Fault detector and fault detection method of alternating current distribution line and related equipment

Abstract

The invention is suitable for the technical field of fault detection, and provides a fault detector, a fault detection method and related equipment of an alternating current distribution line, and the fault detector comprises a power supply circuit, a measurement and control CPU, a radio frequency communication circuit, a display module, a current collection circuit and a current test clamp. The output end of the power supply circuit is respectively connected with the measurement and control CPU, the radio frequency communication circuit and the current acquisition circuit; the input end of the current acquisition circuit is connected with the current test clamp, and the output end of the current acquisition circuit is connected with the input end of the measurement and control CPU; the output end of the measurement and control CPU is connected with the radio frequency communication circuit and the display module. The measurement and control CPU is used for processing received instructions and transmitting the processed data to the radio frequency communication circuit or the display module for feedback, the instructions comprise current signal data transmitted by the current acquisition circuit, an instruction transmitted by the radio frequency communication circuit or an instruction transmitted by the display module, and the parasitic fault detection efficiency and accuracy of the detector are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fault detection, and in particular to a fault detector, a fault detection method and related equipment for an AC power distribution line. Background Art

[0002] In the 400V AC power supply system of the substation, many loads are powered by dual power supplies to ensure the reliability of power production. The dual power supply switch only switches the phase line, not the neutral line. Under normal circumstances, in the three-phase four-wire line, the vector sum of the three-phase current is balanced with the neutral line current. However, since the neutral line is not switched when the dual power supply is switched, the balance relationship between the three-phase current and the neutral line current in the normal distribution line cable will be broken. When a parasitic fault occurs in the AC distribution line, residual current will also appear in the fault line.

[0003] In traditional line current testing, when the line phases A, B, C and N are far apart, if you want to measure the residual current, you need to use a large-range multi-plier to test the current of different cables separately. After completing the four current tests, vector calculations are performed. However, this method has defects in the case of small currents. Because the test accuracy of a large-range measuring tool cannot be guaranteed when measuring small currents, the problem of inaccurate residual current testing will occur. Summary of the invention

[0004] The embodiments of the present application provide a fault detector, a fault detection method and related equipment for an AC power distribution line, which are used to solve the problem of inaccurate residual current testing.

[0005] A first aspect of an embodiment of the present application provides a fault detector for an AC power distribution line, comprising:

[0006] Power supply circuit, measurement and control CPU, radio frequency communication circuit, display module, current acquisition circuit and current test clamp;

[0007] The output end of the power supply circuit is respectively connected to the measurement and control CPU, the radio frequency communication circuit and the current acquisition circuit; the input end of the current acquisition circuit is connected to the current test pliers, and the output end of the current acquisition circuit is connected to the input end of the measurement and control CPU; the output end of the measurement and control CPU is respectively connected to the radio frequency communication circuit and the display module;

[0008] The measurement and control CPU is used to process the received instructions and transmit the processed data to the radio frequency communication circuit or the display module for feedback. The instructions include the current signal data transmitted by the current acquisition circuit, the instructions transmitted by the radio frequency communication circuit or the instructions transmitted by the display module.

[0009] Furthermore, the current acquisition circuit is provided with four input interfaces, and the four input interfaces are equipped with diodes.

[0010] Furthermore, the current testing pliers include four pliers, and the four pliers are respectively connected to four input interfaces of the current acquisition circuit.

[0011] Furthermore, the current acquisition circuit is used to perform vector superposition processing on the four received current signals, and transmit the processed target current signal to the measurement and control CPU.

[0012] Furthermore, the measurement and control CPU is an ARM 32-bit Cortex TM --M3 CPU.

[0013] A second aspect of an embodiment of the present application provides a method for detecting a fault in an AC power distribution line, comprising:

[0014] Perform residual current tests on all distribution branches using several detectors;

[0015] When there is residual current, determining whether the number of branches of the residual current meets a preset condition;

[0016] If so, use several detectors to test the branch with residual current at the same time, and perform vector synthesis operation on the residual current;

[0017] The residual current tracking test is performed based on the results of the vector synthesis operation to determine the target parasitic fault point.

[0018] Furthermore, the use of a plurality of detectors to perform residual current testing on all distribution branches includes:

[0019] The plurality of detectors adopt level physical signal timing and high-precision constant temperature crystal oscillator for time keeping.

[0020] Furthermore, the residual current tracking test is performed according to the result of the vector synthesis operation to determine the target parasitic fault point, including:

[0021] It is determined whether there is a branch combination whose vector operation result is zero according to the result of the vector synthesis operation. If so, it is determined that there is a target branch combination with a parasitic fault.

[0022] Furthermore, the determining of the target branch combination having parasitic faults includes:

[0023] A residual current tracing test is performed starting from a branch in the target branch combination, and the location of the parasitic fault point is determined by continuously tracing the change of the residual current.

[0024] A third aspect of an embodiment of the present application provides a computer device, including a memory, a processor, and computer-readable instructions stored in the memory and executable on the processor, wherein when the processor executes the computer-readable instructions, the steps of the AC distribution line fault detection method as described in any one of the above are implemented.

[0025] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0026] The detector in the present invention supplies power to the measurement and control CPU, the radio frequency communication circuit and the current acquisition circuit through the power supply circuit. The current signal obtained by the current test pliers is transmitted to the measurement and control CPU through the current acquisition circuit. The measurement and control CPU can process various instructions including current signal data, instructions transmitted from the radio frequency communication circuit and instructions transmitted from the display module, and feed back the processed data to the radio frequency communication circuit for communication transmission or presentation on the display module, thus realizing the effective integration of current signal acquisition, instruction processing and feedback, information display and communication functions, and improving the efficiency of data processing. The detector of the present invention can work as a single machine or in parallel with multiple machines. When multiple machines work in parallel, the residual current of the parasitic circuit can be tracked to find the parasitic circuit fault point; the parasitic circuit fault of the feeder branch of the 400V AC power supply system of each plant and station can be effectively found, the fault can be eliminated, and the safe production of electricity can be guaranteed.

[0027] Other advantages, objectives, and features of the present invention will be set forth in part in the following description, and in part will be apparent to those skilled in the art based on an examination of the following or may be taught from the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of an embodiment of a fault detector for an AC power distribution line in the present invention;

[0029] Figure 2 This is a schematic diagram of power distribution of the AC system in the present invention;

[0030] Figure 3 This is a 3.3V power supply circuit diagram of the present invention;

[0031] Figure 4 This is a 2.5V power supply circuit diagram of the present invention;

[0032] Figure 5 The radio frequency communication circuit diagram of the present invention;

[0033] Figure 6 This is a circuit diagram for processing an input current signal in the present invention;

[0034] Figure 7 This is the minimum circuit diagram of the CPU and peripherals used in the present invention;

[0035] Figure 8 The present invention is a flowchart of an embodiment of a method for detecting a fault in an AC power distribution line. DETAILED DESCRIPTION

[0036] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "corresponding to" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0037] Embodiment 1

[0038] See also Figure 1 , an embodiment of a fault detector for an AC power distribution line in the present invention is as follows:

[0039] The fault detector of the AC power distribution line includes a power supply circuit 1, a measurement and control CPU 2, a radio frequency communication circuit 3, a display module 4, a current acquisition circuit 5 and a current test clamp 6, wherein the output end of the power supply circuit 1 is respectively connected to the measurement and control CPU 2, the radio frequency communication circuit 3 and the current acquisition circuit 5; the input end of the current acquisition circuit 5 is connected to the current test clamp 6, and the output end of the current acquisition circuit 5 is connected to the input end of the measurement and control CPU 2; the output end of the measurement and control CPU 2 is respectively connected to the radio frequency communication circuit 3 and the display module 4; the measurement and control CPU 2 is used to process the received instructions, and transmit the processed data to the radio frequency communication circuit 3 or the display module 4 for feedback, and the instructions include the current signal data transmitted by the current acquisition circuit 5, the instructions transmitted by the radio frequency communication circuit 3 or the instructions transmitted by the display module. The detector designed by the present invention can solve the problem of testing residual current and tracking residual current for a station with a wide coverage of 400V lines and a long distance for laying cables, and accurately troubleshooting parasitic fault points.

[0040] See also Figure 2The 400V AC system for the station is composed of multiple transformers, and the power supply is designed with two busbars. To meet the power supply reliability requirements, the load is designed to be an independent power supply and a dual power supply. The power switching device of the dual power load usually only cuts off the phase line, and the N line is not cut off. The dual power load also has a multi-level design, so that the multiple N lines of the distribution branch are connected on the load side. The current vector sum in any cable of the line connected by the N line is not zero. The parasitic faults of the 400V AC system for the station can be divided into two types: N line parasitic and phase line parasitic. N line parasitic is Figure 2 The wiring designed by the principle shown in the figure is a phase line parasitic connection of two phase lines from the source end. Parasitic faults destroy the current loop of the designed power supply circuit. When the current in the distribution cable is not 0, the cable generates eddy currents, which reduces the cable's current carrying capacity. In the worst case, the eddy currents heat up and waste electric energy, and in the worst case, the heat causes a fire. When the parasitic fault comes from different phase power supplies, it will also cause a power short circuit, generate a huge current and cause tripping, etc. Therefore, the current problems can be solved by designing the above detector.

[0041] See also Figure 3-Figure 4 The power supply circuit diagram is shown in the figure. The power supply adopts 4 No. 5 batteries (strong versatility and easy to purchase). The voltage regulator chip is used to design 3.3V and 2.5V stable output to ensure the normal and reliable operation of each functional module circuit. The display module 4 is designed with a 4.3-inch industrial touch screen to meet the needs of detector data display and test control input. Please refer to Figure 5 ,RF communication circuit 3 uses NRF24L01 RF signal chip to design RF communication cable, and the power supply design of the circuit uses capacitor to handle jitter elimination to solve the interference problem.

[0042] In actual applications, when the AC power distribution branch is wired, the phase line passes through the switch and the N line is taken to the N busbar. The phase line and the N line are far apart. It is difficult to use an ammeter to test the residual current of the 400V distribution line or the clamp ammeter commonly used in daily production. Figure 6 In the present invention, the current acquisition circuit 5 is provided with four input interfaces, and the four input interfaces are equipped with diodes. Four input signals are input from the reverse input terminal of the amplifier, and a first-stage discharge is performed. The AD sampling point of large current acquisition AC-IN is designed at the first-stage amplification output position; for small current, the signal needs to be amplified at the second stage and collected at the AD-MAX position. In addition, the current test pliers include four pliers, and the four pliers are respectively connected to the four input interfaces of the current acquisition circuit 5. The current acquisition circuit 5 is used to perform vector superposition processing on the four received current signals, and transmit the processed target current signal to the measurement and control CPU. The detector only collects one processed current signal to ensure accurate measurement of the cable residual current under different line current conditions.

[0043] See also Figure 7The measurement and control CPU uses STM32F103ZET6. The chip is ARM 32-bit Cortex TM --M3CPU, with the characteristics of fast running speed, large storage capacity, low power consumption and a large number of various functional interfaces.

[0044] The above embodiment forms a relatively compact and fully functional detector system architecture by organically integrating the power supply circuit 1, the measurement and control CPU 2, the radio frequency communication circuit 3, the display module 4, the current acquisition circuit 5 and the current test clamp 6. As a component that directly contacts the measured circuit, the current test clamp 6 can effectively obtain the current signal in the circuit; in conjunction with the current acquisition circuit, the collected current signal can be conditioned (such as amplification, filtering, etc.) as necessary to meet the subsequent measurement and control CPU's requirements for signal quality. The measurement and control CPU 2, as the data processing core of the entire system, can timely receive the current signal data transmitted by the current acquisition circuit and process it according to the preset program and algorithm. The existence of the radio frequency communication circuit 3 gives the system the ability to communicate remotely. The display module 4 provides an intuitive information display platform for on-site operators. The measurement and control CPU 2 can process the instructions received from the radio frequency communication circuit or the instructions transmitted by the display module, which makes the system have good operability and controllability.

[0045] Embodiment 2

[0046] See also Figure 8 , an embodiment of a fault detection method for an AC power distribution line in the present invention comprises the following steps:

[0047] S11. Use several detectors to perform residual current tests on all distribution branches;

[0048] The detector in the above embodiment is used to perform residual current test on all power distribution branches. By performing residual current test on each branch in turn, no branch that may have faults is missed, thus ensuring the comprehensiveness of the detection.

[0049] S12. When there is residual current, determine whether the number of branches of the residual current meets the preset conditions;

[0050] When residual current is detected in a branch, it is only a preliminary abnormal prompt. The preset condition here is that if there is residual current and the number of branches is greater than or equal to 2, it means that there is a high possibility of parasitic fault. This is because the residual current of a single branch may be caused by local component failure or short-term interference in the branch. When residual current appears in multiple branches, it is likely that there is some abnormal electrical connection between these branches, that is, parasitic loop, causing current to flow in a path that should not exist, thereby showing residual current abnormality in multiple branches.

[0051] S13. When the number of residual current branches meets the preset conditions, several detectors are used to simultaneously test the branches with residual current, and a vector synthesis operation is performed on the residual current;

[0052] After initially determining that there may be a parasitic fault, multiple detectors need to be used to simultaneously test the branch with residual current. Each detector must accurately measure the magnitude and direction (vector information) of the residual current in the branch.

[0053] Step S13 also includes:

[0054] Several detectors use level physical signal synchronization and high-precision constant temperature crystal oscillator timekeeping. Specifically, one detector realizes the function of residual current test of one current. When testing residual current of multiple cables, multiple detectors are required to measure simultaneously. The current is tested synchronously between different detectors to solve the time synchronization problem; to avoid communication data delay, the patented design of the detector uses level physical signal synchronization; after the synchronization is completed, the clock consistency during operation is guaranteed, and the high-precision constant temperature crystal oscillator is sampled for timekeeping; the time is synchronized before use, and the accuracy of the test current is ensured within a few hours under the action of the crystal oscillator.

[0055] According to circuit theory, in the presence of parasitic loops, since the parasitic loops electrically form additional current paths, the residual currents in these branches will be related to each other through the parasitic loops. From the perspective of vector analysis, if the residual current of each branch is regarded as a vector, then ideally, the residual current vector synthesis result of these branches with parasitic loops should be equal to zero. By performing a synthesis operation on the residual current vectors of multiple branches with residual currents, it is analyzed whether there is a branch combination with a vector operation result equal to zero. If such a combination exists, it can be inferred that these branches have parasitic faults on the load side.

[0056] S14. Perform a residual current tracking test based on the result of the vector synthesis operation to determine whether a parasitic fault point has been detected.

[0057] Step S14 also includes:

[0058] It is determined whether there is a branch combination whose vector operation result is zero according to the result of the vector synthesis operation. If so, it is determined that there is a target branch combination with a parasitic fault.

[0059] The residual current tracing test is performed starting from the branch in the target branch combination, and the location of the parasitic fault point is determined by continuously tracing the changes in the residual current.

[0060] After the branch combinations with parasitic faults are determined, residual current tracing tests are performed starting from these branches. Because these branches have been judged to have parasitic faults, their residual currents are associated with parasitic loops, so tracing from here can find the fault point along the path of abnormal current.

[0061] During the tracing process, the changes in the residual current are gradually detected along the distribution line. This requires the detector to measure along different nodes and sections of the line. For example, for cable lines, the residual current can be measured at key locations such as the joints and branches of the cable. As the parasitic fault point is approached, the magnitude, direction and other characteristics of the residual current will change accordingly. The residual current may gradually increase or change direction, and these changing characteristics provide clues for tracing. By continuously tracking the changes in the residual current, the location of the parasitic fault point is finally determined. When the residual current changes suddenly at a certain point, such as suddenly increasing to the maximum value or changing direction sharply, and physical anomalies can be found around this point, it can be determined that the point is a parasitic fault point.

[0062] The above-mentioned embodiment method can effectively detect parasitic faults. Detectors are used to detect residual currents in all distribution branches. When there is residual current and the number of branches is not less than 2, it is preliminarily determined that there may be a parasitic fault; then multiple detectors are used to test the branches that may have faults at the same time and perform residual current vector synthesis operations. If there is a branch combination with a zero result, it is determined that these branches have parasitic faults on the load side; finally, the residual current changes of the faulty circuit are continuously tracked until the parasitic fault point is found, which improves the comprehensiveness and accuracy of parasitic circuit fault detection and the accuracy of fault location, and ensures the safe and stable operation of the distribution system.

[0063] Embodiment 3

[0064] The present invention provides a computer device, comprising a memory, a processor, and computer-readable instructions stored in the memory and executable on the processor. When the processor executes the computer-readable instructions, the steps of the above method are implemented.

[0065] Those of ordinary skill in the art will appreciate that the units of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition of each example has been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0066] In the embodiments provided by the present invention, it should be understood that the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units can be combined into one unit, one unit can be split into multiple units, or some features can be ignored. In addition, each functional unit in each embodiment of the present invention can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units.

[0067] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-0nlyMemory), random access memory (RAM, RandomAccessMemory), mobile hard disk, magnetic disk or optical disk, etc., which can store program code.

[0068] It can be understood that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A fault detector for an AC power distribution line, characterized in that: include: Power supply circuit, measurement and control CPU, radio frequency communication circuit, display module, current acquisition circuit and current test clamp; The output end of the power supply circuit is respectively connected to the measurement and control CPU, the radio frequency communication circuit and the current acquisition circuit; the input end of the current acquisition circuit is connected to the current test pliers, and the output end of the current acquisition circuit is connected to the input end of the measurement and control CPU; the output end of the measurement and control CPU is respectively connected to the radio frequency communication circuit and the display module; The measurement and control CPU is used to process the received instructions and transmit the processed data to the radio frequency communication circuit or the display module for feedback. The instructions include the current signal data transmitted by the current acquisition circuit, the instructions transmitted by the radio frequency communication circuit or the instructions transmitted by the display module.

2. The fault detector for AC power distribution line according to claim 1, characterized in that: The current acquisition circuit is provided with four input interfaces, and the four input interfaces are equipped with diodes.

3. The fault detector for AC power distribution line according to claim 2, characterized in that: The current testing pliers include four pliers, and the four pliers are respectively connected to four input interfaces of the current acquisition circuit.

4. The fault detector for AC power distribution line according to any one of claims 1 to 3, characterized in that: The current acquisition circuit is used to perform vector superposition processing on the four received current signals, and transmit the processed target current signal to the measurement and control CPU.

5. The fault detector for AC power distribution line according to claim 1, characterized in that: The measurement and control CPU is an ARM32-bit Cortex TM --M3 CPU.

6. A method for detecting faults in an AC power distribution line, characterized in that: include: Perform residual current tests on all distribution branches using several detectors; When there is residual current, determining whether the number of branches of the residual current meets a preset condition; If so, use several detectors to test the branch with residual current at the same time, and perform vector synthesis operation on the residual current; The residual current tracking test is performed based on the results of the vector synthesis operation to determine the target parasitic fault point.

7. The fault detection method for AC power distribution line according to claim 6, characterized in that: The residual current test of all distribution branches is performed using several detectors, including: The plurality of detectors adopt level physical signal timing and high-precision constant temperature crystal oscillator for time keeping.

8. The fault detection method for AC power distribution line according to claim 6, characterized in that: The residual current tracking test is performed according to the result of the vector synthesis operation to determine the target parasitic fault point, including: It is determined whether there is a branch combination whose vector operation result is zero according to the result of the vector synthesis operation. If so, it is determined that there is a target branch combination with a parasitic fault.

9. The method for detecting faults in AC power distribution lines according to claim 8, characterized in that: The determining of a target branch combination having a parasitic fault includes: A residual current tracing test is performed starting from a branch in the target branch combination, and the location of the parasitic fault point is determined by continuously tracing the change of the residual current.

10. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the fault detection method for the AC power distribution line according to any one of claims 6 to 9 is implemented.

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