1. A method for monitoring the state of a blade of a wind generating set in a severe environment is characterized by comprising the following steps:

step 1, selecting a plurality of strain monitoring points on a blade of a monitored wind generating set close to the root of the blade and in a bonding area of the blade, and selecting a plurality of acceleration monitoring points far away from the root of the blade;

step 2, adhering an optical fiber acceleration sensor at the selected acceleration monitoring point according to the position of the monitored wind generating set blade, so that the optical fiber acceleration sensor can measure the vibration of the wind generating set blade in two directions of waving and shimmy; at the selected strain monitoring point, at least four groups of optical fiber strain gauges are adhered to the windward side, the leeward side, the front edge and the rear edge according to the strain measurement section;

step 3, acquiring real-time acceleration of the monitored wind generating set blade through the optical fiber acceleration sensor pasted in the step 2, and acquiring real-time monitoring signals of the monitored wind generating set blade through the optical fiber strain gauge; the real-time monitoring signals comprise strain data of a windward side and a leeward side at the strain monitoring points and strain data of a front edge and a rear edge;

4, an industrial personal computer or a server calculates an acceleration signal time domain and frequency domain analysis value according to the real-time acceleration data of the monitored wind generating set blade acquired by the optical fiber acceleration sensor in the step 3; calculating blade section flapping moment according to strain data of a windward side and a leeward side at a strain monitoring point acquired by an optical fiber strain gauge, and calculating blade section shimmy moment according to the strain data of a front edge and a rear edge;

and 5, comparing and analyzing the real-time acceleration in the step 3 with the acceleration time domain and frequency domain data of the wind generating set blade calculated by the industrial control machine or the server in the step 4, the blade section flapping moment, the blade section shimmy moment and a parameter threshold value set by the wind generating set blade, judging the current state of the wind generating set blade, and generating and sending an alarm signal for the abnormal state of the blade.

2. The method for monitoring the state of the blade of the wind generating set in the severe environment according to claim 1, wherein the method comprises the following steps: in the step 2, before the optical fiber acceleration sensor and the optical fiber strain gauge are adhered, the adhering position on the monitored wind generating set is required to be subjected to dust removal, polishing and surface wiping.

3. The method for monitoring the state of the blade of the wind generating set in the severe environment according to claim 1 or 2, wherein the method comprises the following steps: and 3, before signal acquisition, connecting the optical fiber acceleration sensor and the optical fiber strain gauge adhered in the step 2 with an industrial personal computer or a server, testing the signal transmission states of the optical fiber acceleration sensor and the optical fiber strain gauge and debugging the load through the industrial personal computer or the server, and starting signal acquisition after the debugging is finished.

4. The method for monitoring the state of the blade of the wind generating set in the severe environment according to claim 1, wherein the method comprises the following steps: in the step 4, the time domain analysis mainly includes an average value, a peak-to-peak value, and an effective value.

5. The method for monitoring the state of the blade of the wind generating set in the severe environment according to claim 1, wherein the method comprises the following steps: the frequency domain analysis is to perform fourier transform on the time domain signal to obtain a frequency response value.

6. The method for monitoring the state of the blade of the wind generating set in the severe environment according to claim 1, 4 or 5, wherein the method comprises the following steps: in the step 4, blade section flapping moment is calculated according to strain data of the windward side and the leeward side of the strain monitoring point collected by the optical fiber strain gauge, specifically, actual measurement should be carried outThe strain quantity of the windward side at the monitoring point is changed into epsilon₁The strain amount of the leeward side at the strain monitoring point is epsilon₂The blade section waving momentAnd EI is bending rigidity of the blade in the flapping direction under a chord length coordinate system, and R is the section radius of the strain measuring point.

7. The method for monitoring the state of the blade of the wind generating set in the severe environment according to claim 1, 4 or 5, wherein the method comprises the following steps: in the step 4, the blade section shimmy moment is calculated according to the strain data of the front edge and the rear edge at the strain monitoring point, specifically, the strain data of the actually measured front edge is epsilon₁Strain data epsilon of trailing edge₂The blade section shimmy momentWherein M is₁And M₂Respectively representing section blade bending moments obtained by calculating strains of a leeward side and a windward side, wherein alpha represents an included angle between a connecting line of optical fiber strain gauges adhered to a front edge and a rear edge and a horizontal center line of a strain measurement section; EI (El)₁The bending rigidity in the lower oscillation direction of a chord length coordinate system, the chord length coordinate system is a coordinate system which takes a central point between a geometric front edge point and a back edge point of the strain measurement section as an original point and takes a connecting line of the front edge point and the back edge point as an X axis, E represents the elastic modulus of the blade material, I represents the elastic modulus of the blade material₁Representing the section moment of inertia.

8. The method for monitoring the state of the blade of the wind generating set in the severe environment according to claim 1, wherein the method comprises the following steps: the fiber grating acceleration and strain sensor is formed by packaging a fiber grating.

9. The method for monitoring the state of the blade of the wind generating set in the severe environment according to claim 1 or 8, wherein the method comprises the following steps: the fiber grating acceleration sensor is a low-frequency sensor, and the testing and analyzing frequency range is 0.1-40 Hz.

10. The method for monitoring the state of the blade of the wind generating set in the severe environment according to claim 1 or 8, wherein the method comprises the following steps: the optical fiber acceleration sensor and the optical fiber strain gauge which are pasted in the step 2 are connected with an industrial personal computer or a server through an optical fiber demodulator, the sampling frequency of the optical fiber demodulator is not less than 100Hz, and the optical fiber acceleration sensor and the optical fiber strain gauge have the functions of signal filtering, noise reduction, high-frequency acquisition, signal demodulation and the like.

Background

At present, the wind generating set is moving towards the trend of high-power models, because the average generating cost of the high-power wind generating set is low and the output power is high; and offshore wind field development recently becomes the domestic hot development direction, and offshore wind field is because the construction cost is high, and the construction degree of difficulty is big, generally adopts high-power level unit more than 5MW to reduce fan use number and wind field early later stage service cost. The large-power unit corresponds to the requirement of a long blade, the diameter of a wind wheel designed and manufactured at home is maximally close to 200m, the length of a single blade is close to 100m, however, the larger diameter of the wind wheel enables the blade to bear higher load level, the probability of damage and damage of the blade is increased rapidly, the longer blade enables the fan to be more easily influenced by the change of wind speed intensity in a swept area, and the blade is more easily damaged in severe environments such as sea, strong wind, thunderstorm and the like. The blade serving as a core component of the fan is very necessary to be subjected to safety monitoring, and the early failure of the blade structure is obtained through structure monitoring, so that an operator can better arrange a maintenance plan or implement automatic protection in an emergency, and the operation safety of the blade is protected to the maximum extent.

In addition, the cost of the blade accounts for 20% of the cost of the whole machine in general, and once the blade fracture phenomenon occurs, the loss is not small for the whole machine supplier and the owner, especially in the field of offshore wind power with hot investment at present, the construction, operation and maintenance difficulty and cost are increased compared with those of onshore wind fields, the offshore climate change is multiterminal, extreme environments such as strong wind, thunderstorm and rain exist occasionally, the bearing load of the blade is further increased, and the probability of damage to the blade is not small. In order to ensure safe operation of the blade, reliable monitoring of the health state of the blade is very important, however, a reliable blade state monitoring system is still lacking in the current market, the low-frequency acceleration sensor technology applied to the blade is not mature enough, and the signal anti-interference and low-frequency signal acquisition capabilities are still troublesome problems, and a stable and reliable fan blade state monitoring method suitable for the severe environment of a wind field needs to be invented urgently.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and provides a wind generating set blade state monitoring method with high reliability, which adopts an optical fiber sensor, has strong signal anti-interference capability, has the functions of real-time acquisition, transmission and the like, is suitable for various severe wind field environments, and can analyze strain and acceleration signals to obtain blade state data; when the abnormal state signals of the blades are monitored, the wind field management party can be guided to implement operations such as pitch variation, shutdown and the like so as to protect the safe operation of the blades.

The invention provides a method for monitoring the state of a blade of a wind generating set in a severe environment, which comprises the following steps:

step 1, selecting a plurality of strain monitoring points on a monitored wind generating set blade except for a blade self-bonding area, and selecting a plurality of acceleration monitoring points at positions far away from the blade root, wherein the strain monitoring points are generally arranged at the position of the blade root and only need to avoid the blade self-bonding area, and the strain force of the blade self-bonding area cannot represent the actual strain force of the blade; meanwhile, the acceleration measuring point is selected to avoid the small acceleration response position of the blade root, and the measured data can be more reliable;

step 2, adhering an optical fiber acceleration sensor at the selected acceleration monitoring point according to the position of the monitored wind generating set blade, so that the optical fiber acceleration sensor can measure the vibration of the wind generating set blade in two directions of waving and shimmy, and the principle of the optical fiber acceleration sensor is that when an oscillator inside the sensor is subjected to acceleration, the self inertial force action causes a cantilever beam to bend, a corresponding optical fiber grating can stretch or compress, the central wavelength changes, the association of acceleration data and the wavelength of the optical fiber grating is realized, the optical fiber acceleration sensor senses the acceleration change, the wavelength of an internal optical fiber changes along with the change, a wavelength signal of the sensor is collected and demodulated through a connected optical fiber demodulator, and finally, the sensor is calibrated through professional acceleration calibration equipment, so that the corresponding relation between the wavelength of the sensor and the acceleration is realized; at the selected strain monitoring point, at least four groups of optical fiber strain gauges are adhered to the windward side, the leeward side, the front edge and the rear edge according to the strain measurement section;

preferably, in step 2, before the optical fiber acceleration sensor and the optical fiber strain gauge are attached, the attachment position on the monitored wind turbine generator system is further required to be subjected to processing operations including dust removal, polishing and surface wiping.

Step 3, acquiring real-time acceleration of the monitored wind generating set blade through the optical fiber acceleration sensor pasted in the step 2, and acquiring real-time monitoring signals of the monitored wind generating set blade through the optical fiber strain gauge in the step 2; the real-time monitoring signals comprise strain data of a windward side and a leeward side of the blade and strain data of a front edge and a rear edge at strain monitoring points, and four groups of strain sensors are arranged on the same section, wherein the optical fiber strain sensors arranged on the windward side and the leeward side of the blade are used for calculating and obtaining the flapping moment of the section of the blade, and the strain sensors arranged on the front edge and the rear edge of the blade are used for calculating and obtaining the shimmy moment of the section of the blade;

preferably, in step 3, before signal acquisition, the optical fiber acceleration sensor and the optical fiber strain gauge adhered in step 2 are connected with an industrial personal computer or a server, the signal transmission states of the optical fiber acceleration sensor and the optical fiber strain gauge and the load debugging are tested through the industrial personal computer or the server, and signal acquisition is started after the debugging is finished.

4, an industrial personal computer or a server calculates an acceleration signal time domain and frequency domain analysis value according to the real-time acceleration data of the monitored wind generating set blade acquired by the optical fiber acceleration sensor in the step 3; calculating blade section flapping moment according to strain data of a windward side and a leeward side at a strain monitoring point acquired by an optical fiber strain gauge, and calculating blade section shimmy moment according to the strain data of a front edge and a rear edge;

further, the time domain analysis mainly includes an average value, a peak-to-peak value, an effective value, and the like; the frequency domain analysis mainly performs Fourier transform on the time domain signal to obtain a frequency response value

Preferably, in step 4, the blade section flapping moment is calculated according to the strain data of the windward side and the leeward side of the strain monitoring point collected by the optical fiber strain gauge, specifically, the strain amount of the windward side at the actually measured strain monitoring point is epsilon₁The strain amount of the leeward side at the strain monitoring point is epsilon₂The blade section waving momentAnd EI is bending rigidity of the blade in the flapping direction under a chord length coordinate system, and R is the section radius of the strain measuring point.

Preferably, in the step 4, the blade section shimmy moment is calculated according to the strain data of the front edge and the rear edge at the strain monitoring point, and specifically, the strain data of the actually measured front edge is epsilon₁Strain data epsilon of trailing edge₂The blade section shimmy momentWherein M is₁And M₂The bending moments of the blade with the cross section are calculated only by strain on the leeward side and the windward side, and alpha represents the included angle between the connecting line of the optical fiber strain gauges pasted on the front edge and the rear edge and the horizontal central line of the strain measurement cross section; EI (El)₁The bending rigidity in the lower pendulum vibration direction of a chord length coordinate system, the chord length coordinate system is a coordinate system which takes a central point between a geometric front edge point and a back edge point of the strain measurement section as an original point and takes a connecting line of the front edge point and the back edge point as an X axis, and E representsModulus of elasticity of the blade material, I₁Represents the section moment of inertia; the calculation modes of bending rigidity in the waving and shimmy directions are EI₁It is related to the direction of the strain-bonding cross section, and if the cross section is circular, the moments of inertia in the two directions are not different, and if the cross section is elliptical or other shapes, the moments of inertia in the different directions of the cross section are different, resulting in inconsistent bending stiffness of the cross section.

Step 5, strain in data analysis is mainly used for calculating flapping and shimmy moments born by the blade section, and the blade sticking position is judged to be damaged or the current bearing is overlarge according to the section moment data; the acceleration data is mainly used for time domain and frequency spectrum analysis, the response frequency of the blade is calculated and is compared with the inherent frequency of the blade, the current state of the fan in damage or icing and the like is judged, the real-time acceleration in the step 3, the acceleration time domain and frequency domain data of the blade of the wind generating set calculated by the industrial control machine or the server in the step 4, the blade section flapping moment, the blade section shimmy moment and the parameter threshold value set by the blade of the wind generating set are compared and analyzed, the current state of the blade of the wind generating set is judged, an alarm signal is generated and sent for abnormal state of the blade, when the abnormal state signal of the blade, such as the state of overlarge load, icing, fracture damage and the like, is encountered, the upper computer sends out early warning information, and prompts a wind farm management party to implement shutdown, pitch control and the like so as to protect the safety of the blade.

Further, fiber grating acceleration, strain gauge are all formed by the fiber grating encapsulation, and its theory of operation is fiber grating wavelength and external load, environmental change proportional relation, becomes positive correlation relation like the strain that the optic fibre receives rather than the wavelength, need pass through professional equipment calibration before the sensor design, fiber grating strain gauge test strain data does not receive ambient temperature interference, and an inside encapsulation fiber temperature sensor concatenates with fiber strain gauge, eliminates the temperature influence, and sensor encapsulation is good, possesses advantages such as dustproof, dampproofing, anti-thunderbolt, anti-electromagnetic interference, and the tired number of times reaches more than 10 ten thousand, life more than 5 years.

Preferably, the fiber grating acceleration sensor is a low-frequency sensor, and the test analysis frequency range is 0.1-40 Hz.

Furthermore, the optical fiber acceleration sensor and the optical fiber strain gauge which are pasted in the step 2 are connected with an industrial personal computer or a server through an optical fiber demodulator, the sampling frequency of the optical fiber demodulator is not less than 100Hz, and the optical fiber acceleration sensor and the optical fiber strain gauge have the functions of signal filtering, noise reduction, high-frequency acquisition, signal demodulation and the like.

Compared with the prior art, the technical scheme of the invention at least has the following advantages:

the invention provides a system solution for monitoring the blade state, which has wider application value in the field of monitoring the blade of a large-scale wind turbine generator, has high accuracy of signal acquisition of the system, strong lightning stroke resistance and electromagnetic interference resistance, is suitable for various severe environments such as dust, rain, dew, lightning stroke, electromagnetic interference and the like, can effectively identify the blade state according to load data, protects the blade from the influence of the external environment, effectively prolongs the service life of the blade, can completely know the running state of the blade when a user is not on site, changes the original regular maintenance mode, greatly reduces the later-stage operation and maintenance cost of the blade, avoids shutdown loss caused by the blade problem, and greatly improves the operation efficiency of a wind farm.

If the blade load is too large and a risk damage signal occurs, the industrial personal computer end sends out early warning information to prompt a manager, and the manager controls the main control unit to implement operations such as blade pitch variation or shutdown, so that the operation safety of the blade is guaranteed to the maximum extent.

Drawings

The foregoing and following detailed description of the invention will be apparent when read in conjunction with the following drawings, in which:

FIG. 1 is a flowchart of the method operation of the present invention;

FIG. 2 is a system framework diagram of the present invention;

FIG. 3 is a schematic view of an installation of a fiber grating strain sensor according to the present invention;

FIG. 4 is another schematic view of the fiber grating strain sensor according to the present invention

Fig. 5 is a schematic view of the installation of the fiber grating acceleration sensor according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

The present invention will be described in detail with reference to the following examples.

The method for monitoring the state of the blade of the wind generating set in the severe environment provided by the embodiment comprises the following steps as shown in fig. 1:

step 1, selecting a plurality of strain monitoring points on a monitored wind generating set blade except for a blade self-bonding area, and selecting a plurality of acceleration monitoring points at positions far away from the blade root, wherein as shown in FIG. 2, the strain monitoring points are generally arranged at the position of the blade root and only need to avoid the blade self-bonding area, and the strain force of the blade self-bonding area cannot represent the actual strain force of the blade; meanwhile, the acceleration measuring point is selected to avoid the small acceleration response position of the blade root, and the measured data can be more reliable.

Step 2, as shown in fig. 5, an optical fiber acceleration sensor is adhered to the selected acceleration monitoring point according to the position of the blade, the optical fiber grating acceleration sensor is adhered to the inner surface of the blade and is a bidirectional acceleration sensor, the acceleration response values of the blade in two directions of flap and shimmy are measured, the principle of the optical fiber acceleration sensor is that when the vibrator in the sensor is subjected to acceleration, the cantilever beam is bent under the action of self inertial force, the corresponding fiber grating can be stretched or compressed, the central wavelength is changed, the association of acceleration data and the wavelength of the fiber grating is realized, the fiber acceleration sensor senses the acceleration change, the wavelength of the internal fiber is changed along with the acceleration change, acquiring and demodulating a wavelength signal of the sensor through a connected optical fiber demodulator, and calibrating the sensor through professional acceleration calibration equipment to realize the corresponding relation between the wavelength of the sensor and the acceleration; as shown in fig. 3 or 4, four groups of fiber bragg grating strain sensors are pasted at selected strain monitoring points 11, 12, 13 and 14, at least four groups of fiber bragg grating strain gauges are pasted at windward sides, leeward sides, front edges and rear edges according to strain measurement cross sections, A represents the position (13) of the front edge of the blade, B represents the position (14) of the rear edge of the blade, AB is a chord line of the blade, the windward side (11) is above AB, and the leeward side (12) is below AB; the fiber grating strain sensors at least comprise four groups on each blade, the four groups of strain sensors are positioned on the same section of the blade, and a fan generally comprises three blades.

Preferably, in step 2, before the optical fiber acceleration sensor and the optical fiber strain gauge are adhered, the adhering position on the monitored wind generating set is further required to be subjected to processing operations including dust removal, polishing and surface wiping, the optical fiber grating acceleration sensor and the strain sensor are both formed by packaging the optical fiber grating, the working principle is that the wavelength of the optical fiber grating is in proportional relation with the external load and environmental change, if the strain of the optical fiber is in positive correlation with the wavelength of the optical fiber grating, the optical fiber grating strain sensor needs to be calibrated by professional equipment before the sensor is shaped, the test strain data of the optical fiber grating strain sensor is not interfered by the external temperature, the optical fiber temperature sensor is packaged inside and is connected with the optical fiber strain sensor in series, the temperature influence is eliminated, the sensor is well packaged, and has the advantages of dust prevention, moisture prevention, lightning stroke resistance, electromagnetic interference resistance and the like, and the fatigue frequency reaches more than 10 thousands times, more than 5 years of service life, further, the fiber grating acceleration sensor is a low-frequency sensor, the test analysis frequency range is 0.1-40Hz, moreover, the fiber grating acceleration sensor and the fiber strain gauge which are pasted in the step 2 are connected with an industrial personal computer or a server through a fiber demodulator, the sampling frequency of the fiber demodulator is not less than 100Hz, and the fiber grating acceleration sensor and the fiber strain gauge have the functions of signal filtering, noise reduction, high-frequency acquisition, signal demodulation and the like.

Connecting all optical fiber strain gauges and acceleration sensor connecting cables arranged on a fan blade to the root of the blade through equipment such as a junction box or a concentrator, connecting the root of the blade with an optical fiber demodulator in a hub of the fan through a slip ring or a wireless transmission device, finally connecting the optical fiber demodulator with an industrial personal computer or a server in the hub or a central control room, then testing whether strain and acceleration signal transmission are normal or not on an upper computer interface of the industrial personal computer or the server, starting load debugging work after the signal transmission is normal displayed on the upper computer interface, ensuring that a generator is in a cut-out state during debugging, then verifying the maximum and minimum loads of the blade section obtained in a certain rotation period and the maximum and minimum loads calculated theoretically, and correcting load data.

Then, acquiring real-time acceleration of the monitored wind generating set blade through the optical fiber acceleration sensor pasted in the step 2, and acquiring real-time monitoring signals of the monitored wind generating set blade through the optical fiber strain gauge in the step 2; the real-time monitoring signals comprise strain data of windward sides and leeward sides and strain data of front edges and rear edges of strain monitoring points, and four groups of strain sensors are installed on the same section, wherein the optical fiber strain sensors installed on the windward sides and the leeward sides of the blades are used for calculating the waving moment of the sections of the blades, and the strain sensors installed on the front edges and the rear edges of the blades are used for calculating the shimmy moment of the sections of the blades.

Step 4, an industrial personal computer or a server calculates an acceleration signal time domain and frequency domain analysis value according to the real-time acceleration data of the monitored wind generating set blade collected by the optical fiber acceleration sensor in the step 3, wherein the time domain analysis mainly comprises an average value, a peak-to-peak value, an effective value and the like; the frequency domain analysis is mainly used for carrying out Fourier transform on the time domain signal to obtain a frequency response value; and calculating blade section flapping moment according to strain data of a windward side and a leeward side of a strain monitoring point acquired by the optical fiber strain gauge, and calculating blade section shimmy moment according to the strain data of a front edge and a rear edge.

Specifically, in step 4, the blade section flapping moment is calculated according to the strain data of the windward side and the leeward side of the strain monitoring point collected by the optical fiber strain gauge, specifically, the strain amount of the windward side at the actually measured strain monitoring point is epsilon₁The strain amount of the leeward side at the strain monitoring point is epsilon₂The blade section waving momentAnd EI is bending rigidity of the blade in the flapping direction under a chord length coordinate system, and R is the section radius of the strain measuring point.

Further, in the step 4, the blade section shimmy moment is calculated according to the strain data of the front edge and the rear edge at the strain monitoring point, specifically, the strain data of the actually measured front edge is epsilon₁Strain data epsilon of trailing edge₂The blade section shimmy momentWherein M is₁And M₂Respectively representing the bending moment of the blade with the cross section obtained by calculation only from strains on the leeward side and the windward side, wherein alpha represents the included angle between the connecting line of the optical fiber strain gauges pasted on the front edge and the rear edge and the horizontal central line of the strain measurement cross section, because the optical fiber strain gauges pasted on the front edge and the rear edge are not completely on the horizontal central line of the strain measurement cross section, for example, the strain measurement cross section at the position of the blade root is generally circular, the connecting line between the geometric front edge and the rear edge at the position of the blade root is the horizontal central line, and on the interface shown in fig. 3, the selected monitoring points are the geometric front edge and the rear edge, but in the actual operation, as shown in fig. 4, the monitoring points are selectedThe strain monitoring points of the front edge and the rear edge are possibly higher or lower than the positions of the geometric front edge and the geometric rear edge of the root position of the blade, so that an included angle is formed; EI (El)₁The bending rigidity in the lower oscillation direction of a chord length coordinate system, the chord length coordinate system is a coordinate system which takes a central point between a geometric front edge point and a back edge point of the strain measurement section as an original point and takes a connecting line of the front edge point and the back edge point as an X axis, E represents the elastic modulus of the blade material, I represents the elastic modulus of the blade material₁Represents the section moment of inertia; the calculation modes of bending rigidity in the waving and shimmy directions are EI₁It is related to the direction of the strain-bonding cross section, and if the cross section is circular, the moments of inertia in the two directions are not different, and if the cross section is elliptical or other shapes, the moments of inertia in the different directions of the cross section are different, resulting in inconsistent bending stiffness of the cross section.

Step 5, strain in data analysis is mainly used for calculating flapping and shimmy moments born by the blade section, and the blade sticking position is judged to be damaged or the current bearing is overlarge according to the section moment data; the acceleration data is mainly used for time domain and frequency spectrum analysis, calculating the response frequency of the blade, comparing the response frequency with the natural frequency of the blade, judging the current state of a fan, such as damage or icing, and the like, comparing the real-time acceleration in the step 3 with the acceleration time domain and frequency domain data of the blade of the wind generating set calculated by the industrial control computer or the server in the step 4, and comparing and analyzing the blade section flapping moment, the blade section shimmy moment and the parameter threshold value set by the blade of the wind generating set, judging the current state of the blade of the wind generating set, and generating and sending an alarm signal for abnormal blade state, wherein the strain in the data analysis is mainly used for calculating the flapping and shimmy moment born by the blade section, and the section moment data judges whether the blade is damaged or bears too large load currently and the like at the bonding position; the acceleration data is mainly analyzed by a time domain and a frequency spectrum, the response frequency of the blade is calculated, the response frequency is compared with the inherent frequency of the blade, the current state of the fan, such as damage or icing, is judged, when the abnormal signal of the blade state, such as the states of overlarge load, icing, fracture damage and the like, is encountered, the upper computer sends out early warning information to prompt a wind farm management party to implement shutdown, pitch variation and other operations so as to protect the safety of the blade, as shown in figure 2, when the upper computer processes and analyzes the sensor data and finds that the blade is in the abnormal state, such as overlarge load, frequency reduction and the like, the early warning information is sent out in time, and the wind farm management party implements pitch variation and shutdown operations according to the feedback information so as to ensure the safe operation of the fan blade.