Low-voltage loop latent fault monitoring method and device and storage medium
By collecting the pressure difference and loop current of the three-phase low-voltage cabinet, calculating the equivalent loop impedance and loss, and monitoring latent faults, the limitations of relying on temperature sensors in the existing technology are solved, and fault monitoring is achieved with higher accuracy.
Patent Information
- Application Number
- CN202411925333.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-25
- Publication Date
- 2025-04-22
AI Technical Summary
The existing low-voltage cabinet fault monitoring system relies on temperature sensors and cannot effectively monitor latent faults of components in low-voltage cabinets, and the detection accuracy is greatly affected by the ambient temperature.
By collecting the pressure difference and loop current on the busbar side and line side of the low-voltage cabinet, calculating the equivalent loop impedance and loss, comparing the difference between phases and historical data, and an alarm will be issued if the preset threshold is exceeded, monitoring of latent faults will be achieved.
There is no need to install a large number of temperature sensors to improve fault detection accuracy, reduce implementation costs, and avoid detection accuracy being affected by ambient temperature.
Smart Images
Figure CN119861216A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of low-voltage power distribution, and in particular to a method, a device and a storage medium for monitoring latent faults in a low-voltage circuit. Background Art
[0002] There are a large number of low-voltage cabinets in industrial enterprises. In long-cycle operating enterprises such as petrochemicals, low-voltage cabinets will age during long-term operation, leading to an increase in equipment abnormalities. When a low-voltage cabinet is abnormal, the temperature often rises. In the existing fault monitoring system, temperature abnormalities are usually monitored by temperature sensors installed in the low-voltage cabinet to achieve fault monitoring. However, since the temperature sensor can only monitor temperature abnormalities near the sensor installation location, and there are usually a large number of components in the low-voltage cabinet, the fault points are scattered, and it is impossible to install a large number of sensors. In addition, the detection accuracy of fault monitoring by detecting temperature abnormalities is also easily affected by the ambient temperature. Therefore, the method of using temperature sensors to monitor faults has great limitations. To this end, it is necessary to design a new low-voltage circuit fault monitoring solution that can solve the above technical problems. Summary of the invention
[0003] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a method for monitoring latent faults in low-voltage circuits. By analyzing the loss of the power supply circuit and monitoring whether there is any loss abnormality, it is determined whether there is a latent fault in the low-voltage cabinet, thereby avoiding the installation of a large number of temperature sensors in the low-voltage cabinet and improving the accuracy of fault abnormality detection.
[0004] To solve the above problems, the technical solution adopted by the present invention is as follows: A method for monitoring latent faults in a low-voltage circuit comprises the following steps:
[0005] Collect the voltage difference and loop current on the bus side and line side of the three-phase low-voltage cabinet;
[0006] Calculate and record the three-phase equivalent loop impedances RA, RB, and RC according to the three-phase voltage difference and loop current;
[0007] Calculate and record the three-phase equivalent loop losses PA, PB and PC according to the three-phase equivalent loop impedances RA, RB and RC and the loop currents;
[0008] The equivalent loop impedance and equivalent loop loss of the three phases are compared with each other. If the difference between the equivalent loop impedance or equivalent loop loss of any two phases exceeds the preset threshold range, an alarm is issued;
[0009] The current equivalent loop impedance and equivalent loop loss of the three phases are compared with the recorded historical equivalent loop impedance and historical equivalent loop loss respectively. If the difference between the current equivalent loop impedance and equivalent loop loss and the historical equivalent loop impedance and historical equivalent loop loss exceeds the preset threshold range, an alarm is issued.
[0010] Compared with the prior art, the beneficial effect of the present invention is that the low-voltage circuit latent fault monitoring method calculates the equivalent circuit impedance and equivalent circuit loss of the three phases by collecting the pressure difference and circuit current on the bus side and line side of the three phases of the low-voltage cabinet, and judges whether there is abnormal loss in the circuit by comparing the difference between the equivalent circuit impedance and equivalent circuit loss between the phases, and comparing the difference between the current equivalent circuit impedance and equivalent circuit loss and the historical equivalent circuit impedance and historical equivalent circuit loss, thereby realizing the monitoring of latent faults in the circuit. The monitoring method does not need to set a large number of temperature sensors in the low-voltage cabinet, is easy to implement and has a low implementation cost, and the detection accuracy will not be affected by the internal working environment temperature, which can improve the monitoring accuracy of faults.
[0011] In the above-mentioned low-voltage circuit latent fault monitoring method, the steps of comparing the equivalent circuit impedances and equivalent circuit losses of the three phases with each other, and issuing an alarm if the difference between the equivalent circuit impedances or equivalent circuit losses of any two phases exceeds a preset threshold range, include:
[0012] Calculate the values of RA / RB, RB / RC, RC / RA, PA / PB, PB / PC, and PC / PA;
[0013] The values of RA / RB, RB / RC, RC / RA, PA / PB, PB / PC and PC / PA are compared with the corresponding threshold ranges respectively. If the value of any one of RA / RB, RB / RC, RC / RA, PA / PB, PB / PC and PC / PA exceeds the corresponding threshold range, an alarm is issued.
[0014] In the above-mentioned low-voltage circuit latent fault monitoring method, the steps of comparing the equivalent circuit impedances and equivalent circuit losses of the three phases with each other, and issuing an alarm if the difference between the equivalent circuit impedances or equivalent circuit losses of any two phases exceeds a preset threshold range, include:
[0015] Calculate the average values of equivalent loop impedance and equivalent loop loss of the three phases in the most recent period of time respectively;
[0016] Calculate the average values of the historical equivalent loop impedance and historical equivalent loop loss of the three phases over a period of time respectively;
[0017] The average values of equivalent loop impedance and equivalent loop loss in the most recent period are compared with the average values of historical equivalent loop impedance and historical equivalent loop loss. If the difference between any pair of average values exceeds a preset threshold range, an alarm is issued.
[0018] The above-mentioned low-voltage circuit latent fault monitoring method further includes:
[0019] The recorded data of the three-phase equivalent loop impedance and equivalent loop loss are displayed in real time in the form of a real-time dynamic curve.
[0020] A storage medium stores a computer program, which implements the above-mentioned low-voltage circuit latent fault monitoring method when called and executed by a processor.
[0021] A low-voltage circuit latent fault monitoring device comprises a processor and a memory, wherein the memory is electrically connected to the processor, and the processor can call and execute a computer program in the memory to implement the above-mentioned low-voltage circuit latent fault monitoring method.
[0022] A fault monitoring system for implementing the above-mentioned low-voltage circuit latent fault monitoring method comprises: the above-mentioned low-voltage circuit latent fault monitoring device; a current acquisition circuit, whose output end is electrically connected to the low-voltage circuit latent fault monitoring device, and whose input end is arranged on the three-phase line of the low-voltage cabinet, for detecting the three-phase circuit current of the low-voltage cabinet; a pressure difference acquisition circuit, whose output end is electrically connected to the low-voltage circuit latent fault monitoring device, and whose input end is arranged at the three-phase contacts of the low-voltage cabinet, for detecting the pressure difference between the bus side and the line side of the three-phase low-voltage cabinet.
[0023] The above-mentioned fault monitoring system also includes a communication management machine and a background main station. The low-voltage circuit latent fault monitoring device is communicatively connected to the background main station through the communication management machine.
[0024] In the above-mentioned fault monitoring system, the voltage difference acquisition circuit of each phase includes a Rogowski coil, two voltage sampling circuits with different sampling ranges and an analog-to-digital converter. The Rogowski coil is sleeved on the contact of the corresponding phase, the input ends of the two voltage sampling circuits are electrically connected to the Rogowski coil, and the output ends of the two voltage sampling circuits are electrically connected to the low-voltage circuit latent fault monitoring device through the analog-to-digital converter.
[0025] In the above-mentioned fault monitoring system, the voltage sampling circuit includes a voltage follower and an isolation amplifier connected in sequence, the input end of the voltage follower is electrically connected to the Rogowski coil, and the output end of the isolation amplifier is electrically connected to the analog-to-digital converter.
[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 It is a flow chart of a method for monitoring latent faults in a low-voltage circuit according to an embodiment of the present invention;
[0028] Figure 2 is a system block diagram of a fault monitoring system according to an embodiment of the present invention;
[0029] Figure 3 is a schematic diagram of a current acquisition circuit according to an embodiment of the present invention;
[0030] Figure 4 4 is a schematic diagram of a voltage difference acquisition circuit according to an embodiment of the present invention. DETAILED DESCRIPTION
[0031] The embodiments of the present invention are described in detail below. Figure 1 , an embodiment of the present invention provides a method for monitoring latent faults in a low-voltage circuit, comprising the following steps:
[0032] Collect the voltage difference and loop current on the bus side and line side of the three-phase low-voltage cabinet;
[0033] Calculate and record the three-phase equivalent loop impedances RA, RB, and RC according to the three-phase voltage difference and loop current;
[0034] Calculate and record the three-phase equivalent loop losses PA, PB and PC according to the three-phase equivalent loop impedances RA, RB and RC and the loop currents;
[0035] The equivalent loop impedance and equivalent loop loss of the three phases are compared with each other. If the difference between the equivalent loop impedance or equivalent loop loss of any two phases exceeds the preset threshold range, an alarm is issued;
[0036] The current equivalent loop impedance and equivalent loop loss of the three phases are compared with the recorded historical equivalent loop impedance and historical equivalent loop loss respectively. If the difference between the current equivalent loop impedance and equivalent loop loss and the historical equivalent loop impedance and historical equivalent loop loss exceeds the preset threshold range, an alarm is issued.
[0037] This method collects the voltage difference and loop current on the bus side and line side of the three-phase, and combines Ohm's law to solve the equivalent loop impedance and equivalent loop loss of the three phases. By comparing the difference between the equivalent loop impedance and equivalent loop loss between the phases, and comparing the difference between the current equivalent loop impedance and equivalent loop loss and the recorded historical equivalent loop impedance and historical equivalent loop loss, it is determined whether there is an abnormality in the loop loss of the entire low-voltage cabinet, thereby realizing the monitoring of latent faults in the low-voltage cabinet loop. By adopting this method to monitor the fault of the low-voltage cabinet loop, there is no need to set a large number of temperature sensors in the low-voltage cabinet, which reduces the cost and implementation difficulty of fault monitoring. At the same time, it is not affected by the working environment temperature in the low-voltage cabinet, and the accuracy of fault monitoring can be improved.
[0038] In this embodiment, the voltage differences ΔUA, ΔUB and ΔUC on the bus side and the line side of the three-phase low-voltage cabinet, as well as the three-phase loop currents IA, IB and IC are collected, and according to Ohm's law U = I*R and P = I 2 *R can calculate the three-phase equivalent loop impedance RA = ΔUA / IA, RB = ΔUB / IB and RC = ΔUC / IC, and calculate the three-phase equivalent loop loss PA = IA 2 *RA, PB=IB 2 *RB and PC = IC 2 *RC.
[0039] In this embodiment, the ratio of the equivalent loop impedance and the equivalent loop loss between any two phases is calculated to compare the difference between the equivalent loop impedance and the equivalent loop loss between the phases, that is, the values of RA / RB, RB / RC, RC / RA, PA / PB, PB / PC and PC / PA are calculated respectively, and the calculation results are compared with the preset corresponding threshold ranges. If the value of any phase exceeds the corresponding threshold range, it means that there may be a latent fault in the low-voltage cabinet circuit, and an alarm is sent to the background master station.
[0040] It is understandable that the current equivalent loop impedance and equivalent loop loss values of each phase can be compared with the average values of the historical equivalent loop impedance and equivalent loop loss, or the change trend of the equivalent loop impedance and equivalent loop loss in the most recent period can be compared with the change trend of the historical equivalent loop impedance and historical equivalent loop loss in the historical record to determine whether there is abnormal loss in the low-voltage cabinet circuit, thereby determining whether there is a latent fault in the low-voltage circuit. In this embodiment, by calculating the average value of the equivalent loop impedance and equivalent loop loss in the most recent period, and calculating the average value of the historical equivalent loop impedance and historical equivalent loop loss in a period of the same length, the two average values are compared, and it is determined whether the difference between the two average values exceeds the corresponding threshold range to determine whether the current equivalent loop impedance and equivalent loop loss are abnormal relative to the historical data.
[0041] It can be understood that in some embodiments, the preset threshold range for each item may include multiple threshold ranges of different sizes, each threshold range corresponds to an alarm level, and the alarm level is determined based on which level of the threshold range the difference falls into, and the corresponding level of alarm is executed.
[0042] It can be understood that in some embodiments, in order to facilitate management personnel to intuitively understand the changing trends of the current equivalent loop impedance and equivalent loop loss, the recorded data of the three-phase equivalent loop impedance and equivalent loop loss are displayed on the display of the background main station in the form of real-time dynamic curves.
[0043] It is understandable that in some embodiments, when the drawer cabinet of the low-voltage cabinet is pulled out and pushed in, the voltage difference between the bus side and the line side of the low-voltage cabinet will also change, so it is possible to judge whether the drawer of the low-voltage cabinet is pulled out based on the voltage difference between the bus side and the line side of the low-voltage cabinet, thereby avoiding changing the voltage of the bus side and the line side during maintenance, which may endanger the personal safety of the maintenance personnel. In this embodiment, when the voltage difference between the bus side and the line side is less than or equal to 4V, the drawer of the low-voltage cabinet is in a pushed state; when the voltage difference between the bus side and the line side is greater than 4V, the drawer of the low-voltage cabinet is in a pulled-out state, at which time it is prohibited to change the voltage of the bus side and the line side, and the control relay cuts off the high voltage inside the device to avoid endangering the personal safety of the maintenance personnel. It is understandable that in this embodiment, when a fault is detected, it is prohibited to change the voltage network of the low-voltage cabinet to avoid damage to the equipment in the low-voltage cabinet.
[0044] Based on the same inventive concept, an embodiment of the present invention further provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, the above-mentioned low-voltage circuit latent fault monitoring method can be implemented.
[0045] In some possible embodiments, various aspects of the low-voltage circuit latent fault monitoring method provided by the present invention can also be implemented in the form of a program product, which includes a program code. When the program product is run on the device, the program code is used to enable the control device to execute the steps of the low-voltage circuit latent fault monitoring method according to various exemplary embodiments of the present application described above in this specification.
[0046] Based on the same inventive concept, an embodiment of the present invention also provides a monitoring device for implementing the above-mentioned low-voltage circuit latent fault monitoring method, including a processor and a memory, the memory is electrically connected to the processor, and the processor is used to execute the computer program stored in the memory to implement the above-mentioned low-voltage circuit latent fault monitoring method.
[0047] In one possible design, the processor may include one or more processing units, and the processor and memory may be implemented on the same chip or separately on separate chips. The processor may be a general-purpose processor, such as a central processing unit (CPU), a digital signal processor, an application-specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, and may implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor may be a microprocessor or any conventional processor, etc. The steps of the low-voltage circuit latent fault monitoring method disclosed in the embodiments of the present application may be directly embodied as being executed by a hardware processor, or may be executed by a combination of hardware and software modules in the processor.
[0048] As a non-volatile computer-readable storage medium, the memory can be used to store non-volatile software programs, non-volatile computer executable programs and modules. The memory can include at least one type of storage medium, such as flash memory, hard disk, multimedia card, card-type memory, random access memory (Random Access Memory, RAM), static random access memory (Static Random Access Memory, SRAM), programmable read-only memory (Programmab le Read On ly Memory, PROM), read-only memory (Read On ly Memory, ROM), electrically erasable programmable read-only memory (Electrically Erasable Programmab le Read-Only Memory, EEPROM), magnetic storage, disk, optical disk, etc. The memory is any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory in the embodiment of the present application can also be a circuit or any other device that can realize a storage function, for storing program instructions and / or data.
[0049] By designing and programming the processor, the code corresponding to the low-voltage circuit latent fault monitoring method described in the above embodiment can be fixed into the chip, so that the chip can execute the steps of the low-voltage circuit latent fault monitoring method of the embodiment shown in the present invention when running. How to design and program the processor is a technology well known to those skilled in the art and will not be described here.
[0050] Reference Figure 2 Based on the same inventive concept, the fault monitoring system of the embodiment of the present invention includes the above-mentioned low-voltage circuit latent fault monitoring device, current acquisition circuit and pressure difference acquisition circuit, and the output ends of the current acquisition circuit and the pressure difference acquisition circuit are electrically connected to the low-voltage circuit latent fault monitoring device. The input end of the current acquisition circuit is arranged on the three-phase line of the low-voltage cabinet, and is used to detect the three-phase loop current of the low-voltage cabinet. The input end of the pressure difference acquisition circuit is arranged at the contact of the three-phase of the low-voltage cabinet, and is used to detect the pressure difference between the bus side and the line side of the three-phase of the low-voltage cabinet.
[0051] In practice, when the primary current flows through the contacts of the drawer cabinet in the low-voltage cabinet, since the contact resistance R is generally between 100uΩ-1500uΩ, according to Ohm's law, a voltage difference will be generated at both ends of the contact, that is, the voltage difference between the bus side and the line side. Since the primary current ranges from 10A to 1000A, the voltage difference ranges from 4mV to 1.5V, and the sampling range of the voltage difference is relatively large. So refer to Figure 4In this embodiment, in order to improve the sampling accuracy, two voltage sampling circuits with different sampling ranges are used to collect the voltage at the contact of a certain phase sensed by the Rogowski coil. The voltage difference collection circuit of each phase includes a Rogowski coil, two voltage sampling circuits with different sampling ranges and an analog-to-digital converter. The Rogowski coil is sleeved at the contact of the corresponding phase, the inputs of the two sampling circuits are electrically connected to the Rogowski coil, and the output ends of the voltage sampling circuits are electrically connected to the low-voltage circuit latent fault monitoring device through the analog-to-digital converter.
[0052] Reference Figure 4 In this embodiment, the voltage sampling circuits include a voltage follower and an isolation amplifier, and the sampling ranges of the two voltage sampling circuits are 1mV-250mV and 250mV-5V respectively. The voltage follower in the 1mV-250mV voltage sampling circuit includes an operational amplifier U2C, resistors R1 and R2, the in-phase input terminal of the operational amplifier U2C is connected to the Rogowski coil of the voltage difference acquisition circuit through the resistor R1, the inverting input terminal of the operational amplifier U2C is connected to its output terminal through the resistor R2, and the output terminal of the operational amplifier U2C is connected to the input terminal of the isolation amplifier U2. The voltage follower in the 250mV-5V voltage sampling circuit includes an operational amplifier U2B, resistors R3, R6 and R7. The in-phase input terminal of the operational amplifier U2B is connected to the corresponding Rogowski coil through resistors R5 and R3. The connection node between resistors R5 and R3 is grounded through resistor R6. The inverting input terminal of the operational amplifier U2B is connected to its output terminal through resistor R7. The output terminal of the operational amplifier U2B is connected to the input terminal of the isolation amplifier U3. The sampling range of the two voltage sampling circuits can be adjusted by adjusting the resistance values of resistors R3 and R6.
[0053] Reference Figure 3 In this embodiment, the current acquisition circuit also collects the voltage of the corresponding phase through the Rogowski coil, and then transmits it to the monitoring device through the voltage sampling circuit, isolation amplifier and digital-to-analog converter, and transmits the voltage value corresponding to the loop current value detected by the Rogowski coil to the monitoring device, thereby realizing the collection of the three-phase loop current. Figure 3 In this embodiment, the voltage follower in the current acquisition circuit includes an operational amplifier U2A, a resistor R8, a resistor R9 and a TVS diode TVS1. The in-phase input terminal of the operational amplifier U2A is connected to the corresponding Rogowski coil through the resistor R8, the inverting input terminal of the operational amplifier U2A is connected to its output terminal through the resistor R9, the output terminal of the operational amplifier U2A is connected to the input terminal of the isolation amplifier U1, and the end of the resistor R8 connected to the Rogowski coil is grounded through the TVS diode TVS1.
[0054] Reference Figure 2In this embodiment, the fault monitoring system also includes a communication management machine and a background master station. The monitoring device of each low-voltage cabinet communicates with the communication management machine through the RS485 communication protocol, and transmits the feedback alarm information, real-time equivalent loop impedance and equivalent loop loss to the background master station through the communication management machine, so that the background master station can display the real-time equivalent loop impedance and equivalent loop loss curves, and count the number of failures of each low-voltage cabinet, and analyze the data of each low-voltage cabinet. In this embodiment, the fault monitoring system also includes phase voltage acquisition circuit, debugging network port circuit, B code timing module, watchdog, recording memory, fixed value memory and external real-time module and other commonly used functional modules and circuits in low-voltage power distribution monitoring systems. The above circuits and modules are electrically connected to the low-voltage circuit latent fault monitoring device.
[0055] The present application is described with reference to the flowcharts and / or block diagrams of the methods, apparatus (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.
[0056] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.
[0057] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.
[0058] It should be noted that in the description of the present invention, if there are any orientation descriptions, such as up, down, front, back, left, right, etc., the orientations or positional relationships indicated are all based on the orientations or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and cannot be understood as a limitation on the present invention.
[0059] In the description of the present invention, "several" means one or more, "more" means two or more, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used to distinguish the technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.
[0060] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.
[0061] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.
Claims
1. A method for monitoring latent faults in a low-voltage circuit, characterized in that: The steps include: Collect the voltage difference and loop current on the bus side and line side of the three-phase low-voltage cabinet; Calculate and record the three-phase equivalent loop impedances RA, RB, and RC according to the three-phase voltage difference and loop current; Calculate and record the three-phase equivalent loop losses PA, PB and PC according to the three-phase equivalent loop impedances RA, RB and RC and the loop currents; The equivalent loop impedance and equivalent loop loss of the three phases are compared with each other. If the difference between the equivalent loop impedance or equivalent loop loss of any two phases exceeds the preset threshold range, an alarm is issued; The current equivalent loop impedance and equivalent loop loss of the three phases are compared with the recorded historical equivalent loop impedance and historical equivalent loop loss respectively. If the difference between the current equivalent loop impedance and equivalent loop loss and the historical equivalent loop impedance and historical equivalent loop loss exceeds the preset threshold range, an alarm is issued.
2. The low-voltage circuit latent fault monitoring method according to claim 1 is characterized in that: The step of comparing the equivalent loop impedances and equivalent loop losses of the three phases in pairs, and issuing an alarm if the difference between the equivalent loop impedances or equivalent loop losses of any two phases exceeds a preset threshold range, includes: Calculate the values of RA / RB, RB / RC, RC / RA, PA / PB, PB / PC, and PC / PA; The values of RA / RB, RB / RC, RC / RA, PA / PB, PB / PC and PC / PA are compared with the corresponding threshold ranges respectively. If the value of any one of RA / RB, RB / RC, RC / RA, PA / PB, PB / PC and PC / PA exceeds the corresponding threshold range, an alarm is issued.
3. The low-voltage circuit latent fault monitoring method according to claim 1 is characterized in that: The step of comparing the equivalent loop impedances and equivalent loop losses of the three phases in pairs, and issuing an alarm if the difference between the equivalent loop impedances or equivalent loop losses of any two phases exceeds a preset threshold range, includes: Calculate the average values of equivalent loop impedance and equivalent loop loss of the three phases in the most recent period of time respectively; Calculate the average values of the historical equivalent loop impedance and historical equivalent loop loss of the three phases over a period of time respectively; The average values of equivalent loop impedance and equivalent loop loss in the most recent period are compared with the average values of historical equivalent loop impedance and historical equivalent loop loss. If the difference between any pair of average values exceeds a preset threshold range, an alarm is issued.
4. The method for monitoring latent faults in a low-voltage circuit according to claim 1, characterized in that: Also includes: The recorded data of the three-phase equivalent loop impedance and equivalent loop loss are displayed in real time in the form of a real-time dynamic curve.
5. A storage medium storing a computer program, characterized in that: When the computer program is called and executed by the processor, the method for monitoring latent faults in a low-voltage circuit according to any one of claims 1 to 4 is implemented.
6. A low-voltage circuit latent fault monitoring device, characterized in that: It comprises a processor and a memory, wherein the memory is electrically connected to the processor, and the processor can call and execute a computer program in the memory to implement the low-voltage circuit latent fault monitoring method according to any one of claims 1 to 4.
7. A fault monitoring system for implementing the low-voltage circuit latent fault monitoring method according to any one of claims 1 to 4, characterized in that: include: The low-voltage circuit latent fault monitoring device according to claim 6; A current collection circuit, the output end of which is electrically connected to the low-voltage circuit latent fault monitoring device, and the input end of which is arranged on the three-phase line of the low-voltage cabinet, for detecting the three-phase circuit current of the low-voltage cabinet; The pressure difference acquisition circuit has an output end electrically connected to the low-voltage circuit latent fault monitoring device, and an input end arranged at the three-phase contacts of the low-voltage cabinet, and is used to detect the pressure difference between the bus side and the line side of the three-phase low-voltage cabinet.
8. The fault monitoring system according to claim 7, characterized in that: It also includes a communication management machine and a background main station. The low-voltage circuit latent fault monitoring device is connected to the background main station through the communication management machine.
9. The fault monitoring system according to claim 7, characterized in that: The pressure difference acquisition circuit of each phase includes a Rogowski coil, two voltage sampling circuits with different sampling ranges and an analog-to-digital converter. The Rogowski coil is sleeved on the contact of the corresponding phase, the input ends of the two voltage sampling circuits are electrically connected to the Rogowski coil, and the output ends of the two voltage sampling circuits are electrically connected to the low-voltage circuit latent fault monitoring device through the analog-to-digital converter.
10. The fault monitoring system according to claim 9, characterized in that: The voltage sampling circuit includes a voltage follower and an isolation amplifier connected in sequence, the input end of the voltage follower is electrically connected to the Rogowski coil, and the output end of the isolation amplifier is electrically connected to the analog-to-digital converter.