CN111929532A - 10kV distribution cable intermediate joint positioning method - Google Patents
10kV distribution cable intermediate joint positioning method Download PDFInfo
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Abstract
The invention discloses a 10kV distribution cable intermediate joint positioning method, which comprises the steps of firstly carrying out DFT processing on an input impedance spectrum at the head end of a cable to obtain an original positioning spectrogram, then selecting a window function with superior performance to carry out windowing processing and normalization processing on the window function, and reflecting a distortion area in the spectrogram more intuitively according to the positioning spectrogram after the windowing processing so as to more accurately position an intermediate joint. The invention completely adapts to the test requirement of the 10kV distribution cable, has high test speed, high test precision, portable test device and longer standby time, and can realize the test of the 10kV distribution cable intermediate joint with higher sensitivity by adding the second-order Nuttall self-convolution window processing.
Description
Technical Field
The invention belongs to the power cable state detection technology, relates to distribution cable intermediate joint positioning, and particularly relates to a 10kV distribution cable intermediate joint positioning method.
Background
With the advance of urbanization, the usage of distribution cables and their accessories has increased year by year. Generally, a 10kV distribution cable runs in a channel with a complex environment and is extremely vulnerable to water invasion and external force damage. The intermediate joint plays a role in connecting two sections of cables and serves as a weak link for cable operation, and the insulation performance of the joint directly influences the reliability of power supply. However, the distribution network cable lines are often complicated and complicated, loss of cable laying drawings or uncertainty of laying lines can cause consumption of a large amount of time when joint positions are searched on site, the working efficiency of operation and maintenance of distribution cables is reduced, and great difficulty is brought to operation and maintenance work of cable operation units.
And common power cable defect positioning methods, such as a Partial Discharge (PD) positioning method and a Time Domain Reflectometry (TDR) method. Although the PD method can detect local defects (including intermediate joints) of the cable, the sensitivity of the PD method is easily affected by external noise, resulting in erroneous judgment of the test result. The Time Domain Reflection (TDR) method cannot effectively locate the intermediate joint because of attenuation, dispersion and aliasing of signals in the propagation process due to the fact that incident waves contain too few high-frequency components.
In recent years, the rising Frequency Domain Reflectometry (FDR) method adopts frequency-sweeping signals, so that the incident signals contain more high-frequency components and have higher signal-to-noise ratio, so that the method has more advantages in cable positioning. However, when the test signal is analyzed and processed, the fourier transform algorithm may perform non-integer period truncation on the data, which results in spectrum leakage and a barrier effect, so that the accuracy of the spectrum analysis is greatly reduced. The patent application No. CN201710088838.4 discloses a local fault point detection method for a marine low-voltage power cable based on an FDR method, the method realizes the positioning of cable short circuit/disconnection faults by using standing wave reflection, and the positioning accuracy of the method is determined by the wave velocity ratio of the cable; however, in actual field test, it is difficult to accurately obtain the wave velocity of the cable, and the accuracy of the wave velocity ratio directly affects the positioning accuracy. The patent application No. CN201910273071.1 discloses a method for positioning local defects of a cable line, which uses impedance spectra of a detected cable and a standard cable to realize positioning of the local defects of the cable through integral transformation, and although the method can identify and position the local defects, the positioning curve will oscillate due to the deficiency of the algorithm, and the selection of the integral factor will also affect the positioning accuracy to a certain extent. Patent application documents CN201610351358.8 and CN201910647888.0 disclose power cable local defect positioning methods based on frequency domain reflection methods, which respectively apply Kaiser window and Rectangular window to suppress spectrum leakage, but the Kaiser window needs to select side lobe attenuation coefficient by itself, which is not suitable for simplifying programming and field engineering application, while the Rectangular window has poor window function performance, and is not ideal for improving local defect positioning identification sensitivity.
Meanwhile, the adoption of a Discrete Fourier Transform (DFT) algorithm in the spectrum analysis process causes spectrum leakage and a barrier effect, which greatly reduces the accuracy of the spectrum analysis. Although spectral leakage and a barrier effect can be suppressed to a certain extent by Windowed Fourier Transform (WFT), and spectral analysis accuracy is improved, a classical window function (such as a Hamming window, a Blackman window, a Kaiser window, and the like) hardly satisfies performance conditions of narrow main lobe, small side lobe and fast attenuation, and thus the performance of the classical window function is not superior.
In conclusion, the detection sensitivity of the detection technology for the intermediate joint of the 10kV distribution cable is still low, and the field test requirement cannot be met. The research and development of a nondestructive testing method capable of being used rapidly, accurately and highly sensitively is a problem which needs to be solved urgently for the field detection research of the power distribution cable at present.
Disclosure of Invention
Aiming at the technical current situation that a method for positioning the intermediate joint of the 10kV distribution cable at high sensitivity is lacked at present, the invention aims to provide a method for positioning the intermediate joint of the 10kV distribution cable, wherein a second-order Nuttall self-convolution window with the characteristics of minimum side lobe attenuation and fastest side lobe attenuation is used for carrying out WFT (weighted round trip test) transformation on an input impedance spectrum at the head end of the cable, so that the spectrum leakage and the fence effect are effectively inhibited, the identification sensitivity of the intermediate joint is improved, and the high-sensitivity positioning of the intermediate joint of the 10kV distribution cable is realized.
The invention provides a 10kV distribution cable intermediate joint positioning method, which comprises the following steps:
(1) testing cable data
And carrying out spectrum test on the tested cable to obtain a head end input impedance spectrum Z (f) of the tested cable.
(2) Obtaining original positioning spectrogram of tested cable
And performing DFT conversion on the input impedance frequency spectrum Z (f) obtained by testing, and mapping the processing result to an original distance positioning spectrogram to obtain an original positioning spectrogram L (x), wherein x is the position from the head end of the cable and has the unit of m.
(3) Windowing the original positioning spectrogram
Carrying out windowing Fourier transform processing on the original positioning spectrogram obtained in the step (2) by using a second-order Nuttall self-convolution window to obtain a windowed positioning spectrogram Lw(x)；
The second order Nuttall self-convolution window wNUTTALL-II(n') the time domain expression is:
wNUTTALL-II(n')＝wNUTTALL4-III(n)*wNUTTALL4-III(n)
the window length of the second-order Nuttall self-convolution window is N ', N' is 0, 1, …, N-1, and N is the number of test points.
wNUTTALL4-III(n) is a four-term third-order Nuttall window, the time domain expression of which is:
wherein, W is the window length of the window function, and W is N/2; bmIs a cosine combined term coefficient, b0＝0.338946、b1＝0.481973、b2＝0.161054、b30.018027; n represents the number of discrete points when
When not an integer, this can be achieved by a rounding function.
(4) Normalization process
The original positioning spectrogram L (x) obtained in the step (2) and the positioning after windowing obtained in the step (3)Spectrogram Lw(x) Carrying out normalization processing;
(5) intermediate joint positioning
And comparing the original positioning spectrogram after the normalization processing with the positioning spectrogram after the windowing processing, wherein the position corresponding to the maximum amplitude point of the serious distortion area in the positioning spectrogram after the windowing processing is the position of the intermediate joint of the 10kV distribution cable.
In the 10kV distribution cable intermediate joint positioning method, in the step (1), one end of the cable is selected as a test end (head end), and the tail end of the cable is opened; respectively clamping the test fixture to the cable core and the copper shielding layer (grounding), setting test conditions (including a test frequency range f and a point number N), and then obtaining the input impedance spectrum Z (f) of the head end of the tested cable by using a broadband impedance spectrometer. When obtaining the input impedance spectrum Z (f) at the cable head end, a broadband impedance spectrometer needs to be used to inject a sweep frequency signal from the cable test end (i.e., the cable head end), and to collect a reflected signal at the cable head end. And (4) setting the range of the test frequency f, wherein the upper limit and the lower limit of the sweep frequency range are required to be set according to the length of the cable to be tested.
In the 10kV distribution cable intermediate joint positioning method, in the step (2), the DFT algorithm (discrete Fourier transform) is used for processing the input impedance spectrum Z (f) at the head end of the tested cable, the processed data is mapped into the original distance positioning spectrogram through a mapping method, and the original positioning spectrogram L (x) is obtained by corresponding to the cable. In the DFT algorithm analysis, one of four characteristic quantities (amplitude | Z (f) |, phase Angle (Z (f)), Real component Real (Z (f)), and imaginary component Imag (Z (f))) is included in Z (f) to perform DFT analysis.
According to the positioning method for the intermediate joint of the 10kV distribution cable, the second-order Nuttall self-convolution window is a fixed window function with excellent performance, the side lobe attenuation rate is high, the side lobe peak level is low (compared with a classical window function), and the defects that a Kaiser window needs to select a side lobe attenuation coefficient, a Rectangular window inhibits frequency spectrum leakage and the barrier effect is poor are overcome. Therefore, the second-order Nuttall self-convolution window with superior selectivity in the step (3) carries out WFT algorithm processing on the original positioning spectrogram L (x), can effectively inhibit spectrum leakage and barrier effect caused by non-positive period truncation of data during DFT algorithm analysis, improves accuracy of spectrum analysis on the original positioning spectrogram L (x), and further improves identification sensitivity on a cable intermediate joint.
The invention selects a second-order Nuttall self-convolution window w with excellent performanceNUTTALL-II(n'), the second order Nuttall self-convolution window, whose time domain expression is:
wNUTTALL-II(n')＝wNUTTALL4-III(n)*wNUTTALL4-III(n)
the window length of the second-order Nuttall self-convolution window is N ', N' is 0, 1, …, N-1, and N is the number of test points.
wNUTTALL4-III(n) is a four-term third-order Nuttall window, the time domain expression of which is:
wherein, W is the window length of the window function, and W is N/2; bmThe coefficients of the cosine combination terms are respectively set as follows: b0＝0.338946、b1＝0.481973、b2＝0.161054、b3＝0.018027。
The 10kV distribution cable intermediate joint positioning method comprises the step (4) of positioning the original positioning spectrogram L (x) and the windowing processing positioning spectrogram L of the cablew(x) And amplitude normalization processing is carried out, so that the original data is scaled in an equal proportion, the distribution condition of the data is seen more clearly, and the positioning result is more intuitive. The data normalization method adopted by the invention is ' linear function normalization ' (Min-Max scaling) '. The spectrograms L (x), Lw(x) Converting the ordinate data in (1) to [0, 1%]In the range of (2), the original data is scaled in equal proportion, so that the L after amplitude normalization processing is obtainednorm(x)、Lwnorm(x)。
The 10kV distribution cable intermediate joint positioning method comprises the step (5) of obtaining an original positioning spectrogram L subjected to amplitude normalization processingnorm(x) Positioning spectrogram L processed by windowingwnorm(x) Then, the two data are put in the same coordinate systemComparative analysis was performed. In the location spectrum, with Lnorm(x) Comparison and windowing processing positioning spectrogram Lwnorm(x) And the abscissa position corresponding to the maximum amplitude point of the medium distortion serious region is the position of the middle joint of the 10kV distribution cable. L distributed in the same coordinate system through comparative analysisnorm(x)、Lwnorm(x) Can visually see the application wNUTTALL4-III(n) after WFT conversion, the distortion area is more obvious, thereby greatly improving the identification sensitivity of the position of the intermediate joint, effectively inhibiting the frequency spectrum leakage and the fence effect in a spectrogram, and realizing the effective positioning of the cable intermediate joint.
The invention improves the cable positioning method based on the frequency domain reflection method at the present stage, and adopts a window function second-order Nuttall self-convolution window w with excellent performanceNUTTALL-II(n'), the problems of frequency spectrum leakage and barrier effect existing when the DFT algorithm is adopted to analyze the input impedance spectrum of the cable at the present stage are solved, and the identification sensitivity of the cable intermediate joint positioning is improved, so that the later operation and maintenance of the 10kV distribution cable are facilitated.
Compared with the prior art, the method for positioning the intermediate joint of the 10kV distribution cable has the advantages of multi-joint identification, high sensitivity, short test time, nondestructive test, visual test result, strong anti-interference capability, low cost and the like, and specifically comprises the following steps:
1. according to the method, firstly, DFT processing is carried out on the input impedance spectrum at the head end of the cable to obtain an original positioning spectrogram, then windowing processing and normalization processing are carried out on the original positioning spectrogram by selecting a window function with excellent performance, and a distortion area in the spectrogram can be reflected more visually according to the positioning spectrogram after windowing processing, so that the intermediate connector is positioned more accurately.
2. According to the invention, the second-order Nuttall self-convolution window with more excellent window function performance is used for processing the original positioning spectrogram of the cable, and the second-order Nuttall self-convolution window is low in side lobe and rapid in attenuation, so that the positioning and identifying sensitivity of the intermediate connector can be effectively inhibited from spectral leakage and barrier effect.
3. According to the invention, the original positioning spectrogram and the positioning spectrogram after windowing are subjected to normalization processing, so that the intuitiveness of the positioning result of the intermediate joint can be improved.
4. The test device disclosed by the invention completely meets the test requirements of the 10kV distribution cable, is high in test speed and test precision, portable in test device and long in standby time, and can test the intermediate joint of the 10kV distribution cable with higher sensitivity by adding the second-order Nuttall self-rolling window for processing; in addition, the method is a nondestructive testing method, is also suitable for identifying a plurality of cable joints, and meets the field testing requirement.
5. According to the invention, the input impedance spectrum of the cable is obtained through testing, the test data can be managed in a database mode, the cable is tested at regular intervals, the test data is analyzed and compared with the previous data, and corresponding diagnosis measures are made, so that richer technical means are provided for later operation and maintenance of the 10kV distribution cable.
Drawings
Fig. 1 is a schematic flow chart of a 10kV distribution cable intermediate joint positioning improvement method provided by the invention.
FIG. 2 is a positioning spectrogram (after amplitude normalization) of the middle joint of the cable to be measured in the embodiment of the present invention; wherein, the solid line is the original positioning spectrogram Lnorm(x) The dashed line is a positioning spectrogram L after windowing treatmentwnorm(x)。
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.
Examples
In this embodiment, the test object is a 10kVXLPE power cable (cable type: YJLV 8.7/15-1 x 95), the cable length is 20m, and an intermediate joint is arranged at 10 m.
The method for positioning the intermediate joint of the measured 10kV cable of the embodiment, as shown in fig. 1, includes the following steps:
(1) testing cable data
One end of the tested cable is selected as a testing end (head end), and the tail end of the cable is in an open circuit state. The test fixture was clamped to the cable core and copper shield (ground) respectively. The testing frequency range is set to be 150 kHz-120 MHz, and the number of testing points is 20000. After the test platform is built, a broadband impedance spectrometer is used for injecting high-frequency signals from the head end of the cable, reflected signals are collected at the head end of the cable, and the input impedance spectrum Z (f) of the head end of the tested cable is obtained. This embodiment selects the Real part Real (Z (f)) of the input impedance as the subject.
(2) Obtaining original positioning spectrogram of tested cable
And performing DFT conversion on the input impedance frequency spectrum Z (f) obtained by testing, and mapping the processing result to an original distance positioning spectrogram to obtain an original positioning spectrogram L (x), wherein x is the position from the head end of the cable and has the unit of m.
In this embodiment, DFT processing is performed on the obtained Real (Z (f)), a time point with the maximum energy is recorded, and then a DFT processing result is mapped onto an original distance positioning spectrum, so that an original positioning spectrum L (x) of the measured cable is obtained. The mapping distance at 0s is 0, and the mapping distance at the time point t corresponding to the maximum energy is the total length l of the cable, so as to determine the end of the cable (i.e. the length l of the cable).
(3) Windowing the original positioning spectrogram
In this embodiment, a second-order Nuttall self-convolution window w with superior performance is selectedNUTTALL-II(n')。
The original positioning spectrogram L (x) and the selected second-order Nuttall self-convolution window w are combinedNUTTALL-II(n') to obtain a positioning spectrogram L after windowing treatmentw(x)。
(4) Normalization process
The original positioning spectrogram L (x) obtained in the step (2) and the positioning spectrogram L after windowing treatment obtained in the step (3)w(x) And (6) carrying out normalization processing.
The spectrograms L (x), Lw(x) Converting the ordinate data in (1) to [0, 1%]In the range of (2), the original data is scaled in equal proportion to obtain the L after the amplitude normalization processingnorm(x)、Lwnorm(x) In that respect And the processed data is stored in a database, so that the analysis and comparison of the later test data are facilitated.
The original positioning spectrogram L (x) is subjected to normalization processing according to the following formula:
in the formula, Lnorm(x) Is normalized data of the original positioning spectrogram, L (x) is a vertical coordinate data set in the original positioning spectrogram, and Lmax(x)、Lmin(x) Respectively the maximum value and the minimum value in the ordinate data set in the original positioning spectrogram.
Positioning spectrogram L after windowing treatmentw(x) Normalization is performed according to the following formula:
in the formula, Lwnorm(x) Positioning the normalized data of the spectrogram for windowing, Lw(x) Locating a set of ordinate data, L, in a spectrogram for windowingwmax(x)、Lwmin(x) And respectively locating the maximum value and the minimum value in the ordinate data set in the spectrogram by windowing processing.
(5) Intermediate joint positioning
Obtaining an original positioning spectrogram L after amplitude normalization processingnorm(x) Positioning spectrogram L processed by windowingwnorm(x) And then, the data of the two are put in the same coordinate system for comparative analysis. And Lnorm(x) Comparison and windowing processing positioning spectrogram Lwnorm(x) The position of the abscissa corresponding to the maximum amplitude point of the medium distortion serious region is the position of the middle joint of the 10kV distribution cable.
Original positioning spectrogram L (x) and positioning spectrogram L after windowing treatmentw(x) The normalized results are shown in FIG. 2. As can be seen from fig. 2, the original positioning spectrum (implementation) is poor due to the DFT algorithm, the spectrum leakage and the fence effect are severe,the accuracy of the spectrum analysis is affected, and the position of the middle joint cannot be intuitively located through the positioning spectrogram. And by using a second-order Nuttall self-convolution window wNUTTALL-II(n') after windowing, the obtained windowing positioning spectrogram (dashed line) effectively inhibits frequency spectrum leakage and barrier effect, so that the identification sensitivity of the intermediate joint is greatly improved, the position of the intermediate joint is easily found through the position corresponding to the maximum point of the distortion position, and the high-sensitivity positioning of the intermediate joint of the 10kV distribution cable is realized.
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 (4)
1. A10 kV distribution cable intermediate joint positioning method is characterized by comprising the following steps:
(1) testing cable data
Carrying out spectrum test on the tested cable to obtain a head end input impedance spectrum Z (f) of the tested cable;
(2) obtaining original positioning spectrogram of tested cable
Performing DFT conversion on an input impedance frequency spectrum Z (f) obtained by testing, and mapping a processing result to an original distance positioning spectrogram to obtain an original positioning spectrogram L (x), wherein x is the position from the head end of the cable and has the unit of m;
(3) windowing the original positioning spectrogram
Windowing the original positioning spectrogram obtained in the step (2) by using a second-order Nuttall self-convolution window to obtain a windowed positioning spectrogram Lw(x)；
(4) Normalization process
The original positioning spectrogram L (x) obtained in the step (2) and the positioning spectrogram L after windowing treatment obtained in the step (3)w(x) Carrying out normalization processing;
(5) intermediate joint positioning
And comparing the original positioning spectrogram after the normalization processing with the positioning spectrogram after the windowing processing, wherein the position corresponding to the maximum amplitude point of the serious distortion area in the positioning spectrogram after the windowing processing is the position of the intermediate joint of the 10kV distribution cable.
2. The method for positioning the intermediate joint of the 10kV distribution cable according to claim 1, wherein in the step (3), the second-order Nuttall self-rolling window time domain expression is as follows:
wNUTTALL-II(n')＝wNUTTALL4-III(n)*wNUTTALL4-III(n)
the window length of the second-order Nuttall self-convolution window is N ', N' is 0, 1, …, N-1, and N is the number of test points;
wNUTTALL4-III(n) is a four-term third-order Nuttall window, the time domain expression of which is:
wherein, W is the window length of the window function, and W is N/2; bmIs a cosine combined term coefficient, b0＝0.338946、b1＝0.481973、b2＝0.161054、b3＝0.018027。
3. The method for positioning the intermediate joint of 10kV distribution cable according to claim 1 or 2, characterized in that in the step (4), the spectrograms L (x), L are normalized by using a linear functionw(x) Converting the ordinate data in (1) to [0, 1%]In the range of (1), obtaining the amplitude normalized Lnorm(x)、Lwnorm(x)。
4. The method of claim 3, wherein the 10kV distribution cable intermediate joint is positioned
The original positioning spectrogram L (x) is subjected to normalization processing according to the following formula:
in the formula, Lnorm(x) Is normalized data of the original positioning spectrogram, L (x) is a vertical coordinate data set in the original positioning spectrogram, and Lmax(x)、Lmin(x) Respectively a maximum value and a minimum value in a longitudinal coordinate data set in an original positioning spectrogram;
positioning spectrogram L after windowing treatmentw(x) Normalization is performed according to the following formula:
in the formula, Lwnorm(x) Positioning the normalized data of the spectrogram for windowing, Lw(x) Locating a set of ordinate data, L, in a spectrogram for windowingwmax(x)、Lwmin(x) And respectively locating the maximum value and the minimum value in the ordinate data set in the spectrogram by windowing processing.
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| CN112881862A (en) * | 2021-01-18 | 2021-06-01 | 国网浙江省电力有限公司电力科学研究院 | Three-core cable fault positioning method and device based on relative impedance spectrum |
| CN113466607A (en) * | 2021-05-20 | 2021-10-01 | 深圳供电局有限公司 | Three-phase cable intermediate joint moisture state analysis method |
| CN113702754A (en) * | 2021-06-23 | 2021-11-26 | 四川大学 | Distribution cable defect positioning algorithm adopting windowed Fourier transform |
| 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 |
| CN114019319A (en) * | 2021-10-20 | 2022-02-08 | 四川大学 | Distribution cable line-based moisture defect positioning and diagnosis method |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102435845A (en) * | 2011-10-19 | 2012-05-02 | 广西电网公司电力科学研究院 | Harmonic energy metering method of Nuttall self-convolution weighted Fourier transform |
| CN109782063A (en) * | 2018-10-23 | 2019-05-21 | 国网安徽省电力有限公司芜湖供电公司 | A kind of dynamic m-Acetyl chlorophosphonazo analysis method based on three spectral line interpolation FFT of Nuttall self-convolution window |
| CN109828163A (en) * | 2019-03-20 | 2019-05-31 | 中南大学 | A kind of three-phase imbalance detection method for power grid |
| CN110096676A (en) * | 2019-04-30 | 2019-08-06 | 哈尔滨工业大学 | A kind of metering-type optical current voltage combination transformer frequency analysis device and method |
| CN110794271A (en) * | 2019-11-18 | 2020-02-14 | 四川大学 | Power cable intermediate joint damp positioning diagnosis method based on input impedance spectrum |
| CN110954746A (en) * | 2019-11-27 | 2020-04-03 | 云南电网有限责任公司电力科学研究院 | Six-interpolation FFT algorithm based on four-term Nuttall cosine window |
-
2020
- 2020-08-06 CN CN202010782394.6A patent/CN111929532A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102435845A (en) * | 2011-10-19 | 2012-05-02 | 广西电网公司电力科学研究院 | Harmonic energy metering method of Nuttall self-convolution weighted Fourier transform |
| CN109782063A (en) * | 2018-10-23 | 2019-05-21 | 国网安徽省电力有限公司芜湖供电公司 | A kind of dynamic m-Acetyl chlorophosphonazo analysis method based on three spectral line interpolation FFT of Nuttall self-convolution window |
| CN109828163A (en) * | 2019-03-20 | 2019-05-31 | 中南大学 | A kind of three-phase imbalance detection method for power grid |
| CN110096676A (en) * | 2019-04-30 | 2019-08-06 | 哈尔滨工业大学 | A kind of metering-type optical current voltage combination transformer frequency analysis device and method |
| CN110794271A (en) * | 2019-11-18 | 2020-02-14 | 四川大学 | Power cable intermediate joint damp positioning diagnosis method based on input impedance spectrum |
| CN110954746A (en) * | 2019-11-27 | 2020-04-03 | 云南电网有限责任公司电力科学研究院 | Six-interpolation FFT algorithm based on four-term Nuttall cosine window |
Non-Patent Citations (7)
| Title |
|---|
| 仇新艳等: "基于Nuttall窗DFT校正的微电网谐波检测算法", 《电力科许与技术学报》 * |
| 刘冬梅等: "基于Nuttall自卷积窗四谱线插值FFT的电力谐波分析方法", 《合肥工业大学学报(自然科学版)》 * |
| 曾博等: "纳托尔自卷积窗加权电力谐波分析方法", 《电网技术》 * |
| 李丽格: "电力系统谐波治理相关技术研究", 《中国优秀硕士学位论文全文数据库工程科技Ⅱ辑》 * |
| 李平等: "一种加Nuttall窗三谱线插值FFT谐波检测算法", 《电子技术应用》 * |
| 杨宇祥等: "基于Nuttall 自卷积窗FFT 算法的生物电阻抗谱多频率同步测量方法", 《电子与信息学报》 * |
| 高云鹏等: "基于波动负荷功率分析的闪变源判别方法", 《湖南大学学报(自然科学版)》 * |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| CN112881862A (en) * | 2021-01-18 | 2021-06-01 | 国网浙江省电力有限公司电力科学研究院 | Three-core cable fault positioning method and device based on relative impedance spectrum |
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