CN106837709A - Monitoring method and monitoring system for wind generating set blade - Google Patents

Abstract

A monitoring method and monitoring system for wind turbine blades, including: using sensors to collect vibration signals of blades of wind turbines; extracting the vibration signals through a hub measurement unit provided in the hub; the hub measurement unit The vibration signal is forwarded to a data analysis unit provided in the nacelle; the vibration signal of different blades in the wind turbine generator set is compared to monitor whether the blade is damaged. After adopting the embodiment of the present invention, it is possible to monitor whether the blades in the wind turbine generator are damaged in real time.

Description

Wind turbine blade monitoring method and monitoring system

technical field

The invention relates to the technical field of wind power generation, in particular to a monitoring method and a monitoring system for blades of a wind power generating set.

Background technique

Wind turbines generally consist of blades, hubs, towers and nacelles. A wind turbine is a device that converts wind energy into the mechanical energy of the hub through the blades, and the mechanical energy drives the generator rotor to rotate, and finally outputs alternating current.

Blades are the most stressed components of a wind turbine. It is also one of the most expensive parts to replace if damaged. The blade is a key component of the wind turbine. During the rotation of the blade, when the blade turns from the top to the bottom, the force changes and changes alternately, as well as the instability of the wind condition, which will cause the vibration of the wind turbine. After the wind turbine works for a long time, the physical performance of the blades decreases and is damaged due to material aging, physical fatigue of the hardware, and harsh environment, which affects the working efficiency of the wind turbine. Therefore, it is particularly important to monitor the operating status of the blades.

Currently, the most common method of monitoring blades is visual observation, which is timed. Minor problems with blades and early repairable problems are likely to have occurred and developed into serious problems during the time interval.

To sum up, the following technical problems exist in the prior art: it is impossible to monitor in real time whether the blades in the wind power generating set are damaged.

Contents of the invention

An embodiment of the present invention provides a method for monitoring blades of a wind power generating set, which can monitor in real time whether the blades in the wind generating set are damaged.

The embodiment of the present invention also provides a monitoring system for blades of a wind power generating set, which can monitor in real time whether the blades in the wind generating set are damaged.

A method for monitoring blades of a wind power generating set, comprising:

Use the sensor to collect the vibration signal of the blade of the wind turbine;

extracting the vibration signal through a hub measuring unit arranged in the hub;

The hub measurement unit forwards the vibration signal to a data analysis unit arranged in the nacelle;

and comparing the vibration signals of different blades in the wind power generating set to monitor whether the blades are damaged.

Wherein, the hub measurement unit is connected to the data analysis unit through a wireless network;

or,

The hub measurement unit is connected with the data analysis unit through a cable in the slip ring.

Wherein, the comparing the vibration signals of different blades in the wind power generating set to monitor whether the blades are damaged includes:

Determining the difference between the vibration signals of any two blades in the wind power generating set, and monitoring whether the blade is damaged based on the difference.

Wherein, the determining the difference between the vibration signals of any two blades in the wind power generating set includes:

Obtain vibration signals of any two blades in the wind power generating set in the time domain;

Computing the difference between the vibration signal amplitudes corresponding to any two blades at the same moment.

Wherein, the determining the difference between the vibration signals of any two blades in the wind power generating set includes:

Obtain vibration signals of any two blades in the wind power generating set in the time domain;

Drawing a comparison curve of the vibration signals of the any two blades in the time domain in the wind power generating set, wherein the comparison curve includes the difference of the vibration signal amplitudes of the any two blades.

Wherein, after the hub measurement unit forwards the vibration signal to the data analysis unit arranged in the nacelle, it also includes:

obtaining the total mass of the blades in the wind power generating set based on the vibration signal;

The icing state of the blades is monitored according to the total mass of the blades in the wind power generating set and the standard mass of the blades in the wind generating set.

Wherein, the obtaining the total mass of the blades in the wind power generating set based on the vibration signal includes:

extracting the vibration frequency of the blades in the wind power generating set according to the vibration signal;

The total mass of the blades in the wind turbine is calculated based on the vibration frequency.

Wherein, after monitoring the icing state of the blades according to the total mass of the blades in the wind power generating set and the standard mass of the blades in the wind generating set, it further includes:

Starting blade heating according to the icing state of the blade;

or,

The output power of the wind power generating set is reduced according to the icing state of the blades.

A monitoring system for wind turbine blades, comprising:

The sensor is used to collect the vibration signal of the blade of the wind power generating set;

a hub measurement unit in the hub for extracting and forwarding said vibration signal;

a data analysis unit in the nacelle, configured to receive the vibration signal;

A monitoring module, configured to compare the vibration signals of different blades in the wind power generating set, and monitor whether the blades are damaged.

Wherein, the hub measurement unit is connected to the data analysis unit through a wireless network;

or,

The hub measurement unit is connected with the data analysis unit through a cable in the slip ring.

Wherein, the monitoring module is further configured to determine the difference between the vibration signals of any two blades in the wind power generating set, and monitor whether the blade is damaged based on the difference.

Wherein, the monitoring module is further used for:

Obtain vibration signals of any two blades in the wind power generating set in the time domain;

Computing the difference between the vibration signal amplitudes corresponding to any two blades at the same moment.

Wherein, the monitoring module is further used for:

Obtain vibration signals of any two blades in the wind power generating set in the time domain;

Drawing a comparison curve of the vibration signals of the any two blades in the time domain in the wind power generating set, wherein the comparison curve includes the difference of the vibration signal amplitudes of the any two blades.

Wherein, the monitoring module is further used to obtain the total mass of the blades in the wind power generating set based on the vibration signal;

The icing state of the blades is monitored according to the total mass of the blades in the wind power generating set and the standard mass of the blades in the wind generating set.

Wherein, the monitoring system further includes a control module, configured to start blade heating according to the icing state of the blade;

or,

The output power of the wind power generating set is reduced according to the icing state of the blades.

Wherein, the sensor is located at the maximum chord length of the blade in the direction of the inner leading edge of the blade.

It can be seen from the above technical solution that the vibration signal of the blade of the wind power generating set is collected by the sensor; the vibration signal is extracted by the hub measurement unit arranged in the hub; the hub measurement unit forwards the vibration signal to the data set in the nacelle Analysis unit; compares the vibration signals of different blades in the wind turbine, and monitors whether the blades are damaged. Since the vibration signals of the blades in the wind power generating set can be obtained in real time, it is possible to monitor in real time whether the blades in the wind generating set are damaged.

Description of drawings

The present invention can be better understood from the following description of specific embodiments of the present invention in conjunction with the accompanying drawings, wherein the same or similar reference numerals represent the same or similar features.

Fig. 1 is a schematic flow chart of a monitoring method for wind turbine blades in an embodiment of the present invention;

Fig. 2 is a schematic flow chart of monitoring blade icing in an embodiment of the present invention;

Fig. 3 is a schematic structural diagram of a monitoring system for wind turbine blades in an embodiment of the present invention;

Fig. 4 is a schematic structural diagram of another monitoring system for wind turbine blades in an embodiment of the present invention;

Fig. 5 is a schematic diagram of the installation position of the wind turbine blade sensor in the embodiment of the present invention;

Fig. 6 is a schematic diagram of the usage structure of the monitoring system for the wind turbine blades in the embodiment of the present invention;

Fig. 7 is the frequency domain diagram of the vibration signal of the blade in the embodiment of the present invention;

Fig. 8 is a time-domain diagram of the vibration signal of the damage process of the blade in the embodiment of the present invention;

In the accompanying drawings, the same parts use the same reference numerals, and the description of the numerals is as follows:

301 - sensor; hub measurement unit - 302 ; data analysis unit - 303 ; monitoring module - 304 ; control module 305 .

detailed description

In order to make the object, technical solution and advantages of the present invention more clearly, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

In the embodiment of the present invention, sensors are used to collect the vibration signals of the blades of the wind power generating set, and by comparing the vibration signals of different blades in the wind generating set, it is possible to monitor whether the blades are damaged. In addition, the total mass of the blade can also be obtained based on the vibration signal of the blade, and then the icing state of the blade can be monitored.

Referring to FIG. 1, it is a schematic flow chart of a monitoring method for wind turbine blades in an embodiment of the present invention, specifically including:

S101. Using sensors to collect vibration signals of blades of the wind power generating set.

S102. Extract vibration signals through the hub measuring unit arranged in the hub.

S103. The hub measurement unit forwards the vibration signal to the data analysis unit arranged in the nacelle.

S104, comparing the vibration signals of different blades in the wind power generating set, and monitoring whether the blades are damaged.

In the embodiment of the present invention, firstly, the vibration signals of the blades in the wind power generating set are collected. Then, the vibration signal of the blade is extracted by the hub measurement unit arranged in the hub, and the hub measurement unit forwards the vibration signal of the blade to the data analysis unit arranged in the nacelle. Finally, compare the vibration signals of different blades in the wind turbine to monitor the blades for damage. Since the vibration signal corresponding to the damaged blade will change, it is possible to monitor whether the blade is damaged according to the vibration signal of the blade. The vibration signal of the blades in the wind power generator can be obtained in real time, so the state of the blades in the wind power generator can be monitored in real time.

In an optional embodiment, sensors may be used to collect vibration signals of blades in the wind power generating set. The position of the sensor can be flexibly set, for example, it can be set at the leading edge of the blade or inside the blade.

After the vibration signals of the blades in the wind power generating set are collected, the vibration signals of the blades need to be sent to a hub measurement unit (HMU, Hub Measurement Unit) in the hub. For example, the vibration signal of the blade can be sent to the HMU via a signal cable. In order to protect the signal cables from mechanical tension in the blade, the signal cables can be routed in a sinusoidal manner in the blade.

In an optional embodiment, the HMU is located in the hub, and the data analysis unit (ECU, Evaluation and Communication Unit) is located in the nacelle. The HMU and ECU can be connected in various ways to transmit the vibration signal of the blade. One way is: the HMU and the ECU are connected through a wireless network, and the wireless network can be a wireless local area network, a Bluetooth connection or other wireless connection methods. Another way is: the HMU is connected to the ECU through the cable in the slip ring. A slip ring is provided between the HMU and the ECU, and the slip ring is provided with reserved holes and slots. The cables between the HMU and the ECU can be respectively connected to the HMU and the ECU through the reserved holes and slots.

In an optional embodiment, the difference between the vibration signals of any two blades in the wind power generating set is determined, and based on the difference between the vibration signals of any two blades, it is monitored whether the corresponding blade is damaged. The blades in the wind turbine are all the same, and the vibration signal of each blade is basically the same when the blades are not damaged. In the case of damage to the blade, however, the vibration signal of the blade changes. Specifically, it is possible to monitor whether the corresponding blade is damaged based on the difference between the vibration signals of any two blades.

In an optional embodiment, the vibration signals of any two blades in the wind power generating set in the time domain may be obtained. That is to say, the vibration signals of any two blades in the wind turbine at different time points are obtained, so that the difference of the vibration signal amplitudes corresponding to any two blades at the same time can be calculated. At the same time, the difference between the vibration signal amplitudes of any two blades, that is, each blade has a vibration amplitude at the same time, and the blades are monitored according to the difference of the vibration amplitudes corresponding to different blades at the same time. damage.

In an optional embodiment, the vibration signals of any two blades in the wind power generating set in the time domain are acquired first. Then, the comparison curve of the vibration signals of any two blades in the time domain in the wind turbine is drawn. In the coordinate system, the horizontal axis represents time, and the vertical axis represents the difference in vibration signal amplitude. That is to say, the comparison curve includes the difference between the vibration signal amplitudes of any two blades. The change of the difference between the vibration signal amplitudes of any two blades can be intuitively known according to the comparison curve.

Specifically, a comparison curve of the vibration signals of two different blades in the wind power generating set can be obtained. For example, obtain the comparison curve 1 of the vibration signal of blade 1 and the vibration signal of blade 2, obtain the comparison curve 2 of the vibration signal of blade 1 and the vibration signal of blade 3, and obtain the comparison of the vibration signal of blade 2 and the vibration signal of blade 3 Curve 3.

Comparing Contrast Curve 1, Contrast Curve 2 and Contrast Curve 3, since Blade 1, Blade 2 and Blade 3 are all blades of the same specification, when the blade is not damaged, there is almost no difference between Contrast Curve 1, Contrast Curve 2 and Contrast Curve 3 . When the blade is slightly damaged, the comparison curve 1, the comparison curve 2 and the comparison curve 3 will change. For example, the comparison curve 1 does not change; the comparison curve 2 changes; the comparison curve 3 changes, and at this time it is judged that the blade 3 is damaged.

In an optional embodiment, see FIG. 2 which is a schematic flow chart of monitoring blade icing in an embodiment of the present invention, specifically including:

S201. Obtain the total mass of the blades in the wind power generating set based on the vibration signals of the blades.

The vibration frequency is extracted from the vibration signal of the blade, and the vibration frequency is the current vibration frequency of the blade. Considering that the vibration frequency of the blade is related to the total mass of the blade. That is, the greater the total mass of the blade, the smaller the vibration frequency of the blade. Wherein, the total mass of the blade is the sum of the standard mass of the blade and the load of the blade. When the blade has a large damage, for example, due to long-term operation of the blade or lightning strikes, the blade tip is partially damaged, and the mass of the blade is reduced, the load on the blade is negative; when the surface of the blade is covered with ice, the load on the blade is positive.

Specifically, in this step, the vibration frequency f of the blade is firstly extracted according to the vibration signal; and then the total mass of the blade in the wind power generating set is calculated based on the vibration frequency f.

The relationship between the vibration frequency of the blade and the total mass of the blade is expressed by the expression (1):

Among them, m is the total mass of the blade in the wind turbine unit, k is the stiffness of the blade itself, and f is the vibration frequency of the blade as a whole. The stiffness of the blade itself is determined by factors such as structural shape, cross-sectional shape, and support position.

S202. Monitor the icing state of the blades according to the total mass of the blades in the wind power generating set and the standard mass of the blades in the wind generating set.

Wherein, the standard quality of the blade is the quality of the blade when it leaves the factory. If the difference between the total mass of the blades in the wind generator set and the standard mass of the blades in the wind generator set is a negative number, it is determined that the blades may be damaged. The damage here refers to damage that reduces the mass of the blade due to damage.

If the difference between the total mass of the blades in the wind generating set and the standard mass of the blades in the wind generating set is a positive number, it is determined that the blades may be covered with ice.

That is, when the temperature of the wind turbine generator set is below zero, and the air humidity is high or rain and snow occur, the blades will be covered with ice. The total mass of the blades in the wind turbine gradually increases after the surface of the blades is covered with ice. In order to avoid the impact of icing on the blade surface, different means can be used to reduce the impact on the blade according to the icing state of the blade.

The icing state of the blades can be measured by the difference between the total mass of the blades in the wind turbine and the standard mass of the blades in the wind turbine.

For example, the difference between the total mass of the blades in the wind generator set and the standard mass of the blades in the wind generator set is less than a preset first threshold, and the icing state is mild.

The difference between the total mass of the blades in the wind generator set and the standard mass of the blades in the wind generator set is greater than or equal to the preset first threshold and smaller than the second threshold, and the icing state is moderate.

The difference between the total mass of the blades in the wind generator set and the standard mass of the blades in the wind generator set is greater than or equal to the preset second threshold, and the icing state is severe.

When the icing state is light, the blade heating is activated.

When the icing state is moderate, reduce the output power of the wind power generating set to 50% of the power of the original wind power generation place.

When the icing state is heavy, reduce the output power of the wind turbine to 0, that is, stop.

In the embodiment of the present invention, the total mass of the blades in the wind power generating set can be obtained from the vibration signal. Then, according to the total mass of the blades in the wind power generating set and the standard mass of the blades in the wind generating set, the icing state of the blades is monitored. The blades can be adjusted in different ways when they are iced to avoid damage to the blades.

Referring to FIG. 3 , it is a schematic structural diagram of a monitoring system for wind turbine blades in an embodiment of the present invention, specifically including: a sensor 301 , an HMU 302 , an ECU 303 and a monitoring module 304 .

The sensor 301 is used to collect vibration signals of the blades of the wind power generating set.

HMU302, used to extract and forward the vibration signal of the blade.

ECU303 is used to receive the vibration signal of the blade.

The monitoring module 304 is configured to compare the vibration signals of different blades in the wind power generating set, and monitor whether the blades are damaged.

In the embodiment of the present invention, firstly, the sensor 301 collects the vibration signal of the blades in the wind power generating set. Then, the HMU302 extracts and forwards the vibration signal of the blade, and the ECU303 receives the vibration signal of the blade. Finally, the monitoring module 304 compares the vibration signals of different blades in the wind power generating set to monitor whether the blades are damaged. Since the vibration signal corresponding to the damaged blade will change, it is possible to monitor whether the blade is damaged according to the vibration signal of the blade. The vibration signal of the blades in the wind power generator can be obtained in real time, so the state of the blades in the wind power generator can be monitored in real time.

After the vibration signals of the blades in the wind power generating set are collected, the vibration signals of the blades need to be sent to the HMU302 in the hub. The vibration signal of the blade can be sent to the HMU302 through the signal cable. In order to protect the signal cables from mechanical tension in the blade, the signal cables can be routed in a sinusoidal manner in the blade.

In an alternative embodiment, the HMU 302 is located in the hub and the ECU 303 is located in the nacelle. The HMU302 and the ECU303 can be connected in various ways to transmit vibration signals of the blades. One way is: the HMU302 and the ECU303 are connected through a wireless network, and the wireless network can be a wireless local area network, a Bluetooth connection or other wireless connection methods. Another way is: the HMU302 is connected with the ECU303 through the cable in the slip ring. A slip ring is provided between the HMU302 and the ECU303, and the slip ring is provided with reserved holes and slots. The cables between HMU302 and ECU303 can be connected to HMU and ECU respectively through reserved holes and wire slots.

In an optional embodiment, the monitoring module 304 is further configured to determine the difference between the vibration signals of any two blades in the wind power generating set, and monitor whether the corresponding blade is damaged based on the difference between the vibration signals of any two blades. The blades in the wind turbine are all the same, and the vibration signal of each blade is the same when the blades are not damaged. In the case of damage to the blade, however, the vibration signal of the blade changes. Specifically, it is possible to monitor whether the corresponding blade is damaged based on the difference between the vibration signals of any two blades.

In an optional embodiment, the monitoring module 304 is further configured to acquire vibration signals of any two blades in the wind power generation set in the time domain. That is to say, the vibration signals of any two blades in the wind turbine at different time points are obtained, so that the difference of the vibration signal amplitudes corresponding to any two blades at the same time can be calculated. At the same time, calculate the difference between the vibration signal amplitudes of any two blades, that is, each blade has a vibration amplitude at the same time, and the monitoring module 304 is based on the difference between the vibration amplitudes corresponding to different blades at the same time Monitor the leaves for damage.

In an optional embodiment, the monitoring module 304 further acquires vibration signals of any two blades in the wind power generating set in the time domain. Then, the comparison curve of the vibration signals of any two blades in the time domain in the wind turbine is drawn. In the coordinate system, the horizontal axis represents time, and the vertical axis represents the difference in vibration signal amplitude. That is to say, the comparison curve includes the difference between the vibration signal amplitudes of any two blades. The change of the difference between the vibration signal amplitudes of any two blades can be intuitively known according to the comparison curve.

Specifically, the monitoring module 304 may acquire a comparison curve of vibration signals of two different blades in the wind power generating set. For example, obtain the comparison curve 1 of the vibration signal of blade 1 and the vibration signal of blade 2, obtain the comparison curve 2 of the vibration signal of blade 1 and the vibration signal of blade 3, and obtain the comparison of the vibration signal of blade 2 and the vibration signal of blade 3 Curve 3. The monitoring module 304 compares the comparison curve 1, the comparison curve 2 and the comparison curve 3, and monitors whether the blade is damaged.

In an optional embodiment, the monitoring module 304 is further configured to obtain the total mass of the blades in the wind power generating set based on the vibration signals of the blades. According to the total mass of the blades in the wind power generating set and the standard mass of the blades in the wind generating set, the icing state of the blades is monitored.

In an optional embodiment, refer to FIG. 4 , which is a schematic structural diagram of another monitoring system for wind turbine blades in an embodiment of the present invention, including a sensor 301 , an HMU 302 , an ECU 303 , a monitoring module 304 and a control module 305 . That is, the system in FIG. 4 adds a control module 305 on the basis of the system in FIG. 3 .

The control module 305 is used for starting the heating of the blade according to the icing state of the blade. The control module 305 can also be used to reduce the output power of the wind power generating set according to the icing state of the blades.

In alternative embodiments, the sensor 301 may be located anywhere inside the blade. Considering the vibration amplitude of the blade, the greater the vibration amplitude of the blade, the easier it is to collect the vibration signal of the blade. Referring to Fig. 5 , which is a schematic view showing the structure of the monitoring system for the blades of the wind power generating set according to the embodiment of the present invention, the sensor 301 may be located at the leading edge of the blades of the wind power generating set.

In addition, in order to avoid the lack of vibration signals at some positions and to collect vibration signals from the root of the blade to the tip of the blade, the sensor 301 can be located at the maximum chord length of the blade in the direction of the leading edge inside the blade to collect the vibration of the blades in the wind turbine. Signal. The technical solution of the present invention will be described in detail below in conjunction with specific conditions. In Fig. 6, the wind power generating set has three blades, and a vibration sensor is installed at the leading edge inside each blade. An HMU is installed in the hub, and the HMU collects the data collected by the vibration sensor through the signal cable.

HMU and ECU perform data transmission through wireless WIFI. Considering that there are not enough reserved holes and wire slots on the slip ring between HMU and ECU, for wind turbines that have entered the operation and maintenance wind farm, it is expensive to replace and redesign the slip ring with reserved holes. Not allowed, so the data is transmitted wirelessly. Of course, without considering the cost, a cable can also be installed in the redesigned slip ring, and the cable can be used to connect the HMU and the ECU.

The ECU is connected to the main control cabinet switch at the bottom of the wind turbine tower through an optical fiber, and then connected to the wind farm server through the wind farm ring network. The wind farm server stores and analyzes data, and the analyzed results and real-time monitoring data can be displayed on the WEB terminal through the public network.

The wind farm server compares the vibration signals of different blades in the wind turbine to monitor whether the blades are damaged. The total mass of the blades in the wind power generator can also be obtained based on the vibration signal, and the icing state of the blades can be monitored according to the total mass of the blades in the wind power generator and the standard quality of the blades in the wind power generator.

In a specific application, the monitoring module 304 can be set in the ECU 303 or inside the cabin to process the vibration signal. In the system shown in Fig. 6, the monitoring module 304 may be set on the wind farm server.

Specifically, refer to FIG. 7 which is a frequency domain diagram of the vibration signal of the blade in the embodiment of the present invention, the horizontal axis represents the frequency of the vibration signal of the blade, and the vertical axis represents the amplitude of the blade. Each curve corresponds to a blade, and it can be seen that the amplitudes of each blade at each frequency position are not much different.

Fig. 8 is a time-domain diagram of the vibration signal of the damage process of the blade in the embodiment of the present invention, the horizontal axis represents time, and the vertical axis indirectly represents the difference between the vibration amplitudes of two blades. Among them, part 1 represents the vibration amplitude difference between blade 1 and blade 2; part 2 represents the vibration amplitude difference between blade 2 and blade 3; and part 3 represents the vibration amplitude difference between blade 3 and blade 1.

If the blade is not damaged, the vibration amplitude of each blade is almost the same. When the vibration amplitudes of the blades differ greatly, the blades may fail. It can be seen from Figure 8 that the change range of part 1 and part 2 is relatively large, and the change range of part 3 is small, which means that the vibration amplitude difference between blade 1 and blade 2 is relatively large, and the vibration amplitude difference between blade 2 and blade 3 is relatively large , the vibration amplitude difference between blade 3 and blade 1 is very small. It can be judged that blade 1 and blade 3 are not damaged, and blade 2 may be damaged. After repairing the damage of blade 2, it can be seen that the change ranges of part 1, part 2 and part 3 are all very small, so there is no damage to the blade.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (16)

1. A method for monitoring wind turbine blades, comprising: Use the sensor to collect the vibration signal of the blade of the wind turbine; extracting the vibration signal through a hub measuring unit arranged in the hub; The hub measurement unit forwards the vibration signal to a data analysis unit arranged in the nacelle; and comparing the vibration signals of different blades in the wind power generating set to monitor whether the blades are damaged. 2. The monitoring method of the blade of the wind power generating set according to claim 1, wherein the hub measurement unit is connected with the data analysis unit through a wireless network; or, The hub measurement unit is connected with the data analysis unit through a cable in the slip ring. 3. The method for monitoring blades of a wind power generating set according to claim 1, wherein the comparing the vibration signals of different blades in the wind generating set to monitor whether the blades are damaged comprises: Determining the difference between the vibration signals of any two blades in the wind power generating set, and monitoring whether the blade is damaged based on the difference. 4. The method for monitoring the blades of the wind power generating set according to claim 3, wherein the determining the difference between the vibration signals of any two blades in the wind generating set comprises: Obtain vibration signals of any two blades in the wind power generating set in the time domain; Computing the difference between the vibration signal amplitudes corresponding to any two blades at the same moment. 5. The method for monitoring the blades of the wind power generating set according to claim 3, wherein the determining the difference between the vibration signals of any two blades in the wind generating set comprises: Obtain vibration signals of any two blades in the wind power generating set in the time domain; Drawing a comparison curve of the vibration signals of the any two blades in the time domain in the wind power generating set, wherein the comparison curve includes the difference of the vibration signal amplitudes of the any two blades. 6. The monitoring method of the wind turbine blade according to claim 1, characterized in that, after the hub measurement unit forwards the vibration signal to the data analysis unit arranged in the nacelle, it also includes: obtaining the total mass of the blades in the wind power generating set based on the vibration signal; The icing state of the blades is monitored according to the total mass of the blades in the wind power generating set and the standard mass of the blades in the wind generating set. 7. The method for monitoring blades of a wind power generating set according to claim 6, wherein said obtaining the total mass of blades in said wind generating set based on said vibration signal comprises: extracting the vibration frequency of the blades in the wind power generating set according to the vibration signal; The total mass of the blades in the wind turbine is calculated based on the vibration frequency. 8. The method for monitoring the blades of the wind power generating set according to claim 6, characterized in that, the blades are monitored according to the total mass of the blades in the wind generating set and the standard mass of the blades in the wind generating set. After the icing state, it also includes: Starting blade heating according to the icing state of the blade; or, The output power of the wind power generating set is reduced according to the icing state of the blades. 9. A monitoring system for wind turbine blades, comprising: The sensor is used to collect the vibration signal of the blade of the wind power generating set; a hub measurement unit in the hub for extracting and forwarding said vibration signal; a data analysis unit in the nacelle, configured to receive the vibration signal; A monitoring module, configured to compare the vibration signals of different blades in the wind power generating set, and monitor whether the blades are damaged. 10. The monitoring system for blades of a wind power generating set according to claim 9, wherein the hub measurement unit is connected to the data analysis unit through a wireless network; or, The hub measurement unit is connected with the data analysis unit through a cable in the slip ring. 11. The monitoring system for blades of a wind power generating set according to claim 9, wherein the monitoring module is further configured to determine the difference between the vibration signals of any two blades in the wind generating set, based on the The difference is used to monitor whether the blade is damaged. 12. The monitoring system for blades of wind power generators according to claim 11, wherein the monitoring module is further used for: Obtain vibration signals of any two blades in the wind power generating set in the time domain; Computing the difference between the vibration signal amplitudes corresponding to any two blades at the same moment. 13. The monitoring system for blades of wind power generators according to claim 11, wherein the monitoring module is further used for: Obtain vibration signals of any two blades in the wind power generating set in the time domain; Drawing a comparison curve of the vibration signals of the any two blades in the time domain in the wind power generating set, wherein the comparison curve includes the difference of the vibration signal amplitudes of the any two blades. 14. The monitoring system for blades of a wind power generating set according to claim 9, wherein the monitoring module is further configured to obtain the total mass of the blades in the wind generating set based on the vibration signal; The icing state of the blades is monitored according to the total mass of the blades in the wind power generating set and the standard mass of the blades in the wind generating set. 15. The monitoring system for blades of wind power generators according to claim 14, characterized in that, the monitoring system further comprises a control module for starting blade heating according to the icing state of the blades; or, The output power of the wind power generating set is reduced according to the icing state of the blades. 16. The monitoring system for a blade of a wind power generating set according to any one of claims 9-15, wherein the sensor is located at the maximum chord length of the blade in the direction of the inner leading edge of the blade.