CN110794271B - Power cable intermediate joint damp positioning diagnosis method based on input impedance spectrum - Google Patents
Power cable intermediate joint damp positioning diagnosis method based on input impedance spectrum Download PDFInfo
- Publication number
- CN110794271B CN110794271B CN201911125092.5A CN201911125092A CN110794271B CN 110794271 B CN110794271 B CN 110794271B CN 201911125092 A CN201911125092 A CN 201911125092A CN 110794271 B CN110794271 B CN 110794271B
- Authority
- CN
- China
- Prior art keywords
- intermediate joint
- cable
- positioning
- power cable
- spectrum
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
-
- 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
- G01R31/08—Locating faults in cables, transmission lines, or networks
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Locating Faults (AREA)
Abstract
The invention discloses a power cable intermediate joint damp positioning diagnosis method based on an input impedance spectrum, which comprises the steps of firstly processing the input impedance spectrum obtained by testing a tested cable through time-frequency domain conversion, discrete Fourier transform and the like to obtain a positioning spectrum function of the tested cable, then combining the positioning spectrum function of the tested cable, the positioning spectrum function of a normal cable and an intermediate joint damp condition judgment model or/and an intermediate joint damp severity diagnosis model constructed by the positioning spectrum function of the tested cable, the positioning spectrum function of the normal cable and the intermediate joint damp condition judgment model or/and the intermediate joint damp severity diagnosis model, carrying out high-sensitivity positioning and damp severity accurate evaluation on the power cable intermediate joint, and providing corresponding measures for intermediate joints under different damp conditions.
Description
Technical Field
The invention belongs to a power cable intermediate joint diagnosis technology, relates to a power cable intermediate joint damp positioning diagnosis technology, and particularly relates to a method for high-sensitivity positioning and damp condition diagnosis of a power cable intermediate joint.
Background
With the wide application of power cables, the usage amount of cable accessories is also rising year by year, and according to statistics, the early failure of the cable accessories accounts for about 63% of the failure of the whole cable line, so that the cable accessories become a weak point in safe operation. The external environment for the operation of the power cable is generally severe, and the intermediate joint is usually positioned in a cable channel with water accumulated all the year round, and the air is moist. If the waterproof measure is not available in the installation process of the intermediate joint or the silicon rubber holding force is reduced after the operation of the intermediate joint all the year round, water is easy to migrate towards the inside of the intermediate joint along the composite interface, so that the composite interface inside the intermediate joint is easy to be damaged by water, and the insulating property of the intermediate joint is reduced. Ultra low frequency (VLF) dielectric loss factor testing is currently one of the most effective methods for assessing the overall insulation condition of a cable. However, in actual field tests, the situation that dielectric loss seriously exceeds the standard often occurs, and operation experience shows that the standard exceeding is possibly caused by the fact that a joint is affected with damp, but the position of a damped middle joint cannot be determined, so that great difficulty is brought to troubleshooting and treatment of defects of a field cable, and the problem is very troublesome.
In addition, the commonly used cable defect locating methods also include a Partial Discharge (PD) locating method and a time domain reflectometry (tdeft) method. The cable defect positioning method comprises PD positioning under oscillation wave or resonance, and the PD method is an effective method for detecting the insulation state of the cable, but the detection sensitivity is easily influenced by a complex field electromagnetic environment. The patent application document with the application number of CN201910612395.3 discloses a cable defect detection method based on oscillatory wave voltage period attenuation characteristics, which comprises the steps of preprocessing a partial discharge signal of a cable acquired by oscillatory wave test equipment, converting the acquired time-distributed partial discharge signal into a period-by-period phase distribution mode, counting the distribution of discharge characteristic quantity of each period, performing characteristic extraction on the discharge characteristic quantity of each period by using a convolutional neural network to obtain abstract characteristic expression of each period so as to obtain an abstract characteristic sequence corresponding to the period, processing the abstract characteristic sequence corresponding to the period by using a cyclic neural network, and performing classification prediction; although the method can accurately identify the type of the cable defect, the method mainly detects installation defects (such as impurities, knife marks and the like) and is difficult to detect defects of insulation reduction such as moisture. The traditional Time Domain Reflectometry (TDR) method cannot accurately position and effectively identify weak defects or intermediate joints because of low high-frequency components contained in input signals. The patent application with the application number of CN201410167827.1 discloses a time domain reflection method cable fault positioning simulation method, which is characterized in that a simulation model is established by utilizing Pspie simulation software according to the operation parameters of a power cable to be tested, and the property of a cable fault is judged by operating a test waveform obtained by the simulation model, but the method cannot accurately position the middle joint of the power cable and evaluate the damp condition of the middle joint of the power cable.
In fact, the positioning diagnosis of the power cable intermediate joint affected with damp is different from the positioning diagnosis of other local weak defects, because the intermediate joint is a distortion point in the obtained intermediate joint positioning spectrogram after the power cable containing the intermediate joint is tested by a broadband impedance spectrometer, and even if the positioning spectrograms of the three phases of the cables a, b and c are compared, the damp condition of the power cable intermediate joint cannot be judged. Moreover, the existing power cable intermediate joint detection and diagnosis technology still stays at the stage of low-sensitivity positioning and mounting defect detection, and the diagnosis technology for high-sensitivity positioning and moisture severity of the intermediate joint is extremely lacked. Therefore, a power cable intermediate joint damp positioning diagnosis technology is urgently needed, and related help is provided for later operation and maintenance of a power grid.
Disclosure of Invention
Aiming at the technical current situation that the effective diagnosis of the power cable intermediate joint moisture situation is lacked at present, the invention aims to provide a power cable intermediate joint moisture positioning diagnosis method based on an input impedance spectrum, which realizes the high-sensitivity positioning and moisture severity evaluation of the power cable intermediate joint and has the advantages of high sensitivity, simple and convenient operation, good intuition, low cost, strong anti-interference capability and the like.
The invention provides a power cable intermediate joint damp positioning diagnosis method based on an input impedance spectrum, which comprises the following steps:
(1) testing cable data
Obtaining input impedance spectrum Z of tested power cable by using broadband impedance spectrometerd(f)；
(2) Determining a location spectrum function F of a power cable under testd(x)
Input impedance spectrum Z of tested power cable by using time-frequency domain conversion function f → td(f) Processing, mapping the processing result to the original distance positioning map after discrete Fourier transform and amplitude normalization processing to obtain a positioning spectrum function F of the tested power cabled(x)；
(3) Establishing a power cable intermediate joint damping condition judgment model
K(x)＝Fh(x)-Fd(x)；
In the formula, Fh(x) For cables containing normal intermediate joints, function of location spectrum, Fd(x) Locating a spectral function for the test cable;
if K (x) is 0, the moisture severity of the intermediate joint does not need to be diagnosed, otherwise, the step (4) is carried out;
(4) determining the position of a cable intermediate joint
For positioning spectrum function Fd(x) Windowing to obtain a positioning spectrogram after windowing, comparing the positioning spectrograms before and after windowing to find out distortion points at the same positions, wherein the position corresponding to the maximum amplitude point at the distortion point is the position of the power cable intermediate joint;
or, to the positioning spectrum function Fd(x) Windowing to obtain a windowed positioning spectrogram, wherein the position corresponding to the maximum amplitude point at the distortion position in the windowed positioning spectrogram is the position of the power cable intermediate joint;
(5) power cable intermediate joint moisture severity diagnosis
Establishing a power cable intermediate joint wetting severity evaluation model:
evaluating the moisture severity of the intermediate joint according to a set standard, analyzing according to the moisture condition, and giving corresponding measures: when the content is 0 percent<moisture<The intermediate joint is detected regularly when 40 percent is normal; when motion appears to rise and 40% is less than or equal to motion<80% of the intermediate joint is slightly affected with damp, inspection is enhanced at the moment, and early warning of damp intermediate joint is sent out; when the moisture is more than or equal to 80 percent under the condition that the intermediate joint is severely damped, the reason that the intermediate joint is damped is mainly checked, relevant countermeasures are provided, and the intermediate joint is replaced.
In the method for positioning and diagnosing the damping of the intermediate joint of the power cable based on the input impedance spectrum, in the step (1), in the stage of acquiring the data of the cable, a broadband impedance spectrometer is required to be applied to inject high-frequency signals from the head end of the cableThe input impedance spectrum Zd (f) of the tested power cable is obtained. Through testing, the input impedance spectrum Z of the tested power cable is obtainedd(f) The characteristic parameters of (a) are as follows: amplitude | Zd(f) L, Real part Real (Z)d(f) And imaginary part Imag (Z)d(f) Where f is the frequency of the signal test. If the length of the test cable is long (the length of the cable is 1km or more), the injected signal is seriously attenuated, and the frequency band of the signal is controlled to be injected by a signal of a narrow frequency band (the upper limit of the frequency band is 10 MHz); if the test cable length is short (cable length below 1 km), signal injection in a wider frequency band (the upper band limit can be determined by conventional means depending on the specific length of the cable) should be used.
The purpose of step (S2) is to use the time-frequency domain conversion function f → t' to input impedance spectrum Z of the tested cabled(f) Processing to obtain an input impedance spectrum assumed as a time domain, performing discrete Fourier transform and amplitude normalization processing on the input impedance spectrum, and mapping the processing result to an original distance positioning map to obtain a positioning spectrum function F of the tested cabled(x) In that respect Because the input impedance spectrum contains a plurality of characteristic parameters which can characterize the cable characteristics, the amplitude value | Z of the input impedance spectrum can be obtainedd(f) L, Real part Real (Z)d(f) And imaginary part Imag (Z)d(f) For intermediate joint positioning and moisture confirmation. Therefore, in step (S2), the input impedance spectrum Z is specifically processedd(f) Amplitude of (c) | Zd(f) L, Real part Real (Z)d(f) Or imaginary part Imag (Z)d(f) Carrying out time-frequency domain conversion and discrete Fourier transform processing, and mapping the processing result to the original distance positioning map to obtain a positioning spectrum function F of the power cable to be measuredd(x) In that respect With input impedance imaginary part Imag (Z)d(f) For example, first, the imaginary part Imag (Z) of the input impedance spectrum of the tested power cable is measured by using the time-frequency domain transfer function f → td(f) Is processed to obtain Imag (Z)d(t')), processing the Discrete Fourier Transform (DFT), performing amplitude normalization on the discrete Fourier transform result, recording the frequency point with the maximum energy, and mapping the normalization result to the original distance positioningAnd (4) obtaining a positioning spectrum function of the power cable to be detected in spectrum, wherein the corresponding spectrogram is a positioning spectrogram. The mapping distance at the position of 0Hz is 0, and the mapping distance at the frequency point corresponding to the maximum energy is the total length of the power cable, so that the tail end of the cable (namely the length l of the power cable) is determined, and a positioning spectrum function F of the power cable to be measured is obtainedd(x) In that respect At high frequency, the wave velocity v of the cable approaches to a constant, and the frequency f' corresponding to the maximum energy value in the positioning spectrogram is 2l/v, namely the cable end l.
In the power cable intermediate joint damping positioning diagnosis method based on the input impedance spectrum, the purpose of the step (3) is to determine whether damping positioning evaluation is needed, in the invention, a positioning spectrum function in a normal state (containing a normal intermediate joint) of the power cable to be detected is compared with a positioning spectrum function in a state to be detected (unknown damping condition of the intermediate joint) of the power cable to be detected, if the positioning spectrum function and the positioning spectrum function are the same, the intermediate joint of the power cable to be detected is in a normal state, and the damping severity evaluation is not needed; if the difference is not the same, the moisture severity of the middle joint of the tested power cable needs to be evaluated.
Cable positioning spectrum function F containing normal intermediate jointh(x) The determination methods of (1) include the following two methods:
(I) obtaining a cable positioning spectrum function F of a normal intermediate joint of the cable according to the steps (1) to (2) respectively for normal cables of different models in a measuring modeh(x) Then, a database is constructed by using the obtained positioning spectrum functions of the cables with different models; when the damp positioning diagnosis is carried out on the intermediate joint of any type of cable line, the cable positioning spectrum function of the normal joint of the corresponding type is directly selected from the database. This can be done, for example, for newly built cabling.
(II) obtaining positioning spectrum functions F of the power cables with different types of cables and normal intermediate joints in a simulation modeh(x) Then, a database is constructed by using the obtained positioning spectrum functions of the cables with different models; when the damp positioning diagnosis is carried out on the intermediate joint of any type of cable line, the normal joint cable of the corresponding type is directly selected from the databaseA bit spectrum function; obtaining a cable positioning spectrum function F containing a normal intermediate joint in a simulation modeh(x) The method comprises the following specific steps:
(i) manufacturing a cable intermediate joint with a set length, and testing to obtain a unit capacitance value of the cable body and the intermediate joint;
(ii) through analysis comparison, C is obtainedNormal intermediate jointAnd CNormal cable bodyThe multiple relationship between them;
(iii) establishing a cable transmission line model containing a normal intermediate joint by using MATLAB (matrix laboratory), and then carrying out a test
LObtaining the input impedance spectrum Z of the head end of the power cable containing the normal intermediate joint under the simulation condition for the reflection coefficient of the tail end of the cable lines(f) Wherein f is the frequency of the signal test; and then the time-frequency domain conversion function f → t', discrete Fourier transform and amplitude normalization processing are utilized to carry out Z-shaped input impedance spectrum processing on the head end of the power cables(f) Processing, finally mapping the processing result to the original distance positioning map, and simulating to obtain a cable positioning spectrum function F containing normal jointsh(x)。
The parameters of the power cable transmission line model with the normal intermediate joint are established as follows:
(a) taking the head end of the power cable as a coordinate origin, the input impedance at an arbitrary position x on the cable (with the length of l) is as follows:
the input impedance at the head end of the cable is:
(b) characteristic impedance Z of cable0And propagation constant γ:
in the formula, R0、L0、C0、G0Respectively the resistance, inductance, capacitance and conductance per unit length of the cable, the angular frequency ω being 2 pi f.
(c) Reflection coefficient of end of cable lineL：
In the formula: zLIs the load impedance at the end of the cable.
In the power cable intermediate joint damp positioning diagnosis method based on the input impedance spectrum, in the step (4), in order to improve the positioning identification capability of the intermediate joint and the intuitiveness of a diagnosis spectrogram, a positioning spectrum function F of the power cable to be detectedd(x) And carrying out windowing treatment. The invention comprehensively considers the side lobe leakage, stop band attenuation and field application effect of the common Window function and selects Blackman Window. And obtaining a high-sensitivity positioning spectrogram of the intermediate joint through windowing treatment. And comparing the positioning spectrograms of the intermediate joint before and after windowing, finding out distortion points at the same positions, wherein the position corresponding to the maximum amplitude point at the distortion position is the position of the intermediate joint of the power cable.
The power cable intermediate joint wetting positioning diagnosis method based on the input impedance spectrum aims to realize accurate diagnosis of the intermediate joint wetting severity degree in the step (5). The invention adopts a self-comparison method in the aspect of diagnosing the moisture severity of the intermediate joint, represents the moisture severity of the power cable by means of motion, and defines
The tested power cable and the normal cable are analyzed and compared, and the moisture severity of the intermediate joint can be judged visually. Practice proves that the method has high judgment precision and intuition, is easy to realize, and is particularly suitable for field diagnosis of the power cable.
According to research, the power cable intermediate joint damping condition judgment model and the intermediate joint damping severity evaluation model are utilized to realize damping positioning diagnosis on the intermediate joint, so that the method has the advantages of better intuition, accurate positioning on the position of the intermediate joint, and the amplitude of the amplitude can be used as a basis for judging the damping degree of the intermediate joint, and has important significance on damping diagnosis of the power cable intermediate joint.
Based on the analysis, the invention further provides another power cable intermediate joint damp positioning diagnosis method based on the input impedance spectrum, which comprises the following steps:
(1) testing cable data
Obtaining input impedance spectrum Z of tested power cable by using broadband impedance spectrometerd(f)；
(2) Determining a location spectrum function F of a power cable under testd(x)
Input impedance spectrum Z of tested power cable by using time-frequency domain conversion function f → td(f) Processing, mapping the processing result to the original distance positioning map after discrete Fourier transform and amplitude normalization processing to obtain a positioning spectrum function F of the tested power cabled(x)；
(3) Establishing a power cable intermediate joint damping condition judgment model
K(x)＝Fh(x)-Fd(x)；
In the formula, Fh(x) For cables containing normal intermediate joints, function of location spectrum, Fd(x) Locating a spectral function for the test cable; if K (x) is 0, the position and the moisture degree of the intermediate joint do not need to be diagnosed, otherwise, the step (4)';
(4) ' determining the position of the cable intermediate joint
Selecting a Blackman window to perform windowing treatment on the power cable intermediate joint wetting condition judgment model to obtain a power cable intermediate joint wetting severity diagnosis model Kblackman(x) (ii) a When K isblackman(x) When the amplitude value is more than 0, the map corresponding to the diagnosis model is expressed as a distortion curve, the position corresponding to the maximum amplitude value point on the distortion curve is the position of the power cable middle joint, Kblackman(x) Increases with increasing moisture exposure.
The above steps (1) to (3) are the same as the above, and will not be explained in detail here.
In the step (4)', in order to improve the positioning and identifying capability of the intermediate joint and the intuitiveness of the diagnostic spectrogram, the intermediate joint moisture condition determination model of the tested power cable is subjected to windowing processing. The invention comprehensively considers the side lobe leakage, stop band attenuation and field application effect of the common Window function and takes Blackman Window (Blackman Window). Comparing the diagnosis spectrogram of the diagnosis model of the moisture severity of the intermediate joint, wherein if the intermediate joint is in a normal state, K is the diagnosis spectrogram of the diagnosis modelblackman(x) 0, which appears as a "one-line" on the diagnostic spectrum; if the intermediate joint is wet, Kblackman(x)>0. The diagnostic spectrogram shows a distortion curve, and the position corresponding to the maximum amplitude point of the distortion curve is the position of the power cable intermediate joint. And found that Kblackman(x) Increases with increasing moisture level, so that the diagnostic spectrum function K can be usedblackman(x) And (5) carrying out preliminary diagnosis on the damp severity of the intermediate joint.
In order to accurately diagnose the moisture degree of the intermediate joint, the power cable intermediate joint moisture positioning diagnosis method further comprises the step (5) of establishing a power cable intermediate joint moisture severity evaluation model
Evaluating the moisture severity of the intermediate joint according to a set standard, analyzing according to the moisture condition, and giving corresponding measures: when the content is 0 percent<moisture<40% of the intermediate joints are normal, and the intermediate joints can be periodically detected; if there is a rising trend of motion and 40% is less than or equal to motion<80% of the intermediate joint is slightly affected with damp, inspection should be enhanced at the moment, and the intermediate joint is affected with damp and early warned; the moisture of the intermediate joint is more than or equal to 80%, and the reason that the intermediate joint is heavily damped should be mainly checked at the moment, and relevant countermeasures are provided to replace the intermediate joint.
Compared with the prior art, the power cable intermediate joint damp positioning diagnosis method based on the input impedance spectrum has the following beneficial effects:
1. firstly, processing an input impedance spectrum obtained by testing a tested power cable through a time-frequency domain conversion function f → t', discrete Fourier transform and the like to obtain a positioning spectrum function of the tested power cable, then combining the positioning spectrum function of the tested power cable, the positioning spectrum function of a normal cable and an intermediate joint damping condition judgment model or/and an intermediate joint damping severity diagnosis model constructed by the positioning spectrum function and the positioning spectrum function of the normal cable, performing high-sensitivity positioning and accurate damping severity evaluation on the intermediate joint of the power cable, and providing corresponding measures for the intermediate joints with different damping conditions;
2. the method utilizes the Blackman window function to process the intermediate joint positioning spectrum function or/and the intermediate joint wetting severity diagnosis model, and can improve the identification capability of the intermediate joint of the power cable, so that the intermediate joint can be positioned with higher sensitivity, the position of the intermediate joint and even the wetting degree can be reflected in a more intuitive mode, and the intermediate joint of the power cable can be positioned and the wetting degree can be diagnosed more accurately;
3. the invention adopts low-voltage measurement and non-destructive test modes, does not damage the self insulation performance of the power cable, is not limited by the voltage grade of the tested power cable, has higher sensitivity, stronger anti-interference capability and good intuition, has small volume and portability of test equipment, and is suitable for field test of the power cable in a damp environment.
4. The invention adopts a self-comparison mode in the aspect of diagnosing the damp severity degree of the intermediate joint, obtains the original characteristic parameters of the power cable containing the normal intermediate joint in two modes of measurement and simulation, and constructs a database to provide guidance for the operation and maintenance of the power cable at the later stage.
Drawings
Fig. 1 is a schematic flow chart of a power cable intermediate joint damp location diagnosis method based on an input impedance spectrum.
FIG. 2 is a positioning chart of the middle joint of the b-phase of the tested power cable in example 1 of the present invention; wherein, the solid line represents the positioning result of the middle joint without windowing, and the dashed line represents the positioning result of the middle joint after windowing.
FIG. 3 is a diagnostic map of the moisture of the three phases of the intermediate joints a, b and c of the tested power cables in embodiment 1 of the invention; the solid line represents the moisture condition diagnosis spectrogram of the phase a (normal intermediate joint) of the tested power cable, the dashed line represents the moisture condition diagnosis spectrogram of the phase b (light moisture intermediate joint) of the tested power cable, and the dashed line represents the moisture condition diagnosis spectrogram of the phase c (heavy moisture intermediate joint) of the tested power cable.
FIG. 4 is a chart of the positioning of the middle joint of the tested power cable in example 2 of the present invention; the solid line represents an actual measurement positioning spectrogram of the middle joint of the tested power cable, and the dashed line represents a simulation positioning spectrogram of the middle joint of the tested power cable.
FIG. 5 is a chart of the diagnosis of moisture applied to the intermediate joint of the tested power cable in example 2 of the present invention; the solid line represents a moisture condition diagnosis spectrogram of a normal middle joint (simulation) of the tested power cable, and the dashed line represents a moisture condition diagnosis spectrogram of the middle joint of the tested power cable.
Detailed Description
The present invention is described in detail below by way of examples, it should be noted that the examples are only for illustrating the present invention, but not for limiting the scope of the present invention, and those skilled in the art can make some non-essential modifications and adaptations of the present invention based on the above-mentioned disclosure.
Example 1
In this example, the diagnosis target of moisture is 13m YJLV 8.7/15-3X 95 XLPE power cable under different moisture conditions (phase a: normal condition, phase b: slight moisture, phase c: severe moisture).
In this embodiment, as shown in fig. 1, the method for diagnosing damp-affected positions of three-phase cable intermediate joints of tested power cables a, b, and c includes the following steps:
(1) testing cable data
High-frequency signals are injected from YJLV 8.7/15-3 × 95 XLPE power cable three-phase cable by using broadband impedance spectrometerNumber (150kHz-200MHz), obtaining input impedance spectrum Z of three-phase cabled(f) Obtaining the input impedance spectrum amplitude | Z of the tested power cabled(f) L, Real part Real (Z)d(f) And imaginary part Imag (Z)d(f) Where f is the frequency of the signal test. Since the input impedance spectrum of the cable contains a plurality of characteristic quantities capable of characterizing the cable, the embodiment only selects the imaginary part Imag (Z) of the input impedanced(f) Is a discussion object.
(2) Determining a location spectrum function F of a power cable under testd(x)
Input impedance spectrum imaginary part Imag (Z) of the tested power cable by using time-frequency domain conversion function f → td(f) Is processed to obtain Imag (Z)d(t')), performing Discrete Fourier Transform (DFT) processing and amplitude normalization processing on the power cable, recording the frequency point with the maximum energy, and mapping the normalization processing result to an original distance positioning spectrum to obtain a positioning spectrum function of the power cable to be measured, wherein the corresponding spectrum is a positioning spectrum.
The discrete Fourier transform processing process comprises the following steps:
Imag(Zd(f′))＝DFT[Imag(Zd(t'))]and f' is the frequency of the input impedance spectrum obtained after the discrete fourier transform processing.
The normalization processing process comprises the following steps:
then the normalized processing result is mapped to the original distance positioning spectrum, and the positioning spectrum function F of the power cable to be measured is obtainedd(x) And the corresponding spectrogram is a positioning spectrogram. The mapping distance at 0Hz is 0, and the mapping distance at the frequency point f' corresponding to the maximum energy is the total length l of the power cable, so as to determine the end of the cable (i.e. the length l of the power cable).
Taking the phase b of the power cable as an example, the positioning result obtained according to the above processing procedure is shown as a solid line in fig. 2, where the position is 0Hz → the position of 0m of the cable, and the position is the energy maximum point f → the end of the cable, i.e. 13 m.
(3) Establishing a power cable intermediate joint damping condition judgment model
K(x)＝Fh(x)-Fd(x)；
In the formula, Fh(x) For cables containing normal intermediate joints, function of location spectrum, Fd(x) Locating a spectral function for the test cable;
if k (x) is 0, diagnosis of the position and moisture level of the intermediate joint is not required, otherwise, the process proceeds to step (4).
In this embodiment, the power cable (phase a) with the normal intermediate joint is selected as the reference cable (normal cable), and the processing is performed according to the steps (1) and (2) under the same conditions, so as to obtain the cable positioning spectrum function F with the normal cableh(x) In that respect And then, judging the b phase and the c phase of the tested power cable by using a power cable intermediate joint moisture situation judging model. If K (x) is 0, the cable is in a good state, and the moisture condition of the intermediate joint does not need to be diagnosed; if K (x) ≠ 0, the moisture severity of the middle joint needs to be evaluated.
For this example, calculated Kb(x)、Kc(x) Are not equal to 0, and the moisture conditions of the b phase and the c phase need to be diagnosed.
(4) Determining the position of a cable intermediate joint
From the previous analysis, there are two ways to determine the location of the cable intermediate joint:
(i) in this embodiment, Blackman window function pair positioning spectrum function F is selectedd(x) Windowing is carried out to obtain a positioning spectrogram after windowing, distortion points at the same positions are found by comparing the positioning spectrograms before and after windowing, and the position corresponding to the maximum amplitude point at the distortion point is the position of the power cable intermediate joint.
In this example, a Blackman window is selected and Fd(x) And multiplying by a Blackman window function to obtain a positioning spectrogram of the intermediate joint after windowing.
For example, F of phase b of power cabled(x) Multiplication with the Blackman window function yields the map of the middle junction location as indicated by the dashed line in FIG. 2. Positioning spectrogram before windowing in FIG. 2 (solid line)) Compared with a positioning spectrogram (a dashed line) after windowing, distortion points exist at the same positions (near 7m), and the position (7m) corresponding to the maximum amplitude point of the distortion point is the position of the power cable middle joint.
(ii) In this embodiment, a Blackman window function is selected to perform windowing on the power cable intermediate joint wetting condition determination models corresponding to the three phases a, b and c of the power cable respectively (that is, K (x) is multiplied by the Blackman window function), so as to obtain a wetting severity diagnosis model Kblackman(x) The corresponding spectrogram is a diagnostic spectrogram, and the processing result is shown in FIG. 3. As can be seen from the figure, for phase a, Kblackman(x) 0, appearing as a "one-line" on the diagnostic spectrogram, which belongs to a normal cable; for phases b and c, it can be seen very intuitively that they appear as "distortion curves", with a cable length of 13m and a maximum amplitude at 7m, so that the intermediate joint is located at 7m of the cable.
Compared with a positioning spectrogram of a cable, the positioning and identifying effect on the intermediate joint in the diagnosis spectrogram is more visual, and the positioning and identifying capability is more prominent.
In addition, comparing the damp positioning results of the two-phase intermediate joint of b and c, the K can be seen visually as the damp degree is increasedblackman(x) The value at the maximum point of the amplitude of (A) also rises, which proves that the increase of the wetting degree of the intermediate joint can cause the K of the intermediate jointblackman(x) An increase in amplitude. Thus can pass through Kblackman(x) The maximum value of the amplitude of the damping force is used for evaluating the damping condition of the middle joint of the power cable.
(5) Power cable intermediate joint moisture severity diagnosis
Establishing a power cable intermediate joint wetting severity evaluation model
And (3) evaluating the moisture severity of the intermediate joint according to a set standard by applying the moisture, analyzing according to the moisture condition, and giving corresponding measures: when the content is 0 percent<moisture<The intermediate joint is detected regularly when 40 percent is normal; when there is a rising trend in motion and40％≤moisture<80% of the intermediate joint is slightly affected with damp, inspection is enhanced at the moment, and early warning of damp intermediate joint is sent out; when the moisture is more than or equal to 80 percent under the condition that the intermediate joint is severely damped, the reason that the intermediate joint is damped is mainly checked, relevant countermeasures are provided, and the intermediate joint is replaced.
In this embodiment, for the b-phase cable, its moisture is 41.8%, is close to the light moisture state, needs to strengthen the tour, and sends the early warning that the intermediate head is damped. For the c-phase cable, the moisture is 83.4%, the c-phase cable is in a severe moisture state, the specific position of the intermediate joint is determined at the moment, the reason that the intermediate joint is affected with moisture is mainly checked, and the intermediate joint is replaced.
Example 2
In this embodiment, the damp diagnosis object is 500m YJLV 228.7/15-3X 25XLPE power cable phase b.
In this embodiment, as shown in fig. 1, the method for diagnosing the damp position of the intermediate joint in the phase b of the measured power cable includes the following steps:
(1) testing cable data
Injecting high-frequency signals (150kHz-15MHz) from YJLV228.7/15-3 × 25XLPE power cable b phase by using a broadband impedance spectrometer to obtain an input impedance spectrum Z of the high-frequency signalsd(f) Obtaining the input impedance spectrum amplitude | Z of the tested power cabled(f) L, Real part Real (Z)d(f) And imaginary part Imag (Z)d(f) Where f is the frequency of the signal test. Since the input impedance spectrum of the cable contains a plurality of characteristic quantities capable of characterizing the cable, the embodiment only selects the imaginary part Imag (Z) of the input impedanced(f) Is a discussion object.
(2) Determining a location spectrum function F of a power cable under testd(x)
Input impedance spectrum imaginary part Imag (Z) of the tested power cable by using time-frequency domain conversion function f → td(f) Is processed to obtain Imag (Z)d(t')), performing Discrete Fourier Transform (DFT) processing and amplitude normalization processing, recording frequency points with maximum energy, and mapping the normalization processing result to the original distance positioning spectrum, i.e. obtaining the distance positioning spectrumAnd obtaining a positioning spectrum function of the tested power cable, wherein the corresponding spectrogram is a positioning spectrogram.
The discrete Fourier transform processing process comprises the following steps:
Imag(Zd(f′))＝DFT[Imag(Zd(t'))]and f' is the frequency of the input impedance spectrum obtained after the discrete fourier transform processing.
The normalization processing process comprises the following steps:
then the normalized processing result is mapped to the original distance positioning spectrum, and the positioning spectrum function F of the power cable to be measured is obtainedd(x) And the corresponding spectrogram is a positioning spectrogram. The mapping distance at 0Hz is 0, and the mapping distance at the frequency point f' corresponding to the maximum energy is the total length l of the power cable, so as to determine the end of the cable (i.e. the length l of the power cable).
(3) Establishing a power cable intermediate joint damping condition judgment model
K(x)＝Fh(x)-Fd(x)；
In the formula, Fh(x) For cables containing normal intermediate joints, function of location spectrum, Fd(x) Locating a spectral function for the test cable;
if k (x) is 0, diagnosis of the position and moisture level of the intermediate joint is not required, otherwise, the process proceeds to step (4).
In this embodiment, because the original characteristic parameters of the power cable to be tested are unknown, the positioning spectrum function F of the power cable with the normal joint is obtained by using a simulation methodh(x) The specific process is as follows:
(i) manufacturing a YJLV 228.7/15-3X 25XLPE power cable intermediate joint with the length of 0.8m, and testing by using a capacitance bridge measuring instrument to obtain the unit capacitance value of the cable body and the intermediate joint (under the normal condition);
(ii) through analysis comparison, C is obtainedNormal intermediate joint＝0.848CNormal cable body；
(iii) And establishing a power cable transmission line model containing a normal intermediate connector by using MATLAB.
The established power cable transmission line model containing the normal intermediate joint is divided into a cable body, the intermediate joint and the cable body (the tail end of the cable is open). For each section, the cable parameters include:
(a) taking the head end of the power cable as a coordinate origin, the input impedance at an arbitrary position x on the cable (with the length of l) is as follows:
the input impedance at the head end of the cable is:
(b) characteristic impedance Z of cable0And propagation constant γ:
in the formula, R0、L0、C0、G0Respectively the resistance, inductance, capacitance and conductance per unit length of the cable, the angular frequency ω being 2 pi f, f being the frequency of the signal test.
(c) Reflection coefficient of end of cable lineL：
In the formula: zLIs the load impedance at the end of the cable.
Therefore, by establishing a power cable transmission line model containing a normal intermediate connector, the input impedance spectrum Z of the head end of the power cable containing the normal intermediate connector under the simulation condition can be obtaineds(f) So as to obtain the input impedance spectrum amplitude value | Z containing normal intermediate connectors(f) L, Real part Real (Z)s(f) And imaginary part Imag (Z)s(f) Where f is the frequency of the signal test. Then, the imaginary part Imag (Z) of the input impedance is selecteds(f) For discussion purposes) using the time-frequency domain transfer function f →t', Discrete Fourier Transform (DFT), amplitude normalization processing, Blackman windowing processing (reference may be made to the corresponding operational procedures given above) versus Imag (Z)s(f) Processed), a cable positioning spectrum function F of 500m YJLV228.7/15-3 × 25XLPE cable containing normal intermediate joint is obtained through simulationh(x) And the corresponding cable positioning spectrogram, the result is shown by a dashed line in figure (4).
And then, judging the b phase of the tested power cable by using a power cable intermediate joint moisture situation judgment model. If K (x) is 0, the cable is in a good state, and the moisture condition of the intermediate joint does not need to be diagnosed; if K (x) ≠ 0, the moisture severity of the middle joint needs to be evaluated.
For this example, calculated Kb(x) Not equal to 0, the moisture condition of the phase b needs to be diagnosed.
(4) Determining the position of a cable intermediate joint
From the previous analysis, there are two ways to determine the location of the cable intermediate joint:
(i) in this embodiment, Blackman window function pair positioning spectrum function F is selectedd(x) And performing windowing treatment to obtain a windowed positioning spectrogram, wherein the position corresponding to the maximum amplitude point at the distortion position in the windowed positioning spectrogram is the position of the power cable intermediate joint.
In this example, a Blackman window is selected and Fd(x) And multiplying by a Blackman window function to obtain a positioning spectrogram of the intermediate joint after windowing.
F of phase b of power cabled(x) Multiplication with the Blackman window function yields the map of the intermediate junction locations as indicated by the "solid line" in FIG. 4. As is apparent from fig. 4, a location (250m) corresponding to the maximum amplitude point of the distortion position is the location of the power cable intermediate joint, where the distortion position exists on the positioning spectrogram.
In addition, comparing the positioning spectrogram (solid line) of the middle joint of the tested power cable under the actual measurement condition in fig. 4 with the positioning spectrogram (dashed line) of the normal middle joint of the tested power cable under the simulation condition, it can be seen that the difference between the simulation amplitude of the normal joint and the actual measurement result is not large. Therefore, under the condition that the original characteristic parameters of the cable are unknown, the simulation value can be used as a reference value in field test, and diagnosis and evaluation of the damp condition of the intermediate joint are realized.
(ii) In this embodiment, a Blackman window function is selected to perform windowing on the power cable intermediate joint wetting condition determination model corresponding to the power cable b (that is, K (x) is multiplied by the Blackman window function), so as to obtain a wetting severity diagnosis model Kblackman(x) The processing results are shown in fig. 5. As can be seen from the figure, K for the simulated cableblackman(x) 0, appearing as a "one-line" on the diagnostic spectrogram, which belongs to a normal cable; for phase b, it can be seen very intuitively that it behaves as a "distortion curve", with a cable length of 500m, except at the ends of the cable, where the amplitude is greatest at 250m, and therefore the intermediate joint is located at 250m of the cable.
Compared with a positioning spectrogram of a cable, the positioning and identifying effect on the intermediate joint in the diagnosis spectrogram is more visual, and the positioning and identifying capability is more prominent.
(5) Power cable intermediate joint moisture severity diagnosis
Establishing a power cable intermediate joint wetting severity evaluation model
And (3) evaluating the moisture severity of the intermediate joint according to a set standard by applying the moisture, analyzing according to the moisture condition, and giving corresponding measures: when the content is 0 percent<moisture<The intermediate joint is detected regularly when 40 percent is normal; when motion appears to rise and 40% is less than or equal to motion<80% of the intermediate joint is slightly affected with damp, inspection is enhanced at the moment, and early warning of damp intermediate joint is sent out; when the moisture is more than or equal to 80 percent under the condition that the intermediate joint is severely damped, the reason that the intermediate joint is damped is mainly checked, relevant countermeasures are provided, and the intermediate joint is replaced.
In this embodiment, the b-phase power cable to be tested has a mobility of 23.1%, and is in a normal state, and only the cable needs to be periodically tested.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (7)
1. A power cable intermediate joint damp positioning diagnosis method based on an input impedance spectrum is characterized by comprising the following steps:
(1) testing cable data
Obtaining input impedance spectrum of tested power cable by using broadband impedance spectrometer
；
(2) Determining a location spectrum function of a power cable under testF d (x)
Using time-frequency domain transfer functions
Input impedance spectrum to tested power cable
Processing, mapping the processing result to the original distance positioning map after discrete Fourier transform and amplitude normalization processing to obtain the positioning spectrum function of the tested power cableF d (x)；
(3) Establishing a power cable intermediate joint damping condition judgment model
In the formula (I), the compound is shown in the specification,F h (x) A spectral function is located for a cable containing a normal intermediate joint,F d (x) Locating a spectral function for the test cable;
if it isK(x) =0, the position and the moisture degree of the intermediate joint do not need to be diagnosed, otherwise, the step (4) is carried out;
cable positioning spectrum function with normal intermediate jointF h (x) The determination methods of (1) include the following two methods:
(I) obtaining the cable positioning spectrum function of the normal intermediate joint of the normal cables according to the steps (1) to (2) respectively for the normal cables with different models in a measuring modeF h (x) Then, a database is constructed by using the obtained positioning spectrum functions of the cables with different models; when the damp positioning diagnosis is carried out on the intermediate joint of any type of cable line, selecting a normal joint cable positioning spectrum function of a corresponding type from a database directly;
(II) obtaining positioning spectrum functions of the power cables with different types of cables and normal intermediate joints in a simulation modeF h (x) Then, a database is constructed by using the obtained positioning spectrum functions of the cables with different models; when the damp positioning diagnosis is carried out on the intermediate joint of any type of cable line, the cable positioning spectrum function of the normal joint of the corresponding type is directly selected from the database; obtaining a cable positioning spectrum function containing a normal intermediate joint in a simulation modeF h (x) The method comprises the following specific steps:
(i) manufacturing a cable intermediate joint with a set length, and testing to obtain a unit capacitance value of the cable body and the intermediate joint;
(ii) through analysis and comparison, obtainC Normal intermediate jointAndC normal cable bodyThe multiple relationship between them;
(iii) establishing a cable transmission line model containing a normal intermediate joint by using MATLAB (matrix laboratory), and then carrying out a test
，
For end reflection of cablesCoefficient, obtaining the input impedance spectrum of the head end of the power cable containing the normal intermediate joint under the simulation condition
WhereinfA frequency for signal testing; reusing time-frequency domain transfer functions
Discrete Fourier transform and amplitude normalization processing on input impedance spectrum of head end of power cable
Processing, mapping the processing result to the original distance positioning map, and simulating to obtain the cable positioning spectrum function containing the normal jointF h (x)；
(4) Determining the position of a cable intermediate joint
For positioning spectrum functionF d (x) Windowing to obtain a positioning spectrogram after windowing, comparing the positioning spectrograms before and after windowing to find out distortion points at the same positions, wherein the position corresponding to the maximum amplitude point at the distortion point is the position of the power cable intermediate joint;
or, to locate spectral functionsF d (x) Windowing to obtain a windowed positioning spectrogram, wherein the position corresponding to the maximum amplitude point at the distortion position in the windowed positioning spectrogram is the position of the power cable intermediate joint;
(5) power cable intermediate joint moisture severity diagnosis
Establishing a power cable intermediate joint wetting severity evaluation model:
and evaluating the wetting severity of the intermediate joint according to a set standard, analyzing according to the wetting condition, and giving corresponding measures: when in use
The intermediate joint is detected regularly under the normal condition; when in use
Has a rising tendency and
if the intermediate joint is slightly affected with damp, the inspection should be strengthened, and the damp early warning of the intermediate joint is sent out; when in use
And in order to solve the severe damp condition of the intermediate joint, the reason of the intermediate joint is mainly checked, relevant countermeasures are provided, and the intermediate joint is replaced.
2. The method for diagnosing the damp position of the intermediate joint of the power cable based on the input impedance spectrum as claimed in claim 1, wherein in the step (1), the broadband impedance spectrometer is used to obtain the input impedance spectrum of the power cable to be tested
Obtaining the input impedance spectrum amplitude of the tested power cable
Real part, real part
Imaginary part
WhereinfA frequency for signal testing;
in the step (2), the amplitude value of the input impedance spectrum is measured
Real part, real part
Or imaginary part
After time-frequency domain conversion, discrete Fourier transform and amplitude normalization processing are carried out, the processing result is mapped to the original distance positioning map, and the positioning spectrum function of the power cable to be measured is obtainedF d (x)。
3. The method for diagnosing the damp location of the intermediate joint of the power cable based on the input impedance spectrum as claimed in claim 1 or 2, wherein in the step (4), the location spectrum function is appliedF d (x) And selecting a Blackman window for windowing.
4. The method as claimed in claim 1, wherein the input impedance spectrum is used to determine the damp-proof location of the intermediate connector of the power cable
Amplitude of
Real part, real part
Or imaginary part
Obtaining the cable positioning spectrum function containing normal joint by simulation for processing the objectF h (x)。
5. A power cable intermediate joint damp positioning diagnosis method based on an input impedance spectrum is characterized by comprising the following steps:
(1) testing cable data
Obtaining input impedance spectrum of tested power cable by using broadband impedance spectrometer
；
(2) Determining a location spectrum function of a power cable under testF d (x)
Using time-frequency domain transfer functions
Input impedance spectrum to tested power cable
Processing, mapping the processing result to the original distance positioning map after discrete Fourier transform and amplitude normalization processing to obtain the positioning spectrum function of the tested power cableF d (x)；
(3) Establishing a power cable intermediate joint damping condition judgment model
In the formula (I), the compound is shown in the specification,F h (x) A spectral function is located for a cable containing a normal intermediate joint,F d (x) Locating a spectral function for the test cable;
if it isK(x) =0, no diagnosis is needed for the position and moisture level of the intermediate joint, otherwise step (4)';
cable positioning spectrum function with normal intermediate jointF h (x) The determination methods of (1) include the following two methods:
(I) obtaining the cable positioning spectrum function of the normal intermediate joint of the normal cables according to the steps (1) to (2) respectively for the normal cables with different models in a measuring modeF h (x) Then useConstructing a database by using the obtained positioning spectrum functions of the cables with different models; when the damp positioning diagnosis is carried out on the intermediate joint of any type of cable line, selecting a normal joint cable positioning spectrum function of a corresponding type from a database directly;
(II) obtaining positioning spectrum functions of the power cables with different types of cables and normal intermediate joints in a simulation modeF h (x) Then, a database is constructed by using the obtained positioning spectrum functions of the cables with different models; when the damp positioning diagnosis is carried out on the intermediate joint of any type of cable line, selecting a normal joint cable positioning spectrum function of a corresponding type from a database directly; obtaining a cable positioning spectrum function containing a normal intermediate joint in a simulation modeF h (x) The method comprises the following specific steps:
(i) manufacturing a cable intermediate joint with a set length, and testing to obtain a unit capacitance value of the cable body and the intermediate joint;
(ii) through analysis and comparison, obtainC Normal intermediate jointAndC normal cable bodyThe multiple relationship between them;
(iii) establishing a cable transmission line model containing a normal intermediate joint by using MATLAB (matrix laboratory), and then carrying out a test
，
Obtaining the input impedance spectrum of the head end of the power cable containing the normal intermediate joint under the simulation condition for the reflection coefficient of the tail end of the cable
WhereinfA frequency for signal testing; reusing time-frequency domain transfer functions
Discrete Fourier transform and amplitude normalization processing on power electricityCable head end input impedance spectroscopy
Processing, mapping the processing result to the original distance positioning map, and simulating to obtain the cable positioning spectrum function containing the normal jointF h (x)；
(4) ' determining the position of the cable intermediate joint
Selecting a Blackman window to perform windowing treatment on the power cable intermediate joint wetting condition judgment model to obtain a power cable intermediate joint wetting severity diagnosis modelK blackman(x) (ii) a When in useK blackman(x) When the amplitude is more than 0, the map corresponding to the diagnosis model is expressed as a distortion curve, the position corresponding to the maximum amplitude point on the distortion curve is the position of the power cable middle joint,K blackman(x) Increases with increasing moisture exposure.
6. The method for positioning and diagnosing the wetting of the intermediate joint of the power cable based on the input impedance spectrum as claimed in claim 5, wherein in the step (1), the broadband impedance spectrometer is used to obtain the input impedance spectrum of the power cable to be tested
Obtaining the input impedance spectrum amplitude of the tested power cable
Real part, real part
Imaginary part
WhereinfA frequency for signal testing;
in the step (2), the amplitude value of the input impedance spectrum is measured
Real part, real part
Or imaginary part
After time-frequency domain conversion, discrete Fourier transform and amplitude normalization processing are carried out, the processing result is mapped to the original distance positioning map, and the positioning spectrum function of the tested power cable is obtainedF d (x)。
7. The method for diagnosing damp location of intermediate joint of power cable based on input impedance spectrum according to claim 5 or 6, further comprising:
(5) power cable intermediate joint moisture severity diagnosis
Establishing a power cable intermediate joint wetting severity evaluation model
And evaluating the wetting severity of the intermediate joint according to a set standard, analyzing according to the wetting condition, and giving corresponding measures: when in use
The intermediate joint is detected regularly under the normal condition; when in use
Has a rising tendency and
if the intermediate joint is slightly affected with damp, the inspection should be strengthened, and the damp early warning of the intermediate joint is sent out; when in use
And in order to solve the severe damp condition of the intermediate joint, the reason of the intermediate joint is mainly checked, relevant countermeasures are provided, and the intermediate joint is replaced.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911125092.5A CN110794271B (en) | 2019-11-18 | 2019-11-18 | Power cable intermediate joint damp positioning diagnosis method based on input impedance spectrum |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911125092.5A CN110794271B (en) | 2019-11-18 | 2019-11-18 | Power cable intermediate joint damp positioning diagnosis method based on input impedance spectrum |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110794271A CN110794271A (en) | 2020-02-14 |
| CN110794271B true CN110794271B (en) | 2020-08-18 |
Family
ID=69444928
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911125092.5A Active CN110794271B (en) | 2019-11-18 | 2019-11-18 | Power cable intermediate joint damp positioning diagnosis method based on input impedance spectrum |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110794271B (en) |
Families Citing this family (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111368440B (en) * | 2020-03-06 | 2023-11-21 | 云南电网有限责任公司电力科学研究院 | Exponential decay sinusoidal signal parameter estimation method and device based on multispectral interpolation |
| CN111929532A (en) * | 2020-08-06 | 2020-11-13 | 国网北京市电力公司 | 10kV distribution cable intermediate joint positioning method |
| CN111679159B (en) * | 2020-08-14 | 2020-11-24 | 四川大学 | Method for judging impedance change type in frequency domain reflection method |
| CN112763843A (en) * | 2020-12-21 | 2021-05-07 | 西安交通大学 | Cable multi-section defect positioning method and device based on Chebyshev window |
| CN113075496A (en) * | 2021-02-25 | 2021-07-06 | 深圳供电局有限公司 | Cable fault positioning method and device, computer equipment and storage medium |
| CN112964965A (en) * | 2021-03-15 | 2021-06-15 | 哈尔滨理工大学 | Cable fault type identification system based on frequency response |
| CN113281614B (en) * | 2021-05-18 | 2023-05-02 | 国网江苏省电力有限公司无锡供电分公司 | Power cable broadband impedance spectrum test method |
| CN113466607B (en) * | 2021-05-20 | 2023-06-06 | 深圳供电局有限公司 | Method for analyzing damping state of three-phase cable intermediate joint |
| CN113484694A (en) * | 2021-06-23 | 2021-10-08 | 四川大学 | FDR wave crest displacement measurement and calculation wave velocity cable insulation performance evaluation method |
| CN113702754A (en) * | 2021-06-23 | 2021-11-26 | 四川大学 | Distribution cable defect positioning algorithm adopting windowed Fourier transform |
| CN113740661B (en) * | 2021-07-19 | 2023-08-01 | 深圳供电局有限公司 | Cable defect positioning method, device, computer equipment and storage medium |
| CN113740663B (en) * | 2021-08-19 | 2022-05-10 | 成都飞机工业（集团）有限责任公司 | Airplane installed cable fault positioning method based on impedance characteristics |
| CN114019319A (en) * | 2021-10-20 | 2022-02-08 | 四川大学 | Distribution cable line-based moisture defect positioning and diagnosis method |
| CN113884814A (en) * | 2021-10-20 | 2022-01-04 | 四川大学 | Four-term three-order Lutaler window function cable body damp defect positioning algorithm |
| CN114019309B (en) * | 2021-11-05 | 2023-03-10 | 国网四川省电力公司成都供电公司 | Cable defect positioning method based on frequency domain reflection technology |
| CN114062866B (en) * | 2021-11-12 | 2023-10-20 | 广东电网有限责任公司广州供电局 | Method and device for evaluating insulation performance of cable |
| CN114062852B (en) * | 2021-11-17 | 2023-08-08 | 广东电网有限责任公司广州供电局 | Cable intermediate connector fault diagnosis method, device, equipment and readable storage medium |
| CN114217166B (en) * | 2021-12-01 | 2024-04-23 | 国网山西省电力公司晋中供电公司 | Transformer substation low-voltage cable local defect positioning method based on FDR frequency domain waveform |
| CN114414947B (en) * | 2022-01-05 | 2023-05-09 | 四川大学 | Head-end impedance matching method and cable impedance mismatch position reflection state evaluation method suitable for FDR test |
| CN115062495B (en) * | 2022-08-05 | 2022-12-16 | 深圳市联嘉祥科技股份有限公司 | Method and device for analyzing insulating property of material, electronic equipment and storage medium |
| CN115754611B (en) * | 2022-12-06 | 2023-06-16 | 哈尔滨理工大学 | Cable fault positioning method based on pseudo-trapezoidal wave excitation and impedance spectrum digital reconstruction |
| CN116643132B (en) * | 2023-07-26 | 2023-10-13 | 四川省机场集团有限公司成都天府国际机场分公司 | Cable insulation on-line monitoring method and device based on high-frequency signals |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105699843A (en) * | 2016-02-04 | 2016-06-22 | 华中科技大学 | Electric cable running state diagnosis method and system |
| CN105842596A (en) * | 2016-05-24 | 2016-08-10 | 四川大学 | High-sensitivity local defect diagnosis method for power cable |
| CN108828015A (en) * | 2018-09-10 | 2018-11-16 | 西南石油大学 | A kind of method and device for the local faint physical damnification positioning of cable |
| CN209055624U (en) * | 2018-09-11 | 2019-07-02 | 国网福建省电力有限公司泉州供电公司 | A kind of portion, cable first and last end office (EO) breakdown location device |
-
2019
- 2019-11-18 CN CN201911125092.5A patent/CN110794271B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105699843A (en) * | 2016-02-04 | 2016-06-22 | 华中科技大学 | Electric cable running state diagnosis method and system |
| CN105842596A (en) * | 2016-05-24 | 2016-08-10 | 四川大学 | High-sensitivity local defect diagnosis method for power cable |
| CN108828015A (en) * | 2018-09-10 | 2018-11-16 | 西南石油大学 | A kind of method and device for the local faint physical damnification positioning of cable |
| CN209055624U (en) * | 2018-09-11 | 2019-07-02 | 国网福建省电力有限公司泉州供电公司 | A kind of portion, cable first and last end office (EO) breakdown location device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110794271A (en) | 2020-02-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110794271B (en) | Power cable intermediate joint damp positioning diagnosis method based on input impedance spectrum | |
| CN104090214B (en) | A kind of Cable fault examination and aging analysis method | |
| CN105842596B (en) | A kind of high sensitivity power cable local defect diagnostic method | |
| Hashmi et al. | Calibration of on-line partial discharge measuring system using Rogowski coil in covered-conductor overhead distribution networks | |
| CN109814005A (en) | A kind of cable insulation defect recognition and localization method and system | |
| CN107831404B (en) | Method and system for positioning XLPE cable partial discharge position based on high-frequency pulse current method | |
| CN108896872A (en) | Handheld cable fault detection system and method based on SSTDR | |
| CN109490730A (en) | Cable discharge detection method, device, storage medium and processor | |
| CN113702754A (en) | Distribution cable defect positioning algorithm adopting windowed Fourier transform | |
| CN114217166B (en) | Transformer substation low-voltage cable local defect positioning method based on FDR frequency domain waveform | |
| CN109613407B (en) | Power cable partial discharge positioning system and detection method | |
| CN113075501B (en) | Cable fault positioning method and system based on impedance spectrum periodic characteristics | |
| CN114217175A (en) | Power cable electric tree defect detection method and device and terminal | |
| CN113281612A (en) | Local defect aging diagnosis and evaluation method for power cable | |
| CN113466607B (en) | Method for analyzing damping state of three-phase cable intermediate joint | |
| Li et al. | Location of cable joints with moisture in medium voltage distribution grid based on frequency domain reflection method | |
| CN117434386A (en) | High-voltage cable sheath defect positioning method based on sheath grounding loop broadband impedance spectrum | |
| CN116540016A (en) | Cable defect diagnosis method based on reflection coefficient discrete sequence | |
| CN114062852B (en) | Cable intermediate connector fault diagnosis method, device, equipment and readable storage medium | |
| CN106610464B (en) | Determine the system and method for deformation of transformer winding tester frequency-selective filtering performance | |
| US20050212524A1 (en) | Electric power line on-line diagnostic method | |
| Fantoni et al. | Wire system aging assessment and condition monitoring using line resonance analysis (LIRA) | |
| Hashmi et al. | Covered-conductor overhead distribution line modeling and experimental verification for determining its line characteristics | |
| Zhang et al. | Research on the Influence Mechanism of Thermal Aging Degree of Cable on Frequency Domain Reflectometry and Defect Location Accuracy | |
| Rao et al. | Cable defect location by using frequency domain reflectometry with synchrosqueezing generalized S-transform |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |