CN114019316A - Low-voltage alternating-current distribution network line ground fault positioning detection system and method - Google Patents
Low-voltage alternating-current distribution network line ground fault positioning detection system and method Download PDFInfo
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- CN114019316A CN114019316A CN202111417322.2A CN202111417322A CN114019316A CN 114019316 A CN114019316 A CN 114019316A CN 202111417322 A CN202111417322 A CN 202111417322A CN 114019316 A CN114019316 A CN 114019316A
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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
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
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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
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/58—Testing of lines, cables or conductors
Abstract
The invention relates to the technical field of power failure detection, and discloses a system and a method for positioning and detecting a ground fault of a low-voltage alternating-current distribution network line, wherein an alternating-current signal and a pulsating direct-current signal are injected into a fault line through a transmitter so as to reproduce the ground fault of the fault line, the alternating-current signal and the pulsating direct-current signal in the fault line are respectively collected through a direct-connected sensor and a suspended sensor, the pulsating direct-current signal is subjected to analog-to-digital conversion into a digital signal, meanwhile, the alternating-current signal and the digital signal are sent to a receiver, the digital signal is subjected to waveform fitting calculation through the receiver so as to obtain a fitting waveform diagram so as to judge whether the fault signal exists or not, the alternating-current signal is subjected to signal operation so as to separate resistive current and capacitive current, a fault point can be positioned, so that the fault can be conveniently and quickly found, and the fault finding time is shortened, thereby improving the operation and maintenance efficiency.
Description
Technical Field
The invention relates to the technical field of power fault detection, in particular to a system and a method for positioning and detecting a ground fault of a low-voltage alternating-current distribution network line.
Background
Along with the increasing of living standard of people, the application of electricity in daily life of people is more and more important, but along with the increase of the demand of power consumption, the problems of unstable voltage, overcurrent, overload, short circuit and the like of electricity utilization also come along, so that the electricity utilization system is one of the research hotspots of electric power companies in order to recover power supply for users as soon as possible and reduce the power failure time in the first time.
Wherein, single-phase ground short circuit trouble is that when the direct ground system of neutral point is in single-phase ground state, the short-circuit current appears in trouble looks circuit, and the most obvious weak point of this system is: when the single-phase grounding current value is too large and exceeds the allowed specified range, effective measures are required to control the short-circuit current value.
For the fault position search of the single-phase grounding short circuit fault, due to the phase circuit with the fault, overlarge current can occur, and the maximum value reaches hundreds of amperes. At present, the fault position needs to be searched in a manual inspection mode, and the time for searching the fault in the manual inspection mode is long, so that the operation and maintenance efficiency is low. Therefore, there is a need to solve the problem of how to quickly and easily locate a fault point.
Disclosure of Invention
The invention provides a low-voltage alternating-current distribution network line ground fault positioning detection system and method, and solves the technical problem of low operation and maintenance efficiency caused by long time for manually inspecting and searching faults.
In view of the above, a first aspect of the present invention provides a system for locating and detecting a ground fault of a low-voltage ac distribution network line, including: the system comprises a transmitter, a direct connection sensor, a suspension sensor and a receiver;
the transmitter is used for injecting an alternating current signal and a pulsating direct current signal into a fault line so as to enable the fault line to have a ground fault reappear;
the direct connection sensor is used for collecting the alternating current signal in the fault line and sending the alternating current signal to the receiver;
the suspension sensor is suspended on the fault line, and is used for acquiring the pulsating direct current signal in the fault line, converting the pulsating direct current signal into a digital signal in an analog-to-digital manner, and sending the digital signal to the receiver;
the receiver is used for receiving the alternating current signal and the digital signal which are respectively sent by the direct connection sensor and the suspension sensor, carrying out waveform fitting calculation on the digital signal to obtain a fitted oscillogram, and comparing the fitted oscillogram with a preset oscillogram to judge whether a fault signal exists or not; and the fault locating device is also used for carrying out signal operation on the alternating current signal so as to separate resistive current and capacitive current, and locating a fault point according to the resistive current and the capacitive current.
Preferably, the frequency of the alternating current signal is 22Hz, and the frequency of the pulsating direct current signal is 1 Hz.
Preferably, the system further comprises a controller electrically connected to the transmitter for controlling the frequency and power of the ac signal and the pulsating dc signal output by the transmitter.
Preferably, the built-in antenna of the direct connection sensor is used for collecting the alternating current signal in the fault line through space induction and sending the alternating current signal to the receiver through a wireless transmission mode.
In a second aspect, the present invention further provides a low-voltage ac distribution network line ground fault location detection method based on the low-voltage ac distribution network line ground fault location detection system, including the following steps:
injecting an alternating current signal and a pulsating direct current signal into a fault line through a transmitter so as to reproduce the ground fault of the fault line;
collecting the alternating current signal in the fault line through a direct connection sensor, and sending the alternating current signal to a receiver;
acquiring the pulsating direct current signal in the fault line through a suspension sensor, carrying out analog-to-digital conversion on the pulsating direct current signal into a digital signal, and sending the digital signal to the receiver;
through the receiver is received directly link the sensor with what suspension sensor sent respectively alternating current signal with digital signal will digital signal carries out the wave form fitting calculation to obtain the fitting oscillogram, will fitting oscillogram and preset oscillogram are compared and are judged whether to have fault signal, will alternating current signal carries out signal operation, thereby separates resistive current and capacitive current, according to resistive current with the capacitive current is fixed a position the fault point.
According to the technical scheme, the invention has the following advantages:
according to the invention, an alternating current signal and a pulsating direct current signal are injected into a fault line through a transmitter so as to reproduce the ground fault of the fault line, the alternating current signal and the pulsating direct current signal in the fault line are respectively collected through a direct connection sensor and a suspension sensor, the pulsating direct current signal is subjected to analog-to-digital conversion into a digital signal, meanwhile, the alternating current signal and the digital signal are sent to a receiver, the digital signal is subjected to waveform fitting calculation through the receiver so as to obtain a fitting waveform diagram to judge whether the fault signal exists, the alternating current signal is subjected to signal operation, so that a resistive current and a capacitive current are separated, a fault point can be positioned, the fault is conveniently and rapidly found, the fault finding time is shortened, and the operation and maintenance efficiency is improved.
Drawings
Fig. 1 is a schematic structural diagram of a low-voltage ac distribution network line ground fault positioning detection system according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a direct connection sensor according to an embodiment of the present invention;
fig. 3 is a flowchart of a method for positioning and detecting a ground fault of a line of a low-voltage ac distribution network according to an embodiment of the present invention.
Detailed Description
The single-phase grounding short-circuit fault is that when a neutral point direct grounding system is in a single-phase grounding state, short-circuit current appears in a fault phase line, and the most remarkable weaknesses of the system are as follows: when the single-phase grounding current value is too large and exceeds the allowed specified range, effective measures are required to control the short-circuit current value.
A common concrete approach is to implement partial grounding of the neutral point. After single-phase ground short circuit fault takes place, the protection equipment in the fault line can react, sends the protection action immediately, therefore in the actual fault patrol process, the first step needs to investigate key position, for example: whether the tower collapses or not, whether the line is interrupted or not and the like. In order to control the influence range of the fault, fault isolation should be performed immediately, so that the fault search range is reduced, the position of a fault line is preliminarily predicted, instant power supply test is performed on the line, the current value of the line is measured, and when the voltage of a neutral line is found to be larger and reach 50V, the single-phase ground short-circuit fault occurs on the line. Scientific and effective measures and methods are to be taken to eliminate the faults: firstly, the operation of a non-fault phase is immediately suspended, independent power supply is carried out on a fault, simultaneously, a pincerlike metering device is introduced to correspondingly measure the current of the fault phase, a neutral line and the like, when a large difference occurs between the two sides, the existence of a fault point is indicated, at the moment, the fault direction needs to be distinguished according to the measured current difference, and after repeated measurement tests, if the fault phase current is consistent with the neutral line current, the subsequent line is safe, and on the contrary, the subsequent current easily has fault hidden trouble.
However, for the search for such short-circuit faults, particular attention is paid to: because of the failed phase path, an excessive current, up to hundreds of amperes, occurs therein. The first step of fault finding is to lock the transformer, check whether it has abnormal noise, and observe the user lamp brightness of the fault phase correspondingly, comparing with other phase brightness, if there is large difference, it means the fault problem exists. In order to ensure the troubleshooting safety, the fault phase should be isolated first, so as to protect the safety of the non-fault phase and prevent other electrical equipment from being adversely interfered by the fault phase. And simultaneously, the current of a non-fault phase circuit is temporarily interrupted, only the fault phase is independently powered, and meanwhile, a clamp-on current metering device is introduced to measure the current of the branch rod. In the actual current measurement process, if the current of the branch line and the current of the power distribution cabinet are equal in magnitude and approximately consistent with the current value of the neutral line, the serious fault problem exists in the back-end line. By the method, the fault point searching range is gradually reduced, and the current in the branch line is further measured to correspondingly find the fault point.
For the fault position search of the single-phase grounding short circuit fault, due to the phase circuit with the fault, overlarge current can occur, and the maximum value reaches hundreds of amperes. At present, the fault position needs to be searched in a manual inspection mode, and the time for searching the fault in the manual inspection mode is long, so that the operation and maintenance efficiency is low. Therefore, there is a need to solve the problem of how to quickly and easily locate a fault point.
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
For easy understanding, please refer to fig. 1, the present invention provides a system for positioning and detecting a ground fault of a low-voltage ac distribution network line, comprising: a transmitter 10, a direct connection sensor 20, a suspension sensor 30 and a receiver 40;
the transmitter 10 is used to inject an ac signal and a pulsating dc signal into the faulty line so that the faulty line ground fault is reproduced.
It should be noted that, when the overhead line is in an offline state, the transmitter 10 injects an ac signal and a pulsating dc signal into the faulty line. In a specific example, the frequency of the alternating current signal is 22Hz, and the frequency of the pulsating direct current signal is 1Hz, so that the fault line is grounded to form a fault current loop, and fault recurrence is realized.
The direct connection sensor 20 is configured to collect an ac signal in a faulty line and send the ac signal to the receiver 40;
in this embodiment, as shown in fig. 2, the direct connection sensor is provided with an internal antenna, and is configured to spatially sense and collect an ac signal in a faulty line, and send the ac signal to the receiver 40 in a wireless transmission manner.
The suspension sensor 30 is suspended on the fault line, and is used for collecting the pulsating direct current signal in the fault line, converting the pulsating direct current signal into a digital signal in an analog-to-digital manner, and sending the digital signal to the receiver 40;
in this embodiment, the suspension sensor 30 has a giant magneto-resistance and an a/D processor built therein, and can sense the pulsating direct current signal in the fault line, and convert the pulsating direct current signal into a digital signal through the a/D processor.
The receiver 40 is configured to receive the alternating current signal and the digital signal respectively sent by the direct connection sensor 20 and the suspension sensor 30, perform waveform fitting calculation on the digital signal to obtain a fitted waveform diagram, and compare the fitted waveform diagram with a preset waveform diagram to determine whether a fault signal exists; and the device is also used for performing signal operation on the alternating current signal so as to separate resistive current and capacitive current, and positioning a fault point according to the resistive current and the capacitive current.
It should be noted that the working process of this embodiment is as follows:
the transmitter 10 injects an alternating current signal and a pulsating direct current signal into a fault line so as to reproduce the ground fault of the fault line, collects the alternating current signal in the fault line below the fault line through the direct connection sensor 20, sends the alternating current signal to the receiver 40, is suspended on the fault line through the suspension sensor 30, collects the pulsating direct current signal in the fault line, converts the pulsating direct current signal into a digital signal in an analog-to-digital manner, and sends the digital signal to the receiver 40. After receiving the ac signal and the digital signal respectively sent by the direct connection sensor 20 and the suspension sensor 30, the receiver 40 performs waveform fitting calculation on the digital signal to obtain a fitted waveform diagram, and compares the fitted waveform diagram with a preset waveform diagram to determine whether a fault signal exists, where the preset waveform diagram is a standard fault-free waveform diagram, and compares the fitted waveform diagram with the preset waveform diagram to determine whether a fault signal exists. After the fault signal is judged and stored, the alternating current signal is subjected to signal operation, so that resistive current and capacitive current are separated, the resistive current and the capacitive current are both in front of a fault point, only the capacitive current is in the rear of the fault point, and the resistive current is not in the rear of the fault point, so that the fault point can be positioned through the characteristic, the fault can be conveniently and quickly found, the fault finding time is shortened, and the operation and maintenance efficiency is improved.
In this embodiment, the system further comprises a controller electrically connected to the transmitter 10 for controlling the frequency and power of the ac signal and the pulsating dc signal output by the transmitter 10.
Wherein, according to the field situation, the controller can be clamped on the line side of the switch cabinet by using a short connecting wire; if the cable is connected to an overhead line, a patch panel is selected to extend the connection, and a wire hanging rod is used for hanging the cable on a fault line.
The above is a detailed description of an embodiment of the low-voltage ac distribution network line ground fault positioning detection system provided by the present invention, and the following is a low-voltage ac distribution network line ground fault positioning detection method based on the low-voltage ac distribution network line ground fault positioning detection system provided by the present invention.
As shown in fig. 3, the method for positioning and detecting the ground fault of the low-voltage ac distribution network line based on the system for positioning and detecting the ground fault of the low-voltage ac distribution network line provided by the present invention includes the following steps:
s100, injecting an alternating current signal and a pulsating direct current signal into a fault line through a transmitter so as to reproduce the ground fault of the fault line;
s200, collecting an alternating current signal in a fault line through a direct connection sensor, and sending the alternating current signal to a receiver;
s300, acquiring a pulsating direct current signal in a fault line through a suspension sensor, performing analog-to-digital conversion on the pulsating direct current signal into a digital signal, and sending the digital signal to a receiver;
s400, receiving alternating current signals and digital signals respectively sent by a direct connection sensor and a suspension sensor through a receiver, performing waveform fitting calculation on the digital signals to obtain a fitted oscillogram, comparing the fitted oscillogram with a preset oscillogram to judge whether fault signals exist, performing signal operation on the alternating current signals to separate resistive current and capacitive current, and positioning fault points according to the resistive current and the capacitive current.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (5)
1. The utility model provides a net line ground fault location detecting system is joined in marriage to low pressure interchange, its characterized in that includes: the system comprises a transmitter, a direct connection sensor, a suspension sensor and a receiver;
the transmitter is used for injecting an alternating current signal and a pulsating direct current signal into a fault line so as to enable the fault line to have a ground fault reappear;
the direct connection sensor is used for collecting the alternating current signal in the fault line and sending the alternating current signal to the receiver;
the suspension sensor is suspended on the fault line, and is used for acquiring the pulsating direct current signal in the fault line, converting the pulsating direct current signal into a digital signal in an analog-to-digital manner, and sending the digital signal to the receiver;
the receiver is used for receiving the alternating current signal and the digital signal which are respectively sent by the direct connection sensor and the suspension sensor, carrying out waveform fitting calculation on the digital signal to obtain a fitted oscillogram, and comparing the fitted oscillogram with a preset oscillogram to judge whether a fault signal exists or not; and the fault locating device is also used for carrying out signal operation on the alternating current signal so as to separate resistive current and capacitive current, and locating a fault point according to the resistive current and the capacitive current.
2. The system of claim 1, wherein the frequency of the ac signal is 22Hz, and the frequency of the pulsating dc signal is 1 Hz.
3. The system according to claim 1, further comprising a controller electrically connected to said transmitter for controlling the frequency and power of said ac signal and said pulsating dc signal outputted from said transmitter.
4. The system according to claim 1, wherein the direct connection sensor is provided with an internal antenna, and is configured to spatially sense and collect the ac signal in the faulty line, and transmit the ac signal to the receiver in a wireless transmission manner.
5. A low-voltage AC distribution network line ground fault positioning detection method based on the low-voltage AC distribution network line ground fault positioning detection system of any one of claims 1 to 4 is characterized by comprising the following steps:
injecting an alternating current signal and a pulsating direct current signal into a fault line through a transmitter so as to reproduce the ground fault of the fault line;
collecting the alternating current signal in the fault line through a direct connection sensor, and sending the alternating current signal to a receiver;
acquiring the pulsating direct current signal in the fault line through a suspension sensor, carrying out analog-to-digital conversion on the pulsating direct current signal into a digital signal, and sending the digital signal to the receiver;
through the receiver is received directly link the sensor with what suspension sensor sent respectively alternating current signal with digital signal will digital signal carries out the wave form fitting calculation to obtain the fitting oscillogram, will fitting oscillogram and preset oscillogram are compared and are judged whether to have fault signal, will alternating current signal carries out signal operation, thereby separates resistive current and capacitive current, according to resistive current with the capacitive current is fixed a position the fault point.
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| CN202111417322.2A CN114019316A (en) | 2021-11-25 | 2021-11-25 | Low-voltage alternating-current distribution network line ground fault positioning detection system and method |
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| CN202111417322.2A CN114019316A (en) | 2021-11-25 | 2021-11-25 | Low-voltage alternating-current distribution network line ground fault positioning detection system and method |
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| CN103278737A (en) * | 2013-04-25 | 2013-09-04 | 河北兆联电气设备科技有限公司 | Direct-current self-injection type small-current grounding and route selecting system and method |
| CN103760467A (en) * | 2014-01-27 | 2014-04-30 | 西安兴汇电力科技有限公司 | Method for inspecting single-phase earth fault point of power distribution network |
| CN204228888U (en) * | 2014-11-19 | 2015-03-25 | 中国石油化工股份有限公司 | New distribution line fault position testers |
| JP2021004855A (en) * | 2019-06-27 | 2021-01-14 | 古河電気工業株式会社 | Ground fault detection method and device |
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2021
- 2021-11-25 CN CN202111417322.2A patent/CN114019316A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103278737A (en) * | 2013-04-25 | 2013-09-04 | 河北兆联电气设备科技有限公司 | Direct-current self-injection type small-current grounding and route selecting system and method |
| CN103760467A (en) * | 2014-01-27 | 2014-04-30 | 西安兴汇电力科技有限公司 | Method for inspecting single-phase earth fault point of power distribution network |
| CN204228888U (en) * | 2014-11-19 | 2015-03-25 | 中国石油化工股份有限公司 | New distribution line fault position testers |
| JP2021004855A (en) * | 2019-06-27 | 2021-01-14 | 古河電気工業株式会社 | Ground fault detection method and device |
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