JP2024074769A - Method and system for detecting and warning ground wire currents in armored secondary cables - Google Patents

Abstract

To provide a method that can increase the speed and accuracy of detecting an armor-shielded secondary cable in a substation.SOLUTION: In each armor-shielded secondary cable, the method includes step 1 for covering each ground line with current collecting means for a tip shielding layer, a tip armoring layer, an end shielding layer, and an end armoring layer, step 2 of current collecting means for collecting a tip shielding layer ground line current, a tip armoring layer ground line current, an end shielding layer ground line current, and an end armoring layer ground line current in each armoring shielding secondary cable, step 3 for installing an overcurrent criterion and alarming the secondary cable for over-currents together with the currents collected in step 2, step 4 for installing a convection reference and alarming leakage current for the secondary cable together with the convection reference while re-synchronizing the currents collected in step 2, and step 5 for achieving detection and alarming of the ground wire current in the secondary cable by the results of the alarms according to step 3 and step 4.SELECTED DRAWING: Figure 1

Description

The present invention relates to the field of in-situ detection of electrical substation electrical equipment and circuits, and more particularly to a method and system for detecting and alerting to ground conductor currents in armored secondary cables.

Currently, there are no staff on duty at substations for power systems below 220 kV, and few staff on duty at substations for power systems above 500 kV. This is becoming a gradual trend, and the demand for daily maintenance of substations is increasing. In recent years, electrical fires have frequently occurred at substations due to overheating of the ground wires of electric cables, which poses a challenge to operate substations safely and stably.

Currently, substations use a large amount of armored shielded secondary cables as long electric cables from switch locations to protective rooms. The shielding layer is generally grounded at both ends, i.e., both ends are connected to the secondary ground grid via ground wires. Currently, armored layers are grounded in a variety of ways, but a typical form for armored layer grounding is that both ends are grounded (both ends are connected to the primary ground grid via ground wires). Armored shielded secondary cables using such grounding forms can generate heat in several cases:
1. In some substations, a relatively large current flows through the shield ground wire of a secondary cable due to the action of a temporary interference source (such as lightning or a disconnector), and the current flows through the shield, the shield ground wire and the ground grid.
2. In some substations, a relatively large current flows through the armor layer ground wire due to the action of a temporary interference source (such as lightning or a disconnector), and the current flows through the armor layer, the armor layer ground wire and the ground grid.
3. During construction and operation, the shielding ground wire and the armor ground wire in the secondary cable may be short-circuited for some reason (the armor penetrates the shielding layer, or the twisted wire between the shielding ground wire and the armor ground wire is no longer tight), resulting in a localized closed circuit in the ground wire. A stable interference source (such as near an air-core reactor) acts on a substation, causing a relatively large current to flow through the armor ground wire and the shielding side ground wire. The current mainly flows through the short-circuited part of the shielding armor layer, the shielding ground wire, the armor ground wire, and the earth grid.
4. In the case of a secondary cable, insulation in the shielding layer may be broken down, causing the current flowing through the shielding layer to be diverted at the point where the shielding layer is broken down, resulting in an electric leakage point in the shielding layer.
5. In the secondary cable, the insulation in the armor layer is destroyed, and the current flowing through the armor layer is shunted at the point where the armor layer is destroyed, resulting in a leakage point in the armor layer.

In the above five cases, especially the third, when an overcurrent is detected, and in the latter two cases when a leakage current is detected, if it is not detected immediately and a large current continues to flow for a long period of time, heat is likely to be generated and the corresponding cable may even be burned.

In order to prevent electric cables from causing accidents, it is necessary to detect armored secondary cables in substations. At present, there are two main ways to detect armored secondary cables in substations:
(1) Manual visual inspection method. Since there is currently no specialized means of detecting the ground wire of armored secondary cables, the conventional method is for the maintenance personnel at the substation to manually check it visually. For example, when inspecting a terminal box, the maintenance personnel will observe whether there are any abnormalities in the appearance of the electric cable and the ground wire, whether there is a burnt smell, etc.
(2) Infrared temperature measurement: For armored secondary cables and associated grounding wires, substation maintenance personnel measure the temperature with a handheld infrared sensor to detect whether the temperature of the electrical cables and grounding wires is too high.

However, the conventional detection methods have at least the following problems.
1. Problems that do not have timeliness Whether it is a manual visual inspection or an infrared temperature measurement, manual inspection is required for the terminal box or protective shield near the grounding wire, and even if the inspection frequency is high and the substation has a particularly high voltage of 1000 kV, it must be inspected only once or twice a day. Even if the inspection frequency for the task of ensuring power is limited to four times a day and the interval between two inspections is only a few hours, the entire process from the start of abnormal heating to burning of the secondary cable is fully covered.
2. Limited detection accuracy. Manual visual inspection methods rely heavily on the subjective judgment of the person in charge, and whether or not a problem can be detected depends on the level of ability and mental state of the maintenance personnel, as well as the stage at which the malfunction is progressing, making it difficult to accurately detect malfunctions.
Although the method of measuring temperature using infrared rays is less dependent on the subjective judgment of the person in charge than the method of manual visual inspection, there is still the problem of whether the location where the temperature is measured is blocked or not, and the timing of measuring the temperature depends on the stage at which the current malfunction is progressing, so the probability of accurately detecting the malfunction is not high.

The present invention overcomes the deficiencies existing in the prior art by providing a method and system for detecting and alerting to ground wire current in armored secondary cables that can increase the speed and accuracy of detecting armored secondary cables in electrical substations.

The present invention employs the following technical solutions.
The method for detecting and warning of ground conductor current in armored secondary cables is as follows:
Step 1: for each armored secondary cable, cover the leading edge shielding ground wire with CT11, cover the leading edge shielding ground wire with CT12, cover the terminal shielding ground wire with CT21, and cover the terminal armoring ground wire with CT22;
Step 3: setting an overcurrent criterion and alarming the secondary cable for overcurrent along with the current sampled in step 2;
Step 4: setting up a convection reference and, together with the convection reference, alarming the secondary cable for a leakage current while resynchronizing the currents collected in step 2; and
and step 5, which detects and issues an alarm on the ground wire current in the secondary cable according to the results of the alarms in steps 3 and 4.

Preferably, step 3 comprises:
Establish a shielding grounding conductor overcurrent standard and measure the shielding grounding conductor overcurrent at the tip of the armored shielded secondary cable.
Step 3-2 of transmitting an overcurrent alarm signal for the armor layer of the next cable; and
The method further includes the step 3-3 of transmitting a local close-circuit overcurrent warning signal in the secondary cable once a third predetermined delay t3 has elapsed.

Preferably, in step 3-1, a shield ground wire overcurrent criterion is
or
or
Preferably, in step 3-2, the armor layer ground wire overcurrent criterion is
or
or

Preferably, in step 3-3, a local closing current reference in the secondary cable is
is the alarm value at which continuity is established.

Preferably, step 4 comprises:
It judges whether resynchronization is necessary according to the communication status, and if so, it
a step 4-2 of transmitting an alarm indicating that the shield layer of the secondary cable has become leaky according to the result of judging the shield layer current difference while making a judgment using a different shield layer current difference standard for each of the above; and
The method further includes a step 4-3 of transmitting an alarm that the shield layer of the secondary cable has become leaky according to the result of judging the shield current difference while making a judgment using different shield current difference standards for each of the shield current difference judged.

Preferably, in step 4-1, the electric cable terminal shield ground wire voltage after resynchronization is
The combined signal is continuously transmitted for 100 ms, and the data collection means transmits the combined signal from the terminal.
the current being a shield ground current;

Preferably, step 4-2 includes:
The first shield layer current difference standard is
And then,
the law of nature,
The second shield layer current difference standard is
The method further includes: when the first shielding layer current difference criterion or the second shielding layer current difference criterion is satisfied, the shielding layer current difference criterion is satisfied; and when a fourth predetermined delay t4 has elapsed, transmitting an alarm signal indicating that the shielding layer of the secondary cable has become leaky.

Using the standard, the first armor layer current difference standard is
And,
The second armor layer current difference standard is
When the first armor layer current difference criterion or the second armor layer current difference criterion is met, the armor layer current difference criterion is said to be met, and at this time, when the fifth predetermined delay t5 has elapsed, an alarm signal is sent to indicate that the armor layer of the secondary cable has become leaky.

The present invention includes a current collecting means, a resynchronizing means and an alarm determining means,
Wherein, a current collecting means is installed in each armored shielded secondary cable, and the current collecting means is for collecting a leading shielding layer ground wire current, a leading armoring layer ground wire current, a terminal shielding layer ground wire current and a terminal armoring layer ground wire current in each armored shielded secondary cable;
The resynchronization means is capable of determining whether it is necessary to resynchronize the terminal shield ground wire current and the terminal shield ground wire current of the armored secondary cable, and resynchronizes the currents determined to be necessary;
The alarm judgment means can set alarm criteria for shielding layer overcurrent, armoring layer overcurrent, localized closed circuit overcurrent, shielding layer leakage and armoring layer leakage in the secondary cable, and receives current information from the current collection means and resynchronization means to obtain alarm results. A system for detecting and issuing an alarm for a ground wire current in an armored shielded secondary cable is further provided.

The present invention further provides a terminal having a processor and a storage medium, the storage medium being for storing instructions, and the processor performing operations based on the instructions to execute a method for detecting and warning about ground wire current in the armored shielded secondary cable.

The present invention further provides a computer-readable medium having a computer program stored thereon, the computer-readable medium according to claim 1, which, when executed by a processor, provides a method for detecting and warning about ground conductor current in the armored shielded secondary cable.

The beneficial effects of the present invention are that, compared to the conventional technology, the method of detecting and warning the ground wire current of an armored shielded secondary cable provided by the present invention can instantly detect the operating status of the armored shielded secondary cable in a substation and accurately detect faults, thereby increasing the detection level of the armored shielded secondary cable in the substation; the present invention can instantly detect the appearance of current and detect faults and issue a warning, encouraging workers to take immediate repair measures to eliminate the fault; and it can solve the problem of the conventional method of detecting ground wire current not being able to instantly detect the current, and it can avoid the phenomenon that, for example, the current is likely to heat up the ground wire at the intervals of the air-core reactor, which makes it prone to faults.

FIG. 2 is a schematic diagram showing the overall flow of the method for detecting and warning about ground wire current in an armored screened secondary cable according to the present invention. FIG. 2 is a principle diagram showing the basic logic of local current alarm in a secondary cable according to the present invention. FIG. 2 is a schematic diagram showing the configuration of an electrical cable in a system for detecting and warning about ground wire current in an armored shielded secondary cable according to the present invention. This is a principle diagram showing the basic logic of the alarm regarding the occurrence of a leakage current in the secondary cable armor layer and shielding layer according to the present invention. FIG. 1 is a schematic diagram showing the configuration of a system for detecting and issuing an alarm about a ground wire current in an armored shielded secondary cable according to the present invention.

In order to clarify the purpose, technical means and advantages of the present invention, the technical means of the present invention will be described clearly and completely below with reference to the drawings together with the embodiments of the present invention. The embodiments described in this application are only a part of the embodiments of the present invention, and are not all of the embodiments. Any other embodiments made by those skilled in the art based on the spirit of the present invention without creative work are all within the scope of protection of the present invention.

As shown in Figure 1, the present invention provides a method for detecting and warning the ground wire current of an armored shielded secondary cable, which specifically includes the following steps:
Step 1 involves covering the tip shielding layer ground wire with CT11, covering the tip shielding layer ground wire with CT12, covering the terminal shielding layer ground wire with CT21, and covering the terminal armor layer ground wire with CT22 for each armored secondary cable.
Among them, in the substation, an armored shielded secondary cable is generally used as a long electric cable from the switch location to the protection room. The shielding layer of the secondary cable is grounded at both ends, that is, both ends are connected to the secondary ground grid via ground wires. The secondary ground grid includes an equipotential ground grid and a secondary copper bar. The armored shielded secondary cable has a front end as the protection room and a rear end as the terminal box at the switch location. The front end of the secondary cable is connected to the equipotential ground grid and a rear end is connected to the dedicated copper bar in the drawing, which is the secondary copper bar. In other words, the grounding form of the armored layer of the secondary cable according to the present invention is such that both ends are connected to the primary ground grid via ground wires, so that the armored layer is grounded. The primary power system is the main ground grid.

As shown in Figure 3, in the armored shielded secondary cable, the tip (M side, inside the protected room) shielding layer ground wire is covered with CT11, the armored layer shielding layer ground wire is covered with CT12, and the end of the electric cable (N side, terminal box at the switch location) shielding layer ground wire is covered with CT21, and the armored layer ground wire is covered with CT22.

Step 2: The current collecting means respectively connects the distal shield of each armored shielded secondary cable to the distal shield of the armored shielded secondary cable.
is considered a data point.

Step 3 establishes an overcurrent criterion and, together with the current sampled in step 2, alerts the secondary cable of an overcurrent.
Specifically, as shown in FIG. 2, step 3 further includes:
Step 3-1 is to set the shielding layer grounding conductor overcurrent standard and to
If so, a shield overcurrent alarm signal is sent for the secondary cable once a first predetermined delay t1 has elapsed.

Preferably, referring to the predetermined value of the conventional overload warning, the first predetermined delay t1 is set as 10s.
Among them, the shielding layer grounding conductor overcurrent standard is
or
or
A shield overcurrent alarm signal is sent for the secondary cable once the shield ground conductor overcurrent criterion has been met and a first predetermined delay t1 has elapsed.

When 2 has elapsed, an armor overcurrent alarm signal is sent for the secondary cable.

Preferably, the second predetermined delay t2 is set as 10 s.
Among them, the armor layer ground conductor overcurrent standard is as follows:
or
or

If the armor ground wire overcurrent criterion is met, a shield overcurrent alarm signal is sent for the secondary cable after the second predetermined delay t2 has elapsed. If none of the three armor ground wire overcurrent criterion formulas are met, it is determined that the armor of the secondary cable is normal and no alarm is required.

Step 3-3: Install local closing current reference in secondary cable and terminal shield ground
if so, a local current alarm signal in the secondary cable is sent once a third predetermined delay t3 has elapsed.
Among them, the local closing overcurrent in the ground wire generally has a relatively low probability of occurring at the tip (protected room side) of the electric cable because there must be a stable interference source around it. Therefore, in the present invention, the identification of the closing overcurrent at the end (terminal box side) of the electric cable is not considered.

Preferably, the third predetermined delay t3 is set to 60 s since in scenarios where the third predetermined delay t3 is used, the current does not flow through the entire secondary cable.
The local closing current criteria in the secondary cable are
This is to determine whether or not a road is in the way.

Once t3 has elapsed a local closed circuit overcurrent alarm signal is sent for the secondary cable.

Step 4 is to establish a convection reference, resynchronize the current collected in step 2, and send a leakage current alarm for the secondary cable along with the convection reference.

Step 4-1 determines whether resynchronization is necessary according to the communication state.

Considering the complex electromagnetic environment in a substation, when an electric cable is relatively long, the signal delay at both ends may vary. If the cable is directly connected to the current collection means without considering the delay issue, the current difference may be increased or an alarm may be sent erroneously. In addition, when an optical fiber pair is used in a substation, the problem of synchronizing the current from the current collection means can be solved, but the cost is too high. Therefore, the present invention provides a method for resynchronization. By not adding an optical channel, the impact of delay can be reduced.

Wherein, judging whether resynchronization is necessary according to the communication state may be judged comprehensively by those skilled in the art according to the communication delay and the communication state, and choose whether to perform resynchronization when the current communication delay is relatively small and the communication state is relatively good. When it is judged that the current communication delay is relatively large and the communication state is relatively good, resynchronization should be performed. When it is judged that the current communication state is relatively bad and it is difficult to perform the correction accurately, resynchronization is not performed. The present invention further includes judging that resynchronization is possible when the code error ratio is lower than 1* ^10-5 .
The system sets the tip of the electrical cable as a reference point and adjusts the data at the end to the data at the tip.

The electric cable has an end located at the terminal box of the N-side switch in FIG.

A different shield current difference standard is used for judgment depending on whether the secondary cable has been activated or not, and a shield leakage alarm is sent for the secondary cable according to the result of judging the shield current difference.

Then, using a first shielding layer current difference criterion, the first shielding layer current difference criterion is
And then,

If the currents collected in step 2 are not resynchronized, then the second shield current difference criterion is used, and the alarm setpoints will then take high values together, i.e., a large current will flow through the shield.
Furthermore, if the first shield current difference criterion or the second shield current difference criterion is met, the shield current difference criterion is met, and at this time, a fourth predetermined delay t4 has elapsed, a shield leakage alarm signal is sent for the secondary cable.

Preferably, the fourth predetermined delay t4 is set to 500 ms.

A different shield current difference standard is used depending on whether or not the secondary cable has been activated, and a shield current leakage alarm is sent for the secondary cable based on the result of the determination of the shield current difference.
First armor layer current difference standard
And,
Greater than.

Furthermore, if the first armor layer current difference criterion or the second armor layer current difference criterion is met, the armor layer current difference criterion is said to be met, and at this time, if the fifth predetermined delay t5 has elapsed, an armor layer leakage current alarm signal is sent for the secondary cable.

Preferably, the fifth predetermined delay t5 is set to 500 ms.

Step 5 is realized to detect and alarm the ground wire current in the secondary cable according to the alarm results from steps 3 and 4. The alarm results include a secondary cable shield layer overcurrent alarm, a secondary cable armor layer overcurrent alarm, a secondary cable local closed circuit overcurrent alarm, a secondary cable shield layer leakage alarm, and a secondary cable armor layer leakage alarm.

The present invention further provides a system for detecting and warning the ground wire current of an armored shielded secondary cable, as shown in Figure 5. The above-mentioned method for detecting and warning the ground wire current of an armored shielded secondary cable is realized by the system, specifically, the system includes a current collecting means, a resynchronization means and an alarm judging means.
Wherein, a current collecting means is installed in each armored shielded secondary cable, and the current collecting means is for collecting the leading shielding layer ground wire current, the leading armoring layer ground wire current, the terminal shielding layer ground wire current and the terminal armoring layer ground wire current in each armored shielded secondary cable.
The resynchronization means is capable of determining whether it is necessary to resynchronize the distal shield ground wire current and the distal armor ground wire current in the armored secondary cable, and resynchronizes the currents determined to be necessary.
The alarm judgment means can set alarm criteria for shield overcurrent, armor overcurrent, local closed circuit overcurrent, shield leakage and armor leakage in the secondary cable, and receives current information from the current collection means and the resynchronization means to obtain the alarm result.

The beneficial effect of the present invention is that, compared to the prior art, the present invention allows for instantaneous detection of the operational status of armored shielded secondary cables in substations and accurate detection of faults, thereby increasing the level of detection of armored shielded secondary cables in substations.

The present disclosure may be a system, method, and/or computer application product. The computer application product may be a computer-readable medium having stored therein instructions for implementing, by a processor, a computer-readable program of each aspect of the present disclosure.

A computer readable storage medium is a physical device that holds and stores instructions for use by an instruction execution device. A computer readable storage medium may be, for example, but is not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination of the above. More specific examples of computer readable storage media (not an exhaustive list) include programmable computer disks, hard disks, random access memory (RAM), read only memory (ROM), electrically erasable programmable read only memory (EPROM or flash), static random access memory (SRAM), programmable compact disk read only memory (CD-ROM), digital versatile disk (DVD), memory stick, soft disk, mechanical encoder device (e.g., a card with holes or a grooved structure that stores instructions), and any suitable combination of the above. As used herein, computer-readable storage media is not to be construed as ephemeral signals per se, such as radio waves or other electromagnetic waves transmitted freely, electromagnetic waves transmitted through waveguides or other transmission media (e.g., light pulses through fiber optics), or electrical signals transmitted over electrical wiring.

The computer-readable program instructions described herein may be downloaded from a computer-readable storage medium to each computing/processing device, or may be downloaded from a network, such as the Internet, a local network, a wide area network, and/or a wireless network, to an external computer or external storage device. The network may be a copper transmission cable, a fiber optic transmission, a wireless transmission, a router, a firewall, a switch, a network gateway computer, and/or a peripheral server device. A network card or a network interface in each computing/processing device receives the computer-readable program instructions from the network, and forwards the computer-readable program instructions to the computer-readable storage medium in each computing/processing device for storage.

The computer program instructions for performing the operations of the present disclosure may be assembly language instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code programmed in any combination of one or more programming languages. The programming languages may include object-oriented programming languages, such as Smalltalk, C++, and the like, and conventional procedural programming languages, such as C and other similar programming languages. The computer readable program instructions may be executed entirely on the user's computer, or only in part on the user's computer. They may be executed as a separate software package, or only in part on the user's computer and other parts on a remote computer, or all on a remote computer or server device. In the case of such a remote computer, the remote computer may be connected to the user's computer or to an external computer (e.g., connected via the Internet by an Internet supplier) via any type of network, including a local network (LAN) or a wide area network (WAN)). In this embodiment, the state information of the computer-readable program instructions may be used to customize the electronic circuitry as needed, for example, a programmable logic device, a field programmable gate array (FPGA), or a programmable logic array (PLA). The electronic circuitry may execute the computer-readable program instructions to implement various aspects of the present disclosure.

Aspects of the present disclosure have been described herein with reference to flowcharts and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present disclosure. It should be understood that each block in the flowcharts and/or block diagrams, and each combination of blocks in the flowcharts and/or block diagrams, is implemented by computer-readable program instructions.

These computer-readable program instructions may be provided to a processor of a general-purpose computer, special-purpose computer, or other programming data processing device to form a device that, when executed by a processor of the computer or other programming data processing device, can perform the functions/operations specified in one or more blocks in the flowcharts and/or block diagrams. These computer-readable program instructions may also be stored on a computer-readable medium that causes a computer, programming data processing device, and/or other device to operate in a particular manner. A computer-readable medium having instructions stored thereon may also comprise an article of manufacture, which includes instructions for each aspect of performing the functions/operations specified in one or more blocks in the flowcharts and/or block diagrams.

Loading computer-readable program instructions into a computer, programming data processing device, or other device to cause the computer, programming data processing device, or other device to execute a sequence of operational steps to generate a computer-implemented process that causes the computer, programming data processing device, or other device to execute the instructions to implement the functions/operations defined in one or more blocks in the flowcharts and/or block diagrams.

The flowcharts and block diagrams in the drawings show possible architectures, functions and operations of the systems, methods and computer program products according to several embodiments of the present disclosure. Each block in the flowcharts or block diagrams shows a module, program segment or part of instructions, which includes one or more executable instructions for implementing a given logical function. For equivalent permutation implementations, the functions shown in the blocks may be implemented according to the order shown in the drawings. For example, two consecutive blocks may in fact be essentially executed in parallel or in reverse order, depending on the functionality involved. It should be noted that each block in the block diagrams and/or flowcharts and combinations of blocks in the block diagrams and/or flowcharts may be implemented by a dedicated system using hardware to execute a given function or operation, or by a combination of dedicated hardware and computer instructions.

Finally, it should be noted that the above examples do not limit the technical means of the present invention, but merely explain it. Although the present invention has been described in detail with reference to the above examples, it is still understandable to those skilled in the art that the specific embodiments of the present invention can be amended or equivalently substituted, and any amendments or equivalent substitutions that do not deviate from the spirit and scope of the present invention are included in the scope of the claims of the present invention.

Claims (12)

Step 1: for each armored secondary cable, cover the leading edge shielding ground wire with CT11, cover the leading edge shielding ground wire with CT12, cover the terminal shielding ground wire with CT21, and cover the terminal armoring ground wire with CT22;
Step 3: setting an overcurrent criterion and alarming the secondary cable for overcurrent along with the current sampled in step 2;
Step 4: setting up a convection reference and, together with the convection reference, alarming the secondary cable for a leakage current while resynchronizing the currents collected in step 2; and
A method for detecting and warning a ground wire current in an armored shielded secondary cable, comprising: a step 5 for detecting and warning a ground wire current in the secondary cable based on the results of the alarms in steps 3 and 4. Step 3 includes:
Establish a shielding grounding conductor overcurrent standard and measure the shielding grounding conductor overcurrent at the tip of the armored shielded secondary cable.
Step 3-1, transmitting an overcurrent alarm signal for the shielding layer of the secondary cable after a fixed delay t1 has elapsed;
Step 3-2: transmitting an overcurrent alarm signal for the armor layer of the next cable;
2. The method for detecting and warning an armored secondary cable ground wire current as recited in claim 1, further comprising: step 3-3. transmitting a local close circuit overcurrent warning signal in the secondary cable upon expiration of a third predetermined delay t3. In step 3-1, the shielding layer ground wire overcurrent standard is
Or,
Or,
A method for detecting and warning about ground wire current in secondary cables. The step 3-2 is that the armor layer ground wire overcurrent standard is
or
or
A method for detecting and providing a warning about ground wire current in a shielded secondary cable. Step 3-3 is a step in which the local closing current reference in the secondary cable is
3. The method of claim 2, wherein the alarm value is continuity. Step 4 includes:
It judges whether resynchronization is necessary according to the communication status, and if so, it
a step 4-2 of transmitting an alarm indicating that the shielding layer of the secondary cable has become leaky according to the result of judging the shielding layer current difference while making a judgment using a different shielding layer current difference standard for each of the above; and
The method for detecting and warning the ground wire current of an armored shielded secondary cable as described in claim 1, further comprising step 4-3: making a judgment using different shield current difference standards for each of the armored shield current difference judged, and sending an alarm that the shield layer of the secondary cable has become a leakage current according to the judgment result of the shield current difference. In step 4-1, the terminal shield ground wire current of the electric cable that has undergone resynchronization
the current being a shield ground current;
7. The method for detecting and warning ground wire current in an armored shielded secondary cable according to claim 6, The step 4-2 is
The first shield layer current difference standard is
And then,
The second shield layer current difference standard is
7. The method for detecting and warning about ground wire current in an armored shielded secondary cable as claimed in claim 6, further comprising: sending an alarm signal indicating that the shield layer of the secondary cable has become leaky after a fourth predetermined delay t4, wherein the shield layer current difference criterion is met if the first shield layer current difference criterion or the second shield layer current difference criterion is met. First armor layer current difference standard
And then,
The second armor layer current difference standard is
The method for detecting and warning about the ground wire current of an armored shielded secondary cable as described in claim 6, characterized in that the armor layer current difference criterion is met when the first armor layer current difference criterion or the second armor layer current difference criterion is met, and at this time, when a fifth predetermined delay t5 has elapsed, an alarm signal is sent to indicate that the armor layer of the secondary cable has become leaky. A system for detecting and warning about a ground wire current in an armored shielded secondary cable using the method for detecting and warning about a ground wire current in an armored shielded secondary cable according to any one of claims 1 to 9,
current collecting means, resynchronizing means and alarm determining means;
Wherein, a current collecting means is installed in each armored shielded secondary cable, and the current collecting means is for collecting a leading shielding layer ground wire current, a leading armoring layer ground wire current, a terminal shielding layer ground wire current and a terminal armoring layer ground wire current in each armored shielded secondary cable;
The resynchronization means is capable of determining whether it is necessary to resynchronize the terminal shield ground wire current and the terminal shield ground wire current of the armored secondary cable, and resynchronizes the currents determined to be necessary;
The ground wire current detection and warning system for an armored secondary cable as described in claim 1, characterized in that the alarm judgment means is capable of setting alarm criteria for shielding layer overcurrent, armor layer overcurrent, local closed circuit overcurrent, shielding layer leakage and armor layer leakage in the secondary cable, and receives current information from the current collection means and the resynchronization means to obtain the alarm result. A terminal having a processor and a storage medium,
the storage medium is for storing instructions;
10. The terminal of claim 1, wherein the processor is adapted to perform operations based on the instructions and to execute the steps of the method according to any one of claims 1 to 9. The computer-readable medium according to claim 1, characterized in that the computer-readable medium stores a computer program, which, when executed by a processor, performs the steps of the method according to any one of claims 1 to 9.