CN113176521A - Single-phase earth fault detection method for power transmission and distribution system - Google Patents

Single-phase earth fault detection method for power transmission and distribution system Download PDF

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CN113176521A
CN113176521A CN202110373582.8A CN202110373582A CN113176521A CN 113176521 A CN113176521 A CN 113176521A CN 202110373582 A CN202110373582 A CN 202110373582A CN 113176521 A CN113176521 A CN 113176521A
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current
instantaneous
power transmission
distribution system
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陈志鹏
樊天荣
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Nantong Power Supply Co of State Grid Jiangsu Electric Power Co Ltd
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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
    • 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
    • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
    • 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
    • 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

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
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  • Emergency Protection Circuit Devices (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

The invention provides a single-phase earth fault detection method of a power transmission and distribution system, which comprises the following steps: (1): collecting three-phase current and zero-sequence current; (2): judging whether the zero sequence current is larger than a reference value, if so, to (3); no, to (1); (3): calculating a characteristic frequency band; (4): extracting three-phase current under a characteristic frequency band; (5): instantaneous negative sequence current obtained by phase transformation with different phases as references; (6): extracting instantaneous negative sequence current; (7): calculating a space negative sequence current vector; (8): calculating the negative sequence current variable quantity; (9): judging whether the negative sequence current variation is larger than zero, if so, to (10); if not, no fault exists; (10): judging whether the negative sequence current variation is larger than a reference value, if so, judging that no fault exists; otherwise, a single-phase earth fault occurs. The invention provides a single-phase earth fault detection method for a power transmission and distribution system, which can accurately judge whether the power transmission and distribution system has earth faults or not and ensure the stability of the system.

Description

Single-phase earth fault detection method for power transmission and distribution system
Technical Field
The invention belongs to the technical field of electric power detection, and particularly relates to a single-phase earth fault detection method for a power transmission and distribution system.
Background
The power transmission and distribution system has a plurality of devices, a wide range and a complex environment, is easily influenced by an external environment, and works safely and reliably to ensure the safety of a power grid and the power consumption of users. The ground fault is one of the faults frequently occurring in the power transmission and distribution system line, and if the ground fault is not solved in time after the ground fault occurs, serious consequences and even disasters can be caused to the production and the life of people. At present, people adopt various detection methods to detect the ground fault, but the accuracy of the detection result is unstable.
The invention provides a single-phase earth fault detection method for a power transmission and distribution system, which can extract effective three-phase current according to a line characteristic frequency band, calculate the negative sequence current variable quantity, and judge faults by taking the negative sequence current variable quantity as a characteristic value, so that the accuracy of a detection result is improved.
Disclosure of Invention
The invention provides a single-phase earth fault detection method for a power transmission and distribution system, which can accurately judge whether the power transmission and distribution system has earth faults or not and improve the accuracy of a detection result.
The invention specifically relates to a single-phase earth fault detection method of a power transmission and distribution system, which comprises the following steps:
step (1): collecting three-phase current signals and zero-sequence current signals;
step (2): judging whether the zero-sequence current signal is larger than a zero-sequence current reference value or not, if so, entering the step (3); if not, returning to the step (1);
and (3): calculating the line characteristic frequency band of the power transmission and distribution system;
and (4): extracting the three-phase current signals under the characteristic frequency band;
and (5): the three-phase current signals are subjected to transformation by taking different phases as reference phases to obtain instantaneous negative sequence current;
and (6): extracting instantaneous negative sequence current;
and (7): calculating a space negative sequence current vector;
and (8): calculating the negative sequence current variable quantity;
and (9): judging whether the negative sequence current variation is larger than zero, if so, entering the step (10); if not, no single-phase earth fault occurs;
step (10): judging whether the negative sequence current variation is larger than a negative sequence current variation reference value or not, if so, not generating single-phase earth fault; if not, a single-phase earth fault occurs.
The algorithm for calculating the line characteristic frequency band of the power transmission and distribution system comprises the following steps: omega > [ min (omega)1,ω2),ωc/2]Wherein, ω is1The lower limit cut-off frequency omega of the shortest line of the overhead line of the power transmission and distribution system2A lower cut-off frequency, omega, for the shortest line of the line cable of the power transmission and distribution systemcIs the sampling frequency.
Instantaneous negative-sequence current with a phase a current as reference:
Figure BDA0003010289540000021
ia(1)for instantaneous positive sequence components based on phase A current, ia(2)For instantaneous negative sequence component based on A-phase current, ia(0)For instantaneous zero-sequence components based on phase A current, iaFor phase A current, ibFor phase B current, icIs C phase current; instantaneous negative-sequence current with B-phase current as reference:
Figure BDA0003010289540000022
ib(1)for instantaneous positive sequence components based on phase B current, ib(2)For instantaneous negative sequence components based on phase B current, ib(0)Is an instantaneous zero-sequence component based on the phase B current; instantaneous negative-sequence current with C-phase current as reference:
Figure BDA0003010289540000023
ic(1)for instantaneous positive sequence components based on phase C current, ic(2)For instantaneous negative sequence components based on phase C current, ic(0)Is an instantaneous zero-sequence component based on the C-phase current.
The algorithm for calculating the instantaneous negative sequence current is as follows:
Figure BDA0003010289540000024
the algorithm for calculating the space negative sequence current vector is as follows:
Figure BDA0003010289540000031
the algorithm for calculating the negative sequence current variation is as follows:
Figure BDA0003010289540000032
wherein N is the total number of sampling points per cycle.
Compared with the prior art, the beneficial effects are: according to the method for detecting the single-phase earth fault of the power transmission and distribution system, initial judgment is firstly carried out according to the zero sequence signal, the characteristic frequency band of the line is calculated, effective three-phase current is extracted, then the negative sequence current variable quantity is calculated and is used as the characteristic value to carry out fault judgment, and the accuracy of the detection result is improved.
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Fig. 1 is a flowchart illustrating a method for detecting a single-phase earth fault of a power transmission and distribution system according to the present invention.
Detailed Description
The following describes in detail a specific embodiment of a single-phase ground fault detection method for a power transmission and distribution system according to the present invention with reference to the accompanying drawings.
As shown in fig. 1, the method for detecting a single-phase earth fault of a power transmission and distribution system of the present invention includes the following steps:
step (1): collecting three-phase current signals and zero-sequence current signals;
step (2): judging whether the zero-sequence current signal is larger than a zero-sequence current reference value or not, if so, entering the step (3); if not, returning to the step (1);
and (3): calculating the line characteristic frequency band omega > [ min (omega) of the power transmission and distribution system1,ω2),ωc/2]Wherein, ω is1The lower limit cut-off frequency omega of the shortest line of the overhead line of the power transmission and distribution system2A lower cut-off frequency, omega, for the shortest line of the line cable of the power transmission and distribution systemcIs the sampling frequency;
and (4): extracting the three-phase current signals under the characteristic frequency band;
and (5): and (3) converting the three-phase current signals by taking different phases as reference phases to obtain instantaneous negative sequence current: instantaneous negative with A-phase current as referenceSequence current:
Figure BDA0003010289540000041
ia(1)for instantaneous positive sequence components based on phase A current, ia(2)For instantaneous negative sequence component based on A-phase current, ia(0)For instantaneous zero-sequence components based on phase A current, iaFor phase A current, ibFor phase B current, icIs C phase current; instantaneous negative-sequence current with B-phase current as reference:
Figure BDA0003010289540000042
ib(1)for instantaneous positive sequence components based on phase B current, ib(2) For instantaneous negative sequence components based on phase B current, ib(0)Is an instantaneous zero-sequence component based on the phase B current; instantaneous negative-sequence current with C-phase current as reference:
Figure BDA0003010289540000043
ic(1)for instantaneous positive sequence components based on phase C current, ic(2)For instantaneous negative sequence components based on phase C current, ic(0)Is an instantaneous zero-sequence component based on the C-phase current;
and (6): extracting instantaneous negative sequence current
Figure BDA0003010289540000044
And (7): computing a spatial negative sequence current vector
Figure BDA0003010289540000045
And (8): calculating the negative sequence current variation
Figure BDA0003010289540000051
Wherein N is the total number of sampling points in each period;
and (9): judging whether the negative sequence current variation is larger than zero, if so, entering the step (10); if not, no single-phase earth fault occurs;
step (10): judging whether the negative sequence current variation is larger than a negative sequence current variation reference value or not, if so, not generating single-phase earth fault; if not, a single-phase earth fault occurs.
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 (6)

1. The single-phase earth fault detection method of the power transmission and distribution system is characterized by comprising the following steps of:
step (1): collecting three-phase current signals and zero-sequence current signals;
step (2): judging whether the zero-sequence current signal is larger than a zero-sequence current reference value or not, if so, entering the step (3); if not, returning to the step (1);
and (3): calculating the line characteristic frequency band of the power transmission and distribution system;
and (4): extracting the three-phase current signals under the characteristic frequency band;
and (5): the three-phase current signals are subjected to transformation by taking different phases as reference phases to obtain instantaneous negative sequence current;
and (6): extracting instantaneous negative sequence current;
and (7): calculating a space negative sequence current vector;
and (8): calculating the negative sequence current variable quantity;
and (9): judging whether the negative sequence current variation is larger than zero, if so, entering the step (10); if not, no single-phase earth fault occurs;
step (10): judging whether the negative sequence current variation is larger than a negative sequence current variation reference value or not, if so, not generating single-phase earth fault; if not, a single-phase earth fault occurs.
2. The single-phase earth fault detection method of the power transmission and distribution system according to claim 1, wherein the algorithm for calculating the line characteristic frequency band of the power transmission and distribution system is as follows: omega > [ min (omega)1,ω2),ωc/2]Wherein, ω is1The lower limit cut-off frequency omega of the shortest line of the overhead line of the power transmission and distribution system2A lower cut-off frequency, omega, for the shortest line of the line cable of the power transmission and distribution systemcIs the sampling frequency.
3. The power transmission and distribution system single-phase ground fault detection method of claim 2, wherein the instantaneous negative-sequence current referenced to phase a current is:
Figure FDA0003010289530000011
ia(1)for instantaneous positive sequence components based on phase A current, ia(2)For instantaneous negative sequence component based on A-phase current, ia(0)For instantaneous zero-sequence components based on phase A current, iaFor phase A current, ibFor phase B current, icIs C phase current;
instantaneous negative-sequence current with B-phase current as reference:
Figure FDA0003010289530000021
ib(1)for instantaneous positive sequence components based on phase B current, ib(2)For instantaneous negative sequence components based on phase B current, ib(0)Is an instantaneous zero-sequence component based on the phase B current;
instantaneous negative-sequence current with C-phase current as reference:
Figure FDA0003010289530000022
ic(1)for instantaneous positive sequence components based on phase C current, ic(2)For instantaneous negative sequence components based on phase C current, ic(0)Is an instantaneous zero-sequence component based on the C-phase current.
4. The single-phase ground fault detection method of the power transmission and distribution system according to claim 3, wherein the algorithm for calculating the instantaneous negative sequence current is as follows:
Figure FDA0003010289530000023
5. the single-phase ground fault detection method of the power transmission and distribution system according to claim 4, wherein the algorithm for calculating the spatial negative sequence current vector is as follows:
Figure FDA0003010289530000024
6. the single-phase earth fault detection method of the power transmission and distribution system according to claim 5, wherein the algorithm for calculating the negative sequence current variation is as follows:
Figure FDA0003010289530000025
wherein N is the total number of sampling points per cycle.
CN202110373582.8A 2021-04-07 2021-04-07 Single-phase earth fault detection method for power transmission and distribution system Pending CN113176521A (en)

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CN113484692A (en) * 2021-07-30 2021-10-08 国网江苏省电力有限公司南通供电分公司 Power distribution network ground fault detection method based on zero sequence current analysis
CN113820561A (en) * 2021-08-18 2021-12-21 国网江苏省电力有限公司盐城供电分公司 Power distribution station bus fault detection method based on current analysis
CN115656870A (en) * 2022-10-20 2023-01-31 国网江苏省电力有限公司南京供电分公司 Method and system for monitoring electric leakage of power cable of transformer substation
CN116008802A (en) * 2022-12-09 2023-04-25 中国船舶重工集团公司第七一九研究所 Portable motor detection device and detection method thereof

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CN110579670A (en) * 2019-07-11 2019-12-17 国网江苏省电力有限公司徐州供电分公司 Small current ground fault detection method based on zero sequence component analysis
CN110579669A (en) * 2019-07-11 2019-12-17 国网江苏省电力有限公司徐州供电分公司 small current ground fault detection system and method based on zero sequence component analysis
CN110596510A (en) * 2019-07-11 2019-12-20 国网江苏省电力有限公司徐州供电分公司 Single-phase grounding detection method based on negative sequence current vector analysis

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CN110579679A (en) * 2019-07-11 2019-12-17 国网江苏省电力有限公司徐州供电分公司 power distribution network line fault detection system based on negative sequence current vector analysis and detection method thereof
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113484692A (en) * 2021-07-30 2021-10-08 国网江苏省电力有限公司南通供电分公司 Power distribution network ground fault detection method based on zero sequence current analysis
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CN113820561A (en) * 2021-08-18 2021-12-21 国网江苏省电力有限公司盐城供电分公司 Power distribution station bus fault detection method based on current analysis
CN115656870A (en) * 2022-10-20 2023-01-31 国网江苏省电力有限公司南京供电分公司 Method and system for monitoring electric leakage of power cable of transformer substation
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CN116008802B (en) * 2022-12-09 2024-02-20 中国船舶重工集团公司第七一九研究所 Portable motor detection device and detection method thereof

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