CN114184981A - Low-voltage electric leakage positioning equipment and offline electric leakage evaluation method - Google Patents
Low-voltage electric leakage positioning equipment and offline electric leakage evaluation method Download PDFInfo
- Publication number
- CN114184981A CN114184981A CN202111509614.9A CN202111509614A CN114184981A CN 114184981 A CN114184981 A CN 114184981A CN 202111509614 A CN202111509614 A CN 202111509614A CN 114184981 A CN114184981 A CN 114184981A
- Authority
- CN
- China
- Prior art keywords
- leakage
- voltage
- phase
- low
- line
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000011156 evaluation Methods 0.000 title claims abstract description 33
- 238000005070 sampling Methods 0.000 claims abstract description 22
- 238000005259 measurement Methods 0.000 claims abstract description 10
- 230000006698 induction Effects 0.000 claims description 12
- 238000002347 injection Methods 0.000 claims description 12
- 239000007924 injection Substances 0.000 claims description 12
- 238000009413 insulation Methods 0.000 claims description 9
- 230000016507 interphase Effects 0.000 claims description 9
- 230000008859 change Effects 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 8
- 239000003795 chemical substances by application Substances 0.000 claims description 6
- 230000003750 conditioning effect Effects 0.000 claims description 6
- 238000001514 detection method Methods 0.000 claims description 5
- 230000004907 flux Effects 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 230000035699 permeability Effects 0.000 claims description 3
- 230000001012 protector Effects 0.000 abstract description 8
- 238000009434 installation Methods 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 6
- 230000008901 benefit Effects 0.000 description 3
- 238000001914 filtration Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000003745 diagnosis Methods 0.000 description 1
- 230000004807 localization Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000011218 segmentation Effects 0.000 description 1
Images
Classifications
-
- 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
- G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
-
- 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
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
The invention provides a low-voltage leakage positioning device and an off-line leakage evaluation method, which are used for accurately selecting lines of a leakage fault line of a platform area and positioning the position of the leakage fault, under the power failure state of a tested line, a host of a low-voltage leakage positioning instrument applies specific voltage to A, B, C, N four-phase lines of the tested platform area, current is injected into the four-phase lines through a current sampling circuit for measurement, the resistance value of the tested line is further calculated, the ground resistance value of each phase is measured according to a complex leakage model, the leakage current and the daily average leakage current of each phase line of the tested platform area are finally calculated according to a A, B, C, N ground resistance value, the leakage evaluation is carried out on the tested platform area, and when the ground resistance value of any phase is smaller than a threshold value, the platform area is judged to have the leakage fault; the invention can standardize the configuration of the leakage protector of the rural power distribution transformer station area, improve the installation rate and the commissioning rate of the transformer station area protection, exert the efficiency of the leakage protector and furthest ensure the life and property safety of people.
Description
Technical Field
The invention relates to the technical field of power grid operation and maintenance, in particular to low-voltage electric leakage positioning equipment and an off-line electric leakage evaluation method.
Background
The rural distribution network line electric leakage is a pain point and a difficulty which are puzzled on the safe and economic operation of a low-voltage rural distribution network, and an effective technical means is not available for a long time to accurately position an electric leakage fault, so that the following three problems are brought to a power grid enterprise: firstly, the power supply reliability is reduced, the leakage of a low-voltage line occurs sometimes, the total leakage protection tripping of a transformer area is easy to cause, and the normal production and life power utilization of customers is greatly influenced; secondly, the safety of power utilization is difficult to guarantee, in order to improve the reliability of power supply, part of transformer areas are withdrawn from leakage protection or are adjusted to a high fixed value, and when a leakage fault occurs, the leakage protection cannot act, so that a fire disaster or an electric shock casualty accident is caused; and thirdly, the economic benefit of the enterprise is damaged, intermittent electric leakage occurs sometimes, and the intermittent electric leakage is difficult to find and dispose in time, so that the benefit of the power grid enterprise is lost.
Disclosure of Invention
The invention provides low-voltage leakage positioning equipment and an off-line leakage evaluation method, which can standardize the configuration of leakage protectors of rural distribution substations, improve the installation rate and the commissioning rate of substation protection, exert the efficiency of the leakage protectors, and ensure the life and property safety of people to the maximum extent.
The invention adopts the following technical scheme.
The off-line leakage evaluation method of low-voltage leakage is used for accurately selecting lines of a leakage fault line of a transformer area and accurately positioning the position of the leakage fault, and comprises the steps of applying specific voltage to A, B, C, N four-phase lines of the transformer area by a host of a low-voltage leakage locator in the power failure state of the tested line, injecting current into the four-phase lines through a current sampling circuit for measurement, further calculating to obtain the resistance value of the tested line, then measuring to-ground resistance values of all phases according to a complex leakage model, finally calculating the leakage current and daily average leakage current of all the phase lines of the transformer area to be tested according to a A, B, C, N to-ground resistance value, evaluating the leakage of the transformer area to be tested, and judging that the transformer area has the leakage fault when the ground resistance value of any phase is smaller than a threshold value.
In the complex leakage model, RA0、RB0、RC0、RN0The method comprises the following steps that insulation resistance values of an A phase, a B phase, a C phase and an N phase which need to be measured during off-line leakage evaluation are evaluated, if the insulation resistance values are infinite, the phase is evaluated to have no leakage, if the insulation resistance values are specific values which can be measured in a measuring range, the phase is evaluated to have leakage, and the following formula exists in a model;
RAN＝RAN0//(RA0+RN0//(RBN0+RB0)//(RCN0+RC0) Formula nine;
RBN＝RBN0//(RB0+RN0//(RAN0+RA0)//(RCN0+RC0) Equation ten;
RCN＝RCN0//(RC0+RN0//(RAN0+RA0)//(RBN0+RB0) Formula eleven;
RAG＝RA0//[RAN0+(RBN0+RB0)//(RCN0+RC0)//RN0]a formula twelve;
RBG＝RB0//[RBN0+(RAN0+RA0)//(RCN0+RC0)//RN0]a formula thirteen;
RCG＝RC0//[RCN0+(RAN0+RA0)//(RBN0+RB0)//RN0]a formula fourteen;
RNG＝RN0//(RAN0+RA0)//(RBN0+RB0)//(RCN0+RC0) A formula fifteen;
in the formula nine to the formula fifteen, when the phase A is alternated with the phase N, the resistance RANPhase B and phase N interphase resistance RBNResistance R between C phase and N phaseCNPhase A and phase G interphase resistance RAGPhase B and phase G interphase resistance RBGResistance R between C phase and G phaseCGResistance R between N phase and G phaseNGFor the known quantity obtained by the measurement of the low-voltage leakage locator host, R can be calculated according to a formula from nine to fifteenA0、RB0、RC0、RN0、RAN0、RBN0、RCN0The value is obtained.
The off-line electric leakage evaluation method comprises the steps that under the power failure state of a tested line, a host of a low-voltage electric leakage locator applies specific voltage to an A, B, C, N four-phase line of a tested platform area, and a current sampling circuit of the host of the low-voltage electric leakage locator injects current into the four-phase line for measurement;
hardware of a host of the low-voltage leakage locator for offline leakage evaluation comprises an MCU, a current sampling circuit, a voltage division circuit and a voltage following circuit;
the current sampling circuit comprises a voltage source, a current sampling resistor and an IC1, wherein T is a resistor to be detected;
the voltage division circuit is used for enabling the full-range voltage range output by the current sampling circuit to meet the ADC acquisition range of the MCU.
The low-voltage leakage positioning equipment comprises a low-voltage leakage positioning instrument host and a low-voltage leakage positioning instrument slave, wherein the hardware part of the low-voltage leakage positioning instrument host comprises a battery charging circuit, a battery, a DC/DC circuit, a display, a key, a buzzer, an MCU, a gear shifting circuit, an integrating circuit, an amplifying circuit, a full-wave rectifying circuit, a filter circuit, an MCU, a signal conditioning circuit, a current limiting resistor, an analog channel switch, a current sampling circuit, a voltage dividing circuit and a voltage following circuit.
The hardware part of the low-voltage leakage locator host further comprises a Rogowski coil used for an online leakage evaluation method, and the hardware used for online leakage evaluation further comprises a shift circuit, an integrating circuit, an amplifying circuit, a full-wave rectifying circuit, a low-pass filter circuit and an MCU (microprogrammed control Unit);
the online electric leakage evaluation method comprises the steps that current vector sums of A, B, C, N phases of a tested station area are measured by low-voltage electric leakage positioning equipment through a Rogowski coil in an online working state, if the current vector sum of the tested station area measured by the Rogowski coil is not zero, the electric leakage exists in the station area, and if the current vector sum of the tested station area measured by the Rogowski coil is zero, the electric leakage does not exist in the station area;
when the phase current vector sum of the tested platform area A, B, C, N is measured, the Rogowski coil outputs a differential signal of A, B, C, N phase current vector sum, and the output signal is in a linear relation with the change rate of the tested current;
the output signal of the Rogowski coil enters an integrating circuit through a shifting circuit according to proportions of different weights, the integrating circuit performs integral reduction on a differential signal of a Rogowski coil output current vector sum, and an alternating voltage signal for accurately reproducing the waveform of the measured current signal is obtained after a voltage signal output by the Rogowski coil is integrated;
the amplifying circuit amplifies the signal output by the integrating circuit; the full-wave rectification circuit is connected with the amplifying circuit and performs full-wave rectification on the signal output by the amplifying circuit; the low-pass filter circuit is connected with the full-wave rectifying circuit, and performs low-pass filtering on the signal output by the full-wave rectifying circuit to output an effective value of the current to be measured.
The low-voltage leakage positioning equipment is used for carrying out leakage positioning on leakage current with loop characteristics, when the leakage positioning is carried out, a characteristic signal is injected into a fault line by using a low-voltage leakage positioning instrument host, due to the loop characteristics of the leakage current, the injected characteristic signal only exists in a loop to the ground, namely, the injected characteristic signal exists on the front side of a fault point and cannot be on the rear side of the fault point, and then the leakage fault position is positioned by judging whether the injected characteristic signal exists in a tested line, wherein the specific method comprises the following steps: the accurate positioning of the position of the leakage fault point is realized under the matching use of the slave machine of the low-voltage leakage position indicator, the rough sectional detection is firstly carried out, and then the accurate positioning is carried out.
In the low-voltage leakage locator host, a hardware part for positioning leakage comprises an MCU, a signal conditioning circuit, a current-limiting resistor and an analog channel switch;
when the power-off-state transformer area line is subjected to leakage positioning, a low-voltage leakage positioning instrument host injects characteristic signals into a fault line, the characteristic signals comprise voltage signals for leakage evaluation and pulse signals for leakage positioning, the low-voltage leakage positioning instrument slave receives the characteristic signals and outputs induction signals from a magnetic core coil sensor, and the induction voltage of the induction signals is in direct proportion to the voltage change rate of the characteristic signals injected by the low-voltage leakage positioning instrument host.
The low-voltage leakage locator host machine adopts a pulse signal as a characteristic signal injected into a fault line; the pulse signal is generated by a half-bridge circuit in a low-voltage electric leakage locator host.
In the electric leakage positioning, a low-voltage electric leakage positioning instrument host computer generates a coded frequency signal to be injected into a fault line according to the agreement of a master-slave machine, signal injection characteristic coding signals are only carried out on one phase in the fault line each time, then a low-voltage electric leakage positioning instrument slave computer is used for carrying out characteristic signal decoding in a non-contact mode along the electric leakage fault line, the position of an electric leakage fault point is roughly segmented, and then the electric leakage fault point is accurately positioned.
The software of the low-voltage leakage locator host is based on a Linux + QT framework, and when leakage assessment operation which consumes longer time is executed, independent thread operation is adopted to avoid influencing the execution of other software modules;
when generating the encoded frequency signal for signal injection, the injection signals of the A phase, the B phase, the C phase and the N phase adopt the same encoding mode, and the signal contents of the injection signals of the A phase, the B phase, the C phase and the N phase are different;
the low-voltage leakage locator slave machine comprises a magnetic core coil sensor, a low-voltage leakage locator slave machine PCB and a battery;
after the low-voltage electric leakage locator host computer injects characteristic signal into the fault line, characteristic signal produces magnetic field around the fault line, and it is V to establish the voltage that low-voltage electric leakage locator host computer injects characteristic signal into the electric leakage fault line, and the frequency is F, and fault line ground resistance R, the fault line electric current I of flowing through, then can obtain the magnetic induction strength B who locates apart from fault line d according to biot-savart law and be:
wherein mu0Is a vacuum permeability, mu0＝4π×10-7Tesla meters per ampere;
the low-voltage leakage locator slave machine receives the magnetic field of the characteristic signal through the magnetic core coil sensor and interprets the characteristic signal from the magnetic field, and the magnetic core coil sensor outputs the magnitude of the induced electromotive force xi and the change rate of the magnetic flux passing through the loop according to the Faraday's law of electromagnetic induction
In a direct proportion to the total weight of the composition,
and the low-voltage leakage locator slave machine receives and demodulates the output signal of the magnetic core coil sensor, and further identifies whether the demodulated signal is a characteristic signal injected by the low-voltage leakage locator host machine.
The invention can realize accurate line selection of a leakage fault line and accurate positioning of a leakage fault position, can better implement DL/T736-2010 rural power grid leakage protector installation and operation rules and national power grid company rural low-voltage power grid leakage protector configuration principles (State grid rural safety No. 2012/39), can standardize the configuration of the leakage protector of a rural power distribution station, improve the installation rate and the commissioning rate of station protection, exert the efficiency of the leakage protector, furthest ensure the life and property safety of people, and has important social significance and economic benefit.
The invention innovatively provides that a characteristic signal is injected into a line to be detected by using the characteristics of a low-voltage leakage fault line through a low-voltage leakage position indicator host, and if the line injected by the characteristic signal is a leakage fault line, the characteristic signal injected by the low-voltage leakage position indicator host exists in a fault loop, so that the leakage fault line selection function is realized. And the low-voltage leakage locator host injects a characteristic coding signal into the leakage fault line, and the low-voltage leakage locator slave is used for decoding the characteristic signal along the leakage fault line in a non-contact mode. Before the fault point, the injected characteristic coding signal continuously exists, and after the fault point, the injected characteristic coding signal disappears. The fault location can be determined quickly by performing rough segmentation and then performing accurate positioning.
Drawings
The invention is described in further detail below with reference to the following figures and detailed description:
FIG. 1 is a schematic diagram of the low voltage leakage location principle of the present invention;
FIG. 2 is another schematic diagram of the low voltage leakage localization principle of the present invention;
FIG. 3 is a schematic diagram of the hardware principle of a low-voltage leakage locator host;
FIG. 4 is a schematic diagram of a complex leakage model for offline leakage assessment;
FIG. 5 is a schematic diagram of an A, B, C, N phase coil of a tested station area circuit into a Rogowski coil in the online leakage evaluation;
fig. 6 is a schematic diagram of the operation of the leakage current location of the present invention.
Detailed Description
As shown in the figure, the offline leakage evaluation method of low-voltage leakage is used for accurately selecting a line of a leakage fault line of a transformer area and accurately positioning a leakage fault position, and the offline leakage evaluation method is characterized in that under the power failure state of a tested line, a host of a low-voltage leakage locator applies specific voltage to A, B, C, N four-phase lines of the tested transformer area, current is injected into the four-phase lines through a current sampling circuit for measurement, the resistance value of the tested line is calculated, the ground resistance value of each phase is measured according to a complex leakage model, the leakage current and the daily average leakage current of each phase line of the tested transformer area are calculated according to a A, B, C, N ground resistance value, the leakage evaluation of the tested transformer area is performed, and when the ground resistance value of any phase is smaller than a threshold value, the existence of the leakage fault in the transformer area is determined.
In the complex leakage model, RA0、RB0、RC0、RN0The method comprises the following steps that insulation resistance values of an A phase, a B phase, a C phase and an N phase which need to be measured during off-line leakage evaluation are evaluated, if the insulation resistance values are infinite, the phase is evaluated to have no leakage, if the insulation resistance values are specific values which can be measured in a measuring range, the phase is evaluated to have leakage, and the following formula exists in a model;
RAN＝RAN0//(RA0+RN0//(RBN0+RB0)//(RCN0+RC0) Formula nine;
RBN＝RBN0//(RB0+RN0//(RAN0+RA0)//(RCN0+RC0) Equation ten;
RCN＝RCN0//(RC0+RN0//(RAN0+RA0)//(RBN0+RB0) Formula eleven;
RAG＝RA0//[RAN0+(RBN0+RB0)//(RCN0+RC0)//RN0]a formula twelve;
RBG＝RB0//[RBN0+(RAN0+RA0)//(RCN0+RC0)//RN0]a formula thirteen;
RCG＝RC0//[RCN0+(RAN0+RA0)//(RBN0+RB0)//RN0]a formula fourteen;
RNG＝RN0//(RAN0+RA0)//(RBN0+RB0)//(RCN0+RC0) A formula fifteen;
in the formula nine to the formula fifteen, when the phase A is alternated with the phase N, the resistance RANPhase B and phase N interphase resistance RBNResistance R between C phase and N phaseCNPhase A and phase G interphase resistance RAGPhase B and phase G interphase resistance RBGResistance R between C phase and G phaseCGResistance R between N phase and G phaseNGFor the known quantity obtained by the measurement of the low-voltage leakage locator host, R can be calculated according to a formula from nine to fifteenA0、RB0、RC0、RN0、RAN0、RBN0、RCN0The value is obtained.
The off-line electric leakage evaluation method comprises the steps that under the power failure state of a tested line, a host of a low-voltage electric leakage locator applies specific voltage to an A, B, C, N four-phase line of a tested platform area, and a current sampling circuit of the host of the low-voltage electric leakage locator injects current into the four-phase line for measurement;
hardware of a host of the low-voltage leakage locator for offline leakage evaluation comprises an MCU, a current sampling circuit, a voltage division circuit and a voltage following circuit;
the current sampling circuit comprises a voltage source, a current sampling resistor and an IC1, wherein T is a resistor to be detected;
the voltage division circuit is used for enabling the full-range voltage range output by the current sampling circuit to meet the ADC acquisition range of the MCU.
The low-voltage leakage positioning equipment comprises a low-voltage leakage positioning instrument host and a low-voltage leakage positioning instrument slave, wherein the hardware part of the low-voltage leakage positioning instrument host comprises a battery charging circuit, a battery, a DC/DC circuit, a display, a key, a buzzer, an MCU, a gear shifting circuit, an integrating circuit, an amplifying circuit, a full-wave rectifying circuit, a filter circuit, an MCU, a signal conditioning circuit, a current limiting resistor, an analog channel switch, a current sampling circuit, a voltage dividing circuit and a voltage following circuit.
The hardware part of the low-voltage leakage locator host further comprises a Rogowski coil used for an online leakage evaluation method, and the hardware used for online leakage evaluation further comprises a shift circuit, an integrating circuit, an amplifying circuit, a full-wave rectifying circuit, a low-pass filter circuit and an MCU (microprogrammed control Unit);
the online electric leakage evaluation method comprises the steps that current vector sums of A, B, C, N phases of a tested station area are measured by low-voltage electric leakage positioning equipment through a Rogowski coil in an online working state, if the current vector sum of the tested station area measured by the Rogowski coil is not zero, the electric leakage exists in the station area, and if the current vector sum of the tested station area measured by the Rogowski coil is zero, the electric leakage does not exist in the station area;
when the phase current vector sum of the tested platform area A, B, C, N is measured, the Rogowski coil outputs a differential signal of A, B, C, N phase current vector sum, and the output signal is in a linear relation with the change rate of the tested current;
the output signal of the Rogowski coil enters an integrating circuit through a shifting circuit according to proportions of different weights, the integrating circuit performs integral reduction on a differential signal of a Rogowski coil output current vector sum, and an alternating voltage signal for accurately reproducing the waveform of the measured current signal is obtained after a voltage signal output by the Rogowski coil is integrated;
the amplifying circuit amplifies the signal output by the integrating circuit; the full-wave rectification circuit is connected with the amplifying circuit and performs full-wave rectification on the signal output by the amplifying circuit; the low-pass filter circuit is connected with the full-wave rectifying circuit, and performs low-pass filtering on the signal output by the full-wave rectifying circuit to output an effective value of the current to be measured.
The low-voltage leakage positioning equipment is used for carrying out leakage positioning on leakage current with loop characteristics, when the leakage positioning is carried out, a characteristic signal is injected into a fault line by using a low-voltage leakage positioning instrument host, due to the loop characteristics of the leakage current, the injected characteristic signal only exists in a loop to the ground, namely, the injected characteristic signal exists on the front side of a fault point and cannot be on the rear side of the fault point, and then the leakage fault position is positioned by judging whether the injected characteristic signal exists in a tested line, wherein the specific method comprises the following steps: the accurate positioning of the position of the leakage fault point is realized under the matching use of the slave machine of the low-voltage leakage position indicator, the rough sectional detection is firstly carried out, and then the accurate positioning is carried out.
In the low-voltage leakage locator host, a hardware part for positioning leakage comprises an MCU, a signal conditioning circuit, a current-limiting resistor and an analog channel switch;
when the power-off-state transformer area line is subjected to leakage positioning, a low-voltage leakage positioning instrument host injects characteristic signals into a fault line, the characteristic signals comprise voltage signals for leakage evaluation and pulse signals for leakage positioning, the low-voltage leakage positioning instrument slave receives the characteristic signals and outputs induction signals from a magnetic core coil sensor, and the induction voltage of the induction signals is in direct proportion to the voltage change rate of the characteristic signals injected by the low-voltage leakage positioning instrument host.
The low-voltage leakage locator host machine adopts a pulse signal as a characteristic signal injected into a fault line; the pulse signal is generated by a half-bridge circuit in a low-voltage electric leakage locator host.
In the electric leakage positioning, a low-voltage electric leakage positioning instrument host computer generates a coded frequency signal to be injected into a fault line according to the agreement of a master-slave machine, signal injection characteristic coding signals are only carried out on one phase in the fault line each time, then a low-voltage electric leakage positioning instrument slave computer is used for carrying out characteristic signal decoding in a non-contact mode along the electric leakage fault line, the position of an electric leakage fault point is roughly segmented, and then the electric leakage fault point is accurately positioned.
The software of the low-voltage leakage locator host is based on a Linux + QT framework, and when leakage assessment operation which consumes longer time is executed, independent thread operation is adopted to avoid influencing the execution of other software modules;
when generating the encoded frequency signal for signal injection, the injection signals of the A phase, the B phase, the C phase and the N phase adopt the same encoding mode, and the signal contents of the injection signals of the A phase, the B phase, the C phase and the N phase are different;
the low-voltage leakage locator slave machine comprises a magnetic core coil sensor, a low-voltage leakage locator slave machine PCB and a battery;
after the low-voltage electric leakage locator host computer injects characteristic signal into the fault line, characteristic signal produces magnetic field around the fault line, and it is V to establish the voltage that low-voltage electric leakage locator host computer injects characteristic signal into the electric leakage fault line, and the frequency is F, and fault line ground resistance R, the fault line electric current I of flowing through, then can obtain the magnetic induction strength B who locates apart from fault line d according to biot-savart law and be:
wherein mu0Is a vacuum permeability, mu0＝4π×10-7Tesla meters per ampere;
the low-voltage leakage locator slave machine receives the magnetic field of the characteristic signal through the magnetic core coil sensor and interprets the characteristic signal from the magnetic field, and the magnetic core coil sensor outputs the magnitude of the induced electromotive force xi and the change rate of the magnetic flux passing through the loop according to the Faraday's law of electromagnetic induction
In a direct proportion to the total weight of the composition,
and the low-voltage leakage locator slave machine receives and demodulates the output signal of the magnetic core coil sensor, and further identifies whether the demodulated signal is a characteristic signal injected by the low-voltage leakage locator host machine.
Example 1:
when the fault line is detected from the slave machine to locate the leakage fault point, the whole fault line is roughly segmented, and a plurality of points to be detected are selected. Starting the slave machine, opening the assistant APP of the off/on-line double-channel micro-current leakage diagnosis device, connecting Bluetooth, clicking to start monitoring, enabling a detection area of the slave machine to be close to a measured line and to be vertical to the measured line, and after the assistant APP sounds a tic, going to the next point to be tested until the tic is no longer heard, determining a rough fault position (the line fault point is between the tic and the silent) according to the principle, and gradually reducing the range until the line fault point is found.
And after the fault points of the line are processed, performing off-line electric leakage evaluation on the fault line again, if the result shows that the fault line is a fault-free line, indicating that the fault is removed, and if the line is still detected to be a fault line and indicating that the line has a plurality of fault points, performing secondary machine detection again to continue removing the fault.
Claims (9)
1. The off-line leakage evaluation method of low-voltage leakage is used for accurately selecting a line of a leakage fault line of a transformer area and accurately positioning a leakage fault position, and is characterized in that: the off-line electric leakage evaluation method comprises the steps that under the power failure state of a tested circuit, a host of a low-voltage electric leakage locator applies specific voltage to A, B, C, N four-phase circuits of a tested platform area, current is injected into the four-phase circuits through a current sampling circuit for measurement, then the resistance value of the tested circuit is calculated, the ground resistance value of each phase is measured according to a complex electric leakage model, finally, the leakage current and the daily average leakage current of each phase circuit of the tested platform area are calculated according to a A, B, C, N ground resistance value, electric leakage evaluation is conducted on the tested platform area, and when the ground resistance value of any phase is smaller than a threshold value, the existence of electric leakage fault in the platform area is judged.
2. The off-line leakage assessment method of low-voltage leakage according to claim 1, characterized in that: in the complex leakage model, RA0、RB0、RC0、RN0The method comprises the following steps that insulation resistance values of an A phase, a B phase, a C phase and an N phase which need to be measured during off-line leakage evaluation are evaluated, if the insulation resistance values are infinite, the phase is evaluated to have no leakage, if the insulation resistance values are specific values which can be measured in a measuring range, the phase is evaluated to have leakage, and the following formula exists in a model;
RAN＝RAN0//(RA0+RN0//(RBN0+RB0)//(RCN0+RC0) Formula nine;
RBN＝RBN0//(RB0+RN0//(RAN0+RA0)//(RCN0+RC0) Equation ten;
RCN＝RCN0//(RC0+RN0//(RAN0+RA0)//(RBN0+RB0) Formula eleven;
RAG＝RA0//[RAN0+(RBN0+RB0)//(RCN0+RC0)//RN0]a formula twelve;
RBG＝RB0//[RBN0+(RAN0+RA0)//(RCN0+RC0)//RN0]a formula thirteen;
RCG＝RC0//[RCN0+(RAN0+RA0)//(RBN0+RB0)//RN0]a formula fourteen;
RNG＝RN0//(RAN0+RA0)//(RBN0+RB0)//(RCN0+RC0) A formula fifteen;
in the formula nine to the formula fifteen, when the phase A is alternated with the phase N, the resistance RANPhase B and phase N interphase resistance RBNResistance R between C phase and N phaseCNPhase A and phase G interphase resistance RAGPhase B and phase G interphase resistance RBGResistance R between C phase and G phaseCGResistance R between N phase and G phaseNGFor the known quantity obtained by the measurement of the low-voltage leakage locator host, R can be calculated according to a formula from nine to fifteenA0、RB0、RC0、RN0、RAN0、RBN0、RCN0The value is obtained.
3. The off-line leakage assessment method for low-voltage leakage according to claim 2, characterized in that: the off-line electric leakage evaluation method comprises the steps that under the power failure state of a tested line, a host of a low-voltage electric leakage locator applies specific voltage to an A, B, C, N four-phase line of a tested platform area, and a current sampling circuit of the host of the low-voltage electric leakage locator injects current into the four-phase line for measurement;
hardware of a host of the low-voltage leakage locator for offline leakage evaluation comprises an MCU, a current sampling circuit, a voltage division circuit and a voltage following circuit;
the current sampling circuit comprises a voltage source, a current sampling resistor and an IC1, wherein T is a resistor to be detected;
the voltage division circuit is used for enabling the full-range voltage range output by the current sampling circuit to meet the ADC acquisition range of the MCU.
4. Low pressure electric leakage positioning device, its characterized in that: the low-voltage electric leakage positioning equipment comprises a low-voltage electric leakage positioning instrument host and a low-voltage electric leakage positioning instrument slave, wherein the hardware part of the low-voltage electric leakage positioning instrument host comprises a battery charging circuit, a battery, a DC/DC circuit, a display, a key, a buzzer, an MCU, a gear shifting circuit, an integrating circuit, an amplifying circuit, a full-wave rectifying circuit, a filter circuit, an MCU, a signal conditioning circuit, a current limiting resistor, an analog channel switch, a current sampling circuit, a voltage dividing circuit and a voltage following circuit.
5. The low voltage creepage locating apparatus of claim 4, wherein: the low-voltage leakage positioning equipment is used for carrying out leakage positioning on leakage current with loop characteristics, when the leakage positioning is carried out, a characteristic signal is injected into a fault line by using a low-voltage leakage positioning instrument host, due to the loop characteristics of the leakage current, the injected characteristic signal only exists in a loop to the ground, namely, the injected characteristic signal exists on the front side of a fault point and cannot be on the rear side of the fault point, and then the leakage fault position is positioned by judging whether the injected characteristic signal exists in a tested line, wherein the specific method comprises the following steps: the accurate positioning of the position of the leakage fault point is realized under the matching use of the slave machine of the low-voltage leakage position indicator, the rough sectional detection is firstly carried out, and then the accurate positioning is carried out.
6. The low voltage creepage locating apparatus of claim 4, wherein: in the low-voltage leakage locator host, a hardware part for positioning leakage comprises an MCU, a signal conditioning circuit, a current-limiting resistor and an analog channel switch;
when the power-off-state transformer area line is subjected to leakage positioning, a low-voltage leakage positioning instrument host injects characteristic signals into a fault line, the characteristic signals comprise voltage signals for leakage evaluation and pulse signals for leakage positioning, the low-voltage leakage positioning instrument slave receives the characteristic signals and outputs induction signals from a magnetic core coil sensor, and the induction voltage of the induction signals is in direct proportion to the voltage change rate of the characteristic signals injected by the low-voltage leakage positioning instrument host.
7. The low voltage creepage locating apparatus of claim 4, wherein: the low-voltage leakage locator host machine adopts a pulse signal as a characteristic signal injected into a fault line; the pulse signal is generated by a half-bridge circuit in a low-voltage electric leakage locator host.
8. The low voltage creepage locating apparatus of claim 7, wherein: in the electric leakage positioning, a low-voltage electric leakage positioning instrument host computer generates a coded frequency signal to be injected into a fault line according to the agreement of a master-slave machine, signal injection characteristic coding signals are only carried out on one phase in the fault line each time, then a low-voltage electric leakage positioning instrument slave computer is used for carrying out characteristic signal decoding in a non-contact mode along the electric leakage fault line, the position of an electric leakage fault point is roughly segmented, and then the electric leakage fault point is accurately positioned.
9. The low voltage creepage locating apparatus of claim 7, wherein: the software of the low-voltage leakage locator host is based on a Linux + QT framework, and when leakage assessment operation which consumes longer time is executed, independent thread operation is adopted to avoid influencing the execution of other software modules;
when generating the encoded frequency signal for signal injection, the injection signals of the A phase, the B phase, the C phase and the N phase adopt the same encoding mode, and the signal contents of the injection signals of the A phase, the B phase, the C phase and the N phase are different;
the low-voltage leakage locator slave machine comprises a magnetic core coil sensor, a low-voltage leakage locator slave machine PCB and a battery;
after the low-voltage electric leakage locator host computer injects characteristic signal into the fault line, characteristic signal produces magnetic field around the fault line, and it is V to establish the voltage that low-voltage electric leakage locator host computer injects characteristic signal into the electric leakage fault line, and the frequency is F, and fault line ground resistance R, the fault line electric current I of flowing through, then can obtain the magnetic induction strength B who locates apart from fault line d according to biot-savart law and be:
wherein mu0Is a vacuum permeability, mu0＝4π×10-7Tesla meters per ampere;
the low-voltage leakage locator slave machine receives the magnetic field of the characteristic signal through the magnetic core coil sensor and interprets the characteristic signal from the magnetic field, and the magnetic core coil sensor outputs the magnitude of the induced electromotive force xi and the change rate of the magnetic flux passing through the loop according to the Faraday's law of electromagnetic induction
In a direct proportion to the total weight of the composition,
and the low-voltage leakage locator slave machine receives and demodulates the output signal of the magnetic core coil sensor, and further identifies whether the demodulated signal is a characteristic signal injected by the low-voltage leakage locator host machine.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111509614.9A CN114184981B (en) | 2021-12-10 | 2021-12-10 | Low-voltage electric leakage positioning equipment and off-line electric leakage assessment method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111509614.9A CN114184981B (en) | 2021-12-10 | 2021-12-10 | Low-voltage electric leakage positioning equipment and off-line electric leakage assessment method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114184981A true CN114184981A (en) | 2022-03-15 |
| CN114184981B CN114184981B (en) | 2023-12-22 |
Family
ID=80543206
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111509614.9A Active CN114184981B (en) | 2021-12-10 | 2021-12-10 | Low-voltage electric leakage positioning equipment and off-line electric leakage assessment method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114184981B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115951262A (en) * | 2023-03-13 | 2023-04-11 | 青岛鼎信通讯股份有限公司 | Natural fault leakage current detection method applied to power distribution area |
Citations (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5990685A (en) * | 1996-09-11 | 1999-11-23 | Cegelec Controls Limited | Apparatus for and method of monitoring an earth-leakage state of a power distribution system |
| JP2002125313A (en) * | 2000-10-16 | 2002-04-26 | Kansai Denki Hoan Kyokai | Leakage detector, and leakage alarm and leakage breaker therewith |
| CN202502189U (en) * | 2012-02-27 | 2012-10-24 | 江苏省电力公司扬州供电公司 | Low voltage line leakage fault seeking device |
| JP2014173843A (en) * | 2013-03-05 | 2014-09-22 | Omron Corp | Electric leak detection device and electric leak detection method |
| CN106226652A (en) * | 2016-08-10 | 2016-12-14 | 国网浙江台州市黄岩区供电公司 | A kind of low-voltage overhead line electric leakage long range positioning detection device |
| US20180164361A1 (en) * | 2016-12-14 | 2018-06-14 | General Electric Company | System and method for leakage current and fault location detection in electric vehicle dc power circuits |
| CN108303615A (en) * | 2017-12-29 | 2018-07-20 | 广东电网有限责任公司江门供电局 | A kind of localization method of low voltage electric network leakage point of electricity |
| CN108732425A (en) * | 2018-07-07 | 2018-11-02 | 国网福建省电力有限公司 | A kind of low-voltage distribution network supply line resistance value method of real-time |
| CN109100615A (en) * | 2018-10-19 | 2018-12-28 | 河海大学 | A kind of cable fault localization method based on frequency characteristic |
| CN109375120A (en) * | 2018-10-29 | 2019-02-22 | 积成电子股份有限公司 | The monitoring method of alternating current is scurried into DC power system |
| CN109507539A (en) * | 2018-12-20 | 2019-03-22 | 孟小晶 | Low pressure fault to ground point searches instrument and lookup method |
| CN109932609A (en) * | 2019-03-05 | 2019-06-25 | 国网浙江诸暨市供电有限公司 | Rural area low-voltage power supply platform area failure leakage current measuring tool |
| CN110231552A (en) * | 2019-07-08 | 2019-09-13 | 冯琛 | Coal mine cable insulating monitoring selection method, injection circuit and related device |
| CN212031692U (en) * | 2020-04-18 | 2020-11-27 | 国网福建省电力有限公司电力科学研究院 | Wireless leakage current detector for all-type lines of low-voltage power distribution network |
| CN112731057A (en) * | 2020-12-21 | 2021-04-30 | 青岛鼎信通讯股份有限公司 | Offline low-voltage cable ground fault positioning device based on pulse coding |
-
2021
- 2021-12-10 CN CN202111509614.9A patent/CN114184981B/en active Active
Patent Citations (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5990685A (en) * | 1996-09-11 | 1999-11-23 | Cegelec Controls Limited | Apparatus for and method of monitoring an earth-leakage state of a power distribution system |
| JP2002125313A (en) * | 2000-10-16 | 2002-04-26 | Kansai Denki Hoan Kyokai | Leakage detector, and leakage alarm and leakage breaker therewith |
| CN202502189U (en) * | 2012-02-27 | 2012-10-24 | 江苏省电力公司扬州供电公司 | Low voltage line leakage fault seeking device |
| JP2014173843A (en) * | 2013-03-05 | 2014-09-22 | Omron Corp | Electric leak detection device and electric leak detection method |
| CN106226652A (en) * | 2016-08-10 | 2016-12-14 | 国网浙江台州市黄岩区供电公司 | A kind of low-voltage overhead line electric leakage long range positioning detection device |
| US20180164361A1 (en) * | 2016-12-14 | 2018-06-14 | General Electric Company | System and method for leakage current and fault location detection in electric vehicle dc power circuits |
| CN108303615A (en) * | 2017-12-29 | 2018-07-20 | 广东电网有限责任公司江门供电局 | A kind of localization method of low voltage electric network leakage point of electricity |
| CN108732425A (en) * | 2018-07-07 | 2018-11-02 | 国网福建省电力有限公司 | A kind of low-voltage distribution network supply line resistance value method of real-time |
| CN109100615A (en) * | 2018-10-19 | 2018-12-28 | 河海大学 | A kind of cable fault localization method based on frequency characteristic |
| CN109375120A (en) * | 2018-10-29 | 2019-02-22 | 积成电子股份有限公司 | The monitoring method of alternating current is scurried into DC power system |
| CN109507539A (en) * | 2018-12-20 | 2019-03-22 | 孟小晶 | Low pressure fault to ground point searches instrument and lookup method |
| CN109932609A (en) * | 2019-03-05 | 2019-06-25 | 国网浙江诸暨市供电有限公司 | Rural area low-voltage power supply platform area failure leakage current measuring tool |
| CN110231552A (en) * | 2019-07-08 | 2019-09-13 | 冯琛 | Coal mine cable insulating monitoring selection method, injection circuit and related device |
| CN212031692U (en) * | 2020-04-18 | 2020-11-27 | 国网福建省电力有限公司电力科学研究院 | Wireless leakage current detector for all-type lines of low-voltage power distribution network |
| CN112731057A (en) * | 2020-12-21 | 2021-04-30 | 青岛鼎信通讯股份有限公司 | Offline low-voltage cable ground fault positioning device based on pulse coding |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115951262A (en) * | 2023-03-13 | 2023-04-11 | 青岛鼎信通讯股份有限公司 | Natural fault leakage current detection method applied to power distribution area |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114184981B (en) | 2023-12-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Chen et al. | A new adaptive PMU based protection scheme for transposed/untransposed parallel transmission lines | |
| US9018962B2 (en) | Method and apparatus for protecting power transformers from large electro-magnetic disturbances | |
| EP3069426B1 (en) | Method and apparatus of reactor turn-to-turn protection | |
| CN109742727B (en) | Method for judging low-voltage 400V leakage current | |
| CN114184980A (en) | Low-voltage leakage positioning equipment and online leakage evaluation method | |
| CN103809070A (en) | Method and device for direction grounding fault detection on basis of three-phase current changes | |
| CN101777757A (en) | Small current grounding route selection method | |
| CN103558507A (en) | Sensor for direct current fault line selection and alternating current interlarding line selection | |
| CN103605041B (en) | Non-contact multi-point grounding detection method and system for secondary circuit of current transformer | |
| CN103454544A (en) | Linear field suppression circuit detection method based on electronic jumper | |
| CN114184981B (en) | Low-voltage electric leakage positioning equipment and off-line electric leakage assessment method | |
| CN114113915A (en) | Low-voltage transformer area electric leakage detection method, system, equipment and storage medium | |
| Dong et al. | A diagnosis of grounding grid corrosion defects based on branch voltage disturbance | |
| CN112415429B (en) | Medium voltage grounding fault intelligent diagnostic instrument | |
| CN110174575B (en) | Comprehensive test system and method for induced electricity of power through line along electrified railway | |
| CN113363951A (en) | Direct current residual current protector, protection method and direct current power supply system | |
| CN110174593B (en) | Device and method for judging breakpoint position of grounding grid by adopting electromagnetic induction | |
| CN208172234U (en) | A kind of no-load voltage ratio of current transformer, Check up polarity experimental rig | |
| CN109374954B (en) | Novel transmission line parameter measurement test line | |
| CN105866619A (en) | Method for detecting high impedance earth faults in power transmission line based on amplitude feature of distributed parameter zero sequence impedance | |
| Zhang et al. | Fault locating in ungrounded and compensated systems | |
| CN109991563A (en) | A kind of current transformer disconnection detection method and a kind of measuring device | |
| CN114839569A (en) | Online detection method for over capacity of distribution transformer | |
| CN206420963U (en) | Three-phase alternating current phase demodulation system | |
| CN108089087B (en) | A kind of electric leakage monitoring and guard method suitable for low-voltage power supply and distribution system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |