WO2015196735A1 - Wind power gear box order tracking method based on meshing frequency and spectrum correction technology - Google Patents

Abstract

Disclosed is a wind power gear box order tracking method based on a meshing frequency and spectrum correction technology. The method comprises performing discrete sampling on vibration acceleration signals on the surface of a box body of a fan planet gear box to obtain a non-stationary time domain sequence x_n(t) firstly; adding a hanning window w (t) to intercept a section of x n(t) and performing FFT transformation to obtain a power spectrum G(f); performing frequency correction on the meshing frequency f_m of a gear box high-speed shaft in the G(f) by a four-point energy centrobaric correction method to obtain an instantaneous meshing frequency expressed by the formula(I); moving window functions in turn and extracting the formula(I) by the energy centrobaric method repeatedly to obtain a meshing frequency curve expressed by the formula(II); obtaining a high-speed shaft rotating frequency curve according to the relation between the meshing frequency and the rotating frequency, wherein the high-speed shaft rotating frequency curve is expressed by the formula(III); combining with the formula(III) to performing equal-angle resampling on the x_n(t) to obtain a smooth angle domain sequence θ _n(t); and performing correction on the order time and the amplitude by a window length moving method and the energy centrobaric method to obtain an order tracking curves O_i(t). The solution is good in generality, high in anti-noise performance and accurate and reliable and the problems that a method for measuring the fan rotating speed through a tachometer is difficult in installation, high in cost, poor in accuracy and the like can be avoided.

Description

Wind power gear box order tracking method based on meshing frequency and spectrum correction technology Technical field

The invention relates to the field of power machinery and signal processing, in particular to a wind power gear box order tracking analysis method using a meshing frequency and a discrete spectrum correction technique, and is a calculation order tracking analysis method based on a vibration acceleration signal without a tachometer.

Background technique

The essence of the order analysis is to convert the non-stationary signal in the time domain into a stationary signal in the angular domain by constant angle incremental sampling. The core of the method is to obtain equal-angle sampling data with respect to the reference axis, and the reference axis instantaneous speed n _i is used in the implementation. (t) Correspondence with the instantaneous frequency f _i (t), as in equation (2-1), accurately obtain the time (time stamp) of the order sampling and the corresponding reference speed (or frequency shift).

n _i (t)=60×f _i (t) (2-1)

At present, there are two main methods for order tracking analysis: one is order tracking analysis with tachometer or other auxiliary hardware devices, such as traditional hardware order tracking and calculation order tracking method directly from angular domain sampling; The other type is the order tracking analysis without tachometer, focusing on equal-angle resampling order tracking based on instantaneous frequency estimation.

In practical engineering, the hardware order tracking method has the disadvantages of complicated installation, high price, and poor tracking effect on the signal order of faster rotation speed; the calculation of the order tracking phase detector has high requirements on the installation conditions, and the pulse is lost or wrong. Increasing phenomenon, the speed measurement error is large, and the order tracking accuracy is poor. At present, the main application of signal processing is to estimate the instantaneous frequency by calculating the first moment of the time-frequency distribution. For example, in the formula (2-2), the first moment of the Wigner distribution is equal to the instantaneous frequency, and the short-time Fourier transform The moment is approximately equal to the instantaneous frequency. Where P(t,f) is the time-frequency distribution of the signal, and STFT(t,f) is the short-time Fourier transform of the signal.

However, applying the method to estimate the instantaneous frequency in actual engineering still has the following problems:

(1) The formula (2-2) has only a clear physical meaning for the single component signal, and the actual engineering signal is generally a multi-component signal, which is applicable only when the components can be separated on the time-frequency plane, and the versatility is poor. .

(2) Using the peak search method to extract the instantaneous frequency of each component from the time-frequency distribution of the multi-component signal, estimate The accuracy is limited by the frequency resolution; when the frequency resolution is low, the phenomenon of finding the wrong instantaneous frequency occurs.

(3) Due to energy leakage caused by time domain windowing and frequency domain discretization, the Fourier transform frequency result has a maximum error of 0.5 frequency resolution, which affects the accuracy of instantaneous frequency estimation.

(4) The noise immunity of this method is poor, and the accuracy of instantaneous frequency estimation is not high under noise interference;

(5) The measured frequency components of the vibration signal of the wind power gearbox are many, the frequency conversion components of each axis are not obvious, the signal-to-noise ratio is low, and it is difficult to directly extract the instantaneous frequency conversion.

Summary of the invention

The object of the present invention is to overcome the shortcomings and deficiencies of the prior art, and to provide a wind power gear box order tracking method based on meshing frequency and spectrum correction technology.

The object of the invention is achieved by the following technical solutions:

The wind power gearbox order tracking method based on the meshing frequency and spectrum correction technology includes the following sequence of steps:

(1) obtaining a high-speed shaft vibration acceleration signal from the gear box case by using a vibration acceleration sensor;

(2) adding a Hanning window to the initial point N-point vibration acceleration data, and performing FFT transformation to obtain an amplitude spectrum;

(3) Applying a four-point energy intermediate method to extract and correct the instantaneous meshing frequency of the initial segment;

(4) Move the Hanning window to intercept the next N-point vibration acceleration data, and perform FFT transformation; determine the frequency search range based on the instantaneous meshing frequency extracted from the previous segment of data, and extract and correct the instantaneous meshing frequency of the subsequent segment until all data is analyzed. , obtaining a transient meshing frequency curve;

(5) Combining the gear tooth gear number, meshing frequency and frequency conversion, the instantaneous frequency conversion curve is obtained;

(6) Calculate the time (time scale) corresponding to the equal-angle incremental sampling according to the instantaneous frequency-transition curve; perform amplitude interpolation fitting on the time-domain non-stationary vibration acceleration signal to obtain the angular-domain stationary vibration acceleration signal;

(7) Perform steps (2) to (4) on the obtained angular domain signal, correct the order frequency and amplitude of the meshing frequency, and implement order tracking analysis.

The wind power gear box order tracking method based on the meshing frequency and spectrum correction technology specifically includes the following sequence of steps:

(1) Coordinate system establishment: establish the space coordinate system XYZ, the x-axis forward direction points to the rear end of the wind turbine gearbox output shaft, the z-axis is positively vertical upward, and the x-axis positive direction is determined by the right-hand rule;

(2) Mounting the sensor: Install a one-way acceleration sensor on the surface of the wind power gear box near the output shaft, the test direction is z direction; connect the sensor, data collector and portable computer in turn;

(3) On the actual running wind turbine of the wind farm, the working speed of the gearbox output shaft is S; the sampling frequency of the data collector is f _s , and the sampling time length T is within 100-240 s, then the sampling interval Δt= 1 / f _s, the sampling points N = f _s · T; sync acquisition and recording time domain vibration acceleration test point signal referred to as x _n (t), where n = 0,1,2, ..., N- 1; t=n·Δt;

(4) Obtain a discrete sequence of the initial segment N' point vibration acceleration signal from x _n (t), denoted as x ₁ (t); add xanning window to x ₁ (t)

N' = 0, 1, 2, ..., N'-1;N' point FFT transform according to formula (1-1), obtain spectrum X ₁ (f), and obtain discrete sequence of spectrum according to formula (1-2) X ₁ (k);

(5) Search for the high-speed shaft meshing frequency of the gearbox in X ₁ (k)

Corresponding peak

And the line number k; the power spectrum G(k) is obtained by applying the formula (1-3); similarly, the power spectrum values G(k±1) and G corresponding to the lines k±1 and k±2 are obtained. k±2); compare G(k±2), the larger the amplitude is defined as G(k _m ), and the corresponding line number is k _m ;

(6) According to formula (1-4), the four-point energy center of gravity method is adopted.

Perform frequency correction to obtain corrected instantaneous meshing frequency

(7) Moving the Hanning window w(n'), intercepting the N' point vibration data, denoted as x _i (t), where the overlap ratio of the two pieces of data x _i-1 (t) and x _i (t) E; according to step (4) to (6) in meshing frequency of x _i (t) gearbox output shaft

Calibrate to obtain the corrected instantaneous meshing frequency

Until the analysis of x _n (t), by

The instantaneous meshing frequency curve of the output shaft of the gearbox is recorded as

(8) According to formula (1-5), obtain the instantaneous frequency conversion curve of the gearbox output shaft, recorded as

Calculate the number of turns of the gearbox output shaft at time t in the acquisition time T according to formula (1-6), denoted as R(t):

z: number of teeth (1-5)

(9) Set the number of sampling points per revolution to f _{s_o} , then the equal-angle interval in units of rotation is Δθ=1/f _{s_o} ; discretize the angle of R(t) by Δθ to obtain the discrete sequence R of M points ( i·Δθ), ( sink 0,1,2,...,M-1), where M=R _max ·f _{s_o} ; combined with _equiangular interval sequence R(t) and equal time interval sequence x _n (t), application Cubic spline interpolation method, obtain a sequence of vibration acceleration amplitude corresponding to the equiangular interval Δθ of the M point, denoted as y _m (θ);

(10) for setting the number of revolutions of the order analysis is r, the order of the resolution ΔO = 1 / r, the order of the number of lines _M '= r · f s_o; Application M' point Hanning

Obtain the discrete data segment from y _m (θ), denoted as Y _i (θ); perform FFT transformation on y _i (θ) and correct the instantaneous meshing frequency by four-point energy centroid method according to the methods of steps (4) to (7) f _m corresponds to the order O _m, and press the formula (1-7) correcting the order of magnitude of Y _m (O):

The gear box is a multi-stage hybrid transmission structure of a planetary gear train + a fixed axle train, and the high speed shaft as an output shaft is a fixed axle train transmission.

The normal operating speed S of the gearbox high speed shaft is from 1000 r/min to 1800 r/min.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. The method estimates the instantaneous meshing frequency from the vibration acceleration signal, which can overcome the low signal-to-noise ratio of the frequency-shifting component, and it is difficult to directly extract the defect of the reference axis instantaneous frequency-shifting; and the discrete frequency correction technique is used to correct the instantaneous meshing frequency, which is greatly improved. The frequency accuracy overcomes the shortcomings of easy to find the wrong instantaneous frequency when the frequency resolution is low. The method has low cost, good versatility, high anti-noise performance, accurate and reliable results, and no tachometer And phase detector, the cost is low; the vibration acceleration sensor has limited installation conditions and better applicability.

2. Fully utilize the vibration acceleration frequency characteristics of the wind power gearbox, extract the meshing frequency directly from the vibration acceleration signal, and then convert to the instantaneous speed, which overcomes the defect that the signal-to-noise ratio of the frequency-transfer component is difficult to directly extract the instantaneous speed:

The gearbox transmission structure of the domestic mainstream 1.5MW wind turbine is mainly a first-class planetary gear train + a second-stage fixed-axle gear train or a two-stage planetary gear train + a first-class fixed-shaft train system. These two gearboxes have the same characteristics: the frequency of the gearbox output shaft is very close to the gearbox's first-stage gear meshing frequency, see Table 1. In the normal wind power gearbox vibration acceleration signal, the amplitude of the larger frequency component is mainly the IIIth meshing frequency and its high-order frequency doubling. The amplitude of the frequency conversion and the first two stages of meshing frequency are very small, as shown in Figure 2, therefore It is difficult to extract the speed curve directly from the vibration acceleration signal.

Table 1 Table of relationship between meshing frequency and output shaft frequency conversion of domestic mainstream 1.5MW wind turbine gearbox (Hz)

structure type	Output shaft frequency shift	First stage meshing frequency	Second stage meshing frequency	Third stage meshing frequency
					Two-stage planet + one-stage parallel axis	1.0	0.945	5.346	29
First class planet + two parallel axes	1.0	0.98	5.63	23.00

The general formula for correcting the frequency by the energy center of gravity method in discrete spectrum correction technique (2-3), the general formula for correcting the amplitude (2-4), where f _s is the sampling frequency, N is the number of sampling points, and k is the largest amplitude. The corresponding line number of the point, g _k is the corresponding power spectrum value, and K _t is the energy recovery coefficient. Comparing equations (2-2) and (2-3), equation (2-3) is essentially the exact discrete expression of equation (2-4) right-form, and the frequency obtained by applying energy center of gravity method is approximately equal to instantaneous. The frequency obtained is approximately equal to the average amplitude.

Based on the above characteristics, the energy center of gravity method is used to correct the instantaneous meshing frequency curve of the output shaft from the vibration acceleration signal of the gearbox, and then the reference axis instantaneous is obtained by combining the number of teeth of the meshing gear, the meshing frequency and the frequency shift (1-5). The frequency conversion curve is then determined according to the relationship between the instantaneous speed and the instantaneous frequency shift (2-1), and the time corresponding to the equal-angle resampling is determined, and then the amplitude of the non-stationary signal vibration acceleration in the time domain is interpolated and fitted. The amplitude of the vibration acceleration in the angular domain is obtained, and the FFT is performed to realize the order tracking analysis.

3. Estimate the instantaneous frequency through the four-point energy center-of-gravity method with high anti-noise performance, and correct the frequency, improve the frequency estimation accuracy, and reduce the speed estimation error caused by time domain truncation and frequency domain discretization: due to time domain truncation and In the frequency domain discretization, as long as the time-domain truncation of the signal is not performed, the frequency, amplitude and phase of the harmonic signal are discrete Fourier transform, and the maximum error can reach 0.5 frequency resolution. The meshing frequency error is converted to the rotational speed error, which can achieve a frequency resolution of 60/z times. In order to improve the accuracy of the instantaneous meshing frequency estimation of the output shaft, the four-point energy center-of-gravity correction method with high anti-noise performance is used to correct the obtained meshing frequency, and the reference axis speed with higher accuracy is obtained through calculation.

DRAWINGS

Figure 1 is a schematic view of the transmission structure of the wind power gear box;

Figure 2 is a frequency characteristic diagram of the vibration acceleration of the measuring point of the output shaft of the third stage of the normal wind power gearbox;

3 is a spectrum of amplitude data of an initial stage of vibration of a gearbox output shaft of a wind power gear box order tracking method based on meshing frequency and spectrum correction technology according to the present invention;

Figure 4 is a graph showing the instantaneous meshing frequency of the gearbox output shaft of the method of Figure 3;

Figure 5 is a spectrum diagram of the vibration order of the output shaft of the gearbox of the method of Figure 3;

Figure 6 is a vibration amplitude spectrum diagram of the gearbox output shaft of the method of Figure 3;

7 is a flow chart of a wind power gearbox order tracking method based on meshing frequency and spectrum correction technology according to the present invention.

detailed description

The present invention will be further described in detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

As shown in FIG. 7, the wind power gear box order tracking method based on the meshing frequency and spectrum correction technology specifically includes the following sequence of steps:

(1) obtaining a high-speed shaft vibration acceleration signal from the gear box case by using a vibration acceleration sensor;

(2) adding a Hanning window to the initial point N-point vibration acceleration data, and performing FFT transformation to obtain an amplitude spectrum;

(3) Applying a four-point energy intermediate method to extract and correct the instantaneous meshing frequency of the initial segment;

(4) Moving the Hanning window to intercept the next N-point vibration acceleration data for FFT transformation; The instantaneous meshing frequency of a piece of data extraction, determine the frequency search range, extract and correct the instantaneous meshing frequency of the latter segment, until all the data is analyzed, and obtain the instantaneous meshing frequency curve;

(5) Combining the gear tooth gear number, meshing frequency and frequency conversion, the instantaneous frequency conversion curve is obtained;

(6) Calculate the time (time scale) corresponding to the equal-angle incremental sampling according to the instantaneous frequency-transition curve; perform amplitude interpolation fitting on the time-domain non-stationary vibration acceleration signal to obtain the angular-domain stationary vibration acceleration signal;

(7) Perform steps (2) to (4) on the obtained angular domain signal, correct the order frequency and amplitude of the meshing frequency, and implement order tracking analysis.

The present invention will be further described below in conjunction with the embodiments:

This embodiment specifically includes the following steps:

(1) Coordinate system establishment: establish the space coordinate system XYZ, the x-axis forward direction points to the rear end of the output shaft of the wind turbine gearbox, the z-axis is positively vertical upward, and the x-axis positive direction is determined by the right-hand rule; the gearbox transmission structure is shown in 1. In Figure 1, z1, z2 and z3 respectively represent the number of teeth of the corresponding transmission gears in each gear train. See Table 2 for details:

Table 2 Wind turbine gearbox gear parameters

gear	Z1	Z2	Z3
				Class I planetary gear train	twenty two	36	95
Class II planetary gear train	twenty two	39	101
				Class III fixed axle train	29	98	/

(2) Mounting the sensor: Install a unidirectional acceleration sensor on the surface of the casing of the wind turbine gearbox close to the output shaft of the IIIth stage, the test direction is z direction; the sensor is connected to the Miller Fritillary (BBM) MKII signal collector, data The collector is connected to the portable computer;

(3) Set the sampling frequency f _s of the data collector to 24000 Hz, and the sampling time length T is 240 s, then the sampling time interval Δt=1/f _s = 1/24000 s, the number of sampling points N=f _s ·T=5.28× ^106; when the acquisition and simultaneous recording of the vibration acceleration test point domain signal referred to as x _n (t), where n = 0,1,2, ..., N- 1; t = n · Δt;

(4) Obtain the initial sequence N'=24000 point vibration acceleration discrete sequence from x _n (t), denoted as x ₁ (t); add x Hanning window to x ₁ (t)

N' = 0, 1, 2, ..., N'-1;N' point FFT transform according to formula (1-1), obtain spectrum X ₁ (f), and obtain discrete sequence of spectrum according to formula (1-2) X ₁ (k), see Figure 3, where the frequency resolution

(5) Search for the initial stage gearbox high speed shaft meshing frequency in X ₁ (k)

580Hz, corresponding peak X ₁ (

) is 0.5325, the spectral number k is 580; the power spectrum G(580)=0.2835 is obtained by applying formula (1-3); the power spectrum value G(581) corresponding to k±1 is obtained by the same reason. =0.203, G(579)=0.1039, the power spectrum value corresponding to the line k±2 is G(582)=0.0357, G(578)=0.1014; comparing G(k±2), the larger amplitude is G( k _m ) is G(582), and the corresponding line number is k _m =582:

(6) According to formula (1-4), the four-point energy center of gravity method is adopted.

Perform frequency correction to obtain corrected instantaneous meshing frequency

(7) Move the Hanning window w(n') and intercept the N'=24000 point vibration data, denoted as x _i (t), where the overlap of the two pieces of data x _i-1 (t) and x _i (t) Rate e=0.7; according to steps (4)~(6), the gearbox output shaft meshing frequency in x _i (t)

Calibrate to obtain the corrected instantaneous meshing frequency

End until analysis x _n (t), by the

The instantaneous meshing frequency curve of the output shaft of the gearbox is recorded as

, see Figure 4;

(8) According to formula (1-5), obtain the instantaneous frequency conversion curve of the gearbox output shaft, recorded as

According to formula (1-6), calculate the total number of images R of the gearbox output shaft after the acquisition time T=200s is 5300 rpm:

(9) Set the number of sampling points per revolution f _{s_o} = 1024, then the equal-angle interval Δθ = 1 / f _{s_o} = 1 / 1024 rpm; _{discard the} angle of R (t) by Δθ to obtain M = R · f _{s_o} =5.4625×10 ^6- point discrete sequence R(i·Δθ); combined with the equiangular interval sequence R(i·Δθ) and the isochronous sequence x _n (t), the cubic spline interpolation method is used to obtain the equiangular interval of M points. Δθ corresponding vibration acceleration amplitude sequence y _m (θ);

(10) Set the number of revolutions for order analysis r=40, then the order resolution ΔO=1/r=0.025, the number of order lines M′=r·f _{s_o} =40960; apply M′ point Hanning window

Taken from y _m (θ) for some discrete data segment Y _{i (θ);} for y _i (θ) performing an FFT order spectrum obtained, shown in Figure 5, engage frequency f _m corresponds to the order of three multiplier and O _m Its amplitude Y _m (O) is (29, 0.5711), (57, 0.1141) and (87, 0.1987);

When the order analysis is performed with the gearbox's third-stage output shaft as the reference axis, the theoretical value of the third-order meshing frequency corresponding to the order is equal to the number of teeth of the meshing gear. In the embodiment of the present example, the number of teeth of the meshing gear of the output shaft of the third stage is 29, so the theoretical values of the order of the first three times of the meshing frequency are 29, 58 and 87 steps, respectively. It can be seen from Fig. 5 that the corresponding measured meshing frequency obtained by the algorithm used in the present invention is substantially consistent with the theoretical value, and the effectiveness of the algorithm used in the present invention is verified.

From the original spectrum shown in Fig. 6, it can be seen that there is a frequency blur phenomenon in the triple frequency band of the IIIth meshing frequency, which is a defect of the fast Fourier transform processing the non-stationary vibration signal. The order spectrum obtained by the algorithm of the present invention (see FIG. 5) has clear frequency components in the frequency band around the multiple frequency of the meshing frequency, and the frequency components unrelated to the reference axis frequency conversion are effectively suppressed, which embodies the superiority of the algorithm used in the present invention. Sex.

The accuracy of the order analysis algorithm depends mainly on the reference axis instantaneous frequency shift. By comparing the measured values with the theoretical values, it can be seen that the order analysis results have high precision, which indirectly verifies that the instantaneous frequency shift estimation algorithm adopted by the invention has high precision and can effectively measure the rotational speed of the wind power gear box.

The invention can overcome the defect that the wind power gear box is difficult to directly extract the instantaneous frequency conversion of the reference axis, and the frequency conversion measurement method has low cost and good versatility, and the order analysis has high anti-noise performance and accurate and reliable results.

The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and combinations thereof may be made without departing from the spirit and scope of the invention. Simplifications should all be equivalent replacements and are included in the scope of the present invention.

Claims (4)

1. A wind power gearbox order tracking method based on meshing frequency and spectrum correction technology, characterized in that it comprises the following sequence of steps:

   (1) obtaining a high-speed shaft vibration acceleration signal from the gear box case by using a vibration acceleration sensor;

   (2) adding a Hanning window to the initial point N-point vibration acceleration data, and performing FFT transformation to obtain an amplitude spectrum;

   (3) Applying a four-point energy intermediate method to extract and correct the instantaneous meshing frequency of the initial segment;

   (4) Move the Hanning window to intercept the next N-point vibration acceleration data, and perform FFT transformation; determine the frequency search range based on the instantaneous meshing frequency extracted from the previous segment of data, and extract and correct the instantaneous meshing frequency of the subsequent segment until all data is analyzed. , obtaining a transient meshing frequency curve;

   (5) Combining the gear tooth gear number, meshing frequency and frequency conversion, the instantaneous frequency conversion curve is obtained;

   (6) Calculate the time corresponding to the equal-angle incremental sampling according to the instantaneous frequency-transition curve; perform amplitude interpolation on the non-stationary vibration acceleration signal in the time domain to obtain the angular vibration acceleration signal;

   (7) Perform steps (2) to (4) on the obtained angular domain signal, correct the order frequency and amplitude of the meshing frequency, and implement order tracking analysis.
2. The wind power gearbox order tracking method based on the meshing frequency and spectrum correction technology according to claim 1, characterized in that it comprises the following sequence of steps:

   (1) Coordinate system establishment: establish the space coordinate system XYZ, the X axis points to the rear end of the wind turbine gearbox output shaft, the Z axis is positive and vertical upward, and the X axis is determined by the right hand rule;

   (2) Mounting the sensor: Install a one-way acceleration sensor on the surface of the wind power gear box near the output shaft, the test direction is Z direction; connect the sensor, data collector and portable computer in turn;

   (3) on a wind farm the actual operation of the wind turbine, so that the gearbox output shaft of the operating speed is S; sampling frequency of the data collector is f _s, the length of the sampling time T is within 100 ~ 240s, the sampling time interval Δt = 1/f _s , number of sampling points N=f _s ·T; acquisition and synchronization record the vibration acceleration time domain signal of the test point, denoted as x _n (t), where n=0,1,2,...,N-1; t=n·Δt;

   (4) Obtain a discrete sequence of the initial segment N' point vibration acceleration signal from x _n (t), denoted as x ₁ (t); add xanning window to x ₁ (t)

   

   Perform a N' point FFT transform according to formula (1-1) to obtain a spectrum X ₁ (f), and obtain a discrete sequence of spectra X ₁ (k) according to formula (1-2);

   

   

   (5) Search for the high-speed shaft meshing frequency of the gearbox in X ₁ (k)

   

   Corresponding peak

   

   And the line number k; the power spectrum G(k) is obtained by applying the formula (1-3); similarly, the power spectrum values G(k±1) and G corresponding to the lines k±1 and k±2 are obtained. k±2); compare G(k±2), the larger the amplitude is defined as G(k _m ), and the corresponding line number is k _m ;

   

   (6) According to formula (1-4), the four-point energy center of gravity method is adopted.

   

   Perform frequency correction to obtain corrected instantaneous meshing frequency

   

   

   (7) Moving the Hanning window w(n'), intercepting the N' point vibration data, denoted as x _i (t), where the overlap ratio of the two pieces of data x _i-1 (t) and x _i (t) e; according to steps (4) ~ (6) on the gearbox output shaft meshing frequency in x _i (t)

   

   Calibrate to obtain the corrected instantaneous meshing frequency

   

   Until the analysis of x _n (t), by

   

   The instantaneous meshing frequency curve of the output shaft of the gearbox is recorded as

   

   (8) According to formula (1-5), obtain the instantaneous frequency conversion curve of the gearbox output shaft, recorded as

   

   Calculate the number of turns of the gearbox output shaft at time t in the acquisition time T according to formula (1-6), denoted as R(t):

   

   Z: Number of teeth (1-5)

   

   (9) Set the number of sampling points per revolution to f _{s_o} , then the equal-angle interval in units of rotation is Δθ=1/f _{s_o} ; discretize the angle of R(t) by Δθ to obtain the discrete sequence R of M points ( i · Δθ), (i = 0,1,2, ..., M-1), where _M = R1 _max · f s_o; equal angular intervals binding sequence R (t) and the sequence of time intervals, etc. x _n (t), Applying the cubic spline interpolation method to obtain the vibration acceleration amplitude sequence corresponding to the equiangular interval Δθ of the M point, denoted as y _m (θ);

   (10) Set the number of revolutions for the order analysis to be r, then the order resolution ΔO=1/r, the order line number M′=r·f _{s_o} ; apply the M′ point Hanning window

   

   Obtain the discrete data segment from y _m (θ), denoted as Y _i (θ); perform FFT transformation on y _i (θ) and correct the instantaneous meshing frequency by four-point energy centroid method according to the methods of steps (4) to (7) f _m corresponds to the order O _m, and press the formula (1-7) correcting the order of magnitude of Y _m (O):

   
3. The wind power gear box order tracking method based on the meshing frequency and spectrum correction technology according to claim 1, wherein the gear box is a multi-stage hybrid transmission structure of a planetary gear train + a fixed axle train system, and The high speed shaft as the output shaft is the fixed shaft train.
4. The wind power gear box order tracking method based on the meshing frequency and spectrum correction technology according to claim 1, wherein the gearbox high speed shaft normal working speed S is from 1000 r/min to 1800 r/min.

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