CN110596510A - Single-phase grounding detection method based on negative sequence current vector analysis - Google Patents
Single-phase grounding detection method based on negative sequence current vector analysis Download PDFInfo
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- CN110596510A CN110596510A CN201910624129.2A CN201910624129A CN110596510A CN 110596510 A CN110596510 A CN 110596510A CN 201910624129 A CN201910624129 A CN 201910624129A CN 110596510 A CN110596510 A CN 110596510A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
Abstract
The invention provides a single-phase grounding detection method based on negative sequence current vector analysis, which comprises the following steps of (1): reading three-phase current signals; step (2): the three-phase current signals are converted by taking different phases as reference phases to obtain instantaneous negative sequence current; and (3): extracting instantaneous negative sequence current; and (4): calculating a space negative sequence current vector; and (5): calculating the negative sequence current variable quantity; and (6): judging whether the negative sequence current variation is larger than zero, if so, not generating single-phase earth fault, and if so, entering the step (7); and (7): judging whether the negative sequence current variation is larger than a negative sequence current variation reference value or not, and if so, not generating single-phase earth fault; if not, single-phase earth fault occurs. The invention can more accurately detect the single-phase earth fault, thereby ensuring the safety and reliability of the power distribution system.
Description
Technical Field
The invention belongs to the technical field of electric power detection, and particularly relates to a single-phase grounding detection method based on negative sequence current vector analysis.
Background
With the rapid development of economic society, the power industry in China is continuously developed, people's life increasingly depends on electric energy, and the requirement on the reliability of power supply safety must be improved. The power distribution network directly provides electric energy for users, the safety and the reliability of the operation of the power distribution network directly influence the economic loss and the quality of life of the users, and the condition of system failure is inevitable due to the complexity of the operation of a power system and the interference of external uncertain factors. The single-phase grounding is one of the faults frequently occurring in the power distribution network, the zero sequence voltage can be increased by the single-phase grounding, if measures are not taken immediately, the overvoltage phenomenon can be generated in a non-fault phase, the power distribution equipment is damaged, even a circuit insulating medium is damaged, the interphase short circuit is caused, and the larger power supply hazard is formed. Therefore, efficient detection of the line is needed in a single phase.
The invention provides a single-phase grounding detection method based on negative sequence current vector analysis, which extracts the negative sequence component of fault current, can rapidly and effectively judge single-phase grounding faults through variable quantity, overcomes the problem of misjudgment caused by the fact that the traditional zero sequence voltage is used as a judgment basis, and further ensures the safety and reliability of a power distribution system.
Disclosure of Invention
The invention provides a single-phase grounding detection method based on negative sequence current vector analysis, which can more accurately detect single-phase grounding faults and further ensure the safety and reliability of a power distribution system.
The invention specifically relates to a single-phase grounding detection method based on negative sequence current vector analysis, which comprises the following steps:
step (1): reading three-phase current signals;
step (2): and (3) converting the three-phase current signals by taking different phases as reference phases to obtain instantaneous negative sequence current: instantaneous negative-sequence current with a phase a current as reference: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, ibIs a phase BCurrent, icIs C phase current; instantaneous negative-sequence current with B-phase current as reference: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: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 (3): extracting instantaneous negative sequence current
And (4): calculating a space negative sequence current vector:
and (5): calculating the negative sequence current variationN is the total number of sampling points in each period;
and (6): judging whether the negative sequence current variation is larger than zero, if so, not generating single-phase earth fault; if the value is larger than zero, entering the step (7);
and (7): judging whether the negative sequence current variation is larger than a negative sequence current variation reference value or not, and if so, not generating single-phase earth fault; and if the current is not greater than the reference value of the negative sequence current variation, a single-phase earth fault occurs.
The three-phase current signals are collected through a current sensor installed at the head end of the line.
Compared with the prior art, the beneficial effects are: the single-phase grounding detection method extracts negative sequence current from the collected current signal, calculates the variation, judges whether single-phase grounding fault occurs or not according to the variation, has small error of the detection result, and can reduce the influence of the surrounding environment factors on the detection result.
Drawings
Fig. 1 is a flowchart of a single-phase ground detection method based on negative sequence current vector analysis according to the present invention.
Detailed Description
The following describes in detail a specific embodiment of a single-phase ground detection method based on negative-sequence current vector analysis according to the present invention with reference to the accompanying drawings.
As shown in fig. 1, the single-phase grounding detection method based on negative sequence current vector analysis of the present invention includes the following steps:
step (1): reading three-phase current signals;
step (2): and (3) converting the three-phase current signals by taking different phases as reference phases to obtain instantaneous negative sequence current: instantaneous negative-sequence current with a phase a current as reference: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: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: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 (3): extracting instantaneous negative sequence current
And (4): calculating a space negative sequence current vector:
and (5): calculating the negative sequence current variationN is the total number of sampling points in each period;
and (6): judging whether the negative sequence current variation is larger than zero, if so, not generating single-phase earth fault; if the value is larger than zero, entering the step (7);
and (7): judging whether the negative sequence current variation is larger than a negative sequence current variation reference value or not, and if so, not generating single-phase earth fault; and if the current is not greater than the reference value of the negative sequence current variation, a single-phase earth fault occurs.
When a single-phase earth fault occurs in a low-current earth system, the single-phase short-circuit earth fault cannot form a high-current loop, fault current is mainly provided by a line to ground capacitor, and the three-phase current signals are small in value; in the operation of the power distribution network, when a single-phase earth fault occurs, the negative sequence current variation at the fault point is the same as the zero sequence current variation, so that a smaller threshold value can be set for the reference value of the negative sequence current variation of the single-phase earth fault.
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 (2)
1. A single-phase grounding detection method based on negative sequence current vector analysis is characterized by comprising the following steps:
step (1): reading three-phase current signals;
step (2): and (3) converting the three-phase current signals by taking different phases as reference phases to obtain instantaneous negative sequence current: instantaneous negative-sequence current with a phase a current as reference: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: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: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 (3): extracting instantaneous negative sequence current
And (4): calculating a space negative sequence current vector:
and (5): calculating the negative sequence current variationN is the total number of sampling points in each period;
and (6): judging whether the negative sequence current variation is larger than zero, if so, not generating single-phase earth fault; if the value is larger than zero, entering the step (7);
and (7): judging whether the negative sequence current variation is larger than a negative sequence current variation reference value or not, and if so, not generating single-phase earth fault; and if the current is not greater than the reference value of the negative sequence current variation, a single-phase earth fault occurs.
2. The negative sequence current vector analysis-based single-phase ground detection method as claimed in claim 1, wherein the three-phase current signals are collected by a current sensor installed at the head end of the line.
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| CN113176521A (en) * | 2021-04-07 | 2021-07-27 | 国网江苏省电力有限公司南通供电分公司 | Single-phase earth fault detection method for power transmission and distribution system |
| 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 |
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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 |
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Application publication date: 20191220 |