Method and system for monitoring the condition of a wind turbine blade and pitch bearing bolted connection

Abstract

The application discloses a kind of method and system for monitoring the state of fan blade and variable pitch bearing bolt connection, it is related to bolt monitoring technical field for wind power generation, including monitoring and obtaining the real-time axial strain data of bolt, real-time temperature data;Real-time pressure and real-time yield strength of bolt are calculated;When real-time pressure is greater than real-time yield strength, if the sum of real-time pressure and make-up strength is less than real-time yield strength, then the real-time yield strength of bolt is made to standard yield strength by heat exchange, if the sum of real-time pressure and make-up strength is greater than or equal to real-time yield strength, then fan equipment is stopped and maintained, the application is when the sum of real-time pressure and make-up strength is less than real-time yield strength, by the way of heating bolt, make bolt from failure risk dissociation, and when the sum of real-time pressure and make-up strength is greater than or equal to real-time yield strength, fan equipment is stopped and maintained, avoid the problem of bolt and lead to safety accident.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bolt monitoring for wind power generation, in particular to a method and system for monitoring the state of a bolt connecting piece of a wind turbine blade and a variable pitch bearing. BACKGROUND

[0002] The blade is a key component for capturing wind. The blade root, as the root of the cantilever beam, bears a large load. Part of the load is transmitted through the bolt, and part of the load is transmitted through the contact surface between the blade root and the bearing. The pre-tightening force needs to be guaranteed to ensure the safety of the bolt in operation. The level of the pre-tightening force is affected by various factors such as assembly (e.g. lubrication), dimensioning, wind turbine vibration, load level, etc. During operation, unexpected loosening and breakage of the bolt may occur. At present, the pre-tightening state and breakage of the blade root bolt of the wind turbine in most domestic wind farms are mainly checked by manual visual inspection, hand-held hydraulic wrench or stretcher, and realized by regular or irregular manual inspection. The manual inspection method is passive and cannot identify whether the bolt is loose or broken in time. Therefore, it is particularly important to discover the abnormal state of the bolt at the connecting part of the wind turbine in time.

[0003] In the prior art, a method and system for monitoring the state of a bolt connecting piece of a wind turbine blade and a variable pitch bearing are disclosed in publication No. CN111306011B. The method uses one or more displacement sensors to collect and determine the distance information of each bolt connecting piece in the first monitoring area in real time. According to the distance information of each bolt connecting piece, the position change information of the bolt connecting piece is determined. According to the position change information of the bolt connecting piece, it is determined whether the state of the bolt connecting piece is abnormal, thereby realizing real-time online monitoring of the state of the bolt connecting piece at the connecting part of the wind turbine blade and the variable pitch bearing, and effectively preventing cost loss and blade falling risk caused by abnormal state of the bolt connecting piece.

[0004] However, the prior art still has some defects, such as: during the daily operation of the wind turbine, the bolt is subjected to long-term tensile and compressive alternating loads. Under the action of the tensile and compressive alternating loads, the bolt may undergo permanent plastic deformation, resulting in failure of the bolt. The above-mentioned technology can only monitor the position change of the relative deflection of the bolt and the nut, but cannot monitor the change of the alternating load inside the bolt, which has certain safety hazards. SUMMARY

[0005] The present application aims to provide a method and system for monitoring the state of a bolt connecting piece of a wind turbine blade and a variable pitch bearing to solve the problems raised in the background.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] A method for monitoring the state of a bolt connecting piece of a wind turbine blade and a variable pitch bearing, comprising:

[0008] Monitor and obtain the real-time axial strain data and real-time temperature data of the bolt;

[0009] Calculate the real-time pressure of the bolt according to the real-time axial strain data of the bolt;

[0010] Take the standard yield strength of the bolt under normal temperature environment as the reference, and take the real-time temperature data as the correction parameter to obtain the real-time yield strength of the bolt;

[0011] When the real-time pressure is greater than the real-time yield strength, take the difference between the real-time yield strength and the standard yield strength as the compensation strength, if the sum of the real-time pressure and the compensation strength is less than the real-time yield strength, the real-time yield strength of the bolt reaches the standard yield strength through heat exchange, if the sum of the real-time pressure and the compensation strength is greater than or equal to the real-time yield strength, the fan equipment is shut down for maintenance.

[0012] Preferably, the bolt is entirely made of a straight-buried strain gauge bolt to obtain the real-time axial strain data.

[0013] Preferably, a protective cylinder with an electric heating element is sleeved outside the bolt to perform heat exchange on the bolt.

[0014] Preferably, a split temperature sensor is used to obtain the real-time temperature data of the bolt, and the split temperature sensor is composed of a temperature collection element installed on the bolt, a signal transmission line wound on the bolt, and a signal sending element installed outside the protective cylinder, and when the signal transmission line is broken, the signal sending element emits an alarm signal to shut down the fan equipment for maintenance.

[0015] Preferably, the real-time axial strain data of the bolt is also transmitted through the signal sending element.

[0016] A system for monitoring the state of a bolt connection between a wind turbine blade and a variable pitch bearing, which is used in the method for monitoring the state of the bolt connection between the wind turbine blade and the variable pitch bearing, and comprises a signal collection unit, a signal processing unit, a signal analysis unit, and a negative feedback unit;

[0017] The signal collection unit is used to monitor and obtain the real-time axial strain data and real-time temperature data of the bolt, and transmit the real-time axial strain data and real-time temperature data of the bolt to the signal processing unit;

[0018] The signal processing unit calculates the real-time pressure and real-time yield strength of the bolt according to the real-time axial strain data and real-time temperature data of the bolt, and transmits the real-time pressure and real-time yield strength of the bolt to the signal analysis unit;

[0019] A signal analysis unit analyzes the bolt in combination with the real-time pressure, the real-time yield strength and the make-up strength, controls the negative feedback unit to send a first negative feedback signal when the sum of the real-time pressure and the make-up strength is less than the real-time yield strength, and controls the negative feedback unit to send a second negative feedback signal when the sum of the real-time pressure and the make-up strength is greater than the real-time yield strength;

[0020] The negative feedback unit sending the first negative feedback signal under the control of the signal analysis unit makes the bolt exchange heat so that the real-time yield strength of the bolt reaches the standard yield strength, and the negative feedback unit sending the second negative feedback signal under the control of the signal analysis unit makes the fan equipment stop for maintenance.

[0021] Compared with the prior art, the method and system for monitoring the state of the bolt connection of the fan blade and the variable pitch bearing have the following beneficial effects:

[0022] The method and system for monitoring the state of the bolt connection of the fan blade and the variable pitch bearing take the real-time temperature as a correction parameter to obtain the real-time yield strength of the bolt, analyze the bolt in combination with the real-time yield strength, the real-time pressure and the make-up strength, make the bolt get rid of the state of failure risk by heating the bolt when the sum of the real-time pressure and the make-up strength is less than the real-time yield strength, without stopping the fan equipment for maintenance, thereby greatly reducing the maintenance cost, and stop the fan equipment for maintenance when the sum of the real-time pressure and the make-up strength is greater than or equal to the real-time yield strength, thereby avoiding the problem that the bolt is permanently plastically deformed under the action of external force and then fails when the fan equipment continues to work, improving the monitoring and protection effect of the bolt, and avoiding the problem that a safety accident is caused by the problem of the bolt. BRIEF DESCRIPTION OF DRAWINGS

[0023] Fig. 1 The method flowchart for monitoring the state of the bolt connection of the fan blade and the variable pitch bearing is provided.

[0024] Fig. 2 The embodiment schematic diagram of the system for monitoring the state of the bolt connection of the fan blade and the variable pitch bearing is provided. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0026] Please refer to Figs. 1-2 The present application provides a technical solution:

[0027] A method for monitoring the state of a bolt connection of a wind turbine blade and a variable pitch bearing, comprising:

[0028] S101, the signal acquisition unit 201 monitors and acquires real-time axial strain data and real-time temperature data of the bolt, specifically, the signal acquisition unit 201 includes a directly buried strain gauge bolt, a temperature sensor, and a signal transmission device for sending signals, wherein the strain gauge is pre-buried in the bolt, and the strain gauge is arranged in the axial direction of the bolt, so that the strain gauge can measure the real-time axial strain data of the bolt in real time, the temperature sensor is located outside the bolt and measures the real-time temperature data of the bolt in real time, and then the signal transmission device of the signal acquisition unit 201 transmits the real-time axial strain data of the bolt measured by the strain gauge and the real-time temperature data of the bolt measured by the temperature sensor to the signal processing unit 202;

[0029] S102, the signal processing unit 202 calculates the real-time pressure of the bolt according to the real-time axial strain data of the bolt, wherein the signal processing unit 202 includes a signal receiver for receiving the real-time axial strain data, a signal processor for processing and calculating the real-time axial strain data to obtain the real-time pressure, and a signal transmitter for transmitting the real-time pressure to the signal analysis unit 203, for example, the commonly used material of the wind turbine blade connecting bolt is 42CrMoA, the yield strength is 900MPa, the elastic modulus is 210000MPa, when the strain value measured by the strain gauge is 0.0043, the signal receiver transmits the received real-time axial strain data to the signal processor, the signal processor obtains σ=0.00428×210000MPa=898.8MPa according to the formula σ=εE, that is, the signal processor measures the real-time pressure of the bolt as 898.8MPa, and then the signal processor transmits the real-time pressure to the signal transmitter;

[0030] S103, the signal processing unit 202 takes the standard yield strength of the bolt in the normal temperature environment as the reference, and takes the real-time temperature data as the correction parameter to obtain the real-time yield strength of the bolt, wherein the signal processing unit includes a signal receiver receiving real-time temperature data, a signal processor correcting the standard yield strength according to the real-time temperature data to obtain the real-time yield strength, and a signal transmitter transmitting the real-time yield strength to the signal analysis unit 203, such as the yield strength of 900 MPa of the bolt is the standard yield strength measured at normal temperature 20 degrees Celsius, but the bolt will be affected by the external temperature when used in the external environment, because the nominal stress of the steel structure when brittle failure occurs decreases with the decrease of temperature, the plasticity of the steel decreases, the brittleness increases, so that there is a certain deviation between the real-time yield strength and the standard yield strength of the bolt at a certain temperature, so that the real-time pressure of the bolt exists certain risk when it does not reach the standard yield strength but reaches the real-time yield strength, and it is obvious that there is a defect to directly use the standard yield strength as the alarm threshold of the real-time pressure, therefore, according to the principle that the yield strength of the bolt and the temperature are positively correlated, the signal receiver transmits the real-time temperature data to the signal processor, the signal processor takes the real-time temperature data as the correction parameter to obtain the real-time yield strength of the bolt, and then transmits the real-time yield strength to the signal transmitter, so that the subsequent signal analysis unit 203 can determine whether the bolt at a certain real-time pressure exists risk according to the real-time yield strength;

[0031] S104, the signal analysis unit 203 takes the difference between the real-time yield strength and the standard yield strength as the compensation strength, and analyzes the bolt in combination with the real-time pressure, the real-time yield strength and the compensation strength, the compensation strength is positive when the real-time yield strength is greater than the standard yield strength, and the compensation strength is negative when the real-time yield strength is less than the standard yield strength, wherein the signal analysis unit 203 includes a signal receiver receiving the real-time yield strength and the real-time pressure, a signal analyzer introducing the compensation strength and analyzing the bolt in combination with the real-time pressure, the real-time yield strength and the compensation strength, and a signal transmitter transmitting the analysis result to the negative feedback unit 204;

[0032] The signal receiver sends the real-time pressure and the real-time yield strength into the signal analyzer, the signal analyzer introduces the compensation strength and analyzes the bolt, when the real-time pressure is greater than the real-time yield strength, if the sum of the real-time pressure and the compensation strength is less than the real-time yield strength, the signal transmitter sends the first signal to the negative feedback unit 204 according to the analysis result of the signal analyzer (i.e. the sum of the real-time pressure and the compensation strength is less than the real-time yield strength), the negative feedback unit 204 sends the first negative feedback signal under the control of the first signal, so that the bolt exchanges heat, so that the real-time yield strength of the bolt reaches the value of the standard yield strength, so that the real-time pressure of the bolt is less than the real-time yield strength reaching the standard yield strength, thereby the bolt is out of the state of failure risk by increasing the real-time yield strength of the bolt, without stopping the maintenance of the fan equipment, which greatly reduces the maintenance cost;

[0033] Similarly, when the real-time pressure is greater than the real-time yield strength, if the sum of the real-time pressure and the compensation strength is greater than or equal to the real-time yield strength, the signal transmitter sends the second signal to the negative feedback unit 204 according to the analysis result of the signal analyzer (i.e. the sum of the real-time pressure and the compensation strength is greater than or equal to the real-time yield strength), the negative feedback unit 204 sends the second negative feedback signal under the control of the second signal, so that the fan equipment is maintained, thereby avoiding the problem that the bolt is permanently deformed under the action of external force and then fails while the fan equipment continues to work, wherein the negative feedback unit 204 includes a signal receiver receiving the signal of the signal analysis unit 203, a signal transmitter sending the first negative feedback signal or the second negative feedback signal, and a negative feedback processor controlling the signal transmitter to send the first negative feedback signal or the second negative feedback signal according to the signal of the signal analysis unit 203 received by the signal receiver;

[0034] Further, the protective cylinder with the electric heating element is sleeved outside the bolt to exchange heat with the bolt, the electric heating element is signal-connected with the negative feedback unit 204, so that the electric heating element works and generates heat when the negative feedback unit 204 sends the first negative feedback signal, the electric heating element heats the bolt through the protective cylinder, so that the real-time yield strength of the bolt which is originally low due to too low temperature rises to the value of the standard yield strength after heating, thereby achieving the purpose of making the bolt out of the failure risk state by increasing the real-time yield strength of the bolt, and the negative feedback unit 204 is signal-connected with the fan equipment control terminal, so that the fan equipment control terminal controls the fan equipment to be maintained when the negative feedback unit 204 sends the second negative feedback signal;

[0035] Further, the split temperature sensor is used to obtain the real-time temperature data of the bolt, and the split temperature sensor is composed of a temperature collection part installed on the bolt, a signal transmission line wound on the bolt, and a signal transmitter installed outside the protection cylinder. The real-time temperature data collected by the temperature collection part is transmitted to the signal transmitter through the signal transmission line, and then transmitted to the signal transmission device of the signal acquisition unit 201 by the signal transmitter. The real-time axial strain data measured by the strain gauge is also transmitted to the signal transmitter through the signal transmission line, and then transmitted to the signal transmission device of the signal acquisition unit 201 by the signal transmitter. The signal transmitter and the fan equipment control terminal are signal connected. When the bolt is cracked, the signal transmission line is broken, the signal transmitter cannot receive the real-time temperature data and sends an alarm signal to the fan equipment control terminal, so that the fan equipment control terminal controls the fan equipment to stop and maintain, which is convenient for workers to replace the bolt in time.

[0036] Among them, the signal transmission device of the signal acquisition unit 201, the signal receiver of the signal processing unit 202, the signal transmitter, the signal receiver of the signal analysis unit 203, the signal transmitter, the signal receiver of the negative feedback unit 204, the signal transmitter, and the signal transmitter of the split temperature sensor are all selected from NRF24LE1GNQF32 wireless transmission chip integrated with 16M internal crystal oscillator, SPI interface, serial interface and ADC data conversion. The signal processor of the signal processing unit 202, the signal analyzer of the signal analysis unit 203, and the negative feedback processor of the negative feedback unit 204 are all selected from Cortex-M3 processor as MCU control unit for processing signals.

[0037] A system for monitoring the state of the bolt connection of the wind turbine blade and the variable pitch bearing, which is used for the method for monitoring the state of the bolt connection of the wind turbine blade and the variable pitch bearing, comprising a signal acquisition unit 201, a signal processing unit 202, a signal analysis unit 203 and a negative feedback unit 204.

[0038] The signal acquisition unit 201 is used for monitoring and obtaining the real-time axial strain data and the real-time temperature data of the bolt, and transmitting the real-time axial strain data and the real-time temperature data of the bolt to the signal processing unit.

[0039] The signal processing unit 202 obtains the real-time pressure and the real-time yield strength of the bolt according to the real-time axial strain data and the real-time temperature data of the bolt, and transmits the real-time pressure and the real-time yield strength of the bolt to the signal analysis unit.

[0040] The signal analysis unit 203 analyzes the bolt in combination with the real-time pressure, the real-time yield strength and the make-up strength, controls the negative feedback unit to send a first negative feedback signal when the sum of the real-time pressure and the make-up strength is less than the real-time yield strength, and controls the negative feedback unit to send a second negative feedback signal when the sum of the real-time pressure and the make-up strength is greater than the real-time yield strength;

[0041] The negative feedback unit 204 sends a first negative feedback signal under the control of the signal analysis unit, so that the bolt exchanges heat to make the real-time yield strength of the bolt reach the standard yield strength, and sends a second negative feedback signal under the control of the signal analysis unit, so that the fan equipment is stopped for maintenance.

[0042] Although the embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for monitoring the condition of the bolted connection between wind turbine blades and pitch bearings, characterized in that, include: Monitor and acquire real-time axial strain data and real-time temperature data of the bolts; The real-time pressure of the bolt is calculated based on the real-time axial strain data of the bolt. The real-time yield strength of the bolt is obtained by using the standard yield strength of the bolt at room temperature as the benchmark and real-time temperature data as the correction parameter. as well as When the real-time pressure is greater than the real-time yield strength, the difference between the real-time yield strength and the standard yield strength is used as the compensation strength. If the sum of the real-time pressure and the compensation strength is less than the real-time yield strength, heat exchange is used to make the real-time yield strength of the bolt reach the standard yield strength. If the sum of the real-time pressure and the compensation strength is greater than the real-time yield strength, the fan equipment is shut down for maintenance. A protective sleeve with an electric heating element is placed on the outside of the bolt to facilitate heat exchange. A split-type temperature sensor is used to acquire real-time temperature data of the bolt. The split-type temperature sensor consists of a temperature acquisition component installed on the bolt, a signal transmission line wound on the bolt, and a signal transmitter installed outside the protective cylinder. When the signal transmission line breaks, the signal transmitter emits an alarm signal to stop the fan equipment for maintenance.

2. The method for monitoring the status of the bolted connection between the wind turbine blades and the pitch bearing according to claim 1, characterized in that: The bolts are all direct-embedded strain gauge bolts to obtain real-time axial strain data.

3. The method for monitoring the status of the bolted connection between the wind turbine blade and the pitch bearing according to claim 1, characterized in that: The real-time axial strain data of the bolt is also transmitted via a signal transmitter.

4. A system for monitoring the condition of the bolted connection between wind turbine blades and pitch bearings, used in the method for monitoring the condition of the bolted connection between wind turbine blades and pitch bearings as described in any one of claims 1-3, characterized in that: It includes a signal acquisition unit, a signal processing unit, a signal analysis unit, and a negative feedback unit; The signal acquisition unit is used to monitor and acquire the real-time axial strain data and real-time temperature data of the bolt, and transmit the real-time axial strain data and real-time temperature data of the bolt to the signal processing unit. The signal processing unit calculates the real-time pressure and real-time yield strength of the bolt based on the real-time axial strain data and real-time temperature data of the bolt, and transmits the real-time pressure and real-time yield strength of the bolt to the signal analysis unit. The signal analysis unit analyzes the bolt by combining real-time pressure, real-time yield strength and compensation strength. When the sum of real-time pressure and compensation strength is less than the real-time yield strength, the negative feedback unit is controlled to issue a first negative feedback signal, and when the sum of real-time pressure and compensation strength is greater than the real-time yield strength, the negative feedback unit is controlled to issue a second negative feedback signal. as well as The negative feedback unit, under the control of the signal analysis unit, issues a first negative feedback signal to cause the bolt to undergo heat exchange, thereby enabling the bolt's real-time yield strength to reach the standard yield strength. Under the control of the signal analysis unit, the negative feedback unit issues a second negative feedback signal to cause the fan equipment to be shut down for maintenance.

Images