CN104897269A - Overhead wire vibration frequency measuring system based on linear scanning imaging - Google Patents

Abstract

The invention discloses an overhead wire vibration frequency measuring system based on linear scanning imaging. The overhead wire vibration frequency measuring system is used for solving a technical problem that a conventional vibration frequency measuring system is inaccurate in measured data and small in measuring range, and comprises an image acquiring device and a data processing device. The image acquiring device employs a high-speed camera. The imaging optical path of the high-speed camera is vertical and aligned to an overhead wire to be measured. The high-speed camera performs linear scanning image on the overhead wire multiple times and records the time-dependent image data of the vibration of the overhead wire. The data processing device comprises a computer and a data processing module. The data processing module performs de-noising, enhancement, segmentation process, and computation on the image data. By means of the linear scanning imaging and an image processing method, the overhead wire vibration frequency measuring system may effectively improve the accuracy of measured data, measure the value of low-frequency, medium-frequency, or high-frequency vibration of the overhead wire, and enlarge a measuring range, and is used for providing a basis for measurement of wire vibration frequency and establishment of anti-vibration measures in the field of power transmission wire measurement and maintenance.

Description

Based on the trolley wire vibration frequency measuring system of line sweep imaging

Technical field

The invention belongs to transmission route survey and maintenance technology field, being specifically related to a kind of overhead power transmission conductor vibration frequency measuring system based on line sweep imaging, for measuring the vibration frequency of trolley wire, providing foundation for taking vibration protection further.

Background technology

Along with the fast development of power industry, overhead transmission line is built in a large number.Electric wire in overhead transmission line is in the ground of open field for a long time, be easy to the impact being subject to the natural conditions such as wind, rain, snow, thus there is periodically vibration in trigger wire, vibration frequency range 0.1 ~ 150Hz, wherein 0.1 ~ 3HZ is that low frequency is significantly waved, 3 ~ 5HZ is the secondary span vibration of width in intermediate frequency, the aeolian vibration a little of 5 ~ 150HZ high frequency.The Long-term Vibration of electric wire can cause its tired disconnected stock, gold utensil wear out failure, even can cause line-outage contingency, jeopardize line security stable operation time serious.

The high-frequency aeolian vibration of trolley wire more needs to cause concern.Draw according to a large amount of actual track engineering experiences: aeolian vibration is the most general form of conductor vibration, is also the main cause causing transmission line of electricity to damage.This vibration simultaneously has very high disguise.Aeolian vibration can make electric wire produce tired and wear-out failure, and this destructive process is the process of an accumulation, and is from the internal layer of electric wire.High-frequency aeolian vibration is needed to the vibrationproof instrument of particular design, such as damper, security bar, damping wire, spiral vibration rod etc., these effectively can reduce hazard of vibration.But anti rattler is after long-time running, its parameter becomes, characteristic is aging, anti-vibration property is decayed, be difficult to preparation judges, so need to adjust anti rattler by a portable site survey systems, thus the safety of guarantee transmission of electricity electric wire.

Based on trolley wire vibration monitoring to the importance ensureing transmission line of electricity safe operation, carried out correlative study for the measurement of transmission of electricity conductor vibration both at home and abroad, monitoring method and means mainly concentrate on three aspects: adopt acceleration transducer technology, optical fiber sensing technology and image processing techniques three kinds of methods.

Wherein based on the Vibration-Measuring System of acceleration transducer, mainly measured the accekeration of electric wire by the acceleration transducer be arranged on electric wire, the method can realize significantly waving circuit low frequency analyzing.But the method in actual applications sensor needs to be fixed on iron tower of power transmission line, and cost of layout is high on a large scale, and measurement range is confined to low-frequency electric wire the defect such as to wave, and is not used widely.

Wherein fiber optic sensor technology is the displacement by fiber sensor measuring conductor vibration, thus determines the state of vibration, and the method has the features such as anti-electromagnetic interference capability, higher sensitivity and nonlinearity erron are little.But there is the problem that, sensor large by temperature disturbance is arranged and Signal transmissions difficulty etc. is more complicated in Fibre Optical Sensor, is not suitable as universal measurement means at present when applying.

Wherein adopt the trolley wire Vibration-Measuring System of image processing techniques, usually adopt the collection to on-the-spot conductor vibration image, then treatment and analysis is carried out to the image of conductor vibration.Such as, Chinese patent application, grant number is the patent of invention of CN-102143354 B, discloses a kind of transmission of electricity electric wire based on Computer Vision and waves identification computing method.This invention, by being fixed on the video data of on-the-spot camera collection to conductor vibration, being passed control center back and data is carried out to the process such as image gray processing, segmentation and extraction and identify, obtain the amplitude information vibrated in image.There is following defect in this invention:

First, this invention is based on Surface scan imaging and processes this imaging data and calculate, the image collected comprises all data of electric wire place plane, but the problem that the resolution being limited to video image is low and transmission speed is low, the image gathered can only obtain changing obvious vibration position data, and namely the low frequency position of significantly waving, cannot calculate the aeolian vibration of electric wire high frequency low amplitude, measure conductor vibration frequency range little, apply restricted.Simultaneous camera is because being fixed on iron tower of power transmission line, it can not make accurate measurement to the vibration frequency of each position of electric wire, likely produce so in actual applications and omit and erroneous judgement, thus it is incorrect to cause vibration protection to take, and well can not play vibration-isolating effect.

Summary of the invention

In order to overcome the defect existed in existing measuring method, the present invention proposes a kind of trolley wire Vibration-Measuring System based on line sweep imaging, in order to solve in conventional images process measurement scheme due to video resolution and the low measurement data caused of transmission speed inaccurate, and the vibration of high frequency low amplitude cannot carry out measuring the little technical matters of the measurement range that causes.

For achieving the above object, the technical scheme that the present invention takes is:

A kind of trolley wire vibration frequency measuring system based on line sweep imaging, comprise image collecting device and coupled data processing equipment, described image collecting device adopts high-speed camera, the imaging optical path of this high-speed camera is vertical with trolley wire to be aligned, and to a certain position of trolley wire with trolley wire vertical direction on carry out repeatedly line sweep imaging, record trolley wire and vibrate time dependent view data in this position; Described data processing equipment comprises computing machine and data processing module, and this data processing module carries out denoising, enhancing, segmentation and calculating to this view data.

The above-mentioned trolley wire vibration frequency measuring system based on line sweep imaging, the frequency of operation of described high-speed camera is greater than 150HZ, and long focal length lens of arranging in pairs or groups.

The above-mentioned trolley wire vibration frequency measuring system based on line sweep imaging, described view data denoising adopts gaussian filtering method.

The above-mentioned trolley wire vibration frequency measuring system based on line sweep imaging, described view data strengthens process and adopts stationary point line CLSP method to find datum line, this datum line and view data are made comparisons, for the impact suppressing sky background to rise and fall on trolley wire feature.

The above-mentioned trolley wire vibration frequency measuring system based on line sweep imaging, described prints electrical image data segmentation adopts thresholding method.

The above-mentioned trolley wire vibration frequency measuring system based on line sweep imaging, described view data calculates and comprises electric wire position calculation and conductor vibration frequency computation part.

The above-mentioned trolley wire vibration frequency measuring system based on line sweep imaging, described electric wire position calculation adopts the method for centroid calculation.

The above-mentioned trolley wire vibration frequency measuring system based on line sweep imaging, the method that described conductor vibration frequency computation part adopts Fourier transform to calculate.

The present invention compared with prior art, has the following advantages:

1, the present invention is because employing work is frequently for being greater than 150HZ, the high-speed camera of collocation long focal length lens, and align vertical with tested wire for video camera imaging light path when measuring, can realize low to trolley wire, in or the remote image collection of high vibration frequency and record, compared with the Low Medium Frequency vibration frequency that the common camera adopted with prior art is calculated by conductor vibration amplitude, expand vibration frequency measurement range.

2, image collecting device of the present invention is owing to adopting high-speed camera, utilizes high-speed camera to carry out repeatedly line sweep imaging to a certain position of trolley wire and obtains the method for view data, accurately can obtain the vibration information of this position; And the present invention to high-speed camera to gather and the view data recorded has carried out denoising, enhancing, segmentation, eliminate noise on image data that are extraneous and high-speed camera generation itself and calculate the impact caused, compared with prior art, effectively improve the accuracy of measurement data.

3, the image collecting device that the present invention adopts carries out telemeasurement owing to being placed in ground, can tackle the situation of conductor vibration frequency accidental distribution, have certain portable mobile.

Accompanying drawing explanation

Fig. 1 is the one-piece construction figure of measuring system of the present invention;

Fig. 2 is measuring system workflow diagram of the present invention;

Fig. 3 is image collecting device principle of work of the present invention;

Fig. 4 contrasts before and after view data denoising result in data processing module of the present invention;

Fig. 5 is that in data processing module of the present invention, CLSP method calculates schematic diagram;

Fig. 6 contrasts before and after view data enhancing result in data processing module of the present invention;

Fig. 7 is view data dividing processing result in data processing module of the present invention;

Fig. 8 is electric wire position calculation fructufy mapping in data processing module of the present invention.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail:

With reference to Fig. 1, the data processing equipment that the present invention includes image collecting device He be attached thereto; Wherein image collecting device adopts high-speed camera 1, and data collector comprises computing machine 2 and data processing module.

The frequency of operation of high speed video camera 1 of the present invention is 300HZ, and focal length machine camera lens of arranging in pairs or groups, hot spot 3 information produced when surveying the vibration of trolley wire low, middle and high frequency rate be can realize treating at a distance and image data acquiring and record carried out.Data processing equipment comprises computing machine 2 and data processing module, and this data processing module carries out denoising, enhancing, dividing processing and calculating to the view data that high-speed camera 1 obtains.

With reference to Fig. 2, be the workflow schematic diagram of present system, the job step introducing measuring system according to this flow process is as follows:

The present invention utilizes hot spot 3 motion feature to show the situation that trolley wire vibrates.When system works, high-speed camera 1 is positioned on the ground under trolley wire to be measured, and make that its imaging optical path is vertical with trolley wire to be measured to be aligned, treat location put with trolley wire vertical direction on carry out repeatedly line sweep imaging, record the view data that when vibration of this position occurs, hot spot 3 moves, this view data is called sequence image, and in this sequence image, line number is M, and in every a line, sum of all pixels is N; If its imaging optical path becomes angle of inclination during with trolley wire to be measured, it is fuzzy that the imaging of hot spot 3 can become, and can affect the accuracy of subsequent measurement.

Data processing module receives high-speed camera 1 by data line and gathers and the view data recorded, and carries out processing to it and calculate; Its course of work is as follows:

1, the denoising of view data adopts gaussian filtering method, and object removes when high-speed camera 1 works because of noise that device and circuit produce.

1. needed to generate one dimension gaussian filtering template according to given parameter before carrying out gaussian filtering, process is as follows:

Employing standard gaussian distributes, and formula is:

$G\left(x\right)=\frac{1}{\sqrt{2\mathrm{\π}}{\mathrm{\σ}}_g}\exp (-\frac{{(x-{\mathrm{\μ}}_g)}^2}{2{{\mathrm{\σ}}_g}^2})$

In above formula: x is stochastic variable; μ _gfor average; σ _gfor standard deviation, G (x) is standard gaussian distribution.

For the view data obtained, in order to effectively remove the impact that noise produces, get when generating gaussian filtering template: x scope 0 < x≤30, μ _g=15, σ _g=5.

Normalized is done to G (x), generates normalization coefficient c:

$c=\frac{1}{\underset{x=1}{\overset{30}{\mathrm{\&Sigma;}}}G\left(x\right)}$

Generate gaussian filtering template C (x):

C(x)＝c×G(x)

2., after generation gaussian filtering template, make convolution by this template and every data line of the raw image data obtained, namely obtain gaussian filtering denoising result:

r(n)＝z(n)*C(x)。

In above formula, n is location of pixels in every data line in sequence image, and span is: 0 < n≤N; Z (n) is denoising preceding pixel gray-scale value size; R (n) is the grey scale pixel value after denoising;

2, view data strengthens process and adopts stationary point line CLSP method to find datum line, and the view data after this datum line and filtering process is made comparisons and obtained the result of image enhaucament.Due to the unevenness of sky background, the sky background in imaging results is risen and fallen indefinite, namely its grey scale pixel value of portion is in the picture close to the gray-scale value of electric wire, and such view data can not directly be used for carrying out follow-up process.Therefore also need to carry out enhancing process to view data, the object strengthening process is the feature strengthening trolley wire in view data, suppresses the fluctuating of sky background.

1. the datum line strengthened as view data is found.The present invention adopts the method for stationary point line (CLSP), obtains the grey scale pixel value of the datum line that trolley wire detects, uses r _en () represents.

2. the grey scale pixel value r of datum line is deducted by filter result r (n) _en (), obtains final view data and strengthens result, namely

R(n)＝r(n)-r _e(n)

In formula: R (n) is for image data line is through strengthening the grey scale pixel value of process.

3, the dividing processing of view data adopts threshold method, the method have realize simple, calculated amount is little and the feature of stable performance.

1. the threshold value chosen is Thr=4 σ _th, wherein

σ _thfor the standard deviation of the grey scale pixel value of one-row pixels in sequence image, s _thfor the variance of the grey scale pixel value of one-row pixels in sequence image.

$s_{\mathrm{th}}=\frac{1}{N-1}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{[R\left(n\right)-{\mathrm{\&mu;}}_{\mathrm{th}}]}^2$

μ _thfor the grey scale pixel value average of data line in sequence image, its value is:

${\mathrm{\&mu;}}_{\mathrm{th}}=\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}R\left(n\right)$

2. according to the threshold value chosen, view data is split.Make comparisons with threshold value with gray-scale value R (n) of every data line pixel, be more than or equal to the pixel of threshold value, be labeled as 1; Be less than the pixel of threshold value, be labeled as 0, obtain the labeling function R of every one-row pixels _lab(n).

4, the electric wire position calculation of view data adopts the method for centroid calculation, and centroid calculation formula is as follows:

$p\left(m\right)=\frac{\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}(n\&times;R_{\mathrm{lab}}\left(n\right))}{\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{R}_{\mathrm{lab}}\left(n\right)}$

In above formula: m represents that sequence image m is capable, span 0 < m≤M; P (m) represents the vibration mark position that electric wire m in sequence image is capable.

P (m) is made comparisons with its average, obtains the station-keeping data p of conductor vibration _cf(m):

$p_{\mathrm{cf}}\left(m\right)=p\left(m\right)-\frac{1}{M}\underset{m=1}{\overset{M}{\mathrm{\&Sigma;}}}p\left(m\right)$

5, the vibration frequency of view data calculates and adopts fast fourier transform algorithm FFT.

To p _cfm () carries out Fourier transform:

$F\left(v\right)={\&Integral;}_{-\&infin;}^{+\&infin;}{p}_{\mathrm{cf}}\left(m\right)\exp [-j2\mathrm{\&pi;vm}]\mathrm{dm}$

In above formula, ν is frequency domain variable.

Fourier transform results F (ν) is a plural number.If the real part of F (ν) is Q (ν), imaginary part is I (ν), then F (ν) can be expressed as follows:

F(ν)＝Q(ν)+jI(ν)

Wherein, $\left|F\left(v\right)\right|=\sqrt{Q^2\left(v\right)+I^2\left(v\right)}$

| F (ν) | be p _cfthe fourier modulus spectrum of (m), as | F (ν) | value maximum time, then the frequency ν of its correspondence is the frequency of conductor vibration.

Table 1 is the conductor vibration frequency resultant three different electric wire positions actual measurements.

Position 1	0.97656HZ
		Position 2	0.39062HZ
Position 3	0.78125HZ

Table 1

The present invention can carry out data acquisition to the trolley wire of diverse location and pass through the vibration frequency processing and calculate electric wire as can be seen from the table.

With reference to Fig. 3, it is image collecting device principle of work of the present invention.

When image collecting device works, high-speed camera 1 is positioned on the ground under trolley wire to be measured, and make that its imaging optical path is vertical with trolley wire to be measured to be aligned, to a certain position of trolley wire with trolley wire vertical direction on carry out repeatedly line sweep imaging, and direction of vibration can not be parallel with direction of scanning.

During high-speed camera 1 pair of electric wire imaging, on brightness value, sky is usually high than electric wire brightness, therefore can form the half-light spot 3 of bright background buried wire.When conductor vibration, hot spot 3 moves thereupon.To gather and the motion recording hot spot 3 just can obtain the vibration information of electric wire.

Below in conjunction with accompanying drawing and measurement result, the present invention is remarked additionally.

With reference to Fig. 4, Fig. 4 (a) is the raw image data before denoising, transverse axis is location of pixels n, the longitudinal axis is grey scale pixel value z (n) of raw image data, and as can be seen from the figure the noise of grey scale pixel value fluctuation among a small circle is all contained significantly in original series view data other region except location of pixels n=400.Fig. 4 (b) is the view data through denoising, transverse axis is location of pixels n, the longitudinal axis is grey scale pixel value r (n) after denoising, as can be seen from Fig. 4 (b), the noise in the region containing grey scale pixel value fluctuation among a small circle before denoising is all effectively suppressed.

With reference to Fig. 5, it is schematic diagram calculation schematic diagram in stationary point under CLSP.

Projection for bright target dark background formation is impacted and bottom CLSP can be used as the datum line of input, and the depression impact formed for the bright background of dark target can use top CLSP as the datum line of input.

When for bright target dark background, obtain bottom CLSP.Bottom CLSP can be obtained by the lower stationary point connection of filter result, and lower stationary point satisfies condition, that is:

r′(n)≤0 and r′(n+1)≥0

In above formula, r ' (n) is for filter result is at the derivative at location of pixels n place.

After being met the lower stationary point of above condition, obtained the grey scale pixel value of bottom CLSP baseline by the method for interpolation.Stationary point line CLSP is connected to form by the point in view data after being in filtering process and the point not on filtering image data processing, and the latter is obtained by the point Linear interpolation adjacent thereto be on filtering image data processing.

Bottom CLSP baseline grey value interpolation formula is as follows:

r _e(n)＝r(n-a)+k[r(n+b)-r(n-a)]

Wherein:

$k=\frac{a}{b+a}$

In above formula, k is interpolation coefficient.R _en () is the grey scale pixel value in CLSP stationary point.

Calculating for top CLSP is similar.

With reference to Fig. 6, Fig. 6 (a) for strengthening view data before treatment.The view data obtained due to the present invention is the bright background of dark target, therefore adopts upper stationary point to obtain top CLSP datum line in enhancing process, and in Fig. 6 (a), dotted line is top CLSP datum line, and solid line is the grey scale pixel value after image gaussian filtering.As can be seen from the figure, because sky background is uneven, the grey scale pixel value that location of pixels is in grey scale pixel value between 800 and 1300 and electric wire position (n=400) is close, and grey scale pixel value curve tilts to the right, is unfavorable for carrying out view data dividing processing.Fig. 6 (b) is for view data is through strengthening the result of process.As can be seen from the figure, the situation that location of pixels is in the grey scale pixel value of grey scale pixel value between 800 and 1300 and electric wire position (n=400) close is effectively eliminated, and the situation that grey scale pixel value curve tilts to the right is repaired.Through Fig. 6 (a) and Fig. 6 (b) contrast, the method effectively can eliminate the uneven impact caused trolley wire of sky background.

With reference to Fig. 7, for view data carries out the result of Threshold segmentation process, the place of location of pixels n=400 is marked as 1 as we can see from the figure, and other place is marked as 0.Location of pixels n=400 is the vibration position of electric wire, and this position is effectively marked by Threshold segmentation.

With reference to Fig. 8, it is the view data obtaining wire marker position after centroid calculation process of native system actual measurement.As can be seen from the figure, in sequence image, line number is between 0 to 1400, the station-keeping data p of every a line conductor vibration _cf(m) between-50 and 50, this p _cfm () conductor vibration station-keeping data can be used for the calculating of conductor vibration frequency.

More than describe and embodiment; be only preferred embodiment of the present invention; do not form any limitation of the invention; obviously for those skilled in the art; after having understood content of the present invention and design concept; all when based on principle of the present invention and structure, the various correction in form and in details and change may be carried out, but these corrections based on inventive concept and change are still within the protection domain of claim of the present invention.

Claims (8)

1. the trolley wire vibration frequency measuring system based on line sweep imaging, comprise image collecting device and coupled data processing equipment, it is characterized in that, described image collecting device adopts high-speed camera (1), the imaging optical path of this high-speed camera (1) is vertical with trolley wire to be measured to be aligned, on vertical wire direction, repeatedly line sweep imaging is carried out to a certain position of electric wire, records electric wire and vibrate time dependent view data in this position; Described data processing equipment comprises computing machine (2) and data processing module, and this data processing module carries out denoising, enhancing, dividing processing and calculating to the view data that high-speed camera (1) obtains.

2. the trolley wire vibration frequency measuring system based on line sweep imaging according to claim 1, it is characterized in that, the frequency of operation of described high-speed camera (1) is greater than 150HZ, and long focal length lens of arranging in pairs or groups.

3. the trolley wire vibration frequency measuring system based on line sweep imaging according to claim 1, is characterized in that, described view data denoising adopts gaussian filtering method, for removing the noise that image collecting device produces.

4. the trolley wire vibration frequency measuring system based on line sweep imaging according to claim 1, it is characterized in that, described view data strengthens process and adopts stationary point line CLSP method to find datum line, this datum line and view data are made comparisons, for the impact suppressing sky background to rise and fall on trolley wire feature.

5. the trolley wire vibration frequency measuring system based on line sweep imaging according to claim 1, is characterized in that, described view data dividing processing adopts thresholding method, for extracting electric wire target.

6. the trolley wire vibration frequency measuring system based on line sweep imaging according to claim 1, is characterized in that, described view data calculates and comprises electric wire position calculation and conductor vibration frequency computation part.

7. the trolley wire vibration frequency measuring system based on line sweep imaging according to claim 6, is characterized in that, described electric wire position calculation adopts the method for centroid calculation.

8. the trolley wire vibration frequency measuring system based on line sweep imaging according to claim 6, it is characterized in that, described conductor vibration frequency computation part adopts the method for Fourier transform, calculates, for obtaining conductor vibration frequency data to centroid calculation result.