CN113484692B - Power distribution network ground fault detection method based on zero sequence current analysis - Google Patents
Power distribution network ground fault detection method based on zero sequence current analysis Download PDFInfo
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- CN113484692B CN113484692B CN202110872750.8A CN202110872750A CN113484692B CN 113484692 B CN113484692 B CN 113484692B CN 202110872750 A CN202110872750 A CN 202110872750A CN 113484692 B CN113484692 B CN 113484692B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/088—Aspects of digital computing
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
Abstract
The invention provides a power distribution network ground fault detection method based on zero sequence current analysis, which comprises the following steps: (1): collecting signals; (2): judging whether the zero sequence current is larger than a reference value, if so, going to (3); no, to (1); (3): calculating the similarity between the zero sequence current and the reference value; (4): judging whether the degree of acquaintance is larger than a reference value, if so, going to (1); no, to (5); (5): performing wavelet decomposition on the current; (6): calculating current high-frequency energy; (7): calculating a phase A normalization value; (8): judging whether the A phase normalization value is larger than a reference value, if so, grounding the A phase; to (9); (9): calculating a phase B normalization value; (10): judging whether the B phase normalization value is larger than a reference value, if so, the B phase is grounded; to (11); (11): calculating a C phase normalization value; (12): judging whether the normalized value of the phase C is larger than a reference value, if so, the phase C is grounded; to (13); (13): and judging whether to continue detection.
Description
Technical Field
The invention belongs to the technical field of power detection, and particularly relates to a power distribution network ground fault detection method based on zero sequence current analysis.
Background
Along with the continuous development of the power technology, the power users are continuously increased, the requirements of people on the stability and the reliability of power supply are continuously improved, and higher requirements on the speed and the accuracy of power grid fault rush repair are also provided. The distribution is used as a system which is most contacted with power users, is easily influenced by factors such as climate change, insulation aging, natural damage and the like, and has high fault incidence and high fault inspection difficulty. When the power distribution network breaks down, the production and the life of people can be influenced to a certain extent, so that the power distribution network needs to be effectively detected, and the power distribution network can be found out in time when the power distribution network breaks down, and then is processed.
The invention provides a power distribution network ground fault detection method based on zero sequence current analysis, which is used for judging whether a ground fault occurs according to the difference between a zero sequence current signal and a reference value, calculating high-frequency energy of each phase, judging a specific fault phase and further guaranteeing safe and reliable operation of power distribution equipment.
Disclosure of Invention
The invention provides a power distribution network ground fault detection method based on zero sequence current analysis, which can accurately judge whether the power distribution network has a ground fault and a specific fault phase and ensure the safe and reliable work of power distribution equipment.
The invention particularly relates to a power distribution network ground fault detection method based on zero sequence current analysis, which comprises the following steps:
step (1): collecting the zero sequence current signals and the current signals of each phase of the power distribution network;
step (2): judging whether the zero sequence current signal is larger than a zero sequence current signal reference value or not, if so, entering a step (3); if not, returning to the step (1);
step (3): calculating the similarity between the zero sequence current signal and the zero sequence current signal reference value;
step (4): judging whether the similarity is larger than a similarity reference value, if so, returning to the step (1); if not, go to step (5);
step (5): performing 8-layer wavelet decomposition on the A-phase current signal, the B-phase current signal and the C-phase current signal by using db4 wavelet;
step (6): calculating the high-frequency energy of the A-phase current signal, the high-frequency energy of the B-phase current signal and the high-frequency energy of the C-phase current signal;
step (7): calculating a high-frequency energy normalization value of the A-phase current signal;
step (8): judging whether the high-frequency energy normalization value of the A-phase current signal is larger than a high-frequency energy normalization reference value, if so, performing a step (9) on the A-phase ground fault; if not, go to step (9);
step (9): calculating a high-frequency energy normalization value of the B-phase current signal;
step (10): judging whether the high-frequency energy normalization value of the B-phase current signal is larger than the high-frequency energy normalization reference value, if so, entering a step (11) after the B-phase grounding fault; if not, go to step (11);
step (11): calculating a high-frequency energy normalization value of the C-phase current signal;
step (12): judging whether the high-frequency energy normalization value of the C-phase current signal is larger than the high-frequency energy normalization reference value, if so, entering a step (13) after the C-phase grounding fault; if not, go to step (13);
step (13): judging whether to continue detection, if so, returning to the step (1); if not, the process is ended.
And the zero-sequence current signal reference value adopts the average value of the zero-sequence current signals of the power distribution network 10 days before the time point of the zero-sequence current signal acquisition of the power distribution network.
The high-frequency energy of the A-phase current signal isd Ai (k) High frequency coefficients for the a-phase current signals; the high-frequency energy of the B-phase current signal is +.>d Bi (k) High frequency coefficients for the B-phase current signal; the high-frequency energy of the C-phase current signal is +.>d Ci (k) And a high frequency coefficient for the C-phase current signal.
The high-frequency energy normalization value of the A-phase current signal isThe high-frequency energy normalization value of the B-phase current signal is +.>The high-frequency energy normalization value of the C-phase current signal is +.>
Compared with the prior art, the beneficial effects are that: according to the power distribution network ground fault detection method, whether a ground fault occurs is judged according to the difference between the zero sequence current signal and the reference value, and then high-frequency energy of each phase is calculated, so that a specific fault phase is judged.
Drawings
Fig. 1 is a working flow chart of a power distribution network ground fault detection method based on zero sequence current analysis.
Detailed Description
The following describes a specific embodiment of a power distribution network ground fault detection method based on zero sequence current analysis in detail with reference to the accompanying drawings.
As shown in fig. 1, the method for detecting the ground fault of the power distribution network comprises the following steps:
firstly, collecting the zero sequence current signals and the current signals of each phase of the power distribution network.
Secondly, judging whether a ground fault occurs:
judging whether the zero sequence current signal is larger than a zero sequence current signal reference value or not, and if not, re-acquiring information; if yes, calculating the similarity between the zero sequence current signal and the zero sequence current signal reference value;
judging whether the similarity is larger than a similarity reference value, and if so, re-acquiring information; if not, further analyzing and judging.
Again, the specific faulty phase is determined:
performing 8-layer wavelet decomposition on the A-phase current signal, the B-phase current signal and the C-phase current signal by using db4 wavelet;
calculating the high-frequency energy of the A-phase current signald Ai (k) High frequency coefficients for the a-phase current signals; the high-frequency energy of the B-phase current signal>d Bi (k) High frequency coefficients for the B-phase current signal; the high-frequency energy of the C-phase current signal>d Ci (k) High frequency coefficients for the C-phase current signal;
judging whether the phase A is grounded: calculating the high-frequency energy normalization value of the A-phase current signalJudging whether the high-frequency energy normalization value of the A-phase current signal isIs larger than the high-frequency energy normalization reference value, if yes, the phase A is in ground fault;
judging whether B is grounded: calculating the high-frequency energy normalization value of the B-phase current signalJudging whether the high-frequency energy normalization value of the B-phase current signal is larger than the high-frequency energy normalization reference value, if so, judging that the B-phase current signal is in a ground fault;
judging whether C is grounded: calculating the high-frequency energy normalization value of the C-phase current signalAnd judging whether the high-frequency energy normalization value of the C-phase current signal is larger than the high-frequency energy normalization reference value, and if so, judging that the C-phase current signal is in a ground fault.
Finally, judging whether to continue detection, if so, re-acquiring information; if not, the process is ended.
Finally, it should be noted that the above-mentioned embodiments are merely illustrative of the technical solution of the invention and not limiting thereof. It will be understood by those skilled in the art that modifications and equivalents may be made to the particular embodiments of the invention, which are within the scope of the claims appended hereto.
Claims (3)
1. The power distribution network ground fault detection method based on zero sequence current analysis is characterized by comprising the following steps of:
step (1): collecting the zero sequence current signals and the current signals of each phase of the power distribution network;
step (2): judging whether the zero sequence current signal is larger than a zero sequence current signal reference value or not, if so, entering a step (3); if not, returning to the step (1); the zero-sequence current signal reference value adopts the average value of the zero-sequence current signals of the power distribution network 10 days before the time point of the zero-sequence current signal acquisition of the power distribution network;
step (3): calculating the similarity between the zero sequence current signal and the zero sequence current signal reference value;
step (4): judging whether the similarity is larger than a similarity reference value, if so, returning to the step (1); if not, go to step (5);
step (5): performing 8-layer wavelet decomposition on the A-phase current signal, the B-phase current signal and the C-phase current signal by using db4 wavelet;
step (6): calculating the high-frequency energy of the A-phase current signal, the high-frequency energy of the B-phase current signal and the high-frequency energy of the C-phase current signal;
step (7): calculating a high-frequency energy normalization value of the A-phase current signal;
step (8): judging whether the high-frequency energy normalization value of the A-phase current signal is larger than a high-frequency energy normalization reference value, if so, performing a step (9) on the A-phase ground fault; if not, go to step (9);
step (9): calculating a high-frequency energy normalization value of the B-phase current signal;
step (10): judging whether the high-frequency energy normalization value of the B-phase current signal is larger than the high-frequency energy normalization reference value, if so, entering a step (11) after the B-phase grounding fault; if not, go to step (11);
step (11): calculating a high-frequency energy normalization value of the C-phase current signal;
step (12): judging whether the high-frequency energy normalization value of the C-phase current signal is larger than the high-frequency energy normalization reference value, if so, entering a step (13) after the C-phase grounding fault; if not, go to step (13);
step (13): judging whether to continue detection, if so, returning to the step (1); if not, the process is ended.
2. The method for detecting the ground fault of the power distribution network based on the zero sequence current analysis according to claim 1, wherein the high-frequency energy of the A-phase current signal isd Ai (k) For the A-phase currentSignal high frequency coefficients; the high-frequency energy of the B-phase current signal is +.>d Bi (k) High frequency coefficients for the B-phase current signal; the high-frequency energy of the C-phase current signal is +.>d Ci (k) And a high frequency coefficient for the C-phase current signal.
3. The method for detecting the ground fault of the power distribution network based on the zero sequence current analysis according to claim 2, wherein the high-frequency energy normalization value of the A-phase current signal is as followsThe high-frequency energy normalization value of the B-phase current signal is +.>The high-frequency energy normalization value of the C-phase current signal is
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