CN106501690B - A kind of XLPE power cable partial discharge diagnostic method and system - Google Patents
A kind of XLPE power cable partial discharge diagnostic method and system Download PDFInfo
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- 208000028659 discharge Diseases 0.000 title claims abstract description 157
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1209—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing using acoustic measurements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
- G01R31/1263—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
- G01R31/1272—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of cable, line or wire insulation, e.g. using partial discharge measurements
Abstract
The invention belongs to electrical equipment fault detections and diagnostic techniques field, it is particularly a kind of XLPE power cable partial discharge diagnostic method and system, this method comprises: the ultrasonic signal and ultrahigh frequency partial discharge signal of the low frequency that acquisition power cable shelf depreciation generates, the time delay for obtaining ultrasonic signal, obtains shelf depreciation point at a distance from Partial Discharge Detection point；Determine the phase window for having shelf depreciation；By the phase opening relationships of the ultrasonic signal amplitude of phase window and the power-frequency voltage applied；The phase information of ultrasonic shelf depreciation and amplitude information are depicted as phase spectrogram；Statistical nature calculating is carried out, 27 Statistical Operators of characterization Characteristics of Partial Discharge are extracted.The ultrahigh frequency partial discharge signal that invention is generated using shelf depreciation is combined as time reference, and with the ultrasonic local discharge signal of low frequency, obtains the time delay of ultrasonic signal, the final identification for realizing local discharge signal.
Description
Technical field
The invention belongs to electrical equipment fault detections and diagnostic techniques field, are particularly a kind of XLPE power cable
Partial discharge diagnostic method and system.
Background technique
Cross-inked polyethylene power cable (Cross Linked Polyethylene, XLPE) is applied due to its light weight, installation
If being easy and having many advantages, such as that good electrical and heat resistance is widely used in urban distribution network.However, in actual motion
XLPE power cable due to being influenced by mounting process, laying environment, external force destructions, the factors such as service condition, cause insulation scarce
It falls into or even dielectric breakdown accident constantly occurs, wherein with the ratio of intermediate joint of electric cable and terminals attachment insulation fault
It is more.
Currently, the country is an important means for guaranteeing XLPE power cable reliability service using preventive trial.However,
The disadvantages of state of insulation of preventive trial when long, power failure test result not can accurately reflect operation there are the test period；In addition,
Power cable insulation decline is the process gradually developed, early stage occurs in failure, due to the office of power cable insulation system
Discharge signal caused by portion's defect is very faint, and traditional preventive trial project is difficult to detect abnormal shelf depreciation letter
Number, on the other hand, the outstanding problem that power cable scene Partial Discharge Detection faces is interference, if interference letter can not be rejected
Number, then power cable scene Partial Discharge Detection can not carry out substantially, therefore, single conventional test methods have been unable to satisfy
The requirement of urban power distribution network safe operation.
Shelf depreciation (Partial Discharge, PD) is the main forms of power cable insulation failure early stage, it
It is both one of the main reason for causing insulation degradation and the main feature amount of characterization insulation status.Operating experience and research are equal
Show: power cable partial discharge quantity is insulated from that state is closely related, and the variation of partial discharge quantity implies power cable
There is certain insulation defects to a certain extent for insulation system, are one of the effective ways of quantitative analysis insulation degradation degree.
Therefore, the international electric power standards such as IEC, IEEE and CIGRE are consistent with mechanism of association recommends partial discharge test as XLPE electricity
The best approach of power cable insulation status evaluation.
When shelf depreciation occurs for power cable, pulse current, electromagnetic wave, sound, light, heat and chemistry can be supervened and become
Change etc. physical phenomenons, the Partial Discharge Detection and diagnostic method thus developed have pulse current method, superfrequency method, ultrasonic method,
Light detection method and chemical measure etc..Ultrasonic method is that live interference signal is difficult to inhibit, and superfrequency method is using a sensor
Partial discharge source can not be positioned.
Summary of the invention
Technical problem to be solved by the present invention lies in a kind of XLPE power cable partial discharge diagnostic method is provided, realize
The identification of local discharge signal, the rejecting of interference signal, the positioning and diagnosis of insulation defect.
The invention is realized in this way
A kind of XLPE power cable partial discharge diagnostic method, this method comprises:
Step 1, the ultrasonic signal and ultrahigh frequency partial discharge signal for the low frequency that acquisition power cable shelf depreciation generates,
Using ultrahigh frequency partial discharge signal as time reference, the time difference with the ultrasonic signal of low frequency is calculated, obtains ultrasonic signal
Time delay obtain shelf depreciation point and part by the time difference of delay multiplied by the spread speed of ultrasonic local discharge signal
The distance of discharge examination point；
Step 2, ultrasonic signal is subjected to a point phase window, passes through the maximum amplitude absolute value of ultrasonic signal in phase window
Compared with the discharge threshold of setting, determining has the phase window of shelf depreciation；
Step 3, by ultrasonic signal carry out waveform adjustment calculate after, by the ultrasonic signal amplitude of phase window with applied
Power-frequency voltage phase opening relationships；
Step 4, the phase information of ultrasonic shelf depreciation and amplitude information are depicted as electric discharge amplitude phase spectrogram, maximum is put
Electric amplitude phase spectrogram, averaged discharge amplitude phase spectrogram and discharge time phase spectrogram；
Step 5, the spectrogram of four kinds of ultrasonic local discharge signals in step 4 is subjected to statistical nature calculating, extracts characterization
27 Statistical Operators of Characteristics of Partial Discharge.
Further, step 2 includes: the power-frequency voltage signal that power cable application is measured using divider, and one is adopted
The data of power-frequency voltage signal and ultrasonic signal are each separated into N number of phase window in 1 power frequency period of collection, and each phase window is
M ultrasonic signal and M power-frequency voltage signal, each phase window corresponds to a phase of power-frequency voltage, to every 1 phase
M ultrasonic signal in window seeks maximum amplitude, by the absolute value of maximum amplitude compared with the discharge threshold of setting, determines this phase
Whether there is shelf depreciation in the window of position, records the maximum amplitude of the ultrasonic signal, and using the maximum amplitude as the phase window
Ultrasonic signal amplitude.
Further, step 3, which calculates ultrasonic signal progress waveform adjustment, includes, to M work in every 1 phase window
Frequency voltage signal is averaged, by the ultrasonic signal amplitude of phase window and the phase opening relationships of power-frequency voltage that is applied,
The phase that 1~M phase window is corresponded to 0 °~360 ° makes the ultrasonic signal amplitude of i-th of phase window correspond to sinusoidal waveform
The phase of i*360 °/M.
Further, by the phase opening relationships packet of the ultrasonic signal amplitude of phase window and the power-frequency voltage applied
It includes: the voltage signal of rising edge zero crossing in 1 complete power frequency period being taken out, by voltage signal rising edge zero crossing window position
Ultrasonic signal after setting is toward Forward, backward by the ultrasonic signal before voltage signal rising edge zero crossing the window's position
It moves, obtain the ultrasonic signal amplitude of phase window and applies the relationship of alive phase.
Further, feature includes: mean μ, standard deviation sigma, degree of bias Sk, kurtosis KuAnd cross-correlation coefficient cc.
Further, the parameter of use are as follows: sample rate 20MS/s, acquisition time are 1 power frequency period, and sampling length is
The every acquisition of 400000 points, i.e. capture card 1 time, just obtains 400000 data in 1 complete power frequency period time.
A kind of XLPE power cable partial discharge diagnosis system, the system include:
Ultrasonic sensor and superfrequency integrated sensor are respectively used to the low frequency that acquisition power cable shelf depreciation generates
Ultrasonic signal and ultrahigh frequency partial discharge signal；
Signal amplification and conditioning unit, amplify conditioning to ultrasonic signal and ultrahigh frequency partial discharge signal；
Capture card realizes the real-time of local discharge signal by two channel reception ultrasonic signals and ultrahigh-frequency signal
Acquisition；
Data processing module, ultrasonic signal and superfrequency part to the low frequency of acquisition power cable shelf depreciation generation
Discharge signal calculates the time difference with the ultrasonic signal of low frequency using ultrahigh frequency partial discharge signal as time reference, obtains
The time delay of ultrasonic signal obtains shelf depreciation by the time difference of delay multiplied by the spread speed of ultrasonic local discharge signal
Point is at a distance from Partial Discharge Detection point；
Ultrasonic signal is subjected to a point phase window, maximum amplitude absolute value and setting by ultrasonic signal in phase window
Discharge threshold compare, determining has the phase window of shelf depreciation；
After ultrasonic signal is carried out waveform adjustment calculating, by the ultrasonic signal amplitude of phase window and the power frequency applied
The phase opening relationships of voltage；
The phase information of ultrasonic shelf depreciation and amplitude information are depicted as electric discharge amplitude phase spectrum by spectrogram drafting module
Figure, maximum electric discharge amplitude phase spectrogram, averaged discharge amplitude phase spectrogram and discharge time phase spectrogram；
The spectrogram of four kinds of ultrasonic local discharge signals is carried out statistical nature calculating, mentioned by discharge characteristic parametric statistics module
Take 27 Statistical Operators of characterization Characteristics of Partial Discharge；
Display module shows the spectrogram of four kinds of ultrasonic local discharge signals.
Further, signal amplification and conditioning unit include and the sequentially connected preamplifier of ultrasonic sensor, band logical
Filter and buffer circuit, and with the sequentially connected low-noise amplifier of extra-high video sensor, high-pass filter and wave detector；
Wherein, the output of preamplifier is connected with the input of bandpass filter, bandpass filter will with shelf depreciation ultrasonic signal without
Various ambient noises, mechanical vibration noise for closing etc. filter out, and the output of bandpass filter connects the input of buffer circuit, increase output
Electric current.
Further, the input that the output of extra-high video sensor connects low noise amplifier is followed by the input of high-pass filter,
High-pass filter filters out the low-frequency interference signal unrelated with partial-discharge ultrahigh-frequency signal, and the output of high-pass filter connects detection
Super high band local discharge signal is moved to low-frequency range by the input of device, wave detector.
Further, capture card sample rate is 20MS/s, and acquisition time is 1 power frequency period, sampling length 400000
A, i.e. the every acquisition of capture card 1 time just obtains 400000 data in 1 complete power frequency period time.
Compared with prior art, the present invention beneficial effect is: the present invention is locally put with the superfrequency that shelf depreciation generates
Electric signal is time reference, and is combined with the ultrasonic local discharge signal of low frequency, obtains the time delay of ultrasonic signal, finally
Realize the identification of local discharge signal, the rejecting of interference signal, the method for positioning and the diagnosis of insulation defect.Compared to other inspections
Survey method, ultrasonic method and superfrequency method integrated detection system are non-intrusion type, more satisfactory in-situ check and test method, by outside
Electromagnetic noise influence is smaller, and is easily achieved live detection.Therefore, the insulation shape of power cable can be judged in time and accurately
State finds some early stage latency defects early, avoids the generation of power cable breakdown accident.
Detailed description of the invention
Fig. 1 is system module block diagram of the invention；
Fig. 2 is the circuit diagram of preamplifier；
Fig. 3 is the PRPD spectrogram of ultrasonic local discharge signal；
Fig. 4 is ultrasonic local discharge signalSpectrogram, (a) be 0~180 ° of phase, (b) for 180 ° of phase~
360°；
Fig. 5 is ultrasonic local discharge signalSpectrogram, (a) be 0~180 ° of phase, (b) for 180 ° of phase~
360°；
Fig. 6 is ultrasonic local discharge signalSpectrogram, (a) be 0~180 ° of phase, (b) for 180 ° of phase~
360°。
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to embodiments, to the present invention
It is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not used to
Limit the present invention.
Referring to Fig. 1, system of the invention is amplified by ultrasonic sensor and extra-high video sensor (300MHz-3GHz), signal
It is formed with conditioning unit, capture card, software analysis system and display device.Wherein, signal amplification and conditioning unit include ultrasound
The signal of sensor amplifies and conditioning unit, the signal amplification of extra-high video sensor and conditioning unit, wherein ultrasonic sensor
Signal amplification and conditioning unit include preamplifier, bandpass filter and buffer circuit three parts, the letter of extra-high video sensor
Number amplification and conditioning unit include low-noise amplifier, high-pass filter and wave detector three parts；Software analysis system is by data
Four acquisition control module, data processing module, spectrogram drafting module and discharge characteristic parametric statistics module module compositions；In figure
Ultrasonic sensor uses resonant mode high sensitivity ultrasonic sensor；Extra-high video sensor uses capacitor disk-type acyclic antenna；
Preamplifier is made of low noise operational amplifier；Bandpass filter is made of low distortion, high speed dual operational amplifier；Buffering
Amplifier is made of a buffer amplifier；Low noise amplifier is made of the triode of low noise；Wave detector is examined with diode
Wave circuit composition；Magnificent PCI-9810 is ground in capture card selection；Software analysis system is developed jointly using LabVIEW language and C language
It forms.
When on-site test, ultrasonic sensor, extra-high video sensor are affixed on detected XLPE power cable, when electric power electricity
The insulation system existing defects or hidden danger of cable, and partial discharge phenomenon occurs under normal working voltage, at this point, ultrasonic sensor
The ultrasound and ultrahigh-frequency signal generated with the electric discharge of portion of extra-high video sensor office of acceptance.
Ultrasonic sensor exports the input for connecing preamplifier.Ultrasonic sensor output signal is fainter, and maximum amplitude is only
For 5mV or so, site environment noise and interference are larger, will lead to shelf depreciation ultrasonic signal and are submerged in noise；In addition, super
The output impedance of sonic transducer is high impedance, and therefore, preamplifier is mainly by input stage amplifier section D1, bandpass filtering part
D2 and buffer amplifier D3 is constituted, fixed gain 40dB, and structural schematic diagram is as shown in Fig. 2, another aspect, preposition amplification
Integrated amplifier used in device has low noise and high input impedance.The main function of preamplifier is: 1. amplification ultrasound
The ultra-weak electronic signal of sensor output；2. the high output impedance of ultrasonic sensor is transformed to low output impedance.
The output of preamplifier is connected with the input of bandpass filter.Bandpass filter mainly will be with shelf depreciation ultrasound
The unrelated various ambient noises of signal, mechanical vibration noise etc. filter out.
The output of bandpass filter connects the input of buffer circuit.Purpose is to increase output electric current, improves load capacity, subtracts
Influence of few load to signal source, increases anti-interference ability.
The output of extra-high video sensor connects the input of low noise amplifier.Extra-high video sensor output signal is very faint,
Belong to V magnitude, site environment noise and interference are larger, will lead to partial-discharge ultrahigh-frequency signal and are submerged in noise.
The output of low noise amplifier connects the input of high-pass filter.The effect of high-pass filter is mainly that handle is put with part
The unrelated low-frequency interference signal of electric ultrahigh-frequency signal filters out.
The output of high-pass filter connects the input of wave detector.Wave detector is mainly super high band local discharge signal
(300MHz-3GHz) is moved to low-frequency range (DC-10MHz), the sample rate of such data acquisition unit there is no need to too high, for example,
The capture card of 100MS/s sample rate is just able to satisfy requirement.
Shelf depreciation ultrasonic signal and ultrahigh-frequency signal through signal amplification and conditioning unit are respectively connected to 2 of capture card
The real-time acquisition of local discharge signal is realized in channel.
Data collecting card is controlled by the data acquisition module of local discharge signal software analysis system, it is carried out initially
Change setting, acquires signal, and place the data into queue；Data processing module carries out collected local discharge signal as follows
Processing:
(1) software filtering and Wavelet Denoising Method are carried out；
(2) time difference for calculating ultrasonic signal and ultrahigh-frequency signal, substantially fault location is carried out.
Specifically: subtract each other at the time of corresponding with ultrahigh-frequency signal peak value at the time of corresponding to ultrasonic signal peak value, obtains
The time difference of ultrasonic signal and ultrahigh-frequency signal, this time difference put multiplied by the spread speed of ultrasonic signal, exactly part
Electricity point is at a distance from Partial Discharge Detection point.
(3) ultrasound data is subjected to point phase window and waveform adjustment calculates；
Point phase window mainly provides data for the drafting of shelf depreciation spectrogram, and process is: capture card sample rate is 20MS/
S, acquisition time are 1 power frequency period, and sampling length is 400000 points, i.e. the every acquisition of capture card 1 time, complete with regard to obtaining 1
400000 data in the power frequency period time.Capture card acquires 2 road signals: the 1st tunnel is the work of the application measured by divider
Frequency voltage signal, the 2nd tunnel are the ultrasonic wave letters for being obtained by ultrasonic sensor and being passed through preamplifier and coaxial cable and transmit
Number.The data of 2 road signals in this 1 complete power frequency period are each separated into 100 phase windows, then each phase window just has
4000 points, each phase window correspond to a phase of power-frequency voltage.
Maximum amplitude is asked to 4000 ultrasonic signals in every 1 phase window, if the absolute value of maximum amplitude is greater than
Set discharge threshold, then illustrate there is shelf depreciation in this phase window, record at this time the ultrasonic signal most substantially
Value, and using this maximum amplitude as the ultrasonic signal amplitude of the phase window.
4000 voltage signals in every 1 phase window are averaged and recorded.
Waveform adjusts primarily to making the ultrasonic signal amplitude and the phase of the power-frequency voltage applied of 100 phase windows
Position opening relationships, it may be assumed that the phase for making 1~100 phase window correspond to 0 °~360 °, the ultrasonic signal for making i-th of phase window
Amplitude corresponds to the phase of i*360 ° of sinusoidal waveform/100.This is because the voltage in 1 complete power frequency period of capture card acquisition
The starting point of signal might not correspond to the rising edge zero crossing of sinusoidal waveform, so needing to make adjustment.
Because the voltage signal in 1 complete power frequency period necessarily has rising edge zero crossing, it is possible to be sought out
Come.Voltage signal rising edge zero crossing the window's position is recorded.
By the ultrasonic signal after voltage signal rising edge zero crossing the window's position toward Forward, by voltage signal rising edge
Ultrasonic signal before zero crossing the window's position can be obtained by the ultrasonic signal width of 100 phase windows toward moving back in this way
Value and the relationship for applying alive phase.
(4) phase information of ultrasonic shelf depreciation and amplitude information are depicted as electric discharge amplitude phase spectrum by spectrogram drafting module
Scheme (PRPD spectrogram) (Fig. 3), maximum electric discharge amplitude phase spectrogram (Spectrogram) (Fig. 4 (a) and 4 (b)), averaged discharge width
Value phase spectrogram (Spectrogram) (Fig. 5 (a) and 5 (b)) and discharge time phase spectrogram (Spectrogram) (Fig. 6), these
Typical spectrogram is as shown in figures 3 to 6.
(5) spectrogram of above-mentioned four kinds ultrasonic local discharge signals is subjected to statistical nature calculating, extracts characterization shelf depreciation
27 Statistical Operators of characteristic.
Discharge spectrum shape corresponding to different shelf depreciation types is different, the letter provided using various discharge spectrums
Breath, can distinguish various types of electric discharge.But it is this difference it is only qualitative, it is necessary to by naked eyes and it is abundant
Experience can just distinguish.Therefore, some useful statistical parameters are obtained from various discharge spectrums with regard to necessary.Characterization office
The statistical parameter of portion's electric discharge ultrasonic signal be it is for statistical analysis to Processing of Partial Discharge Ultrasonic Signals distribution parameter, with quantitative
Parameter come describe certain distribution shape feature.The statistical parameter for characterizing Processing of Partial Discharge Ultrasonic Signals includes mean μ, standard deviation
σ, degree of bias Sk, kurtosis Ku, cross-correlation coefficient cc etc., shown in the calculation formula of these statistical parameters such as formula (1)-(5).Utilize this
A little statistical parameters can identify electric discharge type.
A) mean μ
xi-- i-th of sample；
f(xi)──xiThe probability of appearance；
The number of N -- half period (positive half cycle or negative half period) interior phase window；
B) standard deviation sigma
C) degree of bias Sk
Sk=0 indicates that spectrogram is full symmetric, Sk< 0 indicates to be biased to right side, Sk> 0 indicates to be biased to left side；
D) kurtosis Ku
Ku=0 expression projecting degree meets normal distribution, Ku< 0 indicates to mitigate than normal distribution peak, Ku> 0 is indicating ratio just
State distribution of peaks is steeper；
E) cross-correlation coefficient cc
In formula:-- i-th of sample of positive and negative half cycle；
Cc=1 indicates that 100% positive and negative half cycle symmetrical shape, cc=0 indicate completely asymmetric.
Mean μ, standard deviation sigma, degree of bias Sk, kurtosis KuIt is both needed to individually calculate by positive and negative half cycle, and cross-correlation coefficient cc is then not
It must.In this way, fromWith27 statistical parameters can be extracted in three kinds of spectrograms in total.For convenience
It indicates, 27 statistical parameters is numbered, as shown in table 1.27 statistical parameters constitute the fingerprint of partial discharge model.
The statistical parameter table of the ultrasonic local discharge signal of table 1
6) the four kinds of discharge spectrums and 27 flash-over characteristic Statistical Operators that display module display is drawn.
When live live detection, power cable insulation state detection is carried out using the present invention, there are failures or hidden to insulation
The power cable of trouble carries out fault location, characterizes flash-over characteristic by way of drawing discharge spectrum and extracting Statistical Operator, is
On-site test personnel judge that abort situation and fault category provide experimental basis, for the generation for reducing power cable accident, guarantee
Equipment safety operation is of great significance.
Detailed description of the invention
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention
Made any modifications, equivalent replacements, and improvements etc., should all be included in the protection scope of the present invention within mind and principle.
Claims (9)
1. a kind of XLPE power cable partial discharge diagnostic method, which is characterized in that this method comprises:
Step 1, the ultrasonic wave local discharge signal and superfrequency shelf depreciation for the low frequency that acquisition power cable shelf depreciation generates
Signal calculates the time difference with the ultrasonic wave local discharge signal of low frequency using ultrahigh frequency partial discharge signal as time reference,
The time delay for obtaining ultrasonic wave local discharge signal, by the time difference of delay multiplied by the propagation speed of ultrasonic wave local discharge signal
Degree, obtains shelf depreciation point at a distance from Partial Discharge Detection point；
Step 2, ultrasonic wave local discharge signal is subjected to a point phase window, most by ultrasonic wave local discharge signal in phase window
For amplitude absolute value compared with the discharge threshold of setting, determining has the phase window of shelf depreciation；
Step 3, after ultrasonic wave local discharge signal being carried out waveform adjustment calculating, by the ultrasonic wave local discharge signal of phase window
The phase opening relationships of amplitude and the power-frequency voltage signal applied；
Step 4, the phase information of ultrasonic wave local discharge signal and amplitude information are depicted as electric discharge amplitude phase spectrogram, maximum
Discharge amplitude phase spectrogram, averaged discharge amplitude phase spectrogram and discharge time phase spectrogram；
Step 5, the spectrogram of four kinds of ultrasonic wave local discharge signals in step 4 is subjected to statistical nature calculating, extracts characterization office
27 Statistical Operators of portion's flash-over characteristic；
Step 2 includes: the power-frequency voltage signal that power cable application is measured using divider, 1 power frequency week that one is acquired
The data of power-frequency voltage signal and ultrasonic wave local discharge signal are each separated into N number of phase window in phase, and each phase window is M super
Sound wave local discharge signal and M power-frequency voltage signal, each phase window corresponds to a phase of power-frequency voltage, to every 1
M ultrasonic wave local discharge signal in phase window seeks maximum amplitude, by the discharge threshold of the absolute value of maximum amplitude and setting
Compare, determine in this phase window whether there is shelf depreciation, records the maximum amplitude of the ultrasonic wave local discharge signal, and this
Ultrasonic wave local discharge signal amplitude of the maximum amplitude as the phase window.
2. XLPE power cable partial discharge diagnostic method described in accordance with the claim 1, which is characterized in that step 3 will be ultrasonic
Wave local discharge signal carries out waveform adjustment to calculate including averaging to M power-frequency voltage signal in every 1 phase window,
By the ultrasonic wave local discharge signal amplitude of phase window and the phase opening relationships of power-frequency voltage that is applied, by 1~N number of phase
Window corresponds to 0 °~360 ° of phase, and the ultrasonic wave local discharge signal amplitude of i-th of phase window is made to correspond to sinusoidal waveform i*
The phase of 360 °/N.
3. XLPE power cable partial discharge diagnostic method according to claim 2, which is characterized in that by the super of phase window
The phase opening relationships of sound wave local discharge signal amplitude and the power-frequency voltage signal applied includes: by 1 complete power frequency week
The voltage signal of rising edge zero crossing takes out in phase, by the ultrasonic wave part after voltage signal rising edge zero crossing the window's position
Discharge signal is toward Forward, by the ultrasonic wave local discharge signal before voltage signal rising edge zero crossing the window's position toward moving back,
Obtain the relationship of the ultrasonic wave local discharge signal amplitude of phase window and the phase of the power-frequency voltage signal applied.
4. XLPE power cable partial discharge diagnostic method described in accordance with the claim 1, which is characterized in that local discharge characteristic
It include: mean μ, standard deviation sigma, degree of bias Sk, kurtosis KuAnd cross-correlation coefficient cc.
5. XLPE power cable partial discharge diagnostic method described in accordance with the claim 1, which is characterized in that the parameter of sampling
Are as follows: sample rate 20MS/s, acquisition time are 1 power frequency period, and sampling length is 400000 points, i.e. the every acquisition 1 of capture card
It is secondary, just obtain 400000 data in 1 complete power frequency period time.
6. a kind of XLPE power cable partial discharge diagnosis system, which is characterized in that the system includes:
Ultrasonic sensor and extra-high video sensor are respectively used to the ultrasonic wave office for the low frequency that acquisition power cable shelf depreciation generates
Portion's discharge signal and ultrahigh frequency partial discharge signal；
Signal amplification and conditioning unit, amplify conditioning to ultrasonic wave local discharge signal and ultrahigh frequency partial discharge signal；
Capture card realizes that part is put by two channel reception ultrasonic wave local discharge signals and ultrahigh frequency partial discharge signal
The real-time acquisition of electric signal；
Data processing module, the ultrasonic wave local discharge signal for the low frequency that the power cable shelf depreciation of acquisition is generated and extra-high
Frequency local discharge signal calculates and believes with the ultrasonic wave shelf depreciation of low frequency using ultrahigh frequency partial discharge signal as time reference
Number time difference, obtain ultrasonic wave local discharge signal time delay, by the time difference of delay multiplied by ultrasonic wave shelf depreciation
The spread speed of signal obtains shelf depreciation point at a distance from Partial Discharge Detection point；
Ultrasonic wave local discharge signal is subjected to a point phase window, passes through the maximum amplitude of ultrasonic wave local discharge signal in phase window
For absolute value compared with the discharge threshold of setting, determining has the phase window of shelf depreciation, specifically includes: measuring electric power using divider
The power-frequency voltage signal that cable applies, by power-frequency voltage signal and ultrasonic wave shelf depreciation in 1 power frequency period of an acquisition
The data of signal are each separated into N number of phase window, and each phase window is M ultrasonic wave local discharge signal and M power-frequency voltage letter
Number, each phase window corresponds to a phase of power-frequency voltage, to M ultrasonic wave local discharge signal in every 1 phase window
Maximum amplitude is sought, whether by the absolute value of maximum amplitude compared with the discharge threshold of setting, determining in this phase window has part to put
Electricity records the maximum amplitude of the ultrasonic wave local discharge signal, and using the maximum amplitude as the ultrasonic wave office of the phase window
Portion's discharge signal amplitude；
By ultrasonic wave local discharge signal carry out waveform adjustment calculate after, by the ultrasonic wave local discharge signal amplitude of phase window with
The phase opening relationships of the power-frequency voltage signal applied；
The phase information of ultrasonic wave local discharge signal and amplitude information are depicted as electric discharge amplitude phase spectrum by spectrogram drafting module
Figure, maximum electric discharge amplitude phase spectrogram, averaged discharge amplitude phase spectrogram and discharge time phase spectrogram；
The spectrogram of four kinds of ultrasonic wave local discharge signals is carried out statistical nature calculating, extracted by discharge characteristic parametric statistics module
Characterize 27 Statistical Operators of Characteristics of Partial Discharge；
Display module shows the spectrogram of four kinds of ultrasonic wave local discharge signals.
7. XLPE power cable partial discharge diagnosis system according to claim 6, which is characterized in that signal amplification and tune
Managing unit includes and the sequentially connected preamplifier of ultrasonic sensor, bandpass filter and buffer circuit, and and superfrequency
The sequentially connected low-noise amplifier of sensor, high-pass filter and wave detector；Wherein, the output of preamplifier and band logical are filtered
The input of wave device is connected, and bandpass filter filters out the various ambient noises unrelated with ultrasonic wave local discharge signal, band logical filter
The output of wave device connects the input of buffer circuit, increases output electric current.
8. XLPE power cable partial discharge diagnosis system according to claim 7, which is characterized in that extra-high video sensor
Output connect the input of low-noise amplifier and be followed by the input of high-pass filter, high-pass filter handle and superfrequency shelf depreciation are believed
Number unrelated low-frequency interference signal filters out, and the output of high-pass filter connects the input of wave detector, and wave detector is super high band part
Discharge signal moves to low-frequency range.
9. XLPE power cable partial discharge diagnosis system according to claim 6, which is characterized in that capture card sample rate
For 20MS/s, acquisition time is 1 power frequency period, and sampling length is 400000 points, i.e. the every acquisition of capture card 1 time, just obtains 1
400000 data in a complete power frequency period time.
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