A method and device for measuring wind speed and wind direction

Abstract

The present invention relates to a method and device for measuring wind speed and direction, and particularly to the measurement of wind speed and direction. The method includes calculating the component of the wind speed in the x-axis direction according to a preset parameter set, the true acceleration of the tethered balloon in the x-axis direction, the direction angle, and the speed in the x-axis direction; calculating the component of the wind speed in the y-axis direction according to a preset parameter set, the true acceleration of the tethered balloon in the y-axis direction, the direction angle, and the speed in the y-axis direction; calculating the component of the wind speed in the z-axis direction according to a preset parameter set, the true acceleration of the tethered balloon in the z-axis direction, the gravity, the buoyancy force received by the tethered balloon, and the speed in the z-axis direction; calculating the wind speed, the pitch angle of the wind, and the direction angle according to the component of the wind speed in the x-axis direction, the component in the y-axis direction, and the component in the z-axis direction; and determining the wind direction according to the pitch angle and the direction angle of the wind. The present invention can improve the accuracy of the measurement results of wind speed and direction.

Description

Technical Field

[0001] The present invention relates to the technical field of wind speed and direction, and particularly to a method and device for measuring wind speed and direction. Background Art

[0002] Wind energy is a clean and renewable energy source, and using wind power generation is an effective way to obtain energy. To build a wind power plant, it is first necessary to evaluate the wind energy at high altitudes of the selected site. In the existing invention patent of "A Device and Method for Measuring High-Altitude Wind Energy Resources", a method for measuring wind speed and direction based on different motion states of a helium balloon is mentioned. The measurement principle in this invention patent is as follows: The motion states of the helium balloon at high altitude are divided into six types, namely: windless stationary state, windy stationary state, uniform circular motion in the vertical plane, variable-speed circular motion in the vertical plane, orbit-changing motion, and uniform circular motion in the horizontal plane. According to different motion state models, multiple corresponding mechanical models and mechanical equilibrium equations are established, and the wind speed and direction measurement formulas for the helium balloon in different motion states are derived.

[0003] According to the measurement principle of the invention patent of "A Device and Method for Measuring High-Altitude Wind Energy Resources", to measure wind speed and direction, first, it is necessary to obtain the drag coefficient, drag area, lift coefficient, and lift area of the helium balloon through a wind tunnel test. Secondly, relevant parameters such as the triaxial acceleration, attitude angle, tie-point tension, and rope inclination of the helium balloon are obtained through sensors, and the triaxial acceleration of the helium balloon is corrected using the attitude angle. Then, the motion state of the helium balloon is judged, and the parameters measured by the sensors are substituted into the wind speed and direction calculation formulas for the corresponding motion state, so as to calculate the speed and direction of the helium balloon relative to the wind, and then corrected by the motion speed of the helium balloon to finally obtain the true wind speed and direction.

[0004] Therefore, the main disadvantage of the wind speed and direction measurement principle mentioned in the invention patent of "A Device and Method for Measuring High-Altitude Wind Energy Resources" is the low accuracy of the measured wind speed and direction, which is specifically manifested as follows:

[0005] ① Since the shape and structure of the helium balloon are very complex, the drag area and lift area at high altitude will change with the change of the attitude of the helium balloon. Therefore, the calculation of drag and lift will be affected by the attitude of the helium balloon, and the invention patent of "A Device and Method for Measuring High-Altitude Wind Energy Resources" does not clearly give the functional relationship between the drag area, lift area, and the attitude of the helium balloon.

[0006] ② Since the balloon has six motion states at high altitude, the judgment of the motion state is very complex and will increase the complexity of the measurement. The judgment of the motion state also directly affects the accuracy of the wind speed and direction measurement.

[0007] ③ The wind speed measured by this measurement principle is two-dimensional and can only measure the horizontal component of the high-altitude wind speed. Summary of the Invention

[0008] The object of the present invention is to provide a method and device for measuring wind speed and wind direction, which can improve the accuracy of the measurement results of wind speed and wind direction.

[0009] To achieve the above object, the present invention provides the following solutions:

[0010] A method for measuring wind speed and wind direction, comprising:

[0011] Obtaining a preset parameter set, the gravity of the tethered balloon, the buoyancy force received by the tethered balloon, the direction angle of the tethered balloon, the true acceleration of the tethered balloon in the x-axis direction, the true acceleration of the tethered balloon in the y-axis direction, and the true acceleration of the tethered balloon in the z-axis direction; the preset parameter set includes the total mass of the tethered balloon, the tension force received by the tethered balloon, the inclination angle of the tethered balloon, the air density, and the windward area of the tethered balloon; the total mass of the tethered balloon is the sum of the mass of the tethered balloon, the mass of the sensor box, and the mass of the gas inside the tethered balloon; the sensor box is arranged on the tethered balloon;

[0012] Calculating the velocity of the tethered balloon in the x-axis direction, the velocity of the tethered balloon in the y-axis direction, and the velocity of the tethered balloon in the z-axis direction according to the true acceleration of the tethered balloon in the x-axis direction, the true acceleration of the tethered balloon in the y-axis direction, and the true acceleration of the tethered balloon in the z-axis direction;

[0013] Calculating the component of the wind speed in the x-axis direction according to the preset parameter set, the true acceleration of the tethered balloon in the x-axis direction, the direction angle of the tethered balloon, and the velocity of the tethered balloon in the x-axis direction;

[0014] Calculating the component of the wind speed in the y-axis direction according to the preset parameter set, the true acceleration of the tethered balloon in the y-axis direction, the direction angle of the tethered balloon, and the velocity of the tethered balloon in the y-axis direction;

[0015] Calculating the component of the wind speed in the z-axis direction according to the preset parameter set, the true acceleration of the tethered balloon in the z-axis direction, the gravity of the tethered balloon, the buoyancy force received by the tethered balloon, and the velocity of the tethered balloon in the z-axis direction;

[0016] Calculating the wind speed and wind direction according to the component of the wind speed in the x-axis direction, the component of the wind speed in the y-axis direction, and the component of the wind speed in the z-axis direction, wherein the wind direction includes the pitch angle of the wind and the direction angle of the wind.

[0017] Optionally, when there is only a pitch angle for the moored balloon, calculate the true acceleration of the moored balloon in the x-axis direction and the true acceleration of the moored balloon in the z-axis direction based on the acceleration of the moored balloon in the x-axis direction, the pitch angle of the moored balloon, and the acceleration of the moored balloon in the z-axis direction; determine that the acceleration of the moored balloon in the y-axis direction is the true acceleration of the moored balloon in the y-axis direction;

[0018] When there is only a roll angle for the moored balloon, determine that the acceleration of the moored balloon in the x-axis direction is the true acceleration of the moored balloon in the x-axis direction; calculate the true acceleration of the moored balloon in the y-axis direction and the true acceleration of the moored balloon in the z-axis direction based on the acceleration of the moored balloon in the y-axis direction, the roll angle of the moored balloon, and the acceleration of the moored balloon in the z-axis direction;

[0019] When there is only a heading angle for the moored balloon, determine that the acceleration of the moored balloon in the z-axis direction is the true acceleration of the moored balloon in the z-axis direction; calculate the true acceleration of the moored balloon in the x-axis direction and the true acceleration of the moored balloon in the y-axis direction based on the acceleration of the moored balloon in the x-axis direction, the heading angle of the moored balloon, and the acceleration of the moored balloon in the y-axis direction.

[0020] Optionally, the calculating the component of the wind speed in the x-axis direction according to the preset parameter set, the true acceleration of the moored balloon in the x-axis direction, the direction angle of the moored balloon, and the speed of the moored balloon in the x-axis direction specifically includes:

[0021] According to the formula

[0022]

[0023] calculate the component of the wind speed in the x-axis direction, where v 风x represents the component of the wind speed in the x-axis direction, m represents the total mass of the moored balloon, a x represents the true acceleration of the moored balloon in the x-axis direction, T represents the tension force on the moored balloon, θ represents the pitch angle of the moored balloon, α represents the direction angle of the moored balloon, ρ air represents the air density, S D represents the windward area of the moored balloon, C D represents the surface drag coefficient of the moored balloon, v 球x represents the speed of the moored balloon in the x-axis direction, and sign() represents the sign function.

[0024] Optionally, calculating the component of the wind speed in the y-axis direction based on the preset parameter set, the true acceleration of the tethered balloon in the y-axis direction, the direction angle of the tethered balloon, and the speed of the tethered balloon in the y-axis direction specifically includes:

[0025] According to the formula

[0026]

[0027] calculate the component of the wind speed in the y-axis direction, where v 风y represents the component of the wind speed in the y-axis direction, m represents the total mass of the tethered balloon, a y represents the true acceleration of the tethered balloon in the y-axis direction, T represents the tension force on the tethered balloon, θ represents the inclination angle of the tethered balloon, α represents the direction angle of the tethered balloon, ρ air represents the air density, S D represents the windward area of the tethered balloon, C D represents the surface drag coefficient of the tethered balloon, v 球y represents the speed of the tethered balloon in the y-axis direction, and sign() represents the sign function.

[0028] Optionally, calculating the component of the wind speed in the z-axis direction based on the preset parameter set, the true acceleration of the tethered balloon in the z-axis direction, the gravity of the tethered balloon, the buoyancy force on the tethered balloon, and the speed of the tethered balloon in the z-axis direction specifically includes:

[0029] According to the formula

[0030]

[0031] calculate the component of the wind speed in the z-axis direction, where v 风z represents the component of the wind speed in the z-axis direction, m represents the total mass of the tethered balloon, a Z represents the true acceleration of the tethered balloon in the z-axis direction, G represents the gravity of the tethered balloon, T represents the tension force on the tethered balloon, θ represents the inclination angle of the tethered balloon, B represents the buoyancy force on the tethered balloon, ρ air represents the air density, S D represents the windward area of the tethered balloon, C D represents the surface drag coefficient of the tethered balloon, v 球z represents the speed of the tethered balloon in the z-axis direction, and sign() represents the sign function.

[0032] Optionally, according to the formula calculate the wind speed, where v 风x represents the component of the wind speed in the x-axis direction, v 风y represents the component of the wind speed in the y-axis direction, v风z represents the component of the wind speed in the z-axis direction, v 风 represents the wind speed.

[0033] Optionally, according to the formula calculate the pitch angle of the wind, where v 风x represents the component of the wind speed in the x-axis direction, v 风y represents the component of the wind speed in the y-axis direction, v 风z represents the component of the wind speed in the z-axis direction, θ 风 represents the pitch angle of the wind.

[0034] Optionally, according to the formula calculate the direction angle of the wind, where v 风x represents the component of the wind speed in the x-axis direction, v 风y represents the component of the wind speed in the y-axis direction, α 风 represents the direction angle of the wind.

[0035] An anemometer and wind vane measurement device is applied to the above-mentioned anemometer and wind vane measurement method. The device includes:

[0036] A tethered balloon, a tension sensor, a rope, and a sensor box; the tethered balloon is connected to one end of the rope through the tension sensor, the other end of the rope is fixed on the ground, and the sensor box is arranged on the tethered balloon; the tension sensor is used to measure the tension received by the tethered balloon; the sensor box is internally provided with an angle sensor, a triaxial acceleration sensor, and an attitude angle sensor; the angle sensor is used to measure the inclination angle of the tethered balloon, the direction angle of the tethered balloon, the triaxial acceleration sensor is used to measure the acceleration of the tethered balloon in the x-axis direction, the acceleration of the tethered balloon in the y-axis direction, and the acceleration of the tethered balloon in the z-axis direction, and the attitude angle sensor is used to measure the pitch angle, roll angle, and heading angle of the tethered balloon.

[0037] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention: When calculating the wind direction, the pitch angle of the wind is introduced in the present invention, and the motion state of the tethered balloon does not need to be judged during the process of calculating the wind speed and wind direction, avoiding measurement errors caused by misjudgment, improving the accuracy of the anemometer and wind vane measurement results, and being able to measure the three-dimensional wind direction. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0039] Figure 1 The flowchart of a wind speed and direction measurement method provided by an embodiment of the present invention;

[0040] Figure 2 The schematic structural diagram of a wind speed and direction measurement device provided by an embodiment of the present invention;

[0041] Figure 3 The mechanical analysis diagram of a tethered balloon provided by an embodiment of the present invention;

[0042] Figure 4 The mechanical analysis diagram of the vertical plane of a tethered balloon provided by an embodiment of the present invention;

[0043] Figure 5 The three-axis mechanical analysis diagram of a tethered balloon provided by an embodiment of the present invention. Specific embodiments

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0045] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] The present invention can provide a new method for measuring high-altitude wind speed and direction, can perform three-dimensional wind direction measurement, reduces the construction cost of measurement and the complexity of calculation, and improves the accuracy of high-altitude wind speed and direction measurement.

[0047] The wind speed and direction measurement method includes:

[0048] Obtain a preset parameter set, the gravity of the tethered balloon, the buoyancy force received by the tethered balloon, the direction angle of the tethered balloon, the true acceleration of the tethered balloon in the x-axis direction, the true acceleration of the tethered balloon in the y-axis direction, and the true acceleration of the tethered balloon in the z-axis direction; the preset parameter set includes the total mass of the tethered balloon, the tension force received by the tethered balloon, the inclination angle of the tethered balloon, the air density, and the windward area of the tethered balloon; the total mass of the tethered balloon is the sum of the mass of the tethered balloon, the mass of the sensor box, and the mass of the gas inside the tethered balloon; the sensor box is arranged on the tethered balloon. The tethered balloon is a balloon floating at high altitude, filled with helium gas inside, and connected to a ground anchor point through a rope. The connection point is the point where the upper end of the rope is connected to the tethered balloon.

[0049] Calculate the true acceleration of the tethered balloon in the x-axis direction, the true acceleration of the tethered balloon in the y-axis direction, and the true acceleration of the tethered balloon in the z-axis direction based on the attitude angle of the tethered balloon, the acceleration of the tethered balloon in the x-axis direction, the acceleration of the tethered balloon in the y-axis direction, and the acceleration of the tethered balloon in the z-axis direction.

[0050] Calculate the velocity of the tethered balloon in the x-axis direction, the velocity of the tethered balloon in the y-axis direction, and the velocity of the tethered balloon in the z-axis direction based on the true acceleration of the tethered balloon in the x-axis direction, the true acceleration of the tethered balloon in the y-axis direction, and the true acceleration of the tethered balloon in the z-axis direction.

[0051] Calculate the x-axis component of the wind speed based on the preset parameter set, the true acceleration of the tethered balloon in the x-axis direction, the direction angle of the tethered balloon, and the velocity of the tethered balloon in the x-axis direction.

[0052] Calculate the y-axis component of the wind speed based on the preset parameter set, the true acceleration of the tethered balloon in the y-axis direction, the direction angle of the tethered balloon, and the velocity of the tethered balloon in the y-axis direction.

[0053] Calculate the z-axis component of the wind speed based on the preset parameter set, the true acceleration of the tethered balloon in the z-axis direction, the gravity of the tethered balloon, the buoyancy force on the tethered balloon, and the velocity of the tethered balloon in the z-axis direction.

[0054] Calculate the wind speed and wind direction based on the x-axis component of the wind speed, the y-axis component of the wind speed, and the z-axis component of the wind speed, where the wind direction includes the pitch angle of the wind and the direction angle of the wind.

[0055] In practical applications, when the tethered balloon has only a pitch angle, calculate the true acceleration of the tethered balloon in the x-axis direction and the true acceleration of the tethered balloon in the z-axis direction based on the acceleration of the tethered balloon in the x-axis direction, the pitch angle of the tethered balloon, and the acceleration of the tethered balloon in the z-axis direction (specifically using formulas 27 and 29); determine that the acceleration of the tethered balloon in the y-axis direction is the true acceleration of the tethered balloon in the y-axis direction.

[0056] When there is only a roll angle for the moored balloon, determine that the acceleration of the moored balloon in the x-axis direction is the true acceleration of the moored balloon in the x-axis direction; calculate the true acceleration of the moored balloon in the y-axis direction and the true acceleration of the moored balloon in the z-axis direction based on the acceleration of the moored balloon in the y-axis direction, the roll angle of the moored balloon, and the acceleration of the moored balloon in the z-axis direction (specifically using Formulas 31 and 32).

[0057] When there is only a heading angle for the moored balloon, determine that the acceleration of the moored balloon in the z-axis direction is the true acceleration of the moored balloon in the z-axis direction; calculate the true acceleration of the moored balloon in the x-axis direction and the true acceleration of the moored balloon in the y-axis direction based on the acceleration of the moored balloon in the x-axis direction, the heading angle of the moored balloon, and the acceleration of the moored balloon in the y-axis direction (specifically using Formulas 33 and 34).

[0058] In practical applications, calculating the component of the wind speed in the x-axis direction according to the preset parameter set, the true acceleration of the moored balloon in the x-axis direction, the direction angle of the moored balloon, and the speed of the moored balloon in the x-axis direction specifically includes:

[0059] According to the formula

[0060]

[0061] calculate the component of the wind speed in the x-axis direction, where v 风x represents the component of the wind speed in the x-axis direction, m represents the total mass of the moored balloon, a x represents the true acceleration of the moored balloon in the x-axis direction, T represents the tension force on the moored balloon, θ represents the inclination angle of the moored balloon, α represents the direction angle of the moored balloon, ρ air represents the air density, S D represents the windward area of the moored balloon, C D represents the surface drag coefficient of the moored balloon, v 球x represents the speed of the moored balloon in the x-axis direction, sign() represents the sign function, whose function is to take the sign (positive or negative) of a certain number. When the value inside the parentheses is greater than or equal to 0, the function value is 1; when the value inside the parentheses is less than 0, the function value is -1.

[0062] In practical applications, calculating the component of the wind speed in the y-axis direction according to the preset parameter set, the true acceleration of the moored balloon in the y-axis direction, the direction angle of the moored balloon, and the speed of the moored balloon in the y-axis direction specifically includes:

[0063] According to the formula

[0064]

[0065] Calculate the component of the wind speed in the y-axis direction, where v 风y represents the component of the wind speed in the y-axis direction, m represents the total mass of the tethered balloon, a y represents the true acceleration of the tethered balloon in the y-axis direction, T represents the tension force on the tethered balloon, θ represents the inclination angle of the tethered balloon, α represents the direction angle of the tethered balloon, ρ air represents the air density, S D represents the windward area of the tethered balloon, C D represents the surface drag coefficient of the tethered balloon, v 球y represents the velocity of the tethered balloon in the y-axis direction, and sign() represents the sign function.

[0066] In practical applications, calculating the component of the wind speed in the z-axis direction according to the preset parameter set, the true acceleration of the tethered balloon in the z-axis direction, the gravity of the tethered balloon, the buoyancy force on the tethered balloon, and the velocity of the tethered balloon in the z-axis direction specifically includes:

[0067] According to the formula

[0068]

[0069] Calculate the component of the wind speed in the z-axis direction, where v 风z represents the component of the wind speed in the z-axis direction, m represents the total mass of the tethered balloon, a Z represents the true acceleration of the tethered balloon in the z-axis direction, G represents the gravity of the tethered balloon, T represents the tension force on the tethered balloon, θ represents the inclination angle of the tethered balloon, B represents the buoyancy force on the tethered balloon, ρ air represents the air density, S D represents the windward area of the tethered balloon, C D represents the surface drag coefficient of the tethered balloon, v 球z represents the velocity of the tethered balloon in the z-axis direction, and sign() represents the sign function.

[0070] In practical applications, according to the formula Calculate the wind speed, where v 风x represents the component of the wind speed in the x-axis direction, v 风y represents the component of the wind speed in the y-axis direction, v 风z represents the component of the wind speed in the z-axis direction, v 风 represents the wind speed.

[0071] In practical applications, according to the formula Calculate the pitch angle of the wind, where v 风x represents the component of the wind speed in the x-axis direction, v风y represents the component of the wind speed in the y-axis direction, v 风z represents the component of the wind speed in the z-axis direction, θ 风 represents the pitch angle of the wind.

[0072] In practical applications, according to the formula calculate the wind direction angle, where v 风x represents the component of the wind speed in the x-axis direction, v 风y represents the component of the wind speed in the y-axis direction, α 风 represents the wind direction angle.

[0073] An embodiment of the present invention also provides a wind speed and direction measuring device applied to the above method. The device includes:

[0074] A tethered balloon, a tension sensor, a rope, and a sensor box; the tethered balloon is connected to one end of the rope through the tension sensor, the other end of the rope is fixed on the ground, and the sensor box is arranged on the tethered balloon; the tension sensor is used to measure the tension received by the tethered balloon; the sensor box is internally provided with an angle sensor, a triaxial acceleration sensor, and an attitude angle sensor; the angle sensor is used to measure the inclination angle of the tethered balloon, the direction angle of the tethered balloon, the triaxial acceleration sensor is used to measure the acceleration of the tethered balloon in the x-axis direction, the acceleration of the tethered balloon in the y-axis direction, and the acceleration of the tethered balloon in the z-axis direction, and the attitude angle sensor is used to measure the pitch angle, roll angle, and heading angle of the tethered balloon.

[0075] An embodiment of the present invention provides a more specific wind speed and direction measuring method. By using the triaxial acceleration, triaxial attitude angle of the tethered balloon at high altitude, and the tension at the mooring point, through the force analysis of the tethered balloon and combining with the motion state of the tethered balloon, the calculation formulas for wind speed and wind direction are derived. In addition, in the derivation process disclosed in the present invention, the pitch angle of the wind at high altitude is introduced, and the finally measured wind direction data includes the horizontal direction angle and the pitch angle. As Figure 1 shown, the brief steps of this method are as follows:

[0076] Build a tethered balloon wind measurement system device, initialize parameters, read sensor box data, calculate the accurate value of air density, calculate parameters such as the gravity and buoyancy of the tethered balloon, conduct a mechanical analysis of the tethered balloon, calculate the true acceleration of the tethered balloon through the attitude angle, integrate the true acceleration with respect to time to obtain the motion speed of the tethered balloon, calculate the wind speed and wind direction, and recover the tethered balloon.

[0077] Specifically, it includes:

[0078] Step 1: Build a tethered balloon wind measurement system device, i.e., a wind speed and direction measuring device:

[0079] Tethered balloon wind measurement system Figure 2 As shown in the figure, it mainly consists of a flexible solar panel, a tethered balloon, a sensor box, a tension sensor, a rope and a ground station. Among them, the flexible solar panel covers the top of the tethered balloon and is used to charge the battery inside the sensor box during the day. The sensor box is equipped with a high-precision angle sensor, a three-axis acceleration, an attitude angle sensor, a temperature and humidity sensor, an air pressure sensor, a CO2 concentration sensor, a 24-bit AD sampling chip and a wireless transmission module. Among them, the signal output by the tension sensor is an analog signal converted into a digital signal by the 24-bit AD sampling chip built into the sensor box. The sensor box sends all the collected sensor data and the calculated wind speed and direction to the monitoring station on the ground through the wireless transmission module. The tethered balloon and the rope are connected by the tension sensor at the tethering point. The lower end of the rope is connected to the ground station to fix the entire system device.

[0080] Step 2: Initialize parameters

[0081] Initialize the measurement system parameters. The radius of the tethered balloon is R, and the mass of the tethered balloon is m. ball , the filling gas is helium, density ρ he =0.1785kg / m 3 , the rope length is L, and the surface drag coefficient C is determined according to the material of the tethered balloon D , and the acceleration due to gravity g.

[0082] Step 3: Read sensor box data

[0083] The sensor box under the tethered balloon reads the inclination angle θ, the direction angle α, and the three-axis acceleration (the acceleration of the tethered balloon in the x-axis direction, the acceleration of the tethered balloon in the y-axis direction, and the acceleration of the tethered balloon in the z-axis direction a′) of the tethered balloon. x , a′ y , a′ z ), attitude angles (pitch angle, roll angle and heading angle γ1, γ2, γ3), temperature Temp, humidity H, air pressure P, CO2 concentration C, and tension T at the mooring point.

[0084] Step 4: Calculate the exact value of air density

[0085] Air density ρ air It is related to the atmospheric pressure P and the atmospheric thermodynamic temperature Temp. The specific relationship is shown in Formula 1.

[0086]

[0087] Among them, K is a parameter related to the CO2 content and air humidity in the air. It can be seen from this that as long as the temperature, humidity, atmospheric pressure, and CO2 concentration of the high-altitude environment are obtained through sensors, the accurate value ρ of the air density in the high-altitude environment can be calculated. air .

[0088] Step Five: Calculate the gravity, buoyancy, and windward area of the tethered balloon

[0089] The calculation formula for the internal gas volume of the tethered balloon is shown in Formula 2:

[0090]

[0091] The total mass m of the tethered balloon is the sum of the outer shell mass m ball , the sensor box mass m sensor , and the internal gas mass V ball ·ρ he . The gravity of the tethered balloon is shown in Formula 4.

[0092] m = m ball + m sensor + V ball ·ρ he Formula 3

[0093] G = mg Formula 4

[0094] The buoyancy force received by the tethered balloon is shown in Formula 5.

[0095] B = ρ air ·V ball ·g Formula 5

[0096] In addition, the calculation of air resistance requires the windward area of the tethered balloon. Since the shape is spherical, the windward area is not affected by the attitude of the tethered balloon and is shown in Formula 6.

[0097] S D = πR 2 Formula 6

[0098] Step Six: Conduct a mechanical analysis of the tethered balloon

[0099] Conduct a mechanical analysis of the tethered balloon at any moment. As Figure 3 shown, the tethered balloon receives gravity G, lift B, and air resistance D in the vertical direction z ; it receives air resistance D xoy in the horizontal direction; in addition, the tethered balloon also receives a tensile force T along the rope direction. At the current moment, the resultant force of all the forces received by the tethered balloon will produce an acceleration on the tethered balloon.

[0100] Decompose the wind speed at high altitude into three directions: X, Y, and Z, as shown in Formulas 7, 8, and 9.

[0101]

[0102]

[0103]

[0104] Among them, v 风 is the true wind speed at high altitude, θ 风 is the pitch angle of the wind, with a range of 0 to 180°, and α 风 is the direction angle of the wind, with a range of 0 to 360°.

[0105] The air resistances on the tethered balloon in the X, Y, and Z directions are shown in Formulas 10, 11, and 12 respectively.

[0106]

[0107]

[0108]

[0109] Among them, v 球x , v 球y , v 球z are the components of the velocity of the tethered balloon at the current moment in the X, Y, and Z directions, and the sign() function is used to specify the direction of the air resistance.

[0110] The air resistance D xoy on the tethered balloon in the horizontal plane, and the direction angle of the air resistance are shown in Formulas 13 and 14.

[0111]

[0112]

[0113] As Figure 4 shown, combine the forces on the tethered balloon in the vertical direction and conduct a mechanical analysis.

[0114] Among them, F z is the resultant force of the tethered balloon in the vertical direction, as shown in Formula 15.

[0115] F Z = B + D Z - G Formula 15

[0116] F 合 is the force F z in the vertical direction and the air resistance D in the horizontal direction.xoy The resultant force of, F 合 The magnitude is as shown in Equation 16.

[0117]

[0118] F 合 The angle η with the horizontal plane is as shown in Equation 17, and the angle γ in the opposite direction of the pulling force T is as shown in Equation 18.

[0119]

[0120] γ = θ - η Equation 18

[0121] Then decompose F 合 into the directions parallel and perpendicular to the pulling force. Among them, the component force parallel to the pulling force is equal in magnitude and opposite in direction to the pulling force, forming a two-force balance. Then the pulling force T is as shown in Equation 19. At this time, the component force F 动 is the resultant force of all the forces received by the tethered balloon, as shown in Equation 20.

[0122] T = F 合 ·cosγ Equation 19

[0123] F 动 = F 合 ·sinγ Equation 20

[0124] When F 动 is greater than 0, the tethered balloon is in an unsteady state at the current moment and there is an acceleration. Decompose F 动 into the X, Y, and Z directions, as shown in Equation 21, Equation 22, and Equation 23 respectively.

[0125]

[0126]

[0127] F 动z = F 动 ·cosθ Equation 22

[0128] At the current moment, the three-axis accelerations of the tethered balloon are as shown in Equation 24, Equation 25, and Equation 26.

[0129]

[0130]

[0131]

[0132] Step 7: Calculate the true acceleration of the tethered balloon through the attitude angle

[0133] When only the pitch angle γ1 exists, the calculation method of the true three-axis acceleration of the tethered balloon is shown in Formulas 27, 28, and 29.

[0134] a x = a' x ·cosγ1 ± a' z ·sinγ1 Formula 27

[0135] a y = a′ y Formula 28

[0136]

[0137] When only the roll angle γ2 exists, the calculation method of the true acceleration of the tethered balloon is shown in Formulas 30, 31, and 32.

[0138] a x = a' x Formula 30

[0139] a y = a' y ·cosγ2 ± a' z ·sinγ2 Formula 31

[0140]

[0141] When only the heading angle γ3 exists, the calculation method of the true acceleration of the tethered balloon is shown in Formulas 33, 34, and 35.

[0142] a x = a' x ·cosγ3 ± a' y ·sinγ3 Formula 33

[0143]

[0144] a z = a′ z Formula 35

[0145] where a′ x 、a′ y 、a′ z are the three-axis accelerations measured by the sensor, and the "±" in the formula is determined by the ranges of the attitude angles γ1, γ2, and γ3. Substitute the calculated true three-axis acceleration of the tethered balloon into the wind speed and direction measurement formula for calculation.

[0146] Step Eight: Integrate the true acceleration with respect to time to obtain the movement speed of the tethered balloon

[0147] In digital circuits, the operation of integrating the true acceleration uses the infinitesimal method, that is, the acceleration is collected at a high frequency with a sampling interval of t, and the collected acceleration data is …a n-1 , a n , a n+1 …, assuming that the velocity at the nth moment is v n , then the velocity at the (n + 1)th moment is as shown in Equation 36.

[0148] v n+1 = v n + a n t Equation 36

[0149] where v and a generally refer to the true velocity and true acceleration of the tethered balloon along the three-axis directions, that is, v x , v y , v z and a x , a y , a z . Since the infinitesimal method is used, the smaller the sampling time interval t, the smaller the calculated velocity error, but it requires a higher clock frequency of the processor and the power consumption will also increase accordingly.

[0150] Step Nine: Calculate the wind speed and wind direction

[0151] According to the mechanical analysis results in Step Six, analyze the forces on the three axes of the tethered balloon at the current moment. Use the data measured by the sensor as the system input and the wind speed and wind direction as the system output, as Figure 5 shown.

[0152] The resultant force of the forces on the three axes of the tethered balloon constitutes the three-axis acceleration of the tethered balloon at the current moment, as shown in Equations 37, 38, and 39.

[0153] F 合x = ma x = T x + D x Equation 37

[0154] F 合y = ma y = T y + D y Equation 38

[0155] F 合z = ma z = B + D z - G - T z Equation 39

[0156] where T x , T y , T zare the component forces of the tensile force in the three-axis directions, as shown in Formula 40, Formula 41, and Formula 42.

[0157] T x = T·cosθ·cosα Formula 40

[0158] T y = T·cosθ·sinα Formula 41

[0159] T z = T·sinθ Formula 42

[0160] Combining Formula 10, Formula 11, and Formula 12 can derive the components of the wind speed in the three-axis directions, as shown in Formula 43, Formula 44, and Formula 45. The wind speed is as shown in Formula 46.

[0161]

[0162]

[0163]

[0164]

[0165] The pitch angle θ of the wind 风 and the direction angle α 风 are as shown in Formula 47 and Formula 48.

[0166]

[0167]

[0168] Step Ten: Recover the tethered balloon

[0169] When it is detected that the tensile force data collected by the sensor box is less than the threshold, it indicates that the tethered balloon is damaged and leaking air or has natural wear and tear, and the helium gas inside the tethered balloon is not sufficient to provide enough lift to maintain the stability of the entire measurement system device. Then, the tethered balloon is recovered.

[0170] The present invention has the following advantages:

[0171] 1) The present invention provides a new method for measuring the wind speed and direction at high altitudes, improving the measurement accuracy of the wind speed and direction. For application scenarios such as mountains and forests, it effectively reduces the cost of measuring the wind speed and direction at high altitudes and can avoid damage to vegetation. Compared with traditional measurement methods, the present invention can measure the three-dimensional wind direction at high altitudes, which helps to improve the utilization rate of wind energy.

[0172] 2) The tethered balloon structure is adopted for the first time to measure the high-altitude wind speed and direction, reducing the complexity of the algorithm. There is no need to judge the motion state of the tethered balloon, which reduces the complexity of the algorithm and improves the measurement accuracy. The wind speed and direction can be measured by collecting various sensor data through the sensor box.

[0173] 3) The wind measurement system is simple and stable: The wind speed and direction measurement system device based on the mechanical model of the tethered balloon shown in Step 1 adopts a spherical structure, so that no matter what attitude the tethered balloon is in, the windward area is always a fixed constant. The wing structure is omitted, so that when analyzing the forces on the tethered balloon, the influence of lift does not need to be considered. However, for the wind energy measurement device mentioned in the background art, which adopts the shape of an airship, the windward area is affected by the attitude of the airship, resulting in an increase in the complexity of the algorithm, and it has a wing structure, and the calculation of lift also needs to consider the influence of the airship attitude on the projected area of the wing.

[0174] 4) Lower algorithm complexity and higher wind speed measurement accuracy: The mechanical analysis method of the tethered balloon shown in Step 6 does not need to judge the motion state of the tethered balloon at high altitude, but directly analyzes the forces on the tethered balloon. The resultant force will generate an acceleration on the tethered balloon, reducing the complexity of the algorithm and avoiding the influence of the motion state judgment on the wind speed measurement accuracy. However, for the mechanical analysis method mentioned in the background art, it is first necessary to judge the motion state of the helium airship, and each motion state corresponds to a set of wind speed and direction calculation formulas. Compared with the present invention, the algorithm complexity is higher.

[0175] 5) A method for measuring three-dimensional wind direction is provided: The wind speed and direction measurement method shown in Step 9 can measure the components of the high-altitude wind speed in the three-axis directions, and then by using trigonometric relations, the pitch angle and direction angle of the wind can be calculated. However, the wind direction measurement methods mentioned in the background art and common wind speed and direction measurement methods can only measure the direction angle of the wind. The measurement method of the present invention can improve the utilization rate of wind energy resources.

[0176] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same and similar parts among the various embodiments, reference can be made to each other.

[0177] Specific examples are used in this article to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for measuring wind speed and wind direction, characterized in that, Including: Obtain a preset parameter set, the gravity of the tethered balloon, the buoyancy force on the tethered balloon, the direction angle of the tethered balloon, the true acceleration of the tethered balloon in the x-axis direction, the true acceleration of the tethered balloon in the y-axis direction, and the true acceleration of the tethered balloon in the z-axis direction; The preset parameter set includes the total mass of the tethered balloon, the tension force on the tethered balloon, the inclination angle of the tethered balloon, the air density, and the windward area of the tethered balloon; the total mass of the tethered balloon is the sum of the mass of the tethered balloon, the mass of the sensor box, and the mass of the gas inside the tethered balloon; the sensor box is arranged on the tethered balloon; Calculate the velocity of the tethered balloon in the x-axis direction, the velocity of the tethered balloon in the y-axis direction, and the velocity of the tethered balloon in the z-axis direction according to the true acceleration of the tethered balloon in the x-axis direction, the true acceleration of the tethered balloon in the y-axis direction, and the true acceleration of the tethered balloon in the z-axis direction; Calculate the x-axis component of the wind speed according to the preset parameter set, the true acceleration of the tethered balloon in the x-axis direction, the direction angle of the tethered balloon, and the velocity of the tethered balloon in the x-axis direction; Calculate the y-axis component of the wind speed according to the preset parameter set, the true acceleration of the tethered balloon in the y-axis direction, the direction angle of the tethered balloon, and the velocity of the tethered balloon in the y-axis direction; Calculate the z-axis component of the wind speed according to the preset parameter set, the true acceleration of the tethered balloon in the z-axis direction, the gravity of the tethered balloon, the buoyancy force on the tethered balloon, and the velocity of the tethered balloon in the z-axis direction; Calculate the wind speed and wind direction according to the x-axis component of the wind speed, the y-axis component of the wind speed, and the z-axis component of the wind speed, where the wind direction includes the pitch angle of the wind and the direction angle of the wind.

2. The method for measuring wind speed and wind direction according to claim 1, characterized in that When the tethered balloon only has a pitch angle, calculate the true acceleration of the tethered balloon in the x-axis direction and the true acceleration of the tethered balloon in the z-axis direction according to the acceleration of the tethered balloon in the x-axis direction, the pitch angle of the tethered balloon, and the acceleration of the tethered balloon in the z-axis direction; Determine that the acceleration of the tethered balloon in the y-axis direction is the true acceleration of the tethered balloon in the y-axis direction; When the tethered balloon only has a roll angle, determine that the acceleration of the tethered balloon in the x-axis direction is the true acceleration of the tethered balloon in the x-axis direction; Calculate the true acceleration of the tethered balloon in the y-axis direction and the true acceleration of the tethered balloon in the z-axis direction according to the acceleration of the tethered balloon in the y-axis direction, the roll angle of the tethered balloon, and the acceleration of the tethered balloon in the z-axis direction; When the tethered balloon only has a heading angle, determine that the acceleration of the tethered balloon in the z-axis direction is the true acceleration of the tethered balloon in the z-axis direction; Calculate the true acceleration of the tethered balloon in the x-axis direction and the true acceleration of the tethered balloon in the y-axis direction based on the acceleration of the tethered balloon in the x-axis direction, the heading angle of the tethered balloon, and the acceleration of the tethered balloon in the y-axis direction.

3. A wind speed and direction measurement method according to claim 1, characterized in that, The calculation of the x-axis component of the wind speed according to the preset parameter set, the true acceleration of the tethered balloon in the x-axis direction, the direction angle of the tethered balloon, and the speed of the tethered balloon in the x-axis direction specifically includes: According to the formula Calculate the component of the wind speed in the x-axis direction, where v 风x represents the component of the wind speed in the x-axis direction, m represents the total mass of the tethered balloon, and a x represents the true acceleration of the tethered balloon in the x-axis direction, T represents the tension force on the tethered balloon, θ represents the inclination angle of the tethered balloon, α represents the direction angle of the tethered balloon, and ρ air represents the air density, S D represents the windward area of the tethered balloon, and C D represents the surface drag coefficient of the tethered balloon, v 球x represents the velocity of the tethered balloon in the x-axis direction, and sign() represents the sign function.

4. A wind speed and direction measurement method according to claim 1, characterized in that The calculation of the y-axis component of the wind speed according to the preset parameter set, the true acceleration of the tethered balloon in the y-axis direction, the direction angle of the tethered balloon, and the speed of the tethered balloon in the y-axis direction specifically includes: According to the formula Calculate the component of the wind speed in the y-axis direction, where v 风y represents the component of the wind speed in the y-axis direction, m represents the total mass of the tethered balloon, a y represents the true acceleration of the tethered balloon in the y-axis direction, T represents the tension force on the tethered balloon, θ represents the inclination angle of the tethered balloon, α represents the direction angle of the tethered balloon, ρ air represents the air density, S D represents the windward area of the tethered balloon, C D represents the surface drag coefficient of the tethered balloon, v 球y represents the velocity of the tethered balloon in the y-axis direction, and sign() represents the sign function.

5. A method for measuring wind speed and wind direction according to claim 1, characterized in that, The calculation of the z-axis component of the wind speed according to the preset parameter set, the true acceleration of the tethered balloon in the z-axis direction, the gravity of the tethered balloon, the buoyancy force received by the tethered balloon, and the speed of the tethered balloon in the z-axis direction specifically includes: According to the formula Calculate the component of the wind speed in the z-axis direction, where v 风z represents the component of the wind speed in the z-axis direction, m represents the total mass of the tethered balloon, a Z represents the true acceleration of the tethered balloon in the z-axis direction, G represents the gravity of the tethered balloon, T represents the tension force on the tethered balloon, θ represents the inclination angle of the tethered balloon, B represents the buoyancy force on the tethered balloon, ρ air represents the air density, S D represents the windward area of the tethered balloon, C D represents the surface drag coefficient of the tethered balloon, v 球z represents the velocity of the tethered balloon in the z-axis direction, and sign() represents the sign function.

6. A method for measuring wind speed and direction according to claim 1, characterized in that, Calculate the wind speed according to the formula where v 风x represents the component of the wind speed in the x-axis direction, v 风y represents the component of the wind speed in the y-axis direction, v 风z represents the component of the wind speed in the z-axis direction, v 风 represents the wind speed.

7. A method for measuring wind speed and direction according to claim 1, characterized in that, According to the formula calculate the pitch angle of the wind, where v 风x represents the component of the wind speed in the x-axis direction, v 风y represents the component of the wind speed in the y-axis direction, v 风z represents the component of the wind speed in the z-axis direction, θ 风 represents the pitch angle of the wind.

8. A method for measuring wind speed and direction according to claim 1, characterized in that, According to the formula calculate the wind direction angle, where v 风x represents the component of the wind speed in the x-axis direction, v 风y represents the component of the wind speed in the y-axis direction, and α 风 represents the wind direction angle.

9. An air velocity and wind direction measuring device, characterized in that, Applied to the wind speed and direction measurement method according to any one of claims 1-8, the device includes: A tethered balloon, a tension sensor, a rope, and a sensor box; the tethered balloon is connected to one end of the rope through the tension sensor, the other end of the rope is fixed on the ground, and the sensor box is arranged on the tethered balloon; the tension sensor is used to measure the tension received by the tethered balloon; the sensor box is internally provided with an angle sensor, a three-axis acceleration sensor, and an attitude angle sensor; the angle sensor is used to measure the inclination angle of the tethered balloon, the direction angle of the tethered balloon, the three-axis acceleration sensor is used to measure the acceleration of the tethered balloon in the x-axis direction, the acceleration of the tethered balloon in the y-axis direction, and the acceleration of the tethered balloon in the z-axis direction, and the attitude angle sensor is used to measure the pitch angle, roll angle, and heading angle of the tethered balloon.

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