System and method for online monitoring of bolt preload force of wind turbine generator set

Abstract

The present invention provides a system and method for online monitoring of bolt preload of a wind turbine, including a monitoring probe, a temperature sensor, a data acquisition and processing device, and a monitoring system. By accurately positioning a specific wind turbine, a blade, and a bolt, accurate position monitoring of a specific bolt is achieved; by real-time monitoring of the tightening stress of the entire circle of connecting bolts at the root of the wind turbine blade detected by ultrasonic wave, and by correcting the strain error caused by the temperature change of the environment in which the bolt is located, a more accurate actual tightening stress of a bolt is obtained, and it is determined whether the bolt is loose or broken, and early warning and fault judgment are carried out in time, so that the operation and maintenance personnel can grasp the health status of the blade root bolt at any time, filling the gap of the current lack of an online real-time monitoring system for wind turbine bolts.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine monitoring, and in particular to a system and method for online monitoring of bolt preload of a wind turbine set. Background Art

[0002] Wind power generation is an important way to utilize renewable energy on a large scale. With the rapid development of the global wind power industry, the installed capacity and single-unit capacity are constantly expanding. Wind turbine blades are the core components of wind turbines to capture wind energy. They are mostly connected to the main engine with 10.9-grade high-strength bolts. The connecting bolts of wind turbine blades are subjected to alternating loads during operation. The working load is large and the force is complex. They often cause wind turbine operation accidents due to vibration loosening, fatigue or even breakage, causing huge economic losses to the country and enterprises. In addition, wind turbine operation failures caused by factors such as irregular bolt installation operations and poor bolt quality are also common. For wind turbines installed earlier, the bolt connection parts have entered the wear cycle, and the resulting failures are gradually emerging. At present, the operation and maintenance personnel of each wind farm only conduct regular inspections on the bolts, and accidents are often left due to human errors. In existing wind turbines, there is still a lack of effective means and equipment that integrates real-time monitoring of the working status of bolts and fault analysis and diagnosis.

[0003] CN201310378100.3 provides a method for measuring the preload of a bolt group, which overcomes the deficiency that the existing common axial force gauge bolt preload measuring device can only be used for a single threaded fastener, and can measure the preload of multiple bolts, but cannot monitor the preload of the bolts in real time online. CN201310235117.3 discloses a new method for real-time online monitoring of bolt preload, which monitors the change of bolt preload by installing a threaded fastener preload measuring device between the fastener and the fastened object, but this method is not conducive to the measurement of the preload of small bolts. The principle of measuring preload in CN200720087776.7 is similar to that of CN201310235117.3, except that the change of preload is monitored by a gasket sensor, but since the size of the bolt is not fixed, the preload measuring device needs to be specially customized to meet the measurement needs. CN201320360112.9 provides a preload force measuring mechanism, including a measuring device, a driving device and a power device for providing power to the driving device. The method is a method for actively measuring the preload force, rather than a method for monitoring the change of the preload force under the normal service state of the connection structure. It can be seen from the objects of the above inventions and utility models that there is no special monitoring system and monitoring method for the bolt tightening stress of wind turbines. Summary of the invention

[0004] In response to the above technical problems in the related art, the present invention provides a system and method for online monitoring of the bolt preload of a wind turbine generator set, which provides effective means and equipment for fault analysis and diagnosis of the wind turbine generator by real-time online monitoring of the tightening stress of each specific bolt of the wind turbine generator.

[0005] To achieve the above technical objectives, the technical solution of the present invention is implemented as follows:

[0006] On the one hand, the present invention provides a system for online monitoring of the pre-tightening force of bolts of a wind turbine generator set, comprising a monitoring probe installed at the end of a full circle connecting bolt at the root of a blade of a wind turbine generator, a temperature sensor magnetically attracted to the full circle connecting bolt at the root of the blade, a data acquisition and processing device connected to the monitoring probe and the temperature sensor, and a monitoring system for monitoring the pre-tightening force of each bolt of the wind turbine generator;

[0007] The data acquisition and processing equipment includes a data processing system for processing and analyzing the fan information, bolt information, monitoring probes and data collected by temperature sensors;

[0008] The monitoring system is used to calculate the uploaded data, calculate the bolt preload and temperature compensation, and determine whether the preload is within the normal range, thereby issuing corresponding alarm information.

[0009] Furthermore, the monitoring probe comprises a full circle of connecting bolts at the root of the blade, a tightening device, a coupling layer, an ultrasonic sensor and a sensor terminal;

[0010] The tightening device includes a mounting hole, a nesting hole and a bolt hole from top to bottom;

[0011] The protruding outer edge of the bottom of the ultrasonic sensor probe is nested in the nesting hole of the tightening device;

[0012] The ultrasonic sensor body is installed through the installation hole;

[0013] The coupling layer is coated on the bottom of the ultrasonic sensor probe and contacts the end surface of the connecting bolts of the entire circle of the blade root;

[0014] The entire circle of connecting bolts at the root of the blade is threadedly connected to the bolt holes of the tightening device;

[0015] The sensor terminal is arranged in the ultrasonic sensor and connected to the data acquisition and processing equipment; it is used to monitor the bolt preload. The monitoring of the bolt preload is based on the ultrasonic longitudinal wave acoustic elasticity principle, that is, when the isotropic solid material is subjected to stress in a certain direction and the ultrasonic wave is consistent with the stress direction, the sound velocity and the stress are in a linear relationship.

[0016] Furthermore, a plurality of the monitoring probes form a monitoring probe array.

[0017] Furthermore, the fan information includes fan number, IP address, fan IP address, operating time, operating interval, blade parameters, remarks information, etc.

[0018] Furthermore, the blade parameters include blade number, blade acquisition channel number, threshold voltage, gain value, number of acquisition average values, acquisition time interval, etc.

[0019] Furthermore, the bolt information includes bolt specifications, bolt position numbers, number of monitoring probe installations, calibration information, length of the bolt clamping portion, bolt rated preload information, allowable bolt preload deviation range, and the like.

[0020] Furthermore, the uploaded data includes fan number, blade number, bolt position number, sound and time information, temperature information, etc.

[0021] Furthermore, there are at least 8 ultrasonic sensors, which are evenly installed at the ends of the connecting bolts around the entire circle of the blade root.

[0022] Furthermore, the specific installation process of the ultrasonic sensor is as follows:

[0023] 1) coating the bottom of the ultrasonic sensor probe with coupling glue to form a coupling layer;

[0024] II) pressing the component obtained in step I) onto the end face of the connecting bolt of the blade root, inserting the tightening device into the ultrasonic sensor from top to bottom, and tightening it until it cannot rotate any further;

[0025] III) Connect the sensor terminals to the channel collector to complete the installation.

[0026] In one aspect, the present invention provides a method for online monitoring of bolt preload of a wind turbine generator set, comprising the following steps:

[0027] 1) Add fan information and bolt information to the online monitoring system;

[0028] 2) Read the fan information and bolt information, start online monitoring, and monitor the uploaded data provided by the data acquisition and processing equipment;

[0029] 3) Analyze the uploaded data about the fan and bolts, calculate the bolt preload and temperature compensation, determine whether the preload is within the normal range and issue a warning, and save the data; if there is no uploaded data, continue to monitor.

[0030] Furthermore, the normal range refers to a state analysis model obtained by superimposing the tightening stress of the bolts and the fan in a static state and the blade gravity; or a state analysis model obtained by superimposing the tightening stress of the bolts and the fan in a static state and the blade gravity, supplemented by the stress value during actual normal operation.

[0031] Furthermore, in step 3), the analysis process is as follows: intercept the time period to be analyzed and determine whether there is any bolt preload information record: if not, change the time period to be analyzed; if yes, import the bolt preload record corresponding to the fan in the time period to be analyzed, and read the status analysis model in combination with the fan model or bolt information; analyze the force prediction and trend of the overall bolts in the fan monitoring part according to the bolt preload record, the status analysis model and the monitoring data, and give intervention suggestions and judgments.

[0032] Further, in step 3), determine whether the preload force is within the normal range: if it is not within the normal range, issue an early warning, an alarm, write an abnormal log, save the abnormal log, intervene in the report, and enter the save interface; if it is within the normal range, display the preload force information on the corresponding fan monitoring unit interface, save the collected data, and change the time period to be analyzed.

[0033] Beneficial effects of the present invention:

[0034] The present invention provides a system and method for online monitoring of the bolt preload of a wind turbine generator set. The system can accurately locate a specific wind turbine, blades and bolts through the monitoring system, so as to realize accurate position monitoring of a specific bolt. The system can monitor the tightening stress of the entire circle of connecting bolts at the root of a wind turbine blade detected by ultrasonic wave in real time, and correct the strain error caused by the temperature change of the environment in which the bolt is located, so as to obtain a more accurate actual tightening stress of a bolt, judge whether the bolt is loose or broken, and make early warning and fault judgment in time, so that operation and maintenance personnel can grasp the health status of the blade root bolts at any time, thus filling the gap of the current lack of an online real-time monitoring system for wind turbine bolts.

[0035] The monitoring probe of the present invention uses an ultrasonic sensor to detect the axial stress of bolt tightening in real time based on the acoustic elasticity principle, without destroying the bolt structure and without affecting the bolt tightening and disassembly operations.

[0036] The ultrasonic sensor of the present invention has good stability in installation and can be closely fitted with the bolt to be tested, thereby ensuring the precise requirements for bolt preload force detection, reducing the error of the test result, and even avoiding the error of the test result.

[0037] The present invention provides bolt monitoring for wind turbine generator sets, thereby increasing the normal operation time of wind farms, reducing the maintenance costs of sharp generator sets, and improving the safety of wind turbine generator set operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 It is a schematic diagram of the structure of a monitoring probe according to a preferred embodiment of the present invention.

[0040] Figure 2 It is a schematic diagram of the cross-sectional structure of a tightening device according to a preferred embodiment of the present invention.

[0041] Figure 3 This is a schematic diagram of the arrangement of bolt installation sites in a preferred embodiment of the present invention. A represents a bolt site where a monitoring probe is installed; B represents a bolt site where a monitoring probe is not installed.

[0042] Figure 4 1 is a time-varying stress curve diagram of a bolt according to a preferred embodiment of the present invention.

[0043] Figure 5 This is a system topology diagram of a preferred embodiment of the present invention. 6A probe; 6B channel collector; 6C communication controller; 6D main controller; 6E network management platform; 6F power station workstation; 6G cloud and background services; 6H remote monitoring station; 6I head interior; 6J fan interior. DETAILED DESCRIPTION

[0044] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0045] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0046] Example 1

[0047] like Figures 1 to 5As shown, the present invention provides a system for online monitoring of the pre-tightening force of bolts of a wind turbine generator set, comprising a monitoring probe installed at the end of a full circle connecting bolt at the root of a blade of a wind turbine generator, a temperature sensor magnetically attracted to the full circle connecting bolt at the root of the blade, a data acquisition and processing device connected to the monitoring probe and the temperature sensor, and a monitoring system for monitoring the pre-tightening force of each bolt of the wind turbine generator; the data acquisition and processing device includes a channel collector and / or a communication controller;

[0048] The data acquisition and processing equipment includes a data processing system for processing and analyzing the fan information, bolt information, monitoring probes and data collected by temperature sensors;

[0049] The monitoring system is used to calculate the uploaded data, calculate the bolt preload and temperature compensation, determine whether the preload is within the normal range, and issue corresponding alarm information; the monitoring system includes a monitoring platform (main controller), a network management platform, a power station workstation, a cloud / back-end server, and a remote monitoring station;

[0050] The monitoring probe comprises a full circle connecting bolt 1 at the root of the blade, a tightening device 2, a coupling layer 3, an ultrasonic sensor 4 and a sensor terminal 5; the tightening device 2 comprises a mounting hole 21, a nesting hole 22 and a bolt hole 23 from top to bottom; the inner diameter of the mounting hole 21 is smaller than the inner diameter of the nesting hole 22, so as to ensure that the protruding outer edge of the bottom of the ultrasonic sensor probe can be nested in the nesting hole 22, and the ultrasonic sensor 4 can be installed and fixed in the mounting hole 21, so as to realize the fixed installation of the ultrasonic sensor 4; a temperature compensation sensor is magnetically attracted on the surface of the full circle connecting bolt 1 at the root of the blade; the temperature compensation sensor is magnetically attracted to any part of the screw and can sense the temperature of the screw or the surrounding area without special installation requirements; it is used to monitor the bolt preload. The protruding outer edge of the bottom of the ultrasonic sensor 4 probe is nested in the nesting hole 22 of the tightening device; the ultrasonic sensor 4 body is installed through the mounting hole 21 to achieve fixed installation of the ultrasonic sensor; the inner diameter of the bolt hole 23 is smaller than the inner diameter of the nesting hole 22, so as to ensure the contact between the bottom of the ultrasonic sensor 4 probe and the bolt 1, and the inner diameter of the nesting hole 22 can meet the requirements of protruding outer edges of different specifications; the inner diameter of the mounting hole 21 is smaller than the inner diameter of the bolt hole 23, so as to achieve fixed installation of the ultrasonic sensor 4 and improve the stability of the installation; the coupling layer 3 is coated on the bottom of the ultrasonic sensor probe 4 and contacts with the end face of the full circle connecting bolt 1 of the blade root, so as to achieve coupling between the ultrasonic sensor probe and the full circle connecting bolt of the blade root through the coupling glue / coupling agent of the coupling layer; the full circle connecting bolt of the blade root The circle connecting bolt 1 is threadedly connected with the bolt hole 23 of the tightening device 2, and the tightening between the full circle connecting bolt 1 at the root of the blade and the ultrasonic sensor probe 4 is achieved by rotating the tightening device; a tightening thread matching the full circle connecting bolt 1 at the root of the blade is arranged in the bolt hole 23; the sensor terminal 5 is arranged in the ultrasonic sensor 4 and connected to the channel collector; long-term monitoring of the preload force is achieved; the inner diameter of the nesting hole 22 is larger than the outer diameter of the protruding outer edge at the bottom of the ultrasonic sensor 4 probe, so as to ensure the stability of the installation; the depth of the nesting hole 22 is larger than the thickness of the protruding outer edge at the bottom of the ultrasonic sensor 4 probe, so as to ensure the stability of the installation; the periphery of the tightening device 2 is provided with anti-slip grooves, and the structure of the tightening device 2 is hexahedral or annular, so as to facilitate installation and tightening.

[0051] A plurality of the monitoring probes form a monitoring probe array. Preferably, there are at least 8 ultrasonic sensors, which are evenly installed at the ends of the connecting bolts of the blade root. Figure 3The uniform arrangement of the monitoring probe array facilitates real-time and uniform detection of the stress of the blade root bolts. Monitoring the bolt preload is based on the principle of ultrasonic longitudinal wave acoustic elasticity, that is, when an isotropic solid material is stressed in a certain direction and the ultrasonic wave is in the same direction as the stress, the speed of sound and the stress are linearly related. The data processing equipment is used to correct the strain error caused by temperature changes to obtain the actual preload of the bolt, accurately monitor the force of the bolt, and improve the accuracy of monitoring.

[0052] The fan information includes fan number, IP address, fan IP address, operating time, operating interval, blade parameters, remarks information, etc.; the blade parameters include blade number, number of blade collection channels, threshold voltage, gain index, number of times the average value is collected, collection time interval, etc.; the bolt information includes bolt specification, bolt position number, number of monitoring probe installation paths, calibration information, length of bolt clamping part, rated preload force information of bolt, allowable preload force deviation range of bolt, etc.; by correctly positioning the fan, blades and bolts, it is convenient to collect the position of specific bolts of specific blades of specific fans, which is convenient for maintenance personnel to directly carry out maintenance and improve maintenance efficiency.

[0053] The uploaded data includes fan number, blade number, bolt position number, sound time information, temperature information, etc.

[0054] The specific working process is as follows:

[0055] First, the coupling glue is coated on the bottom of the ultrasonic sensor 4 probe to form a coupling layer 3. After the coating is evenly applied, it is pressed on the end face of the connecting bolt 1 of the entire circle at the root of the blade, and the tightening device 2 is penetrated and nested on the ultrasonic sensor 4 from bottom to top, so that the nesting hole 22 is just nested on the protruding outer edge of the bottom of the ultrasonic sensor 4 probe, and then the tightening device 2 and the connecting bolt 1 of the entire circle at the root of the blade are tightened clockwise to achieve fixed installation of the ultrasonic sensor and ensure the stability of data monitoring; the sensor terminal 5 can be connected to the data acquisition and processing equipment.

[0056] Before monitoring, when the wind turbine blade is in a vertical position, the eight probes on the blade bolts are evenly installed, and a hydraulic torque wrench is used to pre-tighten all the bolts in a full circle. At this time, the static tightening stress of the bolts detected by the eight probes is basically the same, which is the superposition of the tightening stress and the blade gravity.

[0057] The method for online monitoring of bolt preload of wind turbine generator set comprises the following steps:

[0058] 1) Add the fan information (including fan number, IP address, fan IP address, operating time, operating interval, blade parameters, remarks, etc.; blade parameters include blade number, number of blade acquisition channels, threshold voltage, gain index, number of acquisition average values, acquisition time interval, etc.) and bolt information (including bolt specifications, bolt position number, number of monitoring probe installation paths, calibration information, bolt clamping part length, bolt rated preload information, bolt allowable preload deviation range, etc.) to the online monitoring system and save them in the database;

[0059] 2) Read the fan information and bolt information, start online monitoring, and monitor the uploaded data provided by the data acquisition and processing equipment;

[0060] 3) Analyze the uploaded data about the fan and bolts monitored, and the analysis process is as follows: intercept the time period to be analyzed and determine whether there is any bolt preload information record: if not, change the time period to be analyzed; if yes, import the bolt preload record corresponding to the fan in the time period to be analyzed, and read the status analysis model in combination with the fan model or bolt information; analyze the force prediction and trend of the overall bolts in the fan monitoring part according to the bolt preload record, the status analysis model and the monitoring data, and give intervention suggestions; calculate the bolt preload and temperature compensation, and determine whether the preload is within the normal range: if it is not within the normal range, warn, alarm, write an abnormal log, save the abnormal log, intervene in the report, and enter the save interface; within the normal range, display the preload information on the corresponding fan monitoring unit interface, save the collected data, and change the time period to be analyzed; if there is no uploaded data, continue to monitor.

[0061] During the monitoring process, all the monitored data is processed and reports are generated to guide the staff to perform maintenance in a timely manner. The staff can also judge the numbering trend of each bolt based on the data report, find hidden accident points in time, and perform maintenance in advance.

[0062] The normal range refers to the state analysis model obtained by superimposing the tightening stress of the bolts and the fan at static state and the blade gravity; or the state analysis model obtained by superimposing the tightening stress of the bolts and the fan at static state and the blade gravity, supplemented by the stress value during normal operation. There are two ways to obtain the value of the normal range: 1) When the wind turbine is stationary, each blade is in a fixed static position. At this time, each bolt has a static preload of different sizes. The measured data at static state is compared with the historical data. If the difference is found, it means that the bolt is loose or broken. The urgency of the abnormal situation can be judged according to the size of the difference; 2) When the wind turbine is running, the system will automatically measure the tightening stress change curve of each monitoring bolt at regular intervals (the tightening stress of each bolt changes dynamically during operation, which is reflected in the superposition of preload, wind load, gravity load and centrifugal load), and compare the measured curve with the historical normal curve. If the comparison result is within the normal range, no alarm will be given. If it deviates from the historical normal value, it means that the bolt is loose or broken. The urgency of the abnormal situation can be judged according to the size of the deviation value, and then an alarm will be given.

[0063] Select 8 (not limited to 8, can be more, the more the more detailed the monitoring data) bolts from the whole circle of connecting bolts at the root of the wind turbine blade to install ultrasonic stress monitoring probes. The built-in program of the measurement system will judge the connection status of the whole circle of bolts according to the changes in the monitoring data of the 8 probes. If a bolt is loose or broken, the stress curves of the 8 monitoring points will change. This change corresponds to the loosening or breaking of the bolt. The monitoring system has built-in this corresponding relationship. Therefore, the monitoring system can infer abnormal conditions such as loosening and breaking of the bolt based on the changes in the data of the 8 monitoring points, and then alarm.

[0064] Regardless of whether any bolts are loose or broken, these monitoring data are transmitted back to the cloud / back-end server and stored, and can be used as a basis for improving the design of wind turbines in the future.

[0065] like Figure 4As shown in the figure, the state analysis model of a bolt and the wind turbine it is located in when static (time-varying stress curve). During actual operation, monitoring is carried out to continuously improve the state analysis model, and then form a state analysis model of actual experience, which is used as a comparison model of the normal range of the online monitoring system within a specific time period. Once the preload monitored by a bolt is significantly offset, and the adjacent bolts around it also have obvious offsets (manifested as the preload exceeds the allowable stress value [σ] (the highest standard value or is lower than the lowest standard value), a bolt is loose or fatigue fractured, and the tightening stress of this bolt and the remaining bolts changes and exceeds the allowable value range, the monitoring system receives data, compares the bolt tightening stress curve drawn by real-time measurement with the historical curve, and the real-time measurement curve is offset), it is judged as abnormal, and an intervention report requiring manual repair and inspection is obtained as abnormal data, which can be positioned and repaired at the next shutdown. If multiple intervention reports appear continuously, an alarm is issued and an emergency shutdown is required for processing. Safety alarms are divided into at least two levels. The second level is general danger, which is handled when the wind turbine is shut down; the first level alarm is a major danger, which should be shut down immediately for disposal. Warning or fault signals may indicate that a bolt has become loose or fatigued and broken. Wind turbine operation and maintenance personnel can take appropriate measures according to the degree of looseness of the bolts. If the looseness is not serious, the corresponding bolts can be tightened during the next shutdown. If the looseness is too large or even judged to be a fracture, the unit can be shut down in time to tighten or replace the bolts for maintenance.

[0066] For a certain type of wind turbine, the stress coefficient and temperature compensation coefficient of the bolt model are obtained by laboratory calibration (the stress error offset caused by the temperature under different test temperatures is used for the correction coefficient). When the ultrasonic longitudinal wave sound of a bolt is actually measured, the actual stress value it bears can be calculated. By using 2KHz frequency sampling, the time-varying stress curve of the bolt can be monitored and plotted, such as Figure 4 As shown, the curve is more detailed when the sampling frequency is high, and the line is roughly approximated when the sampling frequency is low. The sampling frequency does not directly reflect the loosening of the bolts. The sampled bolt tightening stress curve should be compared with the historical curve: if the bolts at a certain monitoring point are loose, the offset will be relatively large; if the bolts between two monitoring points are loose or broken, the bolt tightening stresses of the two adjacent monitoring points will change, and the monitoring point closer to the loose bolt will change more.

[0067] like Figure 3 As shown in the figure, 8 monitoring probes (not limited to 8) are evenly installed along the entire circle of bolts at the blade root. When any of the bolts is loose or broken, the axial load it bears is reduced or even zero, and these axial loads will inevitably be shared by the adjacent bolts, thus causing the axial load of the bolts at the monitoring point to change accordingly. After the system monitors these changes, it can judge the working status of the entire circle of bolts in real time and issue an early warning of bolt loosening or breaking.

[0068] The monitoring probe of the present invention is installed by clamping the tightening device, so that the ultrasonic sensor body is installed in the installation hole; the nested installation of the ultrasonic sensor is realized through the nesting hole of the tightening device; the fixed installation of the ultrasonic sensor and the full circle of connecting bolts at the root of the blade is realized by tightening the bolt hole of the tightening device and the full circle of connecting bolts at the root of the blade, thereby ensuring the stability of the coupling layer thickness. Since the fixed installation is achieved through threaded connection, the continuous consistency of pressure is guaranteed.

[0069] The wind turbine bolt tightening stress monitoring system and monitoring method provided by the present invention monitors the tightening stress of the entire circle of connecting bolts at the root of the wind turbine blades in real time, determines whether the bolts are loose or broken, and promptly issues early warnings and fault judgments, so that operation and maintenance personnel can grasp the health status of the blade root bolts at any time, filling the gap of the current lack of an online real-time monitoring system for wind turbine bolts.

[0070] The monitoring probe of the present invention uses an ultrasonic sensor to detect the axial stress of bolt tightening in real time based on the acoustic elasticity principle, without destroying the bolt structure and without affecting the bolt tightening and disassembly operations.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A system for online monitoring of bolt preload force of wind turbine generator sets, characterized in that: It includes a monitoring probe installed at the end of a full circle connecting bolt at the root of a wind turbine blade, a temperature sensor magnetically attached to the full circle connecting bolt at the root of the blade, a data acquisition and processing device connected to the monitoring probe and the temperature sensor, and a monitoring system for monitoring the pre-tightening force of each bolt of the wind turbine; The data acquisition and processing equipment includes a data processing system for processing and analyzing the fan information, bolt information, monitoring probes and data collected by temperature sensors; The monitoring system is used to calculate the uploaded data, calculate the bolt preload and temperature compensation, determine whether the preload is within the normal range, and issue a corresponding alarm message; The monitoring probe includes a full circle of connecting bolts at the root of the blade, a tightening device, a coupling layer, an ultrasonic sensor and a sensor terminal; The tightening device includes a mounting hole, a nesting hole and a bolt hole from top to bottom; The protruding outer edge of the bottom of the monitoring probe is nested in the nesting hole of the tightening device; The ultrasonic sensor is installed in the installation hole; The coupling layer is coated on the bottom of the ultrasonic sensor probe and contacts the end surface of the connecting bolts of the entire circle of the blade root; The entire circle of connecting bolts at the root of the blade is threadedly connected to the bolt holes of the tightening device; The sensor terminal is arranged in the ultrasonic sensor and connected to the data acquisition and processing equipment; The protruding outer edge at the bottom of the monitoring probe is nested in the nesting hole of the tightening device; the ultrasonic sensor is installed through the mounting hole to achieve fixed installation of the ultrasonic sensor; the inner diameter of the bolt hole is smaller than the inner diameter of the nesting hole, so as to ensure the contact between the bottom of the ultrasonic sensor probe and the bolt, and the inner diameter of the nesting hole can meet the requirements of protruding outer edges of different specifications; the inner diameter of the mounting hole is smaller than the inner diameter of the bolt hole, so as to achieve fixed installation of the ultrasonic sensor and improve the stability of the installation; the coupling layer is coated on the bottom of the ultrasonic sensor probe and contacts the end face of the connecting bolt of the whole circle of the blade root, so as to achieve coupling between the ultrasonic sensor probe and the connecting bolt of the whole circle of the blade root through the coupling glue / coupling agent of the coupling layer; the whole circle of the blade root The connecting bolt is threadedly connected to the bolt hole of the tightening device, and the tightening between the connecting bolt of the whole circle of the blade root and the ultrasonic sensor probe is achieved by rotating the tightening device; a tightening thread matching the connecting bolt of the whole circle of the blade root is arranged in the bolt hole; the sensor terminal is arranged in the ultrasonic sensor and connected to the channel collector; long-term monitoring of the preload force is achieved; the inner diameter of the nested hole is larger than the outer diameter of the protruding outer edge at the bottom of the monitoring probe, so as to ensure the stability of the installation; the depth of the nested hole is larger than the thickness of the protruding outer edge at the bottom of the monitoring probe, so as to ensure the stability of the installation; the periphery of the tightening device is provided with anti-slip grooves, and the structure of the tightening device is hexahedral or annular, which is convenient for installation and tightening.

2. The system for online monitoring of bolt preload force of wind turbine generator set according to claim 1, characterized in that: The fan information includes fan number, IP address, fan IP address, operation time, operation interval, blade parameters or remarks information; The bolt information includes bolt specifications, bolt position numbers, number of monitoring probe installations, calibration information, bolt clamping portion length, bolt rated preload information or bolt allowable preload deviation range.

3. The system for online monitoring of bolt preload force of wind turbine generator set according to claim 2, characterized in that: The blade parameters include blade number, blade acquisition channel number, threshold voltage, gain value, number of acquisition average values ​​or acquisition time interval.

4. The system for online monitoring of bolt preload force of wind turbine generator set according to claim 1, characterized in that: A plurality of the monitoring probes form a monitoring probe array.

5. The system for online monitoring of bolt preload force of wind turbine generator set according to claim 1, characterized in that: The uploaded data includes fan number, blade number, bolt position number, sound timing information or temperature information.

6. A method for online monitoring of bolt preload force of a wind turbine generator set, characterized in that: The steps include: 1) Adding wind turbine information and bolt information to the system for online monitoring of bolt preload force of wind turbine set according to any one of claims 1 to 5; 2) Read the fan information and bolt information, start online monitoring, and monitor the uploaded data provided by the data acquisition and processing equipment; 3) Analyze the uploaded data about the fan and bolts, calculate the bolt preload and temperature compensation, determine whether the preload is within the normal range and issue a warning, and save the data; if there is no uploaded data, continue to monitor.

7. The method for online monitoring of bolt preload of wind turbine generator set according to claim 6, characterized in that: The normal range refers to a state analysis model obtained by superimposing the tightening stress of the bolts and the fan in static state and the blade gravity; or a state analysis model obtained by superimposing the tightening stress of the bolts and the fan in static state and the blade gravity, supplemented by the stress value during actual normal operation.

8. The method for online monitoring of bolt preload of wind turbine generator set according to claim 6, characterized in that: In step 3), the analysis process is as follows: intercept the time period to be analyzed and determine whether there is any bolt preload information record: if not, change the time period to be analyzed; if yes, import the bolt preload record corresponding to the fan in the time period to be analyzed, and read the status analysis model in combination with the fan model or bolt information; analyze the force prediction and trend of the overall bolts in the fan monitoring part according to the bolt preload record, the status analysis model and the monitoring data, and give intervention suggestions and judgments.

9. The method for online monitoring of bolt preload of wind turbine generator set according to claim 6, characterized in that: In step 3), determine whether the preload force is within the normal range: if it is not within the normal range, issue an early warning, an alarm, write an abnormal log, save the abnormal log, intervention report, and enter the save interface; Within the normal range, the preload information is displayed on the corresponding fan monitoring unit interface, the collected data is saved, and the time period to be analyzed is changed.

Images