CN108880505B - Grounding grid potential difference filtering method based on starting judgment element and wavelet transformation - Google Patents
Grounding grid potential difference filtering method based on starting judgment element and wavelet transformation Download PDFInfo
- Publication number
- CN108880505B CN108880505B CN201810337245.1A CN201810337245A CN108880505B CN 108880505 B CN108880505 B CN 108880505B CN 201810337245 A CN201810337245 A CN 201810337245A CN 108880505 B CN108880505 B CN 108880505B
- Authority
- CN
- China
- Prior art keywords
- relay protection
- current transformer
- wavelet
- protection current
- moment
- 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
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H17/00—Networks using digital techniques
- H03H17/02—Frequency selective networks
- H03H17/0211—Frequency selective networks using specific transformation algorithms, e.g. WALSH functions, Fermat transforms, Mersenne transforms, polynomial transforms, Hilbert transforms
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Mathematical Physics (AREA)
- Algebra (AREA)
- Computing Systems (AREA)
- General Physics & Mathematics (AREA)
- Mathematical Analysis (AREA)
- Mathematical Optimization (AREA)
- Pure & Applied Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Computer Hardware Design (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The invention discloses a ground net potential difference filtering method based on a starting judgment element and wavelet transformation, which is used for judging whether a signal meets a steady state condition or not according to a constraint condition of five continuous points of the starting element aiming at a signal acquired by a relay protection current transformer, and further judging unsatisfied sampling data through a judgment element based on a waveform coefficient. If the data is normal data, the data is directly output; if the data is abnormal data, the data is output after being processed by wavelet transform filtering. The invention adds the starting judgment element before the traditional wavelet transformation, can carry out pre-judgment on signals, greatly reduces the calculated amount, overcomes the defect of poor timeliness of the traditional filtering algorithm, can effectively filter noise signals caused by potential difference of the grounding grid by utilizing the wavelet transformation, ensures the accuracy of relay protection data measurement and avoids the misoperation of relay protection equipment.
Description
Technical Field
The invention relates to a ground net potential difference filtering method based on a starting judgment element and wavelet transformation, and belongs to the technical field of filtering algorithms of relay protection equipment.
Background
The ultra-high voltage transformer substation generally adopts GIS (gas insulated switchgear), and when the isolating switch is operated, arcing and arc extinction occur dozens of times or even hundreds of times at the switch fracture. The generated disturbance voltage is continuously refracted and reflected on the bus and the short line to form very fast transient over-Voltage (VFTO). The VFTO is discharged into the ground grid through a protective grounding wire on the primary side of the transformer, so that the local potential of the ground grid rises. Because the secondary cable of the extra-high voltage transformer substation generally adopts a double-end grounding mode, the two ends of the shielding layer can generate a grounding grid potential difference. The potential difference induces disturbance current on a signal core wire coupled in the secondary cable, so that relay protection data measurement is inaccurate, and misoperation of the grounding intelligent equipment is easily caused, so that a method for identifying and eliminating interference signals, such as a hardware filtering method and a signal processing algorithm, is needed to be found out, wherein the signal processing algorithm is simple and efficient, and is more widely used.
The traditional filtering algorithm based on time domain has poor effect on the signals, and the wavelet transformation can carry out wavelet decomposition and reconstruction processing on the signals according to different characteristics expressed by the modulus maximum of current and noise along with the scale change, thereby effectively filtering noise signals caused by the potential difference of the grounding network. Under the actual working condition of the transformer substation, the proportion of disturbance signals is extremely low, and if wavelet transformation is directly adopted to carry out filtering processing on all sampling values, the calculation efficiency is not high, and delay of relay protection processing is easily caused. The traditional filtering algorithm needs to be improved according to the actual condition of the transformer substation, so that the reliability of relay protection of the power system is ensured, and the timeliness of relay protection data processing is improved.
Disclosure of Invention
In order to solve the technical problems, the invention provides a grounding grid potential difference filtering method based on a starting judgment element and wavelet transformation.
The invention adopts the following technical scheme for solving the technical problems:
the invention provides a ground net potential difference filtering method based on a starting judgment element and wavelet transformation, which comprises the following steps of:
step 2, judging whether the relay protection current transformer signal acquired at the current moment meets a steady state condition according to the constraint condition of five continuous points of the starting element: if the relay protection current transformer signal acquired at the current moment meets the steady state condition, outputting the relay protection current transformer signal acquired at the current moment, and returning to the step 1 to continue to execute the acquisition operation at the next moment; otherwise, executing the step 3;
and 3, judging whether the relay protection current transformer signal acquired at the current moment is normal data or not through a judgment element based on the waveform coefficient: if yes, outputting a relay protection current transformer signal acquired at the current moment, and returning to the step 1 to continue to execute the acquisition operation at the next moment; otherwise, executing the step 4;
and 4, filtering the relay protection current transformer signal acquired at the current moment through wavelet transformation, outputting the filtered relay protection current transformer signal, and returning to the step 1 to continue to execute the acquisition operation at the next moment.
As a further technical scheme of the invention, in the step 1, signals of the relay protection current transformer are acquired in real time through an acquisition system, wherein the acquisition system comprises the current transformer, a preposed analog low-pass filter, a sampling holder, an analog-to-digital converter, a multi-way conversion switch and a single chip microcomputer which are sequentially connected.
As a further technical solution of the present invention, step 2 specifically is:
2.1, the constraint condition of five continuous points of the starting element is as follows: y'k＝-yk-4+2yk-3-2yk-2+2yk-1+2cos100πTs(yk-3-2yk-2+yk-1) Wherein, y'kFor the predicted value y of the relay protection current transformer signal at the moment kk-1、yk-2、yk-3、yk-4Respectively are relay protection current transformer signals T acquired at k-1, k-2, k-3 and k-4sSampling period of relay protection current transformer signals;
2.2, if
The relay protection current transformer signal y acquired at the moment kkA steady state condition is not satisfied; otherwise ykSatisfy the steady state condition, output ykAnd continuing to execute the relay protection current transformer signal y at the k +1 momentk+1Whether the signal meets the steady state condition is judged; wherein, ImFor the rated current amplitude of the system, epsilon1Is a set first threshold.
As a further technical solution of the present invention, step 3 specifically is:
if R > ε2And the relay protection current transformer signal y acquired at the moment kkIf it is not normal data, continue to executeStep 4 is executed; otherwise, output ykAnd returning to the step 2 to continue executing the relay protection current transformer signal y acquired at the moment of k +1k+1Judging whether a steady state condition is met; wherein the content of the first and second substances,
alpha is the area occupied by the distortion,
n is judgment ykDecision element data window length, y, selected for normal datak+2、yk+3、yk+4Respectively the relay protection current transformer signals T collected at the moments of k +2, k +3 and k +4sIs the sampling period of the relay protection current transformer signal, s is the waveform area of the selected data window,
ε2is a set second threshold.
As a further technical scheme of the present invention, step 4 performs filtering processing on the relay protection current transformer signal acquired at the present time through wavelet transformation, specifically:
a) selecting a wavelet basis function and determining the wavelet decomposition layer number l;
b) performing wavelet decomposition, performing equal-interval sampling on the acquired relay protection current transformer signal Y, and then performing discrete wavelet transform on a sampling sequence to obtain an expansion coefficient sum of wavelets, wherein the decomposition formula is as follows:
where i is 1,2, …, l, M is the length of the wavelet transform data window, cA0Namely Y, cAiFor decomposed i-th layer low-frequency wavelet coefficients, cDiFor the i-th layer of decomposed high-frequency wavelet coefficients, hm-2For low-frequency filters corresponding to selected wavelet bases, gm-2A high frequency filter corresponding to the selected wavelet basis;
c) determining the threshold value of the wavelet coefficient and selecting a threshold value function, wherein the calculation formula of the ith layer of high-frequency wavelet coefficient after threshold value transformation is as follows
Wherein, th is a threshold value,
wherein σ is a noise standard deviation;
d) according to
Performing wavelet reconstruction to obtain cA after l times of reconstruction0The signal is a relay protection current transformer signal Y' after filtering processing, wherein cAl”＝cAl，cDi' is the ith layer high frequency wavelet coefficient, cA after threshold value transformationi-1' is the low-frequency wavelet coefficient, cA, of the i-1 th layer after reconstructioniAnd the' is the i-th layer low-frequency wavelet coefficient after reconstruction.
Compared with the prior art, the invention adopting the technical scheme has the following technical effects: according to the invention, the starting and judging elements are added before the wavelet transformation, and the signals are preprocessed in advance, so that normal signals can be directly output, the calculation time of a filtering algorithm is saved, the problem of poor timeliness of the traditional wavelet transformation is solved, the accuracy of relay protection data measurement is ensured, and the reliability of relay protection of a power system is improved.
Drawings
FIG. 1 is a flow chart of the method of the present invention.
Detailed Description
The technical scheme of the invention is further explained in detail by combining the attached drawings:
as shown in fig. 1, the earth grid potential difference filtering algorithm based on the start-up decision element and the wavelet transform of the present invention comprises the following steps:
the acquisition system comprises a current transformer, a preposed analog low-pass filter, a sampling retainer, an analog-to-digital converter, a multi-way change-over switch and a single chip microcomputer which are connected in sequence.
Step 2, starting the element to judge the signal;
in the steady state process of the power system, stable power frequency current flows in the power grid, the frequency is 50Hz, the amplitude is determined by factors such as power supply, load, line parameters and the like, and the amplitude is kept unchanged in the steady state process. In the interference of the potential difference of the grounding grid, the current of the power grid not only contains a power frequency steady-state component, but also can generate a transient quantity, and the amplitude of the transient quantity is attenuated along with time and finally reaches zero. The general expression of the grid current can be written as the superposition of a power frequency steady-state component and an attenuation non-periodic component:
wherein A is the amplitude of the power frequency current,
the initial phase angle of the power frequency current, B is the initial value of the attenuation non-periodic component, and tau is the attenuation time constant of the attenuation non-periodic component. There are a total of four unknowns a in this expression,
b and tau, so the current expression can be solved by substituting the first four sampling point data of the current signal, and the sampling value of the fifth point also meets the expression, so that the prediction of the collected signal can be realized. Writing out its expression, and performing taylor expansion, we can get:
wherein, yk、yk-1、yk-2、yk-3、yk-4For sampled data of 5 successive instants, TsIs the sampling period.
The expression is arranged to obtain a starting elementThe constraint conditions of the piece are as follows: y isk′＝-yk-4+2yk-3-2yk-2+2yk-1+2cos100πTs(yk-3-2yk-2+yk-1). So if the actual sample value y at time k iskAnd predicted value y'kThe absolute value of the difference is divided by the system rated current amplitude ImGreater than a set threshold value epsilon1I.e. by
Indicating the value y of the samplekIf the steady state condition is not met, step 3 needs to be executed to carry out the next judgment, and whether the data is normal data or not is judged. Otherwise, directly output ykAnd continuing to execute the relay protection current transformer signal y at the k +1 momentk+1And (4) judging whether the signal meets the steady state condition.
Step 3, the judgment element judges the signal;
if the amplitude and the initial phase corresponding to the current sampling value at the moment are changed at the critical point when the primary system enters the transient process from the steady state process, so that the constraint expression of the starting element is not satisfied, judging whether the acquired signal is normal data or not by adopting the waveform coefficient.
The form factor is defined as:
wherein α is the area occupied by distortion
Obtaining where N is a judgment ykThe length of the data window is selected to be 20 points according to the invention, so that the accuracy and the timeliness are ensured. s is the waveform area of the selected data window and can be obtained by integrating the instantaneous values of the sampled values in the same data window, i.e. by using a single-phase pulse
In an ideal state, the numerator of the form factor R is zero, and its value is also zero; if abnormal data exists in the sampling value, the value of R is not zero, and the larger R is, the more serious the distortion of the sampling value is. So if the form factor R is greater than the set threshold ε2I.e. R > epsilon2Indicates the value y of the samplekIf the data is not normal data, step 4 needs to be executed to filter the signal by using a filtering algorithm. Otherwise, ykIf the data is normal data, returning to the step 1 to continue to execute the next acquisition operation.
Step 4, filtering processing is carried out by wavelet transformation;
because the interference signal of the grounding grid potential difference is mainly a transient signal with sudden change, the filtering algorithm is selected as wavelet transformation and is mainly divided into 4 parts:
a) selecting a wavelet basis function and determining the wavelet decomposition layer number l;
b) performing wavelet decomposition, performing equal-interval sampling on the acquired relay protection current transformer signal Y, and then performing discrete wavelet transform on a sampling sequence to obtain an expansion coefficient sum of wavelets, wherein the decomposition formula is as follows:
wherein i represents the i-th layer decomposition, i is 1,2, …, l, and M is the length of the wavelet transform data window, and cA0Namely Y, cAiFor decomposed i-th layer low-frequency wavelet coefficients, cDiFor the i-th layer of decomposed high-frequency wavelet coefficients, hm-2For low-frequency filters corresponding to selected wavelet bases, gm-2A high frequency filter corresponding to the selected wavelet basis. In this way, the layer-by-layer decomposition is carried out for l times;
c) determining the threshold value of the wavelet coefficient and selecting a threshold value function, wherein the calculation formula of the ith layer of high-frequency wavelet coefficient after threshold value transformation is as follows
Wherein, th is a threshold value,
calculating a threshold value, wherein sigma is a noise standard deviation;
d) according to
Performing wavelet reconstruction, wherein in the reconstruction process, i ═ l, l-1, …,1, cAl”＝cAl，cDi' is the ith layer high frequency wavelet coefficient, cA after threshold value transformationi-1And the' is the low-frequency wavelet coefficient of the i-1 layer after reconstruction. In this way, l reconstructions were carried out, giving cA0The signal is the relay protection current transformer signal Y' after filtering processing, and the signal is output and returned to the step 2 to continue to execute the pair of Yk+1And judging whether a steady state condition is met.
The method adds the starting and judging elements before the wavelet transformation, preprocesses the signals, directly outputs the normal signals, greatly reduces the calculated amount of a filtering algorithm, overcomes the problem of poor timeliness of the traditional wavelet transformation, ensures the accuracy of the relay protection data measurement, and improves the reliability of the relay protection of the power system.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can understand that the modifications or substitutions within the technical scope of the present invention are included in the scope of the present invention, and therefore, the scope of the present invention should be subject to the protection scope of the claims.
Claims (4)
1. The ground net potential difference filtering method based on the starting judgment element and the wavelet transformation is characterized by comprising the following steps of:
step 1, collecting signals of a relay protection current transformer;
step 2, judging whether the relay protection current transformer signal acquired at the current moment meets a steady state condition according to the constraint condition of five continuous points of the starting element: if the relay protection current transformer signal acquired at the current moment meets the steady state condition, outputting the relay protection current transformer signal acquired at the current moment, and returning to the step 1 to continue to execute the acquisition operation at the next moment; otherwise, executing the step 3; the method specifically comprises the following steps:
2.1, the constraint condition of five continuous points of the starting element is as follows: y'k＝-yk-4+2yk-3-2yk-2+2yk-1+2cos100πTs(yk-3-2yk-2+yk-1) Wherein, y'kFor the predicted value y of the relay protection current transformer signal at the moment kk-1、yk-2、yk-3、yk-4Respectively are relay protection current transformer signals T acquired at k-1, k-2, k-3 and k-4sSampling period of relay protection current transformer signals;
2.2, if
The relay protection current transformer signal y acquired at the moment kkA steady state condition is not satisfied; otherwise ykSatisfy the steady state condition, output ykAnd continuing to execute the relay protection current transformer signal y at the k +1 momentk+1Whether the signal meets the steady state condition is judged; wherein I is the rated current amplitude of the system, epsilon1Is a set first threshold;
and 3, judging whether the relay protection current transformer signal acquired at the current moment is normal data or not through a judgment element based on the waveform coefficient: if yes, outputting a relay protection current transformer signal acquired at the current moment, and returning to the step 1 to continue to execute the acquisition operation at the next moment; otherwise, executing the step 4;
and 4, filtering the relay protection current transformer signal acquired at the current moment through wavelet transformation, outputting the filtered relay protection current transformer signal, and returning to the step 1 to continue to execute the acquisition operation at the next moment.
2. The grounding grid potential difference filtering method based on the start judgment element and the wavelet transformation as claimed in claim 1, wherein in step 1, the relay protection current transformer signal is collected in real time through a collection system, wherein the collection system comprises a current transformer, a pre-analog low pass filter, a sample holder, an analog-to-digital converter, a multi-way switch and a single chip microcomputer which are connected in sequence.
3. The earth grid potential difference filtering method based on the start-up decision element and the wavelet transform as claimed in claim 1, wherein step 3 is specifically:
if R > ε2And the relay protection current transformer signal y acquired at the moment kkIf the data is not normal data, continuing to execute the step 4; otherwise, output ykAnd returning to the step 2 to continue executing the relay protection current transformer signal y acquired at the moment of k +1k+1Judging whether a steady state condition is met; wherein the content of the first and second substances,
alpha is the area occupied by the distortion,
n is judgment ykDecision element data window length, y, selected for normal datak+2、yk+3、yk+4Respectively the relay protection current transformer signals T collected at the moments of k +2, k +3 and k +4sIs the sampling period of the relay protection current transformer signal, s is the waveform area of the selected data window,
ε2is a set second threshold.
4. The grounding grid potential difference filtering method based on the start judgment element and the wavelet transformation as claimed in claim 1, wherein the step 4 is to perform filtering processing on the relay protection current transformer signal acquired at the current moment through the wavelet transformation, specifically:
a) selecting a wavelet basis function and determining the wavelet decomposition layer number l;
b) performing wavelet decomposition, performing equal-interval sampling on the acquired relay protection current transformer signal Y, and then performing discrete wavelet transform on a sampling sequence to obtain an expansion coefficient sum of wavelets, wherein the decomposition formula is as follows:
where i is 1,2, …, l, M is the length of the wavelet transform data window, cA0Namely Y, cAiFor decomposed i-th layer low-frequency wavelet coefficients, cDiFor the i-th layer of decomposed high-frequency wavelet coefficients, hm-2For low-frequency filters corresponding to selected wavelet bases, gm-2A high frequency filter corresponding to the selected wavelet basis;
c) determining the threshold value of the wavelet coefficient and selecting a threshold value function, wherein the calculation formula of the ith layer of high-frequency wavelet coefficient after threshold value transformation is as follows
Wherein, th is a threshold value,
wherein σ is a noise standard deviation;
d) according to
Performing wavelet reconstruction to obtain cA after l times of reconstruction0The signal is the relay protection current transformer signal Y' after filtering treatment, wherein cAl″＝cAl，cDi' is the ith layer high frequency wavelet coefficient, cA after threshold value transformationi-1"is the reconstructed i-1 th layer low-frequency wavelet coefficient, cAiAnd the' is the i-th layer low-frequency wavelet coefficient after reconstruction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810337245.1A CN108880505B (en) | 2018-04-16 | 2018-04-16 | Grounding grid potential difference filtering method based on starting judgment element and wavelet transformation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810337245.1A CN108880505B (en) | 2018-04-16 | 2018-04-16 | Grounding grid potential difference filtering method based on starting judgment element and wavelet transformation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108880505A CN108880505A (en) | 2018-11-23 |
| CN108880505B true CN108880505B (en) | 2021-11-30 |
Family
ID=64326350
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810337245.1A Active CN108880505B (en) | 2018-04-16 | 2018-04-16 | Grounding grid potential difference filtering method based on starting judgment element and wavelet transformation |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108880505B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115422982B (en) * | 2022-11-04 | 2023-04-07 | 国网天津市电力公司电力科学研究院 | High-frequency transient signal extraction method, system, storage medium and computing device |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1100197A3 (en) * | 1999-11-10 | 2004-01-28 | Siemens Aktiengesellschaft | Method for filtering a sequence of digital signals |
| CN103513150A (en) * | 2013-09-17 | 2014-01-15 | 广东电网公司东莞供电局 | Device and method for detecting multipoint earthing of voltage transformer for electric system |
| CN105954628A (en) * | 2016-06-23 | 2016-09-21 | 深圳市中智盛安安全技术有限公司 | Fault arc detection method and detection apparatus |
| CN107395157A (en) * | 2017-07-13 | 2017-11-24 | 国网江苏省电力公司电力科学研究院 | Grounded screen potential difference filtering method based on wavelet transformation and weighted moving average |
| CN107782992A (en) * | 2017-09-01 | 2018-03-09 | 许昌许继软件技术有限公司 | A kind of Wave record method and device based on transformer station's antisurge interference |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105510760B (en) * | 2015-12-23 | 2018-08-14 | 国家电网公司 | A kind of short trouble data detection method based on wavelet analysis |
-
2018
- 2018-04-16 CN CN201810337245.1A patent/CN108880505B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1100197A3 (en) * | 1999-11-10 | 2004-01-28 | Siemens Aktiengesellschaft | Method for filtering a sequence of digital signals |
| CN103513150A (en) * | 2013-09-17 | 2014-01-15 | 广东电网公司东莞供电局 | Device and method for detecting multipoint earthing of voltage transformer for electric system |
| CN105954628A (en) * | 2016-06-23 | 2016-09-21 | 深圳市中智盛安安全技术有限公司 | Fault arc detection method and detection apparatus |
| CN107395157A (en) * | 2017-07-13 | 2017-11-24 | 国网江苏省电力公司电力科学研究院 | Grounded screen potential difference filtering method based on wavelet transformation and weighted moving average |
| CN107782992A (en) * | 2017-09-01 | 2018-03-09 | 许昌许继软件技术有限公司 | A kind of Wave record method and device based on transformer station's antisurge interference |
Non-Patent Citations (1)
| Title |
|---|
| Transformer monitoring using harmonic current based on wavelet transformation and probabilistic neural network (PNN);Imam Wahyudi F. 等;《2014 The 1st International Conference on Information Technology, Computer, and Electrical Engineering》;20150326;第419-423页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108880505A (en) | 2018-11-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Costa | Boundary wavelet coefficients for real-time detection of transients induced by faults and power-quality disturbances | |
| Kim et al. | A novel fault-detection technique of high-impedance arcing faults in transmission lines using the wavelet transform | |
| CN108957244B (en) | Single-phase earth fault line selection positioning method for distribution network main station | |
| Kim et al. | Wavelet transforms in power systems. II. Examples of application to actual power system transients | |
| CN106990324B (en) | Power distribution network ground fault detection and positioning method | |
| CN107395157B (en) | Ground net potential difference filtering method based on wavelet transformation and weighted moving average | |
| CN112014773B (en) | Method for detecting early fault of small-current grounding system cable | |
| CN103018629A (en) | Method for analyzing power system fault recording data based on Marla algorithm | |
| JPWO2011111833A1 (en) | Control system, transformer, protection control device, and bitstream storage unit | |
| Barros et al. | A virtual measurement instrument for electrical power quality analysis using wavelets | |
| CN108880505B (en) | Grounding grid potential difference filtering method based on starting judgment element and wavelet transformation | |
| CN110618338B (en) | Electric energy quality transient measurement method, device and equipment | |
| CN108089100A (en) | The detection method of small current neutral grounding system arc light resistance earth fault | |
| CN101510687A (en) | Frequency conversion method for implementing multi-sampling rate signal using window function in electric network | |
| Costa et al. | Detection and classification of transient disturbances in power systems | |
| CN108090270B (en) | Transient oscillation parameter identification method based on morphological filtering and blind source separation | |
| Kapisch et al. | An implementation of a power system smart waveform recorder using FPGA and ARM cores | |
| Lorenc et al. | Detection of the intermittent earth faults in compensated MV network | |
| Johns et al. | Fundamental digital approach to the distance protection of EHV transmission lines | |
| CN110441591A (en) | A kind of improved electronic mutual inductor current acquisition method | |
| CN107144767B (en) | Fault indication device and fault signal detection method | |
| CN107632235B (en) | Device and method for identifying fault line of low-resistance grounding system | |
| CN112782528B (en) | Power distribution network fault section positioning method by utilizing PMU | |
| CN109066584A (en) | A kind of capacitor harmonic protection method of high protection act precision | |
| Wang et al. | Highly accurate frequency estimation for FNET |
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 |