CN103116032A - Method and device for acquiring rotating speed of wind generating set - Google Patents

Abstract

A method and device for obtaining the rotational speed of a wind turbine are provided. The method includes performing band-pass filtering on the vibration data of the wind turbine in the time domain; performing envelope detection on the band-pass filtered data; transforming the envelope-detected data into the frequency domain; and performing peak search on the frequency domain data. Processing to obtain a cogging frequency of a predetermined multiple; use the following equation to obtain the rotation speed of the generator based on the obtained cogging frequency, Fs=k×n, where Fs is the cogging frequency and k is the tooth of the generator The number of slots, n is the rotation speed of the generator. According to the method of obtaining the rotation speed of the generator set according to the exemplary embodiment of the present invention, the accuracy of obtaining the rotation speed can be improved. In addition, since the rotation speed is directly extracted from the vibration data, the consistency of the time series of the vibration data and the rotation speed data can be strictly guaranteed. In addition, since there is no need for any special equipment to measure the rotation speed, the equipment cost and implementation cost of the rotation speed test are reduced to zero.

Description

Method and device for obtaining the rotational speed of a wind power plant

technical field

The present invention relates to the technical field of wind power generation, and more specifically, to a method and equipment for obtaining the rotational speed of a wind power generating set based on vibration data.

Background technique

With the development of wind power generation technology, the current mainstream wind turbines are designed to operate at variable speeds. When a wind turbine fails, in most cases the vibration characteristics (especially the frequency domain characteristics) corresponding to the fault have a direct correspondence with the speed. Therefore, when the state monitoring and fault diagnosis system performs vibration state monitoring and fault diagnosis on variable-speed wind turbines, speed measurement is a very important task. The accuracy of speed measurement directly affects the reliability of vibration data analysis results.

Fig. 1 shows a schematic diagram of a method for obtaining the rotational speed of a wind power generating set according to the prior art. As shown in FIG. 1, a rotational speed sensor 10 (eg, a photoelectric sensor, a magnetic sensor, etc.) is mounted on a stationary component and aligned with a rotating component 30 (eg, a rotating shaft); one or more rotational speed pulses are arranged on the rotating component 30 Trigger markings 20 (such as reflective strips, protruding metal blocks, etc.). When the rotation speed pulse triggers the marker 20 to follow the rotation of the rotating component 30 and face the rotation speed sensor 10 , the rotation speed sensor 10 will output a pulse, and the vibration analysis system 40 calculates the current rotation speed of the rotation component 30 according to the time interval of collecting pulses.

Meanwhile, as shown in FIG. 1 , the vibration analysis system 40 obtains vibration data from the vibration sensor 50 .

Another method for obtaining the rotational speed of the wind power generating set according to the prior art is to exchange data with the main control system and read the rotational speed data in the main control system, so as to obtain the rotational speed value at the time of vibration data collection.

However, according to the technical solution of obtaining the rotational speed of the wind power generating set in the prior art, since a separate rotational speed sensor needs to be installed or data exchange with the main control system is required, the system cost is increased and the data exchange increases the main control system. risk; due to the extremely low speed of wind turbines, the measurement error based on the existing technical solutions is relatively large; once the clocks of the main control system and the condition monitoring and fault diagnosis system are inconsistent, the collected vibration data and speed data cannot be in time sequence corresponding to the above.

Contents of the invention

In order to solve at least one of the above problems or other problems existing in the prior art, a technical solution for obtaining the rotational speed of a wind power generating set based on vibration data is provided.

According to an exemplary embodiment of the present invention, a method for obtaining the rotational speed of a wind power generator includes the following steps: performing band-pass filtering on the vibration data of the wind power generator in the time domain; performing envelope detection on the band-pass filtered data ;Transform the data detected by the envelope into the frequency domain; search the peak value for the data in the frequency domain, so as to obtain the cogging frequency of a predetermined multiple; use the following equation to obtain the rotational speed of the generator according to the obtained cogging frequency , Fs=k×n, where Fs is the cogging frequency, k is the number of cogging of the generator, and n is the rotational speed of the generator.

Preferably, the envelope detected data is transformed into the frequency domain by a Fast Fourier Transform.

Preferably, the vibration data of the wind power generator in the time domain is obtained through a vibration sensor or through communication with a main control system.

Preferably, the vibration data is bandpass filtered by a constant bandwidth digital bandpass filter.

Preferably, the extracted frequency range of the constant bandwidth digital bandpass filter is set to a frequency range twice the frequency of the cogging frequency.

Preferably, digital envelope detection is performed on the band-pass filtered data by Hilbert transform.

According to another exemplary embodiment of the present invention, a device for obtaining the rotational speed of a wind power generator includes: a band-pass filter for band-pass filtering the vibration data of the wind power generator in the time domain; an envelope detector , to perform envelope detection on the band-pass filtered data; the frequency domain converter, to transform the data detected by the envelope into the frequency domain; the searcher, to search the peak value of the data in the frequency domain, so as to obtain a predetermined multiple of cogging Frequency; rotational speed calculator, use the following equation to obtain the rotational speed of the generator according to the obtained cogging frequency, Fs=k×n, wherein, Fs is the cogging frequency, k is the number of cogging of the generator, and n is The speed of the generator.

Preferably, the frequency domain transformer transforms the envelope detected data into the frequency domain by fast Fourier transform.

Preferably, the vibration data of the wind power generator in the time domain is obtained through a vibration sensor or through communication with a main control system.

Preferably, the bandpass filter is a constant bandwidth digital bandpass filter.

Preferably, the extracted frequency range of the constant bandwidth digital bandpass filter is set to a frequency range twice the frequency of the cogging frequency.

Preferably, the envelope detector performs digital envelope detection on the band-pass filtered data through Hilbert transform.

According to the method for obtaining the rotational speed of a generator set according to the exemplary embodiment of the present invention, the accuracy of obtaining the rotational speed can be improved. In addition, since the rotational speed is directly extracted from the vibration data, the consistency of the vibration data and the rotational speed data in time series can be strictly guaranteed. In addition, since no special equipment for measuring the rotational speed is required, the equipment cost and implementation cost of the rotational speed test are reduced to zero.

Description of drawings

These and/or other aspects and advantages of the present invention will become clearer and easier to understand through the following description of embodiments in conjunction with the accompanying drawings, wherein:

Fig. 1 shows a schematic diagram of a method for obtaining the rotational speed of a wind power generating set according to the prior art;

Fig. 2 is a flow chart showing a method for obtaining the rotational speed of a wind power generating set according to an exemplary embodiment of the present invention;

FIG. 3 shows a spectrogram obtained according to the method of FIG. 2 .

Detailed ways

Embodiments of the invention will now be described in detail, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like parts throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

Generally speaking, a plurality of cogging slots are installed on the stator of the generator to place coils, so the vibration data obtained when the generator set is running includes the cogging frequency Fs of the generator set. The rotational speed n of the generator set can be obtained based on the cogging frequency Fs using Equation 1 below.

[Equation 1]

Fs=k×n

where k is the number of slots installed on the stator.

Fig. 2 shows a technical solution for obtaining the rotational speed of a wind power generating set according to an exemplary embodiment of the present invention.

As shown in FIG. 2 , at step 210 , bandpass filtering is performed on the vibration data in the time domain.

Here, preferably, the vibration data in the time domain is band-pass filtered by a constant-bandwidth digital band-pass filter. Meanwhile, the extraction frequency of the digital bandpass filter is preferably set to 2 times the motor cogging frequency Fs. For example, if the possible range of motor cogging frequency Fs is 10Hz to 10000Hz, set the extraction frequency range of the digital bandpass filter to 20Hz to 20000Hz. In addition, when collecting vibration data, it is preferable to adopt a sampling frequency of 2000 Hz.

In step 220, envelope detection is performed on the bandpass filtered data. Digital envelope detection is performed on the filtered signal by Hilbert transform (90 degree phase shift) technology.

In step 230, the envelope detected data is transformed into the frequency domain. Preferably, Fourier transform is performed on the enveloped signal to obtain the final fault feature extraction map. Here, the envelope detected data may be transformed into the frequency domain by Fast Fourier Transform (FFT). For example, a frequency domain diagram as shown in FIG. 3 can be obtained.

In step 240, peak search processing is performed on the data in the frequency domain, so as to obtain a predetermined multiple of the cogging frequency (for example, a 4-fold cogging frequency). In the spectrogram shown in Figure 3, within the frequency range where the quadruple frequency FS of Fs appears, the quadruple frequency FS of the cogging frequency Fs of the generator can be identified simply by searching for the maximum value as 671.4Hz. This data corresponds to The unit speed n=60×FS/(4×576)=17.48RPM.

At step 250 , the rotational speed of the generator set is obtained according to Equation 1 . As shown in Figure 3, the 4 times the cogging frequency is 671.4Khz. When the number of slots is 576, the rotational speed of the wind power generating set n=Fs/576=17.48RPM.

Here, the vibration data may be vibration data obtained through a vibration sensor or vibration data obtained through communication with a master control system.

According to the method for obtaining the rotational speed of a generator set according to the exemplary embodiment of the present invention, the accuracy of obtaining the rotational speed can be improved. In the example described above, the 4 times the cogging frequency is 2304 times the rotation speed of the generator set, even if the difference between the extracted value of the characteristic frequency and the true value is 10Hz, the error between the calculated value and the true value of the rotation speed is (10×60)/ (576×4)=0.26RPM, during the calculation of the rotational speed, the error converges at a ratio of 1/2304, so the measurement accuracy of the rotational speed has been greatly improved.

According to an exemplary embodiment of the present invention, the device for obtaining the rotational speed of a wind power generating set includes: a band-pass filter for band-pass filtering the vibration data of the wind power generator in the time domain; an envelope detector for band-pass filtering The filtered data is subjected to envelope detection; the frequency domain converter transforms the data detected by the envelope into the frequency domain; the searcher performs peak search processing on the data in the frequency domain to obtain a predetermined multiple of the cogging frequency; the speed calculation According to the obtained cogging frequency, use the following equation to obtain the rotational speed of the generator, Fs=k×n, where Fs is the cogging frequency, k is the number of cogging of the generator, and n is the rotational speed of the generator .

In addition, since the rotational speed is directly extracted from the vibration data, the consistency of the vibration data and the rotational speed data in time series can be strictly guaranteed.

In addition, since no special equipment for measuring the rotational speed is required, the equipment cost and implementation cost of the rotational speed test are reduced to zero.

While certain embodiments of the present invention have been shown and described, it should be understood by those skilled in the art that modifications may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents. to modify.

Claims (12)

1. A method for obtaining the rotational speed of a wind power generating set, comprising the steps of: Perform band-pass filtering on the vibration data of the wind turbine in the time domain; Perform envelope detection on the bandpass filtered data; transforming the envelope detected data into the frequency domain; Perform peak search processing on the data in the frequency domain, so as to obtain a predetermined multiple of the cogging frequency; From the obtained cogging frequency use the following equation to obtain the rotational speed of the generator, Fs=k×n, Among them, Fs is the cogging frequency, k is the number of cogging of the generator, and n is the rotational speed of the generator. 2. The method of claim 1, wherein the envelope detected data is transformed into the frequency domain by a Fast Fourier Transform. 3. The method according to claim 1, wherein the vibration data of the wind power generator in the time domain is obtained through a vibration sensor or through communication with a main control system. 4. The method of claim 1, wherein the vibration data is bandpass filtered by a constant bandwidth digital bandpass filter. 5. The method of claim 4, wherein the extracted frequency range of the constant bandwidth digital bandpass filter is set to a frequency range of 2 times the cogging frequency. 6. The method of claim 1, wherein digital envelope detection is performed on the bandpass filtered data by Hilbert transform. 7. An apparatus for obtaining the rotational speed of a wind power generating set, said apparatus comprising: A band-pass filter is used to band-pass filter the vibration data of the wind turbine in the time domain; An envelope detector, performing envelope detection on the bandpass filtered data; a frequency domain converter, which transforms the data detected by the envelope into the frequency domain; A searcher, which performs peak search processing on the data in the frequency domain, so as to obtain a cogging frequency of a predetermined multiple; RPM calculator, use the following equation to get the RPM of the generator based on the obtained cogging frequency, Fs=k×n, Among them, Fs is the cogging frequency, k is the number of cogging of the generator, and n is the rotational speed of the generator. 8. The apparatus of claim 7, wherein the frequency domain transformer transforms the envelope detected data into the frequency domain by fast Fourier transform. 9. The device according to claim 7, wherein the vibration data of the wind power generator in the time domain is obtained through a vibration sensor or through communication with a master control system. 10. The apparatus of claim 7, wherein the bandpass filter is a constant bandwidth digital bandpass filter. 11. The apparatus of claim 10, wherein the extracted frequency range of the constant bandwidth digital bandpass filter is set to a frequency range of 2 times the cogging frequency. 12. The apparatus of claim 7, wherein the envelope detector performs digital envelope detection on the bandpass filtered data by Hilbert transform.

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