Method and equipment for evaluating beam efficiency of wind turbine airborne wind laser radar

Abstract

This invention provides a method and device for evaluating the beam efficiency of an airborne wind-measuring lidar for wind turbines. The method includes: acquiring the blade diameter and blade chord length under different cross-sectional conditions, the blade pitch angle and rotor azimuth angle under different operating conditions, the hub diameter and hub rotation speed, the spatial position of the airborne wind-measuring lidar, and the parameters of the emitted lidar beam. The lidar beam parameters include the lidar beam switching frequency. The method calculates the number of times the lidar beam is not blocked by the blades. The efficiency of each lidar beam is obtained by dividing the number of times the lidar beam is not blocked by the blades by the number of times the lidar beam switches and the switching frequency. This invention can solve the problem that after large-megawatt wind turbines are in operation, blade obstruction reduces the efficiency of wind condition information measured by nacelle-mounted lidar at the turbine rotor front end, increasing the amount of useless wind condition information fed back to the turbine rotor front end. This, in turn, leads to increased redundancy errors and prevents the turbine from generating electricity normally according to design requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine generator sets, and in particular to a method and device for evaluating the efficiency of a beam of an airborne wind-measuring laser radar of a wind turbine generator set. Background Art

[0002] A wind turbine is a device that converts wind energy into kinetic energy, and then into electrical energy. It is mainly composed of a wind rotor system, a transmission chain system, a nacelle system, and a tower system. An airborne wind laser radar is a device installed on the top of the nacelle system to measure the wind within a certain distance from the front end of the wind rotor.

[0003] In recent years, under the severe pressure of cost reduction in the market, wind turbine manufacturers have had to optimize the design of their wind turbines in line with market changes. Nacelle-type lidar has become the only choice for optimizing the design of wind turbines, because it can transmit the wind condition information (wind speed, wind direction, wind shear, turbulence, etc.) detected at the front end of the wind rotor to the wind turbine. The wind turbine uses the wind condition information to make reasonable judgments, such as precise yaw control of wind, turbulence pre-pitch control, wake optimization control, and minimum clearance protection control, etc., to increase the power generation of the unit while reducing the load on the unit, thereby achieving the purpose of optimizing the design of the generator set.

[0004] However, with the rapid development of large-megawatt wind turbines on land and at sea, the use of nacelle-type lidar for power testing and control is also limited. Specifically, the hub diameter and blade root diameter of the wind rotor system become larger, resulting in a decrease in the efficiency of the wind condition information at the front end of the wind rotor measured by the lidar, a decrease in the useful wind condition information, and an increase in useless wind condition information. The more useless wind condition information fed back to the front end of the wind rotor of the unit, the longer the test cycle will undoubtedly be and the higher the test cost; at the same time, due to the poor data quality caused by the increase in useless wind condition information, the redundancy error of the unit will also be large, and the unit cannot generate electricity normally according to the design requirements. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention proposes a method and device for evaluating the efficiency of an airborne wind measuring laser radar beam of a wind turbine set to solve the technical problems existing in the prior art: for large-megawatt wind turbines, the efficiency of the wind condition information at the front end of the wind rotor measured by the nacelle-type laser radar will be reduced due to blade shading after the operation of the wind turbine set, and the amount of useless wind condition information fed back to the front end of the wind rotor of the set will increase, which in turn affects the redundant error of the set and makes the set unable to generate electricity normally according to the design requirements.

[0006] The technical solution adopted by the present invention is as follows:

[0007] In a first aspect, a method for evaluating the beam efficiency of an airborne wind laser radar for a wind turbine is provided, comprising the following steps:

[0008] Obtaining the blade diameter and blade chord length under different cross-sectional states, the blade pitch angle and wind rotor azimuth angle under different working conditions, the hub diameter and hub speed, the spatial position of the airborne wind measuring laser radar, and the parameters of the emitted radar beam; the radar beam parameters include the radar beam switching frequency;

[0009] Count the number of times the radar beam is not blocked by the blades;

[0010] The lidar beam effectiveness is calculated based on the number of times the radar beam is not blocked by the blades, the number of times the radar beam is emitted, and the radar beam switching frequency.

[0011] Furthermore, the spatial position of the airborne wind measuring laser radar includes the vertical distance between the laser radar and the hub center, the vertical distance between the laser radar and the center line of the cabin, and the horizontal distance between the laser radar and the wind rotor plane;

[0012] The radar beam parameters also include the radar beam vertical angle and the radar beam horizontal angle.

[0013] Furthermore, the number of times the radar beam is not blocked by the blades is calculated, including:

[0014] When the laser radar beam point falls into the following intervals, the radar beam is not blocked by the leaves:

[0015]

[0016] In the above formula, It represents the motion displacement of the beam point on the straight line segment at a certain point in time. represents the length of the straight line segment; Corresponding to the situation where the beam point from the starting point to the first leaf is blocked, Corresponding to the situation from the starting point to the beam point before being blocked by the second blade, Corresponding to the situation where the beam point from the starting point to the second leaf is blocked, Corresponding to the situation from the starting point to the beam point before being blocked by the third blade, Corresponding to the situation where the beam point from the starting point to the beam point is blocked by the third blade, Corresponds to the situation from the starting point to the hub driving the blade to rotate one circle; the starting point corresponds to the moment when the hub drives the blade to start rotating; the length of each straight line segment satisfies .

[0017] Furthermore, motion displacement It is calculated as follows:

[0018]

[0019] In the above formula, represents the diameter of a circle, which is formed by the trajectory of the points on the wind wheel surface emitted by the laser radar in sequence. The circumference of the circle is equal to the circumference of the straight line segment. are the same length;

[0020] represents the wind rotor azimuth, Indicates the wheel hub speed, Indicates time, represents the initial time, Indicates the time required for the hub to rotate.

[0021] Furthermore, the circle diameter It is calculated as follows:

[0022]

[0023] In the above formula, Indicates the vertical distance between the laser radar and the center of the wheel hub. Indicates the distance between the laser radar and the wind wheel plane, represents the vertical angle of the radar beam, represents the horizontal angle of the radar beam, Indicates the vertical distance between the laser radar and the centerline of the cabin.

[0024] Furthermore, the circle diameter should be larger than the hub diameter.

[0025] Furthermore, the length of each straight line segment is calculated as follows:

[0026]

[0027] In the above formula, represents the diameter of a circle, represents the blade chord length, Indicates the blade pitch angle.

[0028] Furthermore, the number of times the radar beam is not blocked by the blades is divided by the quotient of the number of times the radar beam is emitted and the radar beam switching frequency to obtain the laser radar beam efficiency.

[0029] Furthermore, the airborne wind measurement lidar has at least four laser transmitters.

[0030] In a second aspect, an electronic device is provided, including:

[0031] One or more processors; a storage device for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors implement the method for evaluating the efficiency of the wind turbine airborne wind laser radar beam provided in the first aspect.

[0032] It can be seen from the above technical solution that the beneficial technical effects of the present invention are as follows:

[0033] 1. The complex three-dimensional model is converted into multiple plane models, and the rotation of the wind wheel is equivalent to the rotation of the light beam around the hub at an equal speed. The principle of relative motion is used to derive an evaluation method for the efficiency of the airborne wind laser radar beam, which can be applied to both the model development stage and the unit operation stage.

[0034] 2. After using this method to obtain the efficiency evaluation results of the radar beam, it is possible to avoid the problems of long power curve test cycle, large redundant errors in unit power increase and load reduction control, and the unit being unable to generate electricity normally according to design requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the prior art description. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0036] Figure 1 Schematic diagram of a laser radar beam efficiency evaluation method according to an embodiment of the present invention;

[0037] Figure 2 Schematic diagram of radar beam emission of an airborne wind laser radar according to an embodiment of the present invention Figure 1 ;

[0038] Figure 3 Schematic diagram of radar beam emission of an airborne wind laser radar according to an embodiment of the present invention Figure 2 ;

[0039] Figure 4 A schematic diagram of a circle formed by a radar beam spot trajectory according to an embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram of an embodiment of the present invention showing the arc motion of a radar beam around the center of a wind wheel as the motion of a beam point on a straight line;

[0041] Reference numerals:

[0042] 1-blade, 2-hub, 3-laser radar, 4-nacelle, 5-tower, 6-a beam point emitted by the laser radar;

[0043] The distance between the laser radar and the wind wheel plane, The vertical distance between the laser radar and the center of the wheel hub, The vertical angle of the radar beam, The horizontal angle of the radar beam, The vertical distance between the laser radar and the centerline of the cabin. DETAILED DESCRIPTION

[0044] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0045] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the invention belongs.

[0046] This embodiment provides a method for evaluating the efficiency of a wind turbine airborne wind laser radar beam. Figure 1 As shown, the following steps are included:

[0047] Step 1: Obtain the blade diameter and blade chord length under different cross-sectional states, blade pitch angle and wind rotor azimuth under different working conditions, hub diameter and hub speed, spatial position of the airborne wind laser radar, and parameters of the emitted radar beam.

[0048] Through the design file data, the chord length of the blade under different cross-sectional conditions can be directly read, that is, the length of the reference straight line connecting the leading edge to the trailing edge of the blade airfoil section.

[0049] Through the existing main control system of the wind turbine, the changes in the corresponding blades under different working conditions, that is, the blade pitch angle; and the state of the wind rotor at this time, that is, the wind rotor azimuth angle, can be directly read.

[0050] The hub speed can be directly read through the existing main control system of the wind turbine; the hub diameter can be obtained through design documents or on-site measurements.

[0051] The spatial position of the airborne wind measuring lidar includes: the vertical distance between the lidar and the center of the hub, the vertical distance between the lidar and the centerline of the cabin, and the horizontal distance between the lidar and the wind rotor plane. The above three distances can be obtained through design documents or on-site measurements.

[0052] The radar beam parameters emitted by the airborne wind measurement lidar include: the vertical angle of the radar beam, the horizontal angle of the radar beam, and the switching frequency of the radar beam; the radar beam parameters can be read through the existing main control system of the wind turbine.

[0053] Step 2: Calculate the number of times the radar beam is not blocked by the blades

[0054] Radar beam emission of airborne wind laser radar, such as Figure 2 , Figure 3If the radar beam is always blocked, then it is definitely not just the blades that block the beam. Therefore, it can be understood that the radar beam will hit the hub 2, which should meet the following conditions: the laser radar emits multiple beam points 6 in time, assuming that the diameter of the circle I formed by the point trajectory of the laser radar plane beam hitting the hub , must be less than or equal to the wheel hub diameter ,Right now Therefore, it is necessary to ensure that the diameter of the circle formed by the point trajectory of the laser radar lower plane beam projected onto the hub Larger than wheel hub diameter , see the schematic diagram Figure 4 . The calculation is shown in the following formula (1):

[0055]

[0056] In the above formula (1), Indicates the vertical distance between the laser radar and the center of the wheel hub. Indicates the distance between the laser radar and the wind wheel plane, Indicates the vertical angle of the radar beam (definition: calculation of the diameter of the circle of the upper plane beam calculation For positive values, the diameter of the circle calculated by the lower plane beam is a negative value), represents the horizontal angle of the radar beam, Indicates the vertical distance between the laser radar and the center line of the cabin (definition: the radar is installed on the left side of the center of the cabin and the left beam of the radar is a positive value, the right beam is a negative value and vice versa).

[0057] Based on the theory of relative motion, assuming that the rotating wind wheel is a stationary coordinate system, the trajectory formed by the multiple beam points emitted by the laser radar in sequence can also be expressed as a circle moving around the center of the wind wheel, that is, a circle formed by the point trajectory of the multiple beam points emitted in sequence and projected onto the wind wheel surface (the plane formed by the wind turbine blades rotating one circle). Figure 4 In this way, the arc motion of the laser radar beam around the center of the wind wheel can be expressed as a theoretical model of the beam point moving on a straight line, as shown in Figure 5 As shown, 1 represents a blade, and there are 3 blades; the straight line segment The length of is equal to the length of circle I or circle II, and the length of each straight line segment satisfies: .in Corresponding to the situation where the beam point from the starting point to the first leaf is blocked, Corresponding to the situation from the starting point to the beam point before being blocked by the second blade, Corresponding to the situation where the beam point from the starting point to the second leaf is blocked, Corresponding to the situation from the starting point to the beam point before being blocked by the third blade, Corresponding to the situation where the beam point from the starting point to the beam point is blocked by the third blade, Corresponding to the situation from the starting point to the hub driving the blades to rotate one circle. Those skilled in the art should understand that the starting point corresponds to the moment when the hub drives the blades to start rotating. The wind turbine has three blades, namely the first, second and third blades. When the hub drives the blades to rotate, the beam point may be blocked by the three blades in turn.

[0058] Beam point 6 from the straight line segment The movement from the leftmost to the rightmost corresponds to the circle I (beam point on the lower radar plane) and circle II (beam point on the upper radar plane) formed by the hub rotating around the center of the wind wheel. Figure 5 It can be seen that when the hub rotates around the center of the wind wheel, when the beam point 6 moves to the position of blade 1 on the straight line segment, the beam will be blocked by the blade. Suppose the corresponding motion displacement of the beam point 6 on the straight line segment at a certain time point is , when beam spot 6 is located at Figure 5 The following intervals in the image indicate that the beam will be blocked:

[0059] (2)

[0060] The intervals where the beam is not blocked include:

[0061] (3)

[0062] For displacement As time goes by and the radar beam switches, the wind wheel azimuth is used, and then the rotation speed of the hub is used to obtain the displacement of beam point 6 at a certain point in time. , calculated as follows:

[0063]

[0064] In the above formula (4), Indicates the diameter of circle Ⅰ or Ⅱ, represents the wind rotor azimuth, Indicates the wheel hub speed, Indicates time, represents the initial time, Indicates the time required for the hub to rotate. Indicates Divide the previous number by Take the remainder of the number that follows.

[0065] For each straight line segment, the calculation method is as follows (5):

[0066]

[0067] In the above formula (5), Indicates the diameter of circle I or circle II, represents the blade chord length, represents the blade pitch angle, It represents the length of the blade's chord width projected onto the rotor plane.

[0068] Compared with the existing traditional wind turbine airborne wind measurement lidar which only has two laser emitters, the airborne wind measurement lidar used in this method has four or more laser emitters. For ease of understanding, four laser emitters are used as an example: when the lidar beam is measuring wind information, the four laser emitters will emit beams in sequence at the same time interval according to the radar beam switching frequency within the set time. For example, if the radar beam switching frequency is set to 4Hz, the lidar will emit four beams in one second, and the four laser emitters will emit one beam in sequence at a time interval of 250 milliseconds. = 250 ms, 500 ms, 750 ms, 1000 ms are substituted into formula (4) to obtain four different value; at the same time, according to formula (5) ; then judge 4 different The number of values ​​that fall into the interval of formula (3) is used to determine the number of times the beam is not blocked.

[0069] Step 3: Calculate the laser radar beam efficiency based on the number of times the radar beam is not blocked by the blade, the radar beam switching frequency, and the number of times the radar beam is emitted.

[0070] The number of times a single radar beam is not blocked by a blade is divided by the quotient of the number of times the single radar beam is transmitted and the radar beam switching frequency to obtain the laser radar beam efficiency, which is as follows:

[0071] For example, the time it takes for the hub of a 10MW wind turbine to drive the blades to rotate once is 5 seconds, and the radar beam switching frequency is set to 4Hz. As the hub rotates, the four laser emitters of the lidar emit a total of 20 beams within 5 seconds. Assuming that the number of times a single radar beam is not blocked by the blades obtained in step 2 is 3 times, and the radar beam switching frequency is 4Hz, it is 4 times, then the lidar beam efficiency = 3 / (20 / 4) = 60%.

[0072] Based on the calculation results of the laser radar beam efficiency, it is possible to evaluate whether the wind condition information at the front end of the wind rotor measured by the nacelle-mounted laser radar meets the control requirements. In principle, the efficiency of each beam should be 50% or above.

[0073] The technical solution of this embodiment converts a complex three-dimensional model into multiple plane models, and equates the rotation of the wind wheel to the rotation of the light beam around the hub at the same speed. The principle of relative motion is used to derive an evaluation method for the efficiency of the airborne wind laser radar beam, which can be applied to both the model development stage and the unit operation stage. After the radar beam efficiency evaluation result is obtained by this method, the problems of long power curve test cycle, large redundant errors in the unit power increase and load reduction control, and the unit's inability to generate electricity normally according to the design requirements can be avoided.

[0074] Finally, 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for evaluating the beam efficiency of an airborne wind laser radar for a wind turbine, characterized in that: The following steps are involved: Obtaining the blade diameter and blade chord length under different cross-sectional states, the blade pitch angle and wind rotor azimuth angle under different working conditions, the hub diameter and hub speed, the spatial position of the airborne wind measuring laser radar, and the parameters of the emitted radar beam; the radar beam parameters include the radar beam switching frequency; Count the number of times the radar beam is not blocked by the blades; including: When the laser radar beam point falls into the following intervals, the radar beam is not blocked by the leaves: ， ， In the above formula, It represents the motion displacement of the beam point on the straight line segment at a certain point in time. ~ Both represent the length of a straight line segment; in Corresponding to the situation where the beam point from the starting point to the first leaf is blocked, Corresponding to the situation from the starting point to the beam point before being blocked by the second blade, Corresponding to the situation where the beam point from the starting point to the second leaf is blocked, Corresponding to the situation from the starting point to the beam point before being blocked by the third blade, Corresponding to the situation where the beam point from the starting point to the beam point is blocked by the third blade, Corresponds to the situation from the starting point to the hub driving the blade to rotate one circle; the starting point corresponds to the moment when the hub drives the blade to start rotating; the length of each straight line segment satisfies ； Movement displacement It is calculated as follows: In the above formula, represents the diameter of a circle, which corresponds to the circle formed by the trajectory of the points on the wind wheel surface emitted by the laser radar in sequence. Circumference of a circle and straight line segments are the same length; represents the wind rotor azimuth, n Indicates the wheel hub speed, t Indicates time, represents the initial time, Indicates the time required for the hub to rotate; Circle diameter It is calculated as follows: In the above formula, h Indicates the vertical distance between the laser radar and the center of the wheel hub. Indicates the distance between the laser radar and the wind wheel plane, represents the vertical angle of the radar beam, represents the horizontal angle of the radar beam, o Indicates the vertical distance between the laser radar and the centerline of the cabin; The length of each straight line segment is calculated as follows: In the above formula, represents the diameter of a circle, represents the blade chord length, represents the blade pitch angle; The LiDAR beam effectiveness is calculated based on the number of times the radar beam is not blocked by the blades, the number of times the radar beam is emitted, and the radar beam switching frequency.

2. The method for evaluating the beam efficiency of an airborne wind laser radar for a wind turbine according to claim 1, characterized in that: The spatial position of the airborne wind measuring laser radar includes the vertical distance between the laser radar and the center of the hub, the vertical distance between the laser radar and the center line of the cabin, and the horizontal distance between the laser radar and the plane of the wind wheel; The radar beam parameters also include a radar beam vertical angle and a radar beam horizontal angle.

3. The method for evaluating the beam efficiency of an airborne wind laser radar for a wind turbine according to claim 1, characterized in that: The diameter of the circle should be larger than the hub diameter.

4. The method for evaluating the beam efficiency of an airborne wind laser radar for a wind turbine according to claim 1, characterized in that: The number of times the radar beam is not blocked by the blades is divided by the quotient of the number of radar beam transmissions and the radar beam switching frequency to obtain the lidar beam efficiency.

5. The method for evaluating the beam efficiency of an airborne wind laser radar for a wind turbine according to claim 1, characterized in that: The airborne wind measurement laser radar is provided with at least four laser transmitters.

6. An electronic device, characterized in that: include: one or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the method for evaluating the efficiency of the wind turbine airborne wind measurement laser radar beam as described in any one of claims 1-5.

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