An Automatic and Precise Measurement Experimental Method for Horizontal Axis Wind Turbine Impellers

Abstract

An automatic and precise measurement experimental method for a horizontal-axis wind turbine impeller, the steps are as follows: transform the conventional horizontal-axis wind turbine impeller aerodynamic performance experimental system; preset experimental parameters in the computer; install the transformed experimental system into the experimental section of the low-speed wind tunnel, connect and debug the system, and compile an experimental outline after meeting the requirements; turn on the wind tunnel, adjust the experimental wind speed to the designed rated wind speed of the impeller, and carry out self-learning; analyze the learning content by the computer to establish the matching relationship between the dynamic characteristics of the impeller and the control parameters; repeat the learning process until the control parameters reach an excellent measurement standard, and the control software in the computer completes the mastery of the dynamic characteristics of the impeller; according to the compiled experimental outline, carry out the aerodynamic performance experiment of the horizontal-axis wind turbine impeller by using the control parameters mastered in the self-learning process until the experiments at all wind speeds in the experimental outline are completed; process the experimental data by the computer to establish the dynamic load capacity performance curve of the impeller.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind turbine experiments, and in particular relates to an automatic and precise measurement experimental method for a horizontal-axis wind turbine impeller. Background Art

[0002] At present, although the horizontal axis wind turbine power generation technology is quite mature, mature technology still cannot do without advanced design and precise experimental testing methods. Taking the horizontal axis wind turbine impeller aerodynamic performance experiment as an example, the experiment is generally carried out in a low-speed wind tunnel, which is similar to the actual application, with a scaled-down appearance design and a complete power detection and loading system.

[0003] However, conventional horizontal-axis wind turbine impeller aerodynamic performance test systems have the problem of poor synchronization between the loading device and the impeller power output, which can easily lead to excessive loading or untimely loading in the wind turbine impeller speed regulation, resulting in the inability to accurately measure the parking point data of the wind turbine impeller. In severe cases, even impeller runaway accidents may occur, causing unbalanced vibration damage to the entire experimental system, resulting in irreparable economic losses. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides an experimental method for automatic and precise measurement of horizontal-axis wind turbine impellers. Based on a conventional horizontal-axis wind turbine impeller aerodynamic performance experimental system, the method effectively meets the requirements of automatic and precise measurement of horizontal-axis wind turbine impellers by modifying the conventional system and expanding its functions.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solution: an experimental method for automatic and accurate measurement of a horizontal axis wind turbine impeller, comprising the following steps:

[0006] Step 1: Establish a conventional horizontal axis wind turbine impeller aerodynamic performance experimental system, transform the conventional system, add reflective stickers, photoelectric tachometers, dynamic collectors, current controllers and computers; attach the reflective stickers to the main shaft surface of the conventional system to ensure that the laser beam of the photoelectric tachometer accurately irradiates the reflective stickers; connect the signal output ends of the photoelectric tachometer and the torque meter in the conventional system to the dynamic collector, connect the signal output end of the dynamic collector to the computer, and install control software with self-learning function in the computer; connect the signal input end of the loader in the conventional system to the current controller, and connect the signal input end of the current controller to the computer;

[0007] Step 2: Preset the experimental parameters in the computer, including the acceleration / deceleration rate, the maximum current given step of the current controller, the control error of the maximum current given step of the current controller, the braking upper speed limit acceleration, the maximum safe speed, the maximum safe torque and the acquisition excitation stabilization time;

[0008] Step 3: Install the modified experimental system into the test section of the low-speed wind tunnel, complete the connection and debugging of the system, ensure normal signal reception, no jitter, and the accuracy meets the design requirements, and then compile the experimental outline;

[0009] Step 4: Start the wind tunnel, adjust the experimental wind speed to the designed rated wind speed of the impeller, and the control software in the computer starts self-learning. The learning content includes the relationship between the preset loading parameter of the loader and the rising / falling rate of the main shaft, the changing trend of the main shaft speed over time, and the changing trend of the main shaft torque over time; when the impeller stops rotating under the loading of the loader and the wind tunnel stops, the self-learning stops;

[0010] Step 5: Analyze the learning content by the computer to establish the matching relationship between the dynamic characteristics of the impeller and the control parameters. The excellent measurement standard for the control parameters is that the rotation speed of the impeller or the rising / falling rate of the main shaft changes uniformly, that is, the magnitude of the acceleration remains unchanged;

[0011] Step 6: Repeat Step 4 and Step 5, conduct the self-learning process multiple times until the control parameters reach the excellent measurement standard. At this time, the control software in the computer completes the mastery of the dynamic characteristics of the impeller;

[0012] Step 7: According to the compiled experimental outline, carry out the aerodynamic performance experiment of the horizontal axis wind turbine impeller by using the control parameters mastered during the self-learning process until the experiments at all wind speeds in the experimental outline are completed;

[0013] Step 8: Process the experimental data by the computer to establish the dynamic load capacity performance curve of the impeller.

[0014] Advantages of the present invention:

[0015] The automatic and precise measurement experimental method for the horizontal axis wind turbine impeller of the present invention adopts an automatic control mode, realizes equal-gradient or equal-spacing loading, the acquisition of data is more accurate, is synchronous with the change of the impeller rotation speed, effectively improves the measurement accuracy of the experimental data, and has repeatability.

[0016] The automatic and precise measurement experimental method for the horizontal axis wind turbine impeller of the present invention detects and controls the impeller rotation speed and acceleration in real time, effectively avoids the occurrence of the impeller running-away accident, and at the same time can also obtain the torque change data of the main shaft during the acceleration process of the impeller, thereby providing a reference basis for the strength design of the main shaft.

[0017] The automatic and precise measurement experimental method for the impeller of a horizontal-axis wind turbine realizes self-learning through the control software in the computer. Through multiple self-learning processes, the control parameters can quickly reach excellent measurement standards, thereby completing the mastery of the dynamic characteristics of the impeller and being able to quickly adapt to the experimental requirements for the aerodynamic performance of different horizontal-axis wind turbine impellers.

[0018] The automatic and precise measurement experimental method for the impeller of a horizontal-axis wind turbine can realize the micro-control of measurement and loading, effectively broadening the experimental speed range of the impeller. It can not only increase the inflection point speed of the impeller of the horizontal-axis wind turbine but also measure the speed point data after the inflection point, which is beneficial to the analysis and evaluation of the aerodynamic performance of the impeller of the horizontal-axis wind turbine. Description of the Drawings

[0019] Figure 1 It is a structural schematic diagram of the experimental system modified by the present invention;

[0020] Figure 2 It is the rotational speed control curve obtained in three learning processes in the embodiment;

[0021] Figure 3 It is the performance curve of the impeller dynamic load capacity established in the embodiment;

[0022] In the figure, 1 - reflective sticker, 2 - photoelectric tachometer, 3 - dynamic acquisition instrument, 4 - current controller, 5 - computer, 6 - main shaft, 7 - torque meter, 8 - loader, 9 - impeller. Detailed Embodiment

[0023] The following further elaborates on the present invention in detail in conjunction with the drawings and specific embodiments.

[0024] An automatic and precise measurement experimental method for the impeller of a horizontal-axis wind turbine includes the following steps:

[0025] Step 1: Establish a set of conventional experimental systems for the aerodynamic performance of the impeller of a horizontal-axis wind turbine, modify the conventional system, and add a reflective sticker 1, a photoelectric tachometer 2, a dynamic acquisition instrument 3, a current controller 4, and a computer 5; attach the reflective sticker 1 to the surface of the main shaft 6 in the conventional system to ensure that the laser beam of the photoelectric tachometer 2 accurately irradiates the reflective sticker 1; connect the signal output ends of the photoelectric tachometer 2 and the torque meter 7 in the conventional system to the dynamic acquisition instrument 3, connect the signal output end of the dynamic acquisition instrument 3 to the computer 5, and install control software with self-learning function in the computer 5; connect the signal input end of the loader 8 in the conventional system to the current controller 4, and connect the signal input end of the current controller 4 to the computer 5; the modified experimental system is as Figure 1 shown.

[0026] In this embodiment, the signal output frequency of the optoelectronic tachometer 2 is 15 KHz. When the maximum speed limit of the main shaft 6 is 4000 revolutions per minute, the optoelectronic tachometer 2 can measure the dynamic changes in the rotational speed of the main shaft 6; the output current value of the current controller 4 is 0 - 3 A; the control input voltage is 0 - 5 V; the acquisition frequency of the dynamic acquisition instrument 3 is 1 MHz, and the dynamic acquisition instrument 3 is of the 8-channel digital type; the maximum torque measurement value of the torque meter 7 is 2 Nm, and the signal output frequency of the torque meter 7 is 15 KHz; the maximum loading capacity of the loader 8 is 3 Nm, and the loader 8 is of the current control type.

[0027] Step two: Preset the experimental parameters in the computer 5. The experimental parameters include the increase / decrease rate, the maximum current given step of the current controller, the control error of the maximum current given step of the current controller, the braking high-limit rotational speed acceleration, the maximum safe rotational speed, the maximum safe torque, and the acquisition excitation stabilization time; among them, the increase / decrease rate is defined as: the amount of increase or decrease in the rotational speed per unit time; the maximum current given step of the current controller is defined as: (maximum rotational speed - minimum rotational speed) / average rotational speed × 100%.

[0028] In this embodiment, the increase / decrease rate is ±1 n / ms, the maximum current given step of the current controller is 200 mA, the control error of the maximum current given step of the current controller is 5%, and the braking high-limit rotational speed acceleration is 300 n / s 2 , the maximum safe rotational speed is 4000 rpm, the maximum safe torque is 2 Nm, and the acquisition excitation stabilization time is 10 ms.

[0029] Step three: Install the modified experimental system into the experimental section of the low-speed wind tunnel, complete the connection and debugging of the system, ensure normal signal reception, no jitter, and the accuracy meets the design requirements, and then compile the experimental outline; the experimental outline in this embodiment is shown in Table 1.

[0030] Table 1

[0031] Wind speed (m / s) 8 9 10 11 12 13 14 Installation angle 6 degrees √ √ √ √ √ √ √ Installation angle 8 degrees × × √ √ √ √ × Installation angle 12 degrees × × × √ √ √ ×

[0032] Step four: Start the wind tunnel, adjust the experimental wind speed to the designed rated wind speed of the impeller 9, and the control software in the computer 5 starts self-learning. The learning content includes the relationship between the preset loading amount parameter of the loader 8 and the increase / decrease rate of the main shaft 6, the change trend of the rotational speed of the main shaft 6 over time, and the change trend of the torque of the main shaft 6 over time; when the impeller 9 stops rotating under the loading of the loader 8 and the wind tunnel stops, the self-learning stops.

[0033] In this embodiment, the designed rated wind speed of the impeller 9 is 12 m / s, and the self-learning process starts from the stationary state of the impeller 9; the preset loading amount of the loader 8 is 200 mA; for the learning of the variation trend of the rotation speed and torque of the main shaft 6 over time, 200 ms needs to be advanced during prediction.

[0034] Step Five: The computer 5 analyzes the learned content to establish the matching relationship between the dynamic characteristics of the impeller 9 and the control parameters. The excellent measurement standard for the control parameters is that the rotation speed of the impeller 6 or the acceleration / deceleration rate of the main shaft 6 changes uniformly, that is, the magnitude of the acceleration remains unchanged.

[0035] Step Six: Repeat Step Four and Step Five, and conduct the self-learning process multiple times until the control parameters reach the excellent measurement standard. At this time, the control software in the computer 5 has mastered the dynamic characteristics of the impeller 9.

[0036] In this embodiment, the self-learning process is carried out three times because usually, after three times of learning, the specified error range can be reached, and the more the number of learning times, the smaller the error. As Figure 2 shown, it is the rotation speed control curve obtained during the three times of learning ( Figure 2 a, Figure 2 b, Figure 2 c). It can be seen that the requirements can be met after three times of learning.

[0037] Step Seven: According to the prepared experimental outline, carry out the aerodynamic performance experiment of the horizontal axis wind turbine impeller by using the control parameters mastered during the self-learning process until the experiments at all wind speeds in the experimental outline are completed. Specifically, first, adjust the wind tunnel wind speed to the first experimental wind speed in the experimental outline, use the control parameters mastered during the self-learning process to accelerate the impeller 9 to a stable rotation speed, give the first loading amount through the loader 8, measure the rotation speed change rate of the main shaft 6 by cooperating the reflective sticker 1 and the optoelectronic tachometer 2, measure three times continuously, and the time interval between two adjacent measurements is 10 ms. If the rotation speed of the main shaft 6 is stable and there is no fluctuation, the acquisition condition is established, and the rotation speed and torque of the impeller 9 in the current state are collected by the dynamic data collector 3; subsequently, give the second loading amount through the loader 8 and continue to measure, and so on until the measurement of all loading amounts is completed; since the control software in the computer 5 has mastered the dynamic characteristics of the impeller 9 through the self-learning process, the loading process and the data acquisition process can be completed very quickly, and the real-time change law of the impeller 9 during the deceleration process can be measured, which could not be achieved by the previous manual method; in addition, the equal loading amount experiment and the equal rotation speed drop experiment can also be carried out, and these two types of experiments can also be automatically completed by the system.

[0038] In this embodiment, taking the constant rotational speed drop experiment as an example, it can be seen from the experimental outline in Table 1 that the first experimental wind speed is 8 m / s. Therefore, the wind tunnel wind speed is initially adjusted to 8 m / s as well. The impeller 9 is uniformly accelerated to 2400 rpm under the control parameters, and then the rotational speed is reduced by 200 rpm each time. The time interval between adjacent rotational speed changes is 10 ms until the rotational speed is reduced to 400 rpm and the experiment ends. All the data is summarized in Table 2.

[0039] Table 2

[0040] Rotational speed (rpm) 2400 2200 2000 1800 1600 1400 1200 1000 800 600 400 Power (W) 9.6 16.5 24.3 27.4 29.5 27.4 23.3 18.2 14.5 10.6 8.2

[0041] Step Eight: The computer 5 processes the experimental data to establish the dynamic load capacity performance curve of the impeller 9, as Figure 3 shown.

[0042] The solutions in the embodiments are not intended to limit the patent protection scope of the present invention. Any equivalent implementation or modification without departing from the present invention is included in the patent scope of this case.

Claims

1. An automatic and precise measurement experimental method for the impeller of a horizontal-axis wind turbine, characterized in that The steps are as follows: Step 1: Establish a set of conventional horizontal axis wind turbine impeller aerodynamic performance experimental systems, transform the conventional system, and add reflective stickers, photoelectric tachometers, dynamic data loggers, current controllers and computers; attach the reflective stickers to the surface of the main shaft in the conventional system to ensure that the laser beam of the photoelectric tachometer accurately irradiates the reflective stickers; connect the signal output ends of the photoelectric tachometer and the torque meter in the conventional system to the dynamic data logger, connect the signal output end of the dynamic data logger to the computer, and install control software with self-learning function in the computer; connect the signal input end of the loader in the conventional system to the current controller, and connect the signal input end of the current controller to the computer; Step 2: Preset the experimental parameters in the computer. The experimental parameters include the rise / fall rate, the maximum current given step of the current controller, the control error of the maximum current given step of the current controller, the brake high limit speed acceleration, the highest safe speed, the highest safe torque and the acquisition excitation stabilization time; Step 3: Install the transformed experimental system into the test section of the low-speed wind tunnel, complete the connection and debugging of the system, ensure normal signal reception, no jitter, and the accuracy meets the design requirements, and then compile the experimental outline; Step 4: Start the wind tunnel, adjust the experimental wind speed to the designed rated wind speed of the impeller, and the control software in the computer starts self-learning. The learning content includes the relationship between the preset loading parameter of the loader and the rise / fall rate of the main shaft, the change trend of the main shaft speed over time, and the change trend of the main shaft torque over time; when the impeller stops rotating under the loading of the loader and the wind tunnel stops, the self-learning stops; Step 5: Analyze the learning content by the computer to establish the matching relationship between the dynamic characteristics of the impeller and the control parameters. The excellent measurement standard for the control parameters is that the rotation speed of the impeller or the rise / fall rate of the main shaft changes uniformly, that is, the magnitude of the acceleration remains unchanged; Step 6: Repeat Step 4 and Step 5, and carry out the self-learning process multiple times until the control parameters reach the excellent measurement standard. At this time, the control software in the computer completes the mastery of the dynamic characteristics of the impeller; Step 7: According to the compiled experimental outline, carry out the horizontal axis wind turbine impeller aerodynamic performance experiment by using the control parameters mastered during the self-learning process until the experiments at all wind speeds in the experimental outline are completed; Step 8: Process the experimental data by the computer to establish the dynamic load capacity performance curve of the impeller.

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