Wind turbine blade wake wind field characteristics measurement system and method

Abstract

The present invention discloses a wind field characteristic measurement system and method for the wake of a wind turbine blade, comprising a traction device, which is arranged at a height position N times that of a wind turbine and is located in the wake area of ​​the wind turbine; a traction rope, one end of which is connected to the traction device and the other end is fixedly connected to the ground; a plurality of wind speed acquisition devices, which are arranged on the traction rope along the height direction of the traction rope; and an accelerometer, which is installed on the traction rope. The present invention can synchronously measure the real-time wind speed of measuring points at different heights, and can conveniently and quickly switch the measurement position, so as to facilitate accurate and efficient acquisition of the wind field distribution in the wake area of ​​the wind turbine.

Description

Technical Field

[0001] The present invention relates to the technical field of wind field characteristic measurement, and in particular to a system and method for measuring wind field characteristics of a fan blade wake. Background Art

[0002] The wind turbine wake effect has a serious impact on the performance of downstream wind turbines. In order to reduce the output power loss of downstream wind turbines and increase the life of wind turbines, it is very necessary and urgent to carry out research on the wind field characteristics of wind turbine wakes. However, in field measurements, it is still very difficult to accurately measure the wind field characteristics of wind turbine wakes due to the scale relationship of the actual wind turbine wake flow field and the limitations of testing methods. The existing technology uses sodar and lidar to measure the characteristics of wind turbine wakes, but their cost is very expensive and cannot be widely used. At present, the most commonly used method is to place a wind tower behind the wind turbine to measure the wake characteristics, but due to cost constraints, only limited wake positions can be measured, and it is difficult to obtain flow field information in all directions. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a system and method for measuring the wind field characteristics of a wind turbine blade wake, so as to synchronously measure the time-course wind speed at different height measurement points, in view of the deficiencies in the prior art.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a wind turbine blade wake wind field characteristic measurement system, comprising:

[0005] The traction device is arranged at a height position of N times (in the present invention, N=1.1-1.3) the fan and is located in the wake area of ​​the fan;

[0006] A traction rope, one end of which is connected to the traction device and the other end of which is fixedly connected to the ground;

[0007] A plurality of wind speed collection devices are arranged on the traction rope along the height direction of the traction rope;

[0008] An accelerometer is installed on the traction rope.

[0009] In the present invention, a plurality of wind speed collection devices are evenly arranged on the traction rope, thereby improving calculation accuracy.

[0010] In order to further improve the calculation accuracy and reduce the amount of calculation, the accelerometer is installed in the middle of the traction rope.

[0011] The wind speed collection device includes a probe; a mounting groove and a through hole are respectively provided on the left and right sides of the center line of the probe; the bottom end of the first probe penetrates the probe from the mounting groove and extends out of the probe; the bottom of the mounting groove is fixedly connected to the top end of the second probe; the traction rope passes through the through hole; the wind speed collection device of the present invention has a simple structure and strong practicality.

[0012] The bottom ends of the first probe and the second probe are both fixedly connected to the pressure measuring tube, which facilitates the connection and fixation of the probes.

[0013] The traction rope is fixedly connected to an anchor frame arranged on the ground, and the anchor frame can be moved to facilitate adjustment of the position of the bottom end of the traction rope.

[0014] Preferably, the length of the traction rope is 1.1 to 1.3 times the test height to ensure the safety of the drone and prevent the traction rope from being too tight and causing the traction device to overturn.

[0015] A scanning valve is arranged at the top of the anchor frame; the multiple wind speed collection devices are all electrically connected to the scanning valve, so that the wind field signal at the probe position can be quickly and accurately acquired.

[0016] Preferably, the scanning valve is electrically connected to a computer to facilitate timely transmission of the collected information to the computer for processing.

[0017] The traction device is a drone;

[0018] Preferably, it also includes a plurality of GPS locators, which are respectively installed on the bottom of the drone, the middle of the traction rope and the ground.

[0019] The measured wind speed of the i-th wind speed collection device is corrected, and the actual wind speed at the location of the i-th wind speed collection device is obtained as:

[0020]

[0021] Among them, V i 欧 is the wind speed collected by the i-th wind speed collection device; is the tilt correction coefficient of the i-th wind speed collection device; i is the number of the wind speed collection device. From the ground to the traction device position, the numbers of all wind speed collection devices are 1, 2, 3, ..., n; f(t) is the collection signal of the accelerometer at time t; i = 1, 2, 3, ..., n; H is the test height, that is, the hovering height of the drone; θ is the angle between the center line of the wind speed collection device and the horizontal direction.

[0022] The angle θ between the center line of the i-th wind speed measuring device and the horizontal direction i The calculation formula is: n is the total number of wind speed measuring devices on the traction rope; c is the multiple of the traction rope length and the test height H.

[0023] The present invention also provides a method for measuring the wind field characteristics of the wake of a fan blade, wherein a plurality of measuring points are set in a wind tunnel in the wake area of ​​the fan blade along the height direction from the ground to the top of the fan, and a wind speed collection device is set at each measuring point; the actual wind speed of the i-th measuring point is obtained using the following formula:

[0024]

[0025] Among them, V i 欧 is the wind speed collected by the i-th wind speed collection device; is the tilt correction coefficient of the i-th wind speed collection device; i is the number of the wind speed collection device. From the ground to the traction device position, all wind speed collection devices are numbered 1, 2, 3, ..., n; f(t) is the collection signal of the accelerometer at time t; i = 1, 2, 3, ..., n; H is the test height, that is, the hovering height of the drone; θ is the angle between the center line of the wind speed collection device and the horizontal direction.

[0026] The angle θ between the center line of the wind speed measuring device corresponding to the i-th measuring point and the horizontal direction i The calculation formula is:

[0027]

[0028] Wherein, n is the total number of wind speed measuring devices on the traction rope; c is the length of the traction rope connecting all wind speed collection devices in series and a multiple of H; preferably, c is 1.1 to 1.3.

[0029] The wind direction angle α of the incoming wind speed is calculated according to the following formula, which makes up for the defect that the Owen probe cannot measure wind direction:

[0030]

[0031] Among them: (x1, y1, z1) are the coordinates of the anchor point of the anchor frame; (x2, y2, z2) are the coordinates of the middle part of the traction rope; (x3, y3, z3) are the coordinates of the position of the traction device.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention can synchronously measure the real-time wind speed at measuring points at different heights, and can conveniently and quickly switch the measuring position, thereby facilitating accurate and efficient acquisition of the wind field distribution in the wind turbine wake area.

[0034] 2. The present invention is provided with a mobile fixed frame (anchor frame) and a load-carrying drone. Since the wind field in the wind turbine wake area is very complex, it is difficult to find a suitable measurement position. The mobile fixed frame and the load-carrying drone can conveniently and flexibly switch the measurement position, thereby obtaining wind field data of multiple measurement positions in the wake area.

[0035] 3. The pressure difference at different monitoring points on the high-strength thin rope (traction rope) is measured through the Owen probe (wind speed collection device) and the scanning valve, and then converted into wind speed, so as to accurately obtain the time-course wind speed of the measuring point.

[0036] 4. Multiple Owen probes are installed on the high-strength thin rope, which can synchronously measure the time-course wind speed at measuring points at different heights, thereby obtaining the wind speed profile at the measuring location.

[0037] 5. Through wind tunnel tests, the law of the vertical angle of the swing of high-strength thin rope and the speed of the incoming wind was studied, which can be used to correct the measured wind speed.

[0038] 5. The acceleration of the swing in the middle of the high-strength thin rope is tested by an acceleration sensor, and then converted into the swing speed of the thin rope for correction of the measured wind speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the on-site measurement system of the wind field characteristics of the wind turbine blade wake of the present invention;

[0040] Figure 2 This is a schematic diagram of the structure of the Owen probe according to an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of wind speed probe inclination calibration;

[0042] Figure 4 Schematic diagram of wind tunnel calibration of the measurement system;

[0043] Figure 5 This is a schematic diagram of the shape of a high-strength thin rope (traction rope);

[0044] Figure 6 Vertical test system for wind energy in mountainous areas. DETAILED DESCRIPTION

[0045] like Figure 1As shown, it includes a traction module and a measurement module. The traction module includes a load-carrying drone 3 (traction device), a lock 4, a high-strength thin rope 5 (traction rope), a cable tie 8 and an anchor frame 11. The measurement module includes an Owen probe 6, a pressure measuring tube 7, an accelerometer 9, a scanning valve 10, a collection host 13 and a computer 14. The mobile anchor frame 11 is set on the ground 12 in the wake area of ​​the wind turbine 2. The high-strength thin rope 5 is connected to the anchor frame 11 at one end through the lock 4, and is connected to the load-carrying drone 3 at the other end, and is pulled to the height of the top of the wind turbine by the load-carrying drone 3. The accelerometer 9 is installed in the middle of the high-strength thin rope 5, and the Owen probe 6 is evenly fixed on the high-strength thin rope 5, and is connected to the scanning valve 10 fixed on the anchor frame 11 (a mobile bracket) through the pressure measuring tube 7. The scanning valve 10 is also connected to the collection host 13. 1 is a GPS locator, which is installed on the drone, the middle of the thin rope and the ground respectively, and can be used to obtain three-dimensional coordinates of different positions.

[0046] The traction module load-carrying UAV 3, high-strength thin rope 5, and anchor frame 11 are flexible and simple, not limited by the terrain, and can easily switch the measurement position. The pressure measuring tube 7 is tightly combined with the high-strength thin rope 5 through multiple tie bands 8, which has little impact on the wind field. The overall light weight has little impact on the flight time of the load-carrying UAV 3.

[0047] The Owen probe used in this embodiment is as follows Figure 2 As shown, the diameter of the probe 15 is 15 mm, and a hole 16 is opened on the right side of the center of the probe 15. The high-strength string 5 passes through the hole C to fix the Owen probe; a slot 17 is opened on the left side of the center of the probe, and a hollow steel needle 18 with a diameter of 1 mm is inserted in the center of the slot, and another hollow steel needle 19 with a diameter of 1 mm is arranged at the lower end of the slot. One end of the pressure measuring tube 7 is connected to the bottom ends of the hollow steel needles 18 and 19, and the other end is connected to the scanning valve 10. The scanning valve 10 measures the pressure at the A and B ends of the Owen probe through the pressure measuring tube 7. Multiple pressure measuring tubes 7 are arranged, and the specific number depends on the number of Owen probes 6.

[0048] The scanning valve 10 is fixed on the top of the anchor frame 11 to reduce the length of the pressure measuring tube 7, shorten the tube length, and thus reduce the measurement error. The scanning valve 10 is connected to the acquisition host 13 on the ground through a data line, and the pressure signal is converted into an electrical signal and transmitted to the acquisition host 13. The acquisition host 13 is directly connected to the computer 14, and the pressure time course data is transmitted to the computer 14, and the pressure is converted into speed through processing by the computer 14.

[0049] Since the high-strength string will swing with the wind during the measurement process, the wind speed measured by the probe needs to be corrected at the end. According to the analysis, the measured wind speed is related to the angle θ between the high-strength string and the horizontal direction. Therefore, the wind speed measured by the Owen probe at different angles is tested in the wind tunnel 20 to establish the relationship between the wind speed measured by the probe at different angles and the actual wind speed, such as Figure 4 shown.

[0050] In the wind tunnel 20, the Cobra anemometer 21 is arranged 1 meter in front of the line connecting the drone and the anchor point. One end of the high-strength thin rope 5 with the Owen probe 6 is fixed to the bottom of the wind tunnel, and the other end is connected to the top of the wind tunnel. Then, the angle θ of the Owen probe can be adjusted by moving the position of the connection point, so as to establish the relationship between the wind speed measured by the probe at different angles and the actual wind speed:

[0051]

[0052] Where: V 测 It is the actual wind speed measured by the Cobra anemometer; V is the Owen probe tilt correction coefficient, and its value is related to the tilt angle; 欧 Indicates the wind speed measured by the Owen probe.

[0053] In the actual measurement process of the wind turbine wake wind field, since the swing of the high-strength thin rope with the wind will affect the measured wind speed of the Owen probe on the thin rope, the relationship between the swing of the high-strength thin rope with the wind and the measured wind speed can be measured through wind tunnel tests, such as Figure 5 shown.

[0054] In the wind tunnel 20, the load-carrying drone 3 tows one end of a high-strength thin rope 5 with an Owen probe 6, and the other end of the high-strength thin rope is connected to the bottom of the wind tunnel. The Cobra anemometer 21 is arranged 1 meter in front of the connection point between the high-strength thin rope and the ground, and an accelerometer 9 is installed in the middle of the high-strength thin rope 5.

[0055] In the actual measurement process, since the high-strength thin rope will swing with the wind, it is also necessary to measure the speed of the thin rope swinging for the correction of the measured wind speed. The accelerometer measures the acceleration of the middle part of the thin rope as a, which is a function that changes with time t and can be expressed as:

[0056] a=f(t) (2)

[0057] According to the relationship between velocity and acceleration The swing speed of the middle part of the rope is:

[0058]

[0059] Assuming the length of the high-strength string is c times the hovering height H of the drone, it is approximately assumed that the high-strength string is distributed in an elliptical nonlinear manner in the air, as shown in the figure below. Figure 6 It can be seen that the major axis of the ellipse a = H / 2, and according to the ellipse circumference formula L = 2πb + 4(ab), the minor axis b value can be calculated as follows.

[0060] 2cH=2πb+4(H / 2-b) (4)

[0061]

[0062] From the above, we can see that the major axis of the ellipse is a = H / 2, and the minor axis is Let the horizontal direction be the X axis and the horizontal direction be the Y axis, such as Figure 6 As shown, the function expression of high-strength thin rope is:

[0063]

[0064]

[0065] From formula (4), we know that the swing speed of the middle part of the high-strength thin rope is The swing speed of the high-strength thin rope at different heights is for:

[0066]

[0067] Where H is the height of the drone; n is the number of Owen probes; c is the multiple of the high-strength rope length and H.

[0068] Since the high-strength string is distributed in an elliptical nonlinear manner in the air, each probe on the high-strength string has an angle θ with the horizontal direction, such as Figure 6 As shown, the slope k is obtained by differentiating x in equation (6):

[0069]

[0070] Substituting formula (7) into formula (9), we get:

[0071]

[0072] Because the angle θ between the Owen probe and the horizontal direction and the slope k have the following relationship:

[0073] θ=arctank (11)

[0074] Therefore, the angle θ between the probes at different heights on the high-strength string and the horizontal direction is i for:

[0075]

[0076] Where H is the hovering height of the UAV (test height); n is the number of Owen probes; c is the multiple of the high-strength thin rope length and H.

[0077] Therefore, the actual wind speed after correction of the wind speed measured by each probe is:

[0078]

[0079] The wind field characteristic measurement system of the fan blade wake based on field measurements can synchronously measure the time-course wind speeds at measuring points at different heights, and can conveniently and quickly switch the measuring positions to efficiently and accurately obtain the wind field distribution in the fan wake area.

[0080] The present invention installs three GPS coordinate locators on the drone, the middle of the string and the ground, respectively, and can obtain the three-dimensional coordinates of the three positions. Since the coordinates of the top and bottom are fixed, when the incoming wind direction changes, the coordinates of the middle of the string will show different values. Suppose the coordinates of the ground anchor point are (x1, y1, z1), the coordinates of the middle of the string are (x2, y2, z2), and the coordinates of the drone towing position are (x3, y3, z3). Through the geometric relationship, the wind direction angle α of the incoming wind speed can be obtained as follows:

[0081]

Claims

1. A wind turbine blade wake wind field characteristics measurement system, characterized in that: include: The traction device is arranged at a height N times that of the wind turbine and is located in the wake area of ​​the wind turbine; A traction rope, one end of which is connected to the traction device and the other end of which is fixedly connected to the ground; A plurality of wind speed collection devices are arranged on the traction rope along the height direction of the traction rope; an accelerometer, mounted on the traction rope; The measured wind speed of the i-th wind speed collection device is corrected, and the actual wind speed at the location of the i-th wind speed collection device is obtained as: Among them, V i 欧 is the wind speed collected by the i-th wind speed collection device; is the tilt correction coefficient of the i-th wind speed collection device; i is the number of the wind speed collection device. From the ground to the traction device position, all wind speed collection devices are numbered 1, 2, 3, ..., n in sequence; f(t) is the collection signal of the accelerometer at time t; i = 1, 2, 3, ..., n; H is the test height, that is, the hovering height of the drone; θ is the angle between the center line of the wind speed collection device and the horizontal direction.

2. The wind turbine blade wake wind field characteristic measurement system according to claim 1 is characterized in that: The multiple wind speed collection devices are evenly arranged on the traction rope.

3. The wind turbine blade wake wind field characteristic measurement system according to claim 1, characterized in that: The accelerometer is installed in the middle of the traction rope.

4. The wind turbine blade wake wind field characteristic measurement system according to claim 1, characterized in that: The wind speed collection device includes a probe; a mounting groove and a through hole are respectively provided on the left and right sides of the center line of the probe; the bottom end of the first probe penetrates the probe from the mounting groove and extends out of the probe; the bottom of the mounting groove is fixedly connected to the top end of the second probe; the traction rope passes through the through hole.

5. The wind turbine blade wake wind field characteristic measurement system according to claim 4, characterized in that: The bottom end of the first probe and the bottom end of the second probe are each fixedly connected to a pressure measuring tube.

6. The wind turbine blade wake wind field characteristic measurement system according to any one of claims 1 to 4, characterized in that: The traction rope is fixedly connected to an anchor frame arranged on the ground.

7. The wind turbine blade wake wind field characteristic measurement system according to claim 6, characterized in that: The length of the traction rope is 1.1 to 1.3 times the test height.

8. The wind turbine blade wake wind field characteristic measurement system according to claim 6, characterized in that: A scanning valve is arranged at the top of the anchoring frame; and the plurality of wind speed collection devices are all electrically connected to the scanning valve.

9. The wind turbine blade wake wind field characteristic measurement system according to claim 8, characterized in that: The scanning valve is electrically connected to the computer.

10. The wind turbine blade wake wind field characteristic measurement system according to claim 1, characterized in that: The traction device is a drone.

11. The wind turbine blade wake wind field characteristic measurement system according to claim 10, characterized in that: It also includes multiple GPS locators, which are installed on the bottom of the drone, the middle of the traction rope and the ground.

12. The wind turbine blade wake wind field characteristic measurement system according to claim 1, characterized in that: The angle θ between the center line of the i-th wind speed collection device and the horizontal direction i The calculation formula is: n is the total number of wind speed collection devices on the traction rope; c is the multiple of the traction rope length of all wind speed collection devices connected in series and the test height H.

13. A method for measuring the wind field characteristics of a fan blade wake using the system according to any one of claims 1 to 12, characterized in that: In the wind tunnel in the wake area of ​​the fan blade, multiple measuring points are set along the height direction from the ground to the top of the fan, and a wind speed collection device is set at each measuring point; the actual wind speed at the i-th measuring point is obtained using the following formula: Among them, V i 欧 is the wind speed collected by the i-th wind speed collection device; is the tilt correction coefficient of the i-th wind speed collection device; i is the number of the wind speed collection device. From the ground to the traction device position, all wind speed collection devices are numbered 1, 2, 3, ..., n; f(t) is the collection signal of the accelerometer at time t; i = 1, 2, 3, ..., n; H is the test height, that is, the hovering height of the drone; θ is the angle between the center line of the wind speed collection device and the horizontal direction.

14. The method according to claim 13, characterized in that The angle θ between the center line of the wind speed collection device corresponding to the i-th measurement point and the horizontal direction i The calculation formula is: Wherein, n is the total number of wind speed collection devices on the traction rope; c is the length of the traction rope connecting all wind speed collection devices in series and a multiple of H.

15. The method according to claim 14, characterized in that The value of c is 1.1~1.

3.

16. The method according to claim 14, characterized in that The wind direction angle α of the incoming wind speed is calculated according to the following formula: Among them: (x1, y1, z1) are the coordinates of the anchor point; (x2, y2, z2) are the coordinates of the middle of the traction rope; (x3, y3, z3) are the coordinates of the UAV traction position.

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