CN113447847A - Power distribution system fault identification method based on zero sequence signal analysis - Google Patents
Power distribution system fault identification method based on zero sequence signal analysis Download PDFInfo
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- CN113447847A CN113447847A CN202110373578.1A CN202110373578A CN113447847A CN 113447847 A CN113447847 A CN 113447847A CN 202110373578 A CN202110373578 A CN 202110373578A CN 113447847 A CN113447847 A CN 113447847A
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- 238000000034 method Methods 0.000 title claims abstract description 16
- 238000005070 sampling Methods 0.000 claims description 18
- 230000005350 ferromagnetic resonance Effects 0.000 claims description 6
- 238000001514 detection method Methods 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
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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
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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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
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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
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
Abstract
The invention provides a power distribution system fault identification method based on zero sequence signal analysis, which collects various information of a power distribution system, firstly carries out primary judgment on the system according to phase voltage signals of each phase, and then adopts different characteristic values to carry out judgment according to different zero sequence current signals: if the zero sequence current signal is zero, determining the fault type according to the zero sequence voltage signal fluctuation value; and if the zero-sequence current signal is not zero, determining the fault type according to the phase difference between the zero-sequence voltage signal and the zero-sequence current signal. The invention provides a power distribution system fault identification method based on zero sequence signal analysis, which can accurately judge whether a power distribution system has a ground fault and a fault phase, thereby ensuring the safety and reliability of the work of the power distribution system.
Description
Technical Field
The invention belongs to the technical field of electric power detection, and particularly relates to a power distribution system fault identification method based on zero sequence signal analysis.
Background
The power distribution system is used as a part of the power system directly connected with power consumers, and the safe and reliable work of the power distribution system plays an important role in the normal work of the whole power system. The most common fault of the power distribution system is a single-phase earth fault, when the single-phase earth fault occurs, the generated fault current is small, the influence on the load current is small, and the power distribution system can continuously run for a period of time under the general condition. However, if the device is operated with a fault for a long time, the device insulation is damaged, even the insulation is broken down to cause a multipoint grounding short circuit, and further cause a power system fault, so that a fault line needs to be found and cut as soon as possible.
The invention provides a power distribution system fault identification method based on zero sequence signal analysis, which collects various information of a power distribution system, firstly carries out primary judgment on the system according to phase voltage signals of each phase, and then adopts different characteristic values to carry out judgment according to different zero sequence current signals: if the zero sequence current signal is zero, determining the fault type according to the zero sequence voltage signal fluctuation value; and if the zero-sequence current signal is not zero, determining the fault type according to the phase difference between the zero-sequence voltage signal and the zero-sequence current signal.
Disclosure of Invention
The invention provides a power distribution system fault identification method based on zero sequence signal analysis, which can accurately judge whether a power distribution system has a ground fault and a fault phase, thereby ensuring the safety and reliability of the work of the power distribution system.
The invention specifically relates to a power distribution system fault identification method based on zero sequence signal analysis, which comprises the following steps:
step (1): acquiring a zero-sequence voltage signal, a zero-sequence current signal and a three-phase voltage signal of the power distribution system;
step (2): judging whether one-phase voltage signal of the three-phase voltage signals is reduced and is smaller than a voltage reference value or not, and the other two-phase voltage signals are increased and are smaller than the voltage reference value, if so, entering the step (3); if not, returning to the step (1);
and (3): extracting the zero sequence voltage signal and the zero sequence current signal;
and (4): judging whether the zero sequence current signal is larger than zero, if so, entering the step (5); if not, entering the step (9);
and (5): calculating the phase difference between the zero sequence voltage signal and the zero sequence current signal;
and (6): calculating the average value of the phase difference in the sampling period;
and (7): judging whether the average phase differences of the three phases are all smaller than 0 degree, if so, generating a power frequency ferromagnetic resonance fault in the power distribution system; if not, entering the step (8);
and (8): the phase corresponding to the phase difference average value larger than 0 degree has single-phase earth fault;
and (9): calculating the zero sequence voltage signal fluctuation value;
step (10): judging whether the zero sequence voltage signal fluctuation value is smaller than a first voltage fluctuation reference value or not, if so, judging that the power distribution system has a ground fault, and judging that the phase corresponding to the voltage signal reduction is a ground fault phase; if not, entering the step (11);
step (11): and judging whether the zero sequence voltage signal fluctuation value is larger than a second voltage fluctuation reference value or not, and if so, judging that the power frequency ferromagnetic resonance fault occurs in the power distribution system.
To calculate the phase difference between the zero-sequence voltage signal and the zero-sequence current signal, first the zero-sequence voltage signal i (t) Isin [ ω t + θ ═ is measuredi(t)]And the zero sequence current signal U (t) is Usin [ ω t + θ ═ U sin [ [ ω t + θ ]u(t)]Performing Hilbert transform to obtain
Calculating the phase difference between the zero sequence voltage signal and the zero sequence current signal
The zero sequence voltage signal fluctuation value
UmaxIs the maximum value, U, of the zero-sequence voltage signal in the sampling periodminIs the minimum value, U, of the zero sequence voltage signal in the sampling periodNFor the effective value of the zero sequence voltage signal in the sampling period,
and N is the total number of sampling points in the sampling period.
Compared with the prior art, the beneficial effects are: the power distribution system fault identification method collects multiple information of a power distribution system, firstly carries out primary judgment on the system according to phase voltage signals of each phase, and then adopts different characteristic values to carry out judgment according to different zero-sequence current signals: if the zero sequence current signal is zero, determining the fault type according to the zero sequence voltage signal fluctuation value; and if the zero-sequence current signal is not zero, determining the fault type according to the phase difference between the zero-sequence voltage signal and the zero-sequence current signal.
Drawings
Fig. 1 is a working flow chart of a method for identifying a fault of a power distribution system based on zero sequence signal analysis according to the present invention.
Detailed Description
The following describes in detail a specific embodiment of the method for identifying a fault of a power distribution system based on zero sequence signal analysis according to the present invention with reference to the accompanying drawings.
As shown in fig. 1, the method for identifying faults of a power distribution system of the present invention includes the following steps:
firstly, acquiring a zero sequence voltage signal, a zero sequence current signal and a three-phase voltage signal of a power distribution system, and preliminarily judging the system by each phase voltage signal:
judging whether one-phase voltage signal is reduced and is smaller than a voltage reference value or not in the three-phase voltage signals, and judging whether the other two-phase voltage signal is increased and is smaller than the line voltage reference value or not, if so, further analyzing and judging; if not, the signal is reacquired.
Further, different characteristic values are adopted for judgment according to different zero sequence current signals: if the zero sequence current signal is zero, determining the fault type according to the zero sequence voltage signal fluctuation value; if the zero-sequence current signal is not zero, determining the fault type according to the phase difference between the zero-sequence voltage signal and the zero-sequence current signal; the method specifically comprises the following steps:
(1): judging whether the zero sequence current signal is larger than zero, if so, entering (2); if not, entering (7);
(2): zero sequence voltage signal i (t) ═ Isin [ ω t + θ [ ]i(t)]And zero sequence current signal U (t) ═ U sin [ ω t + θu(t)]Performing Hilbert transform to obtain
(3): calculating the phase difference between the zero sequence voltage signal and the zero sequence current signal
(4): calculating the average value of the phase difference in the sampling period;
(5): judging whether the average values of the three-phase differences are all smaller than 0 degree, if so, generating a power frequency ferromagnetic resonance fault in the power distribution system; if not, entering (6);
(6): the phase with the average phase difference value larger than 0 degree has single-phase earth fault;
(7): calculating effective value of zero sequence voltage signal in sampling period
N is the total number of sampling points in the sampling period;
(8): calculating the fluctuation value of the zero sequence voltage signal
UmaxIs the maximum value of zero sequence voltage signal in the sampling period, UminThe minimum value of the zero sequence voltage signal in the sampling period is obtained;
(9): judging whether the zero sequence voltage signal fluctuation value is smaller than a first voltage fluctuation reference value or not, if so, judging that the power distribution system has a ground fault, and judging that the phase corresponding to the voltage signal reduction is a ground fault phase; if not, entering (10);
(10): and judging whether the zero sequence voltage signal fluctuation value is larger than a second voltage fluctuation reference value or not, and if so, causing power frequency ferromagnetic resonance fault to occur in the power distribution system.
In order to increase the speed of fault detection, the first voltage fluctuation reference value and the second voltage fluctuation reference value may use the same reference value, for example 15%.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the same. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (3)
1. A power distribution system fault identification method based on zero sequence signal analysis is characterized by comprising the following steps:
step (1): acquiring a zero-sequence voltage signal, a zero-sequence current signal and a three-phase voltage signal of the power distribution system;
step (2): judging whether one-phase voltage signal of the three-phase voltage signals is reduced and is smaller than a voltage reference value or not, and the other two-phase voltage signals are increased and are smaller than the voltage reference value, if so, entering the step (3); if not, returning to the step (1);
and (3): extracting the zero sequence voltage signal and the zero sequence current signal;
and (4): judging whether the zero sequence current signal is larger than zero, if so, entering the step (5); if not, entering the step (9);
and (5): calculating the phase difference between the zero sequence voltage signal and the zero sequence current signal;
and (6): calculating the average value of the phase difference in the sampling period;
and (7): judging whether the average phase differences of the three phases are all smaller than 0 degree, if so, generating a power frequency ferromagnetic resonance fault in the power distribution system; if not, entering the step (8);
and (8): the phase corresponding to the phase difference average value larger than 0 degree has single-phase earth fault;
and (9): calculating the zero sequence voltage signal fluctuation value;
step (10): judging whether the zero sequence voltage signal fluctuation value is smaller than a first voltage fluctuation reference value or not, if so, judging that the power distribution system has a ground fault, and judging that the phase corresponding to the voltage signal reduction is a ground fault phase; if not, entering the step (11);
step (11): and judging whether the zero sequence voltage signal fluctuation value is larger than a second voltage fluctuation reference value or not, and if so, judging that the power frequency ferromagnetic resonance fault occurs in the power distribution system.
2. The method as claimed in claim 1, wherein, to calculate the phase difference between the zero-sequence voltage signal and the zero-sequence current signal, the zero-sequence voltage signal I (t) is first subjected to I sin [ ω t + θ ]i(t)]And the zero sequence current signal U (t) is Usin [ ω t + θ ═ U sin [ [ ω t + θ ]u(t)]Performing Hilbert transform to obtain
Calculating the phase difference between the zero sequence voltage signal and the zero sequence current signal
3. The method of claim 2, wherein the zero sequence voltage signal fluctuation value is a zero sequence voltage signal fluctuation value
UmaxIs the maximum value, U, of the zero-sequence voltage signal in the sampling periodminIs the minimum value, U, of the zero sequence voltage signal in the sampling periodNFor the effective value of the zero sequence voltage signal in the sampling period,
and N is the total number of sampling points in the sampling period.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103941079A (en) * | 2014-04-16 | 2014-07-23 | 华北电力大学 | On-line monitoring and fault diagnosis system for power distribution network PT |
| CN110244122A (en) * | 2019-06-19 | 2019-09-17 | 国网山东省电力公司东营供电公司 | Resonant Overvoltage in Power Systems Detection & Controling method |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103941079A (en) * | 2014-04-16 | 2014-07-23 | 华北电力大学 | On-line monitoring and fault diagnosis system for power distribution network PT |
| CN110244122A (en) * | 2019-06-19 | 2019-09-17 | 国网山东省电力公司东营供电公司 | Resonant Overvoltage in Power Systems Detection & Controling method |
Non-Patent Citations (1)
| Title |
|---|
| 喻一帆: "配电网工频铁裕谐振和单相接地故障辨识", 中国优秀硕士论文全文数据库, 15 March 2017 (2017-03-15), pages 4 * |
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