CN110632462A - Small current grounding fault positioning method and system, computer equipment and medium - Google Patents
Small current grounding fault positioning method and system, computer equipment and medium Download PDFInfo
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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
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
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- 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
Abstract
The invention provides a method and a system for positioning a low-current ground fault, computer equipment and a medium, which comprise the following steps: receiving zero-mode current wave recording data of each monitoring node of a line when the line fails in real time; each line is divided into a plurality of sections, and each section is provided with a plurality of monitoring nodes; extracting a transient component of the zero-mode current recorded wave data, and determining a transient amplitude and a transient resonant frequency of the zero-mode current recorded wave data according to the transient component; generating transient characteristic quantities of each monitoring node according to the transient amplitude and the transient resonance frequency; and determining the section where the fault point is located according to the transient characteristic quantity of each monitoring node. The invention can improve the reliability and sensitivity of positioning detection of the small-current ground fault, find the ground fault position in time and isolate the ground fault position, and ensure the safe and stable operation of a power distribution network and power distribution equipment.
Description
Technical Field
The invention relates to the field of power distribution network fault processing, in particular to a small current ground fault positioning method and system, computer equipment and medium.
Background
A small current grounding mode is mostly adopted for a 6-35 kV medium-voltage power distribution network in China, and the system is called a small current grounding system. When a single-phase earth fault occurs in a low-current earth system, the fault current is very small, so that the low-current earth fault is called. Because the fault signal is weak, the detection, line selection and positioning of the low-current ground fault are difficult. After a small current ground fault occurs, the three-phase voltage of the system is still symmetrical, and the system can operate for a period of time with the fault, so that the power supply reliability is improved. However, the system can not operate in a fault mode for a long time, large overvoltage can be generated due to intermittent arc grounding faults commonly existing on the site, and if the system operates in a fault mode for a long time, the large overvoltage can possibly damage insulation, so that insulation weak points are subjected to flashover or breakdown, two-phase grounding short circuit faults are caused, even more serious faults are caused, and the safe operation of a power grid is threatened. Therefore, the grounding fault position is found and isolated in time, and the method has important significance for ensuring safe and stable operation of the power distribution network and the power distribution equipment. The traditional fault detection (line selection, positioning and ranging) method utilizing the steady-state electric quantity has the problems of unobtrusive fault quantity, instability, uncertainty and the like, and the reliability and sensitivity of detection cannot be ensured.
Disclosure of Invention
The invention aims to provide a small-current ground fault positioning method and a system, computer equipment and medium thereof, so as to improve the reliability and sensitivity of small-current ground fault positioning detection, find and isolate ground fault positions in time and ensure the safe and stable operation of a power distribution network and power distribution equipment.
In a first aspect, an embodiment of the present invention provides a method for positioning a low-current ground fault, including the following steps:
receiving zero-mode current wave recording data of each monitoring node of a line when the line fails in real time; each line is divided into a plurality of sections, and each section is provided with a plurality of monitoring nodes;
extracting a transient component of the zero-mode current recorded wave data, and determining a transient amplitude and a transient resonant frequency of the zero-mode current recorded wave data according to the transient component;
generating transient characteristic quantities of each monitoring node according to the transient amplitude and the transient resonance frequency;
and determining the section where the fault point is located according to the transient characteristic quantity of each monitoring node.
Preferably, the method comprises the following steps:
monitoring transient zero-mode current of each monitoring node in real time;
and when the sudden change of the zero-mode current of the node is monitored to be larger than a first threshold value, recording to obtain zero-mode current recording data.
Preferably, the extracting the transient component of the zero-mode current recorded wave data comprises:
filtering the zero-mode current recorded wave data to extract a transient component of the zero-mode current recorded wave data;
the transient amplitude is the maximum absolute value point in the filtered transient data;
the transient resonant frequency is calculated according to the following formula:
in the formula (f)0Representing the transient resonance frequency, t2、t1Respectively corresponding to the first inflection point and the second inflection point of the recording data.
Preferably, the generating the transient characteristic quantity of each monitoring node according to the transient amplitude and the transient resonant frequency includes:
calculating the transient characteristic quantity of each monitoring node according to the transient amplitude value and the transient resonance frequency corresponding to each monitoring node and the following formula;
D＝I0/f0
wherein D represents a characteristic quantity of the monitoring node, I0Representing the transient zero mode current magnitude.
Preferably, the determining the section where the fault point is located according to the transient characteristic quantity of each monitoring node includes:
step S1, taking the first section of the fault line as an initial pending section;
step S2, judging whether the undetermined section has a downstream monitoring node, if not, the section is a fault section; if the section to be determined has a downstream monitoring node, determining a fault section according to the comparison result of the characteristic quantities of the downstream monitoring node and the upstream monitoring node;
step S3, if the section to be determined is a fault section, ending the judgment of the section where the fault point is located; if the undetermined section is a sound section, selecting the monitoring node with the largest characteristic quantity from all the downstream monitoring nodes as the upstream monitoring node of the next undetermined section, returning to the step S2, and taking the next section of the fault line as the undetermined section to continue the judgment of the section where the fault point is located.
Preferably, the determining the fault section according to the comparison result of the characteristic quantities of the downstream monitoring node and the upstream monitoring node comprises:
if the difference value of transient zero-mode current characteristic quantities of at least one downstream monitoring node and one upstream monitoring node in the section to be determined is smaller than a second threshold value, the section is a healthy section;
and if all the downstream monitoring nodes of the section to be determined meet the condition that the characteristic quantity of the upstream monitoring nodes is more than 3 times of the characteristic quantity of the downstream monitoring nodes, the section is determined as a fault section.
In a second aspect, an embodiment of the present invention provides a small-current ground fault location system, which is used to implement the small-current ground fault location method described in the embodiment, and includes:
the data receiving unit is used for receiving zero-mode current wave recording data of each monitoring node of the line when the line fails in real time; each line is divided into a plurality of sections, and each section is provided with a plurality of monitoring nodes;
the data processing unit is used for extracting a transient component of the zero-mode current recorded wave data and determining a transient amplitude and a transient resonant frequency of the zero-mode current recorded wave data according to the transient component;
the characteristic quantity generating unit is used for generating transient characteristic quantities of all the monitoring nodes according to the transient amplitude and the transient resonance frequency;
and the fault point judging unit is used for determining the section where the fault point is located according to the transient characteristic quantity of each monitoring node.
Preferably, the method comprises the following steps:
and the node monitoring unit is used for monitoring the transient zero-mode current of each monitoring node in real time, and when the sudden change of the monitored zero-mode current of the node is greater than a first threshold value, recording to obtain zero-mode current recording data.
In a third aspect, an embodiment of the present invention provides a computer device, including: a low current ground fault location system according to an embodiment; or a memory and a processor, the memory having stored therein computer readable instructions which, when executed by the processor, cause the processor to perform the steps of the low current ground fault location method according to an embodiment.
In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the low-current ground fault location method according to the embodiment.
The embodiment of the invention provides a small current ground fault positioning method and a system, computer equipment and a medium thereof, wherein each line is divided into a plurality of sections, a plurality of monitoring nodes are arranged on the sections, and the positioning method of the section where the fault point is located is determined by utilizing the amplitude and frequency difference, the structure and the comparison characteristic quantity of the transient zero-mode current of the upstream monitoring node and the transient zero-mode current of the downstream monitoring node of the fault point, so that the effective positioning of the small current ground fault of a power distribution system is realized, and the method has wide practical application value.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. Of course, not all of the advantages described above need to be achieved at the same time in the practice of any one product or method of the invention.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flow chart of a method for positioning a low-current ground fault according to a first embodiment of the present invention.
Fig. 2 is a schematic structural diagram of a typical single-phase earth fault location system based on a transient recording type fault indicator.
Fig. 3 is a flowchart of a method for locating a low-current ground fault corresponding to the system shown in fig. 2.
Fig. 4 is a schematic structural diagram of a simulation model of a single-phase earth fault of a power distribution network.
Fig. 5 is a transient zero-mode current waveform before each monitoring node records when a metallic single-phase earth fault occurs in the section 2 in the model shown in fig. 4.
Fig. 6 is a transient zero-mode current waveform recorded by each monitoring node when a metallic single-phase earth fault occurs in the section 2 in the model shown in fig. 4.
Fig. 7 is a block diagram of a low-current ground fault location system according to a second embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying 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.
It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures closely related to the solution according to the present invention are shown in the drawings, and other details not closely related to the present invention are omitted.
Example one
The embodiment of the invention provides a small current ground fault positioning method, which comprises the following steps:
step S201, receiving zero-mode current wave recording data of each monitoring node of the line when the line fails in real time; each line is divided into a plurality of sections, and each section is provided with a plurality of monitoring nodes;
step S202, extracting a transient component of the zero-mode current recorded wave data, and determining a transient amplitude and a transient resonant frequency of the transient component according to the transient component;
step S203, generating transient characteristic quantities of each monitoring node according to the transient amplitude and the transient resonance frequency;
and step S204, determining a section where the fault point is located according to the transient characteristic quantity of each monitoring node.
Specifically, when a low-current ground fault of the line occurs, the transient electric quantities before and after the fault point are obviously different and are not influenced by the arc suppression coil, so that the transient electric quantities can be used as the basis for positioning the low-current ground fault.
In one embodiment, the method may further include the steps of:
s101, monitoring transient zero-mode current of each monitoring node in real time;
and S102, when the sudden change of the zero-mode current of the node is monitored to be larger than a first threshold value, recording to obtain zero-mode current recording data.
Specifically, each monitoring node is correspondingly provided with a node monitoring unit for monitoring the transient zero-mode current of each monitoring node in real time, and when the sudden change of the zero-mode current of the node is greater than a first threshold value, wave recording is started to obtain zero-mode current wave recording data, and the data is used for carrying out fault point positioning judgment of steps S201-S203.
In an embodiment, the extracting the transient component of the zero-mode current log wave data includes: and filtering the zero-mode current recorded wave data to extract a transient component of the zero-mode current recorded wave data.
Specifically, according to the line selection result of the line selection device of the transformer substation, zero-mode current data of each monitoring node of the fault line is filtered, the transient component of the zero-mode current data is extracted, and healthy line terminal data is not processed.
And the transient amplitude is the maximum absolute value point in the filtered transient data.
Wherein the transient resonant frequency is calculated according to the following formula:
in the formula (f)0Representing the transient resonance frequency, t2、t1The time corresponding to the first and second inflection points of the recorded data is considered as 1/2 transient resonance periods.
In an embodiment, the generating the transient characteristic quantity of each monitoring node according to the transient amplitude and the transient resonant frequency includes:
calculating the transient characteristic quantity of each monitoring node according to the transient amplitude value and the transient resonance frequency corresponding to each monitoring node and the following formula;
D＝I0/f0
wherein D represents a characteristic quantity of the monitoring node, I0Representing the transient zero mode current magnitude.
In an embodiment, the determining, according to the transient characteristic quantity of each monitoring node, a section in which the fault point is located includes:
step S301, taking a first section of a fault line as an initial undetermined section;
step S302, judging whether a section to be determined has a downstream monitoring node or not, if not, the section is a fault section; if the section to be determined has a downstream monitoring node, determining a fault section according to the comparison result of the characteristic quantities of the downstream monitoring node and the upstream monitoring node;
step S303, if the section to be determined is a fault section, finishing the judgment of the section where the fault point is located; if the undetermined section is a sound section, selecting the monitoring node with the largest characteristic quantity from all the downstream monitoring nodes as the upstream monitoring node of the next undetermined section, returning to the step S302, taking the next section of the fault line as the undetermined section, and continuing the judgment of the section where the fault point is located.
Wherein, the determining the fault section according to the comparison result of the characteristic quantities of the downstream monitoring nodes and the upstream monitoring nodes comprises:
1) if the difference value of transient zero-mode current characteristic quantity of at least one downstream monitoring node and the upstream monitoring node in the section to be determined is smaller than a second threshold value, namely the relation of the transient zero-mode current characteristic quantity of the downstream monitoring node, of which the transient zero-mode current characteristic quantity of the upstream monitoring node is larger than 3 times, is not met, the section is a healthy section;
2) and if all the downstream monitoring nodes of the section to be determined meet the condition that the characteristic quantity of the upstream monitoring nodes is more than 3 times of the characteristic quantity of the downstream monitoring nodes, the section is determined as a fault section.
Fig. 2 is a schematic structural diagram of a single-phase ground fault positioning system, and the method according to an embodiment of the present invention will be described in detail below by taking the system shown in fig. 2 as an example.
As shown in fig. 2, the positioning system is composed of a transient recording type Fault Indicator (FI) installed at each monitoring node of the line, a low-current ground fault line selection device installed inside a substation, a single-phase ground fault positioning master station installed in a master control room, and a communication network.
The specific working flow of the positioning system shown in fig. 2 is shown in fig. 3.
Specifically, a transient recording type fault indicator installed on a line monitors three-phase current and ground electric field signals of each monitoring node of the line all the time, when the line current or the ground electric field suddenly changes, the fault indicator judges that a fault occurs, starts wave recording, records sudden change instant three-phase current and electric field waveforms, synthesizes zero-mode current signals and sends the zero-mode current signals to a background positioning main station. The line selection device is responsible for monitoring bus zero-mode voltage in the transformer substation and zero-mode current signals of each feeder outlet, comparing a sampling value of the zero-mode voltage with a device starting threshold value, and judging whether a fault occurs in a line; when a single-phase earth fault occurs, a fault line is selected according to the transient zero-mode voltage and the transient zero-mode current signal, and a fault line selection result is sent to the background positioning main station. And the positioning main station is responsible for receiving fault data reported by the fault indicator and the line selection device, judging a fault line according to the result of the line selection device, and positioning the fault according to the recording data of the fault indicator and the flow to determine the section where the ground fault point is located.
Fig. 4 shows a simulation circuit model with a neutral point grounded through an arc suppression coil, and the following describes the method according to an embodiment of the present invention in detail by taking the simulation circuit model shown in fig. 4 as an example.
Referring to fig. 4, the simulation line model is a cable overhead hybrid network, and there are 5 outgoing lines from L1 to L5, and each line uniformly adopts a 1MW constant impedance load. 4 monitoring nodes of Q1-Q4 are arranged on an outgoing line L5, and L5 is divided into 4 sections, namely: q1 and Q2 enclose a section 1, Q2 and Q3 enclose a section 2, Q3 and Q4 enclose a section 3, and Q4 is downstream of the section 4, and the lengths of the sections are 4km, 4km and 3km in sequence. The time of fault occurrence is 0.02s, the grounding point K is positioned in the middle of the section 2, and the grounding resistance is 10 omega. The specific parameters of the circuit are shown in table 1, the capacitance current to ground of the system is 73A, the system operates in an overcompensation mode, the compensation degree is 10%, and the inductance of the arc suppression coil is 0.229H; the rest parameters, such as the line type and length of each outgoing line, are shown in figure 3.
TABLE 1 line model parameters
When a single-phase earth fault occurs at the point K, the zero-mode voltage amplitude exceeds a preset threshold, the low-current earth line selection device is started, the line selection device selects a fault line as L5, and the line selection result and fault line outlet zero-mode current acquisition data are reported to the master station;
meanwhile, the zero-mode current break variable of each monitoring node exceeds a preset threshold, each transient wave recording type fault indicator starts wave recording, and fault zero-mode current acquisition data are reported to the main station;
the main station receives zero-mode current acquisition data of the line selection device and the fault indicator, and the zero-mode current waveforms of the fault line monitoring nodes Q1-Q4 during fault are shown in FIG. 5; the zero-mode current data of each monitoring node of the fault line is filtered, the transient characteristic component of the zero-mode current data is extracted, the transient zero-mode current of each monitoring node is obtained, and the transient zero-mode current data is shown in figure 6, and wave recording data of a sound line is not processed.
Through data analysis, the transient zero-mode current amplitudes and inflection point moments of the obtained monitoring nodes Q1-Q4 are shown in Table 2.
TABLE 2 zero-mode Current parameters of each monitoring node
According to the following formula:
the calculated transient zero-mode current resonant frequencies of the monitoring nodes Q1-Q4 are respectively as follows: 276.2Hz, 274.7Hz, 1190.5Hz, 1190.5 Hz;
and then according to the following formula:
D＝I0/f0
the transient zero-mode current characteristic values D of the monitoring nodes Q1-Q4 are calculated as follows: 0.9432, 1.038, 0.07725, 0.03878;
therefore, single-phase earth fault positioning can be carried out according to the transient zero-mode current characteristic values of all monitoring nodes, and the specific flow of the fault positioning is as follows:
firstly, selecting a fault line L5 section 1 as a pending section, wherein a downstream monitoring node exists in the pending section, and executing the following steps;
comparing the transient zero-mode current characteristic value of an upstream (bus side) monitoring node Q1 of the section to be determined to be 0.9432 with the transient zero-mode current characteristic value of 1.038 between a downstream (load side) monitoring node Q2, wherein 0.9432/1.038 is 0.91, and the relation of the downstream monitoring node characteristic value of which the upstream monitoring node characteristic value is more than 3 times is not satisfied, so that the section 1 is judged to be a healthy section;
When other terminal devices (such as FTU, PMU, etc.) are installed on the line or other communication methods are adopted, the situation is similar to the case of applying the fault indicator, and details are not repeated here. In the same way, the method provided by the embodiment of the invention is also applicable to other line structure forms, including but not limited to space network structures such as a multi-segment multi-network overhead network, a single-ring cable network, and a double-ring cable network.
Example two
As shown in fig. 7, a second embodiment of the present invention provides a small-current ground fault location system, which is used to implement the small-current ground fault location method according to the first embodiment, and includes:
the data receiving unit 1 is used for receiving zero-mode current recorded wave data of each monitoring node of the line in real time when the line fails; each line is divided into a plurality of sections, and each section is provided with a plurality of monitoring nodes;
the data processing unit 2 is configured to extract a transient component of the zero-mode current recorded wave data, and determine a transient amplitude and a transient resonant frequency of the transient component according to the transient component;
the characteristic quantity generating unit 3 is used for generating transient characteristic quantities of all the monitoring nodes according to the transient amplitude and the transient resonant frequency;
and the fault point judging unit 4 is used for determining the section where the fault point is located according to the transient characteristic quantity of each monitoring node.
In one embodiment, the method comprises the following steps:
and the node monitoring unit is used for monitoring the transient zero-mode current of each monitoring node in real time, and when the sudden change of the monitored zero-mode current of the node is greater than a first threshold value, recording to obtain zero-mode current recording data.
It should be noted that the system according to the second embodiment corresponds to the method according to the first embodiment, and therefore, a part of the system according to the second embodiment that is not described in detail can be obtained by referring to the content of the method according to the first embodiment, and is not described again here.
It is to be noted that, based on the content, those skilled in the art can clearly understand that the embodiments of the present invention can be implemented by software and necessary general hardware, and certainly can be implemented by hardware, but in many cases, the former is a better implementation manner. Based on such understanding, the technical solutions of the embodiments of the present invention may be embodied in the form of a software product, which may be stored in a computer-readable storage medium, such as a floppy disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a FLASH Memory (FLASH), a hard disk or an optical disk of a computer, and includes several instructions to enable a computer device (which may be a personal computer, a server, or a network device) to implement the methods/systems described in the foregoing embodiments.
EXAMPLE III
An embodiment of the present invention provides a computer device, including: a low current ground fault location system according to an embodiment; or, a memory and a processor, the memory having stored therein computer readable instructions, which, when executed by the processor, cause the processor to perform the steps of the low current ground fault location method according to embodiment one.
Of course, the computer device may also have components such as a wired or wireless network interface, a keyboard, and an input/output interface, so as to perform input/output, and the computer device may also include other components for implementing the functions of the device, which are not described herein again.
Example four
A fourth embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the low-current ground fault location method according to the first embodiment.
The foregoing is directed to embodiments of the present invention, and it is understood that various modifications and improvements can be made by those skilled in the art without departing from the spirit of the invention.
Claims (10)
1. A small current ground fault positioning method is characterized by comprising the following steps:
receiving zero-mode current wave recording data of each monitoring node of a line when the line fails in real time; each line is divided into a plurality of sections, and each section is provided with a plurality of monitoring nodes;
extracting a transient component of the zero-mode current recorded wave data, and determining a transient amplitude and a transient resonant frequency of the zero-mode current recorded wave data according to the transient component;
generating transient characteristic quantities of each monitoring node according to the transient amplitude and the transient resonance frequency;
and determining the section where the fault point is located according to the transient characteristic quantity of each monitoring node.
2. The low current ground fault location method of claim 1, comprising the steps of:
monitoring transient zero-mode current of each monitoring node in real time;
and when the sudden change of the zero-mode current of the node is monitored to be larger than a first threshold value, recording to obtain zero-mode current recording data.
3. The small-current ground fault location method of claim 1, wherein the extracting the transient component of the zero-mode current log wave data comprises:
filtering the zero-mode current recorded wave data to extract a transient component of the zero-mode current recorded wave data;
the transient amplitude is the maximum absolute value point in the filtered transient data;
the transient resonant frequency is calculated according to the following formula:
in the formula (f)0Representing the transient resonance frequency, t2、t1Respectively corresponding to the first inflection point and the second inflection point of the recording data.
4. The small-current ground fault location method according to claim 3, wherein the generating the transient characteristic quantity of each monitoring node according to the transient amplitude and the transient resonant frequency comprises:
calculating the transient characteristic quantity of each monitoring node according to the transient amplitude value and the transient resonance frequency corresponding to each monitoring node and the following formula;
D＝I0/f0
wherein D represents a characteristic quantity of the monitoring node, I0Representing the transient zero mode current magnitude.
5. The method for locating a low-current ground fault according to claim 4, wherein the determining the section where the fault point is located according to the transient characteristic quantity of each monitoring node comprises:
step S1, taking the first section of the fault line as an initial pending section;
step S2, judging whether the undetermined section has a downstream monitoring node, if not, the section is a fault section; if the section to be determined has a downstream monitoring node, determining a fault section according to the comparison result of the characteristic quantities of the downstream monitoring node and the upstream monitoring node;
step S3, if the section to be determined is a fault section, ending the judgment of the section where the fault point is located; if the undetermined section is a sound section, selecting the monitoring node with the largest characteristic quantity from all the downstream monitoring nodes as the upstream monitoring node of the next undetermined section, returning to the step S2, and taking the next section of the fault line as the undetermined section to continue the judgment of the section where the fault point is located.
6. The low-current ground fault location method of claim 5, wherein the determining the fault section according to the comparison of the characteristic quantities of the downstream monitoring node and the upstream monitoring node comprises:
if the difference value of transient zero-mode current characteristic quantities of at least one downstream monitoring node and one upstream monitoring node in the section to be determined is smaller than a second threshold value, the section is a healthy section;
and if all the downstream monitoring nodes of the section to be determined meet the condition that the characteristic quantity of the upstream monitoring nodes is more than 3 times of the characteristic quantity of the downstream monitoring nodes, the section is determined as a fault section.
7. A low current ground fault location system for implementing the low current ground fault location method of any one of claims 1-6, comprising:
the data receiving unit is used for receiving zero-mode current wave recording data of each monitoring node of the line when the line fails in real time; each line is divided into a plurality of sections, and each section is provided with a plurality of monitoring nodes;
the data processing unit is used for extracting a transient component of the zero-mode current recorded wave data and determining a transient amplitude and a transient resonant frequency of the zero-mode current recorded wave data according to the transient component;
the characteristic quantity generating unit is used for generating transient characteristic quantities of all the monitoring nodes according to the transient amplitude and the transient resonance frequency;
and the fault point judging unit is used for determining the section where the fault point is located according to the transient characteristic quantity of each monitoring node.
8. The low current ground fault location system of claim 7, comprising:
and the node monitoring unit is used for monitoring the transient zero-mode current of each monitoring node in real time, and when the sudden change of the monitored zero-mode current of the node is greater than a first threshold value, recording to obtain zero-mode current recording data.
9. A computer device, comprising: a low current ground fault location system according to any one of claims 7-8; or a memory and a processor, the memory having stored therein computer readable instructions which, when executed by the processor, cause the processor to perform the steps of the low current ground fault location method according to any one of claims 1-6.
10. A computer-readable storage medium having stored thereon a computer program, characterized in that: the computer program when being executed by a processor realizes the steps of the low current ground fault location method of any one of claims 1-6.
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