodic boundary conditions are applied respectively according to the low-speed incompressible flow characteristics.

[0086] Among them, a is the velocity inlet; b is the periodic boundary; c is the pressure outlet; and d is the blade.

[0087] The calculation area size is 10 and 15 times the blade span length in the upstream and downstream directions respectively, and 10 times the blade span length in the span direction. Multi-block structured grids are used, with a total number of about 38 million grids. The calculation area and blade surface structured grid division are as follows: Figure 2 .

[0088] like Figure 3 As shown, the design parameters of the tip winglet include the airfoil, height H, inclination angle γ, installation angle λ, twist angle θ, and leading edge starting position L of the winglet.

[0089] like Figure 4 As shown, the selected wind turbine main blade airfoil and the blade tip winglet airfoil with the same size parameters of the NACA airfoil structure are calculated. The main blade airfoil has a maximum thickness of 20%, the maximum thickness is located at 24% of the chord length, and the maximum curvature is 2% at 60% of the chord length; the NACA-6412 airfoil has a maximum thickness of 12%, the maximum thickness is located at 30% of the chord length, and the maximum curvature is 6% at 40% of the chord length.

[0090] like Figure 5 As shown, two airfoil lift-to-drag ratio curves: main blade airfoil and NACA-6412 lift-to-drag ratio curve (Re=1.09×106).

[0091] like Figure 6 As shown in the figure, the use of the NACA6412 airfoil with a larger lift-to-drag ratio further increases the negative pressure at the main blade tip, and the power coefficient of the winglet itself also increases. This is because the winglet uses the flow field around the main blade tip to generate an inward lateral force, and the winglet has a certain installation angle and camber angle, so that this lateral force is projected in the lift and thrust direction of the main blade to generate positive lift and positive thrust. Therefore, the positive lift generated by the tip winglet with a large lift-to-drag ratio airfoil is greater, thereby increasing the power coefficient of the winglet itself.

[0092] In order to study the influence of the starting position of the leading edge of the root chord of the winglet at the tip of the wind turbine blade on the power coefficient of the whole blade, the leading edge sweep angle of the winglet is fixed at 6°, the trailing edge sweep angle is 0°, and only the starting position of the leading edge of the root chord of the winglet is changed.

[0093] The leading edge of the root chord of the winglet is closer to the front, which makes the power coefficient of the main blade tip larger. The main reason is that under the calculation state, the main blade tip does not have an excessive adverse pressure gradient on the upper surface to cause airflow separation. After the negative pressure suction peak of the winglet is superimposed on the suction peak of the main blade, the main blade tip generates a greater lift.

[0094] In order to study the influence of the root chord installation angle and tip chord twist angle of the blade tip winglet on the aerodynamic characteristics of the whole blade, the root chord and tip chord of the blade tip winglet are defined as parallel to the tip chord of the main blade as the angle zero, and the installation angle and twist angle are both positive with the leading edge of the winglet pointing outward.

[0095] The tip chord twist angle of the bladelet remains unchanged, and the smaller the root chord installation angle value is, that is, the more the leading edge of the root chord points to the inside of the main blade, the greater the power coefficient of the middle and tip of the main blade, and the power coefficient of the tip winglet itself is slightly reduced. The main reason is that the more the leading edge of the root chord points to the inside of the main blade, the greater the local angle of attack of the winglet under the tip flow field, and the more obvious the compression effect of the winglet on the airflow on the upper surface of the main blade tip, thereby increasing the lift of the middle and tip of the main blade.

[0096] like Figure 7 As shown in the figure, in order to study the influence of winglets with different heights and tilt angles on the blade power coefficient, four winglets with different heights and tilt angles are defined. Case 2 / Case 3 and Case 4 / Case 5 are all different heights under the same tilt angle condition.

[0097] In Case 2 / Case 3 and Case 4 / Case 5, at the same tilt angle, the higher the tip winglet height, the more obvious the effect of the winglet in suppressing the wingtip vortex intensity, thereby reducing the induced drag of the main blade and increasing the lift, the greater the power coefficient of the middle and tip of the main blade, and the greater the power coefficient generated by the winglet itself. In Case 2 / Case 4, when the full blade span is the same, the winglet height has a more obvious effect on improving the power coefficient of the main blade than the tilt angle.

[0098] Based on the load calculation and verification data after the aerodynamic shape of the blades is optimized, as well as the on-site wind resources, a customized control strategy based on environmental conditions is formulated, and relevant parameters such as the yaw, pitch, speed, torque, vibration, and temperature of the unit are corrected one by one.

[0099] Based on the different states of the blades that have been determined, CFD simulation obtains the aerodynamic parameters (CL, Cd, Cm, etc.) of the winglet at different angles of attack, and CFD is used to calculate the aerodynamic loads of the efficiency-enhancing blades under major working conditions, thereby establishing a Bladed equivalent model. This equivalent model is used to simulate the entire machine, including but not limited to all indicators related to the safety of the entire machine, such as the load, clearance, frequency characteristics of the entire machine and its main components.

[0100] Based on the simulation results, the final efficiency-enhancing design of each aircraft position is further confirmed, and on this basis, the detailed design of the internal structure and the lay-up process are carried out.

[0101] According to the simulation results of the whole machine after efficiency enhancement, combined with the simulation results of the standard design of the whole machine before efficiency enhancement, various indicators are compared, and it is ensured that the comparison results of various indicators are within the safety range of the original design. All safety-related indicators need to comply with the relevant specifications of IEC61400.

[0102] On this basis, the verification machine is manufactured to obtain a prototype.

[0103] Test verification:

[0104] The entire wind farm is divided into three types of units according to low, medium and high wind speeds, and the units are arranged at a point corresponding to low, medium and high wind speeds respectively, and the obtained power curve is compared with the actual power curve of the unit previously located at the point. Of course, in order to obtain more accurate verification data, units can be arranged at multiple points corresponding to low, medium and high wind speeds to avoid errors in the units and cause inaccurate parameters.

[0105] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for improving blade efficiency based on safety margin customization for low-speed wind farms, characterized in that: The following steps are involved: Calculate the load based on the wind resource simulation results and build the whole machine load model; Based on the design load of the unit, the unit's safety margin is obtained, and the blade efficiency enhancement customization is designed; Simulate the whole machine with blade efficiency enhancement design; Based on the simulation results, the load of the whole machine with blade efficiency enhancement design is checked and the prototype test is carried out for verification; In the load calculation based on the wind resource simulation results and the construction of the whole machine load model, the wind resource data analysis uses the sector analysis method to derive the conduction function between adjacent positions, and combines the wind speed and power data of the corresponding time period of each position to correct the corresponding cabin anemometer wind speed, and finally obtain the wind speed, turbulence intensity and wake effect of each position; The safety margin is based on wind resource simulation and a correction method for the wind resource calculation results of each machine position. A wind rotor model is established at each machine point to perform load simulation, and the load simulation results are compared one by one with the simulation results of the corresponding prototype machine under the standard wind zone. Then, based on a comprehensive evaluation of each component, the safety margin between the whole machine load at each machine position and the standard design load is obtained; The correction method is to obtain correction factors at different wind speeds based on the ratio of the actual power curve of each position to the theoretical power curve, and bring the correction factors into the theoretical power curve after efficiency enhancement for correction; The method for obtaining the theoretical power curve after efficiency enhancement is to sample the historical operation data of each machine position, calculate and obtain the average wind speed and average power of the data, calculate the power values ​​of wind speed points with an interval of 0.5 m / s between 0 and 20 m / s, and use this to draw the power curves of each machine position in the actual operation of the wind farm. Based on the power curves of each machine position, a wind wheel model is established, and the theoretical power curve after efficiency enhancement is obtained after simulation.

2. The method for enhancing the efficiency of low-speed wind farm blades based on safety margin customization according to claim 1, characterized in that: The wind resource simulation result is based on the historical operation data obtained from the wind towers at each position of the wind farm and the topographic map of the location of the wind farm, to establish a simulation model, and to estimate the wind resources at each position based on the historical operation data.

3. The method for increasing the efficiency of low-speed wind farm blades based on safety margin customization according to claim 2, characterized in that: The historical operation data include the 10-minute average wind speed, the 10-minute average generator speed, the 10-minute average generator power, and the unit power generation data with a sampling interval of 10 minutes, the duration of which is one full year, the statistical values ​​of wind speed data for each machine position with a sampling interval of 10 seconds, air density, turbulence intensity, annual average wind speed and maximum wind speed.

4. The method for enhancing the efficiency of low-speed wind farm blades based on safety margin customization according to claim 3, characterized in that: The sampling method of the historical operation data is to divide the range by wind speed, with 0.5m / s as the center and continuous intervals divided by 0.25m / s on the left and right, calculate the average power of each interval respectively, select sampling data in the interval of (μ-1.96σ,μ+1.96σ), calculate and obtain the average wind speed and average power of the sampling data.

5. The method for enhancing the efficiency of low-speed wind farm blades based on safety margin customization according to claim 4, characterized in that: The prototype test verification divides the entire wind farm into three types of units according to low, medium and high wind speeds, and arranges the units at a machine position corresponding to low, medium and high wind speeds respectively. The obtained power curve is compared with the actual power curve of the unit at the same machine position when the blade efficiency enhancement design is not adopted.

6. The method for improving the efficiency of low-speed wind farm blades based on safety margin customization according to claim 5, characterized in that: The blade efficiency enhancement is customized and designed, the tip chord twist angle of the bladelet remains unchanged, the smaller the root chord installation angle value is, that is, the more the leading edge of the root chord points to the inside of the main blade, the greater the power coefficient of the middle and tip of the main blade, and the power coefficient of the tip winglet itself is slightly reduced.

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