A method and device for judging insulation fault of a low-voltage AC long cable

Abstract

The present application provides a method and device for judging insulation fault of a low-voltage AC long cable, which relates to the field of fault detection of electric power equipment, including: determining the maximum current error threshold of each long cable according to the residual current value of each long cable in the substation area; determining the corresponding residual current correction coefficient according to the characteristic parameters of the long cable; determining the real-time residual current value of the long cable according to the residual current correction coefficient and the residual current value; judging whether the long cable has an insulation fault according to the real-time residual current value and the maximum current error threshold. The present application can monitor the residual current of a low-voltage AC long cable, thereby judging whether it has an insulation fault.

Description

Technical Field

[0001] The present application relates to the field of power equipment fault detection, and specifically to a method and device for determining insulation faults of long low-voltage AC cables. Background Art

[0002] The causes of fires caused by cable faults in the AC system of substations can generally be divided into two types: metal short circuit and insulation damage. If a fire is caused by a metal short circuit, it can be protected by short-circuit protection; if a fire is caused by cable insulation damage, due to the existence of creepage arc impedance, the arc fault current is small and cannot be protected by traditional short-circuit protection. In the current industry standards, it is recommended to use residual current monitoring devices for electrical fire protection, but currently residual current monitoring devices are mostly used in industrial and civil construction fields, and there is no mature monitoring method in the AC system of low-voltage stations. Summary of the invention

[0003] In response to the problems in the prior art, the present application provides a method and device for determining insulation faults of a low-voltage AC long cable, which can monitor the residual current of the low-voltage AC long cable to determine whether there is an insulation fault.

[0004] In order to solve the above technical problems, this application provides the following technical solutions:

[0005] In a first aspect, the present application provides a method for determining insulation fault of a low-voltage AC long cable, comprising:

[0006] Determine the maximum current error threshold of each long cable according to the obtained residual current value of each long cable in the substation area;

[0007] Determining a corresponding residual current correction coefficient according to characteristic parameters of the long cable;

[0008] Determine the real-time residual current value of the long cable according to the residual current correction coefficient and the residual current value;

[0009] It is determined whether the long cable has an insulation fault according to the real-time residual current value and the maximum current error threshold.

[0010] Furthermore, the step of obtaining the residual current background mean value in the substation area includes:

[0011] Determining corresponding weights according to the operating load values ​​of the long cables;

[0012] A residual current background mean value is determined according to the weight and the residual current value.

[0013] Further, the characteristic parameters include: the voltage level of the substation, the length of the long cable, the number of historical operating failures and the historical operating years; the corresponding residual current correction coefficient is determined according to the characteristic parameters of the long cable, including:

[0014] Determining the importance of the long cable according to the voltage level of the substation;

[0015] Determining the influence range of the long cable according to the length of the long cable;

[0016] The residual current correction coefficient is determined according to the historical number of operating failures of the long cable, the historical operating years, the importance and the impact scope.

[0017] Furthermore, the residual current value includes: a cable head end vector value and a cable end vector value; the real-time residual current value of the long cable is determined according to the residual current correction coefficient and the residual current value, including:

[0018] Determine the vector sum of the residual current according to the vector value of the cable head end and the vector value of the cable end;

[0019] Determining a vector difference of the residual current according to the vector sum of the residual current and the residual current background mean;

[0020] The real-time residual current value is determined according to the residual current vector difference and the residual current correction coefficient.

[0021] Further, judging whether the long cable has an insulation fault according to the real-time residual current value and the maximum current error threshold value includes:

[0022] When the real-time residual current value is greater than the maximum current error threshold, it is determined that the long cable has the insulation fault;

[0023] When the real-time residual current value is less than or equal to the maximum current error threshold, it is determined that the insulation fault does not exist in the long cable.

[0024] In a second aspect, the present application provides an insulation fault judgment device for a low-voltage AC long cable, comprising:

[0025] An error threshold determination unit, used to determine the maximum current error threshold of each long cable according to the acquired residual current value of each long cable in the substation area;

[0026] A correction coefficient determination unit, used to determine a corresponding residual current correction coefficient according to characteristic parameters of the long cable;

[0027] A real-time current determination unit, used to determine the real-time residual current value of the long cable according to the residual current correction coefficient and the residual current value;

[0028] A fault judgment unit is used to judge whether the long cable has an insulation fault according to the real-time residual current value and the maximum current error threshold.

[0029] Furthermore, the insulation fault judgment device for the low-voltage AC long cable further includes:

[0030] A load weight determination unit, used to determine a corresponding weight according to the operating load value of each long cable;

[0031] The background mean value determining unit is used to determine the residual current background mean value according to the weight and the residual current value.

[0032] Furthermore, the correction coefficient determination unit includes:

[0033] An importance determination module, used to determine the importance of the long cable according to the voltage level of the substation;

[0034] An influence range determination module, used to determine the influence range of the long cable according to the length of the long cable;

[0035] The correction coefficient determination module is used to determine the residual current correction coefficient according to the historical number of operating failures of the long cable, the historical operating years, the importance and the impact range.

[0036] Furthermore, the residual current value includes: a cable head end vector value and a cable end vector value; the real-time current determination unit includes:

[0037] A vector sum determination module, used to determine the vector sum of the residual current according to the vector value of the cable head end and the vector value of the cable end;

[0038] A vector difference determination module, used to determine the vector difference of the residual current according to the vector sum of the residual current and the residual current background mean;

[0039] The real-time current determination module is used to determine the real-time residual current value according to the vector difference of the residual current and the residual current correction coefficient.

[0040] Furthermore, the fault judgment unit includes:

[0041] A fault determination module, configured to determine that the long cable has the insulation fault when the real-time residual current value is greater than the maximum current error threshold;

[0042] The fault elimination module is used to determine that the insulation fault does not exist in the long cable when the real-time residual current value is less than or equal to the maximum current error threshold.

[0043] In a third aspect, the present application provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the method for determining insulation faults of low-voltage AC long cables are implemented.

[0044] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method for determining insulation faults of low-voltage AC long cables.

[0045] In a fifth aspect, the present application provides a computer program product, including a computer program / instruction, which, when executed by a processor, performs the steps of the method for determining insulation faults of long low-voltage AC cables.

[0046] In response to the problems in the prior art, the insulation fault judgment method and device for low-voltage AC long cables provided in the present application can calculate the residual current of the low-voltage AC long cable based on factors such as the residual current background average of the substation, the voltage level, the length of the long cable, the number of historical operating failures and the historical operating years, and effectively monitor the operating status of the AC cable in the substation. When an insulation fault occurs in the long cable in the substation, the faulty line can be discovered in time, thereby ensuring the safe operation of the station's low-voltage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 This is one of the flow charts of the insulation fault judgment method of the low-voltage AC long cable in the embodiment of the present application;

[0049] Figure 2 This is the second flow chart of the insulation fault judgment method of the low-voltage AC long cable in the embodiment of the present application;

[0050] Figure 3 A flow chart for determining a residual current correction coefficient in an embodiment of the present application;

[0051] Figure 4 A flow chart for determining a real-time residual current value in an embodiment of the present application;

[0052] Figure 5 This is a flow chart for determining insulation faults in an embodiment of the present application;

[0053] Figure 6 This is one of the structural diagrams of the insulation fault judgment device for a low-voltage AC long cable in an embodiment of the present application;

[0054] Figure 7 This is the second structural diagram of the insulation fault judgment device for a low-voltage AC long cable in an embodiment of the present application;

[0055] Figure 8 This is a structural diagram of a correction coefficient determination unit in an embodiment of the present application;

[0056] Fig. 9 This is a structural diagram of a real-time current determination unit in an embodiment of the present application;

[0057] Fig.10 This is a structural diagram of a fault judgment unit in an embodiment of the present application;

[0058] Fig.11 A schematic diagram of the structure of an electronic device in an embodiment of the present application;

[0059] Fig.12 This is a wiring diagram of a residual current detection device for an AC system used in a substation in an embodiment of the present application;

[0060] Fig.13 This is a schematic diagram of monitoring device data in an embodiment of the present application. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0062] In one embodiment, see Figure 1 In order to monitor the residual current of a low-voltage AC long cable and determine whether it has an insulation fault, the present application provides a method for determining an insulation fault of a low-voltage AC long cable, comprising:

[0063] S101: determining a maximum current error threshold of each long cable according to the obtained residual current value of each long cable in the substation area and the residual current background average value;

[0064] It is understandable that in order to determine the maximum current error threshold of each long cable, it is first necessary to obtain the residual current background mean value in the substation area, see Figure 2The specific steps include: determining the corresponding weight according to the operating load value of each long cable (S201); determining the residual current background mean value according to the weight and the residual current value (S202).

[0065] In specific implementation, low-voltage AC cables (also called long cables) in the substation area have background residual current during normal operation. This value will fluctuate greatly with the change of line load. These fluctuations will interfere with the judgment of the insulation status of the cable (whether there is an insulation fault). Therefore, the background current value of each long cable should be checked first. In engineering, CT monitoring devices can be installed at both ends of each long cable. Through measurement, the residual current background values ​​I1, I2, .....I of each long cable at each moment of normal operation can be obtained. N Among them, I n It represents the background current value of the nth long cable. This value can generally be taken as the average value of the values ​​measured by the CT monitoring devices installed at both ends of the cable, n=1...N.

[0066] Then the weight p is assigned based on the line load current or the operating load in the station at that time.

[0067] If the load supplied by the line is an important load, p is selected as 1.2; if it is a relatively important load, p is selected as 1.1; for general loads, it is 1.

[0068]

[0069] The residual current background mean value I0 of each long cable in the substation (generator) area is obtained.

[0070] According to the calculation formula

[0071] σ=|I n -I0| (2)

[0072] Calculate the maximum error σ between the residual current background value of each long cable and the residual current background mean value.

[0073] S102: determining a corresponding residual current correction coefficient according to characteristic parameters of the long cable;

[0074] For specific implementation, see Figure 3 The characteristic parameters include: the voltage level of the substation, the length of the long cable, the number of historical operating failures and the historical operating years; the corresponding residual current correction coefficient is determined according to the characteristic parameters of the long cable, including:

[0075] S301: Determine the importance of the long cable according to the voltage level of the substation;

[0076] S302: Determine the influence range of the long cable according to the length of the long cable;

[0077] S303: Determine the residual current correction coefficient according to the historical number of operating failures of the long cable, the historical operating years, the importance and the impact scope.

[0078] It is understandable that the operating conditions and surrounding environments of different long cables are different. These differences will affect the residual current monitoring of the cable. In the embodiment of the present application, the operating status of each long cable can be divided and the weight can be determined. The residual current correction coefficient is determined in combination with the operating mode, location, load current, fault probability, etc. of the long cable.

[0079]

[0080] In the formula,

[0081] A1 is the importance of the substation (power station) where the long cable is located. It can be divided according to the voltage level of the substation (power station). In one embodiment, the value range is as follows: 0.6 for 500kV and above, 0.5 for 220kV, and 0.4 for 110kV and below;

[0082] A2 is the influence range of long cables. It can be divided according to the cable length. In one embodiment, the value range is as follows: 0.65 for a length of more than 300m, 0.55 for 300m to 200m, 0.5 for 200m to 150m, and 0.45 for less than 150m;

[0083] B m is the history of the long cable. It can be divided according to the historical fault situation (how many faults have occurred in history). In one embodiment, the number of cable faults that occurred in the substation (power station) every year in the past 10 years can be counted. If there was no fault in the year, it is recorded as 0; if there was a fault in the year, it is recorded as 0.05; if there was more than one fault in the year, it is recorded as 0.08, and the counts are summed for the past 10 years.

[0084] C is the service life of the long cable. In one embodiment, the value of a cable with a service life of more than 10 years is 0.98, the value of a cable with a service life of 10 to 5 years is 0.99, and the value of a cable with a service life of less than 5 years is 1.

[0085] S103: determining a real-time residual current value of the long cable according to the residual current correction coefficient, the residual current background mean value and the residual current value;

[0086] In one embodiment, see Figure 4, the residual current value includes: a cable head end vector value and a cable end vector value; the real-time residual current value of the long cable is determined according to the residual current correction coefficient and the residual current value, including:

[0087] S401: Determine the vector sum of the residual current according to the vector value of the cable head end and the vector value of the cable end;

[0088] S402: Determine a vector difference of the residual current according to the vector sum of the residual current and the residual current background mean value;

[0089] S403: Determine the real-time residual current value according to the residual current vector difference and the residual current correction coefficient.

[0090] It can be understood that the residual current monitoring device is installed at both ends of the long cable, and the residual current at both ends of the long cable is monitored by connecting the A phase, B phase, C phase, and N phase cable lines through the monitoring CT measuring clamp, and the residual current vector I at the beginning and end is obtained. A ,I B . The calculation is performed in the residual current detection slave device according to the calculation formula

[0091]

[0092] Get the real-time residual current value of each long cable in, It can be considered as the actual measured real-time residual current value.

[0093] S104: Determine whether the long cable has an insulation fault according to the real-time residual current value and the maximum current error threshold.

[0094] In one embodiment, see Figure 5 , judging whether the long cable has an insulation fault according to the real-time residual current value and the maximum current error threshold value, comprises:

[0095] S501: Compare the real-time residual current value and the maximum current error threshold, and when the real-time residual current value is greater than the maximum current error threshold, determine that the long cable has the insulation fault;

[0096] S502: Compare the real-time residual current value and the maximum current error threshold, and when the real-time residual current value is less than or equal to the maximum current error threshold, determine that the long cable does not have the insulation fault.

[0097] It is understandable that the residual current value is determined. Under normal operation (i.e. when no insulation fault occurs) The value should be less than or equal to the maximum error σ, that is When the cable insulation is damaged, the fault current flows into the ground instead of flowing through the N line. At this time, there is an unbalanced current, that is, the residual current exceeds the maximum error, that is,

[0098] After judgment, the cable status can also be centrally monitored and displayed:

[0099] According to the judgment result, the cable operation status is displayed at the centralized monitoring point, and the residual current value is displayed. The cable operation status is determined by comparing with the pre-set warning value α, t1 and the alarm value β, t2. When the duration t≥t1, a warning signal is issued to prompt the staff to check the cables; When the duration t≥t2, an alarm signal is issued and the staff should make emergency preparations. Generally speaking, α and β are greater than σ.

[0100] From the above description, it can be seen that the insulation fault judgment method of the low-voltage AC long cable provided in the present application can calculate the residual current of the low-voltage AC long cable by combining factors such as the residual current background average of the substation, the voltage level, the length of the long cable, the number of historical operating failures and the historical operating years, and effectively monitor the operating status of the AC cable in the substation. When an insulation fault occurs in the long cable in the substation, the faulty line can be discovered in time to ensure the safe operation of the station's low-voltage system.

[0101] In order to better illustrate the method and device provided by the present application, the specific implementation methods of the present application are exemplified below with reference to the accompanying drawings.

[0102] ① Verify the residual current background mean value in the substation

[0103] See also Fig.12 Taking the low voltage AC 35KV switch cabinet electric heating power cable as an example, the 24h residual current background value is shown in the following table.

[0104]

[0105] The residual current weight at each moment is divided according to the load polarity, and in this example, it is divided according to the total load current ratio.

[0106] The average load current is 397.833A. Taking 0h as an example, the specific gravity is 340 / 397.83=0.855.

[0107] According to formulas (1) and (2), the residual current background mean value can be calculated as:

[0108]

[0109] The maximum deviation value is:

[0110] σ=|21-15.25|=5.75mA

[0111] ②Calculate the residual current correction factor

[0112] The basic information of substation and cables is as follows:

[0113]

[0114] According to formula (3), we can get

[0115]

[0116] ③Measurement with CT monitoring device

[0117] Based on the residual current background value of the cable measured within 24 hours in step ①, the residual current monitoring work of the CT monitoring device is carried out. The measured data is as follows: Fig.13 As shown, the maximum value is 20mA and the minimum value is 11mA.

[0118] According to formula (4), the actual maximum residual current can be calculated as

[0119]

[0120] i. Data determination in the background

[0121] According to the judgment The cable is in normal operating condition.

[0122] ii. Centralized monitoring and display of cable status

[0123] Set the pre-alarm value α, t1 and the alarm value β, t2 to 5mA, 10s; 40mA, 10s respectively.

[0124]

[0125] Centralized monitoring shows that the cable is in normal operation and no alarm is issued.

[0126] Based on the same inventive concept, the embodiments of the present application also provide an insulation fault judgment device for a low-voltage AC long cable, which can be used to implement the method described in the above embodiments, as described in the following embodiments. Since the principle of solving the problem by the insulation fault judgment device for a low-voltage AC long cable is similar to the insulation fault judgment method for a low-voltage AC long cable, the implementation of the insulation fault judgment device for a low-voltage AC long cable can refer to the implementation of the method based on software performance benchmark determination, and the repeated parts will not be repeated. As used below, the term "unit" or "module" can be a combination of software and / or hardware that implements a predetermined function. Although the system described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived.

[0127] In one embodiment, see Figure 6 In order to monitor the residual current of a low-voltage AC long cable and determine whether it has an insulation fault, the present application provides an insulation fault judgment device for a low-voltage AC long cable, including: an error threshold determination unit 601, a correction coefficient determination unit 602, a real-time current determination unit 603 and a fault judgment unit 604.

[0128] The error threshold determination unit 601 is used to determine the maximum current error threshold of each long cable according to the acquired residual current value of each long cable in the substation area;

[0129] A correction coefficient determination unit 602, configured to determine a corresponding residual current correction coefficient according to characteristic parameters of the long cable;

[0130] A real-time current determination unit 603, configured to determine the real-time residual current value of the long cable according to the residual current correction coefficient and the residual current value;

[0131] The fault judgment unit 604 is used to judge whether the long cable has an insulation fault according to the real-time residual current value and the maximum current error threshold.

[0132] In one embodiment, see Figure 7 The insulation fault judgment device for a low-voltage AC long cable also includes: a load weight determination unit 701 and a background mean value determination unit 702.

[0133] A load weight determination unit 701, configured to determine a corresponding weight according to the operating load value of each long cable;

[0134] The background mean value determining unit 702 is used to determine the residual current background mean value according to the weight and the residual current value.

[0135] In one embodiment, see Figure 8The correction coefficient determination unit 602 includes: an importance determination module 801, an impact range determination module 802 and a correction coefficient determination module 803.

[0136] An importance determination module 801 is used to determine the importance of the long cable according to the voltage level of the substation;

[0137] An influence range determining module 802, configured to determine the influence range of the long cable according to the length of the long cable;

[0138] The correction coefficient determination module 803 is used to determine the residual current correction coefficient according to the historical number of operating failures of the long cable, the historical operating years, the importance and the impact range.

[0139] In one embodiment, see Fig. 9 The residual current value includes: the vector value of the cable head end and the vector value of the cable end; the real-time current determination unit 603 includes: a vector sum determination module 901, a vector difference determination module 902 and a real-time current determination module 903.

[0140] A vector sum determination module 901, configured to determine the vector sum of the residual current according to the vector value of the cable head end and the vector value of the cable end;

[0141] A vector difference determination module 902, configured to determine a vector difference of the residual current according to the vector sum of the residual current and the residual current background mean value;

[0142] The real-time current determination module 903 is used to determine the real-time residual current value according to the vector difference of the residual current and the residual current correction coefficient.

[0143] In one embodiment, see Fig.10 The fault judgment unit 604 includes: a fault determination module 1001 and a fault elimination module 1002.

[0144] A fault determination module 1001 is used to determine that the long cable has the insulation fault when the real-time residual current value is greater than the maximum current error threshold;

[0145] The fault elimination module 1002 is used to determine that the insulation fault does not exist in the long cable when the real-time residual current value is less than or equal to the maximum current error threshold.

[0146] From a hardware perspective, in order to monitor the residual current of a low-voltage AC long cable and determine whether it has an insulation fault, the present application provides an embodiment of an electronic device for implementing all or part of the contents of the insulation fault determination method of the low-voltage AC long cable, and the electronic device specifically includes the following contents:

[0147] Processor, memory, communication interface and bus; wherein the processor, memory and communication interface communicate with each other through the bus; the communication interface is used to realize information transmission between the insulation fault judgment device of the low-voltage AC long cable and related equipment such as the core business system, user terminal and related database; the logic controller can be a desktop computer, a tablet computer and a mobile terminal, etc., but the present embodiment is not limited thereto. In the present embodiment, the logic controller can be implemented with reference to the embodiment of the insulation fault judgment method of the low-voltage AC long cable and the embodiment of the insulation fault judgment device of the low-voltage AC long cable in the embodiment, and the contents thereof are incorporated herein, and the repeated parts are not repeated.

[0148] It is understandable that the user terminal may include a smart phone, a tablet electronic device, a network set-top box, a portable computer, a desktop computer, a personal digital assistant (PDA), a vehicle-mounted device, a smart wearable device, etc. Among them, the smart wearable device may include smart glasses, a smart watch, a smart bracelet, etc.

[0149] In practical applications, part of the insulation fault judgment method for a low-voltage AC long cable can be executed on the electronic device side as described above, or all operations can be completed in the client device. The selection can be made based on the processing capability of the client device and the limitations of the user's usage scenario. This application does not limit this. If all operations are completed in the client device, the client device may also include a processor.

[0150] The client device may have a communication module (i.e., a communication unit) that can communicate with a remote server to achieve data transmission with the server. The server may include a server on the task scheduling center side, and other implementation scenarios may also include a server on an intermediate platform, such as a server on a third-party server platform that has a communication link with the task scheduling center server. The server may include a single computer device, or a server cluster consisting of multiple servers, or a server structure of a distributed device.

[0151] Fig.11 FIG. 9 is a schematic block diagram of the system structure of the electronic device 9600 according to an embodiment of the present application. Fig.11 As shown, the electronic device 9600 may include a central processor 9100 and a memory 9140; the memory 9140 is coupled to the central processor 9100. It is worth noting that Fig.11is exemplary; other types of structures may also be used to supplement or replace this structure to implement telecommunication functions or other functions.

[0152] In one embodiment, the insulation fault judgment method function of the low-voltage AC long cable can be integrated into the central processing unit 9100. The central processing unit 9100 can be configured to perform the following control:

[0153] S101: determining a maximum current error threshold of each long cable according to the obtained residual current value of each long cable in the substation area and the residual current background average value;

[0154] S102: determining a corresponding residual current correction coefficient according to characteristic parameters of the long cable;

[0155] S103: determining a real-time residual current value of the long cable according to the residual current correction coefficient, the residual current background mean value and the residual current value;

[0156] S104: Determine whether the long cable has an insulation fault according to the real-time residual current value and the maximum current error threshold.

[0157] From the above description, it can be seen that the insulation fault judgment method of the low-voltage AC long cable provided in the present application can calculate the residual current of the low-voltage AC long cable by combining factors such as the residual current background average of the substation, the voltage level, the length of the long cable, the number of historical operating failures and the historical operating years, and effectively monitor the operating status of the AC cable in the substation. When an insulation fault occurs in the long cable in the substation, the faulty line can be discovered in time to ensure the safe operation of the station's low-voltage system.

[0158] In another embodiment, the insulation fault judgment device of the low-voltage AC long cable can be configured separately from the central processing unit 9100. For example, the insulation fault judgment device of the low-voltage AC long cable of the data composite transmission device can be configured as a chip connected to the central processing unit 9100, and the function of the insulation fault judgment method of the low-voltage AC long cable can be realized through the control of the central processing unit.

[0159] like Fig.11 As shown, the electronic device 9600 may also include: a communication module 9110, an input unit 9120, an audio processor 9130, a display 9160, and a power supply 9170. It is worth noting that the electronic device 9600 does not necessarily have to include Fig.11 In addition, the electronic device 9600 may also include Fig.11 For components not shown, reference may be made to the prior art.

[0160] like Fig.11As shown, the central processing unit 9100 is sometimes also referred to as a controller or an operation control, and may include a microprocessor or other processor device and / or logic device. The central processing unit 9100 receives input and controls the operation of various components of the electronic device 9600.

[0161] The memory 9140 may be, for example, one or more of a cache, a flash memory, a hard drive, a removable medium, a volatile memory, a non-volatile memory or other suitable devices. The above-mentioned information related to the failure may be stored, and a program for executing the relevant information may also be stored. The CPU 9100 may execute the program stored in the memory 9140 to implement information storage or processing, etc.

[0162] The input unit 9120 provides input to the central processing unit 9100. The input unit 9120 is, for example, a key or a touch input device. The power supply 9170 is used to provide power to the electronic device 9600. The display 9160 is used to display display objects such as images and texts. The display may be, for example, an LCD display, but is not limited thereto.

[0163] The memory 9140 may be a solid-state memory, such as a read-only memory (ROM), a random access memory (RAM), a SIM card, etc. It may also be a memory that saves information even when the power is off, can be selectively erased, and is provided with more data, examples of which are sometimes referred to as EPROMs, etc. The memory 9140 may also be some other type of device. The memory 9140 includes a buffer memory 9141 (sometimes referred to as a buffer). The memory 9140 may include an application / function storage unit 9142, which is used to store application programs and function programs or processes for executing the operation of the electronic device 9600 through the central processor 9100.

[0164] The memory 9140 may also include a data storage unit 9143 for storing data, such as contacts, digital data, pictures, sounds, and / or any other data used by the electronic device. The driver storage unit 9144 of the memory 9140 may include various drivers for communication functions of the electronic device and / or for executing other functions of the electronic device (such as messaging applications, address book applications, etc.).

[0165] The communication module 9110 is a transmitter / receiver 9110 that sends and receives signals via an antenna 9111. The communication module (transmitter / receiver) 9110 is coupled to the central processor 9100 to provide input signals and receive output signals, which may be the same as the case of a conventional mobile communication terminal.

[0166] Based on different communication technologies, multiple communication modules 9110 may be provided in the same electronic device, such as a cellular network module, a Bluetooth module and / or a wireless LAN module. The communication module (transmitter / receiver) 9110 is also coupled to a speaker 9131 and a microphone 9132 via an audio processor 9130 to provide an audio output via the speaker 9131 and receive an audio input from the microphone 9132, thereby realizing a common telecommunication function. The audio processor 9130 may include any suitable buffer, decoder, amplifier, etc. In addition, the audio processor 9130 is also coupled to the central processor 9100, so that recording can be performed on the local machine through the microphone 9132, and the sound stored on the local machine can be played through the speaker 9131.

[0167] The embodiments of the present application also provide a computer-readable storage medium capable of implementing all the steps of the insulation fault determination method for a low-voltage AC long cable in the above-mentioned embodiment, the execution subject of which is a server or a client. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, all the steps of the insulation fault determination method for a low-voltage AC long cable in the above-mentioned embodiment are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0168] S101: determining a maximum current error threshold of each long cable according to the obtained residual current value of each long cable in the substation area and the residual current background average value;

[0169] S102: determining a corresponding residual current correction coefficient according to characteristic parameters of the long cable;

[0170] S103: determining a real-time residual current value of the long cable according to the residual current correction coefficient, the residual current background mean value and the residual current value;

[0171] S104: Determine whether the long cable has an insulation fault according to the real-time residual current value and the maximum current error threshold.

[0172] From the above description, it can be seen that the insulation fault judgment method of the low-voltage AC long cable provided in the present application can calculate the residual current of the low-voltage AC long cable by combining factors such as the residual current background average of the substation, the voltage level, the length of the long cable, the number of historical operating failures and the historical operating years, and effectively monitor the operating status of the AC cable in the substation. When an insulation fault occurs in the long cable in the substation, the faulty line can be discovered in time to ensure the safe operation of the station's low-voltage system.

[0173] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, devices, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0174] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (apparatus), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of 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.

[0175] 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.

[0176] 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.

[0177] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for judging insulation fault of a low voltage AC long cable, characterized in that: include: Determine a maximum current error threshold of the long cable according to the obtained residual current value of the long cable in the substation area; Determining a real-time residual current value of the long cable according to the characteristic parameters of the long cable and the residual current value; Determine whether the long cable has an insulation fault according to the real-time residual current value and the maximum current error threshold; Wherein, determining the real-time residual current value of the long cable according to the characteristic parameters of the long cable and the residual current value includes: Determining a corresponding residual current correction coefficient according to characteristic parameters of the long cable; Determine the real-time residual current value of the long cable according to the residual current correction coefficient and the residual current value; Wherein, the insulation fault judgment method of the low-voltage AC long cable also includes: Determining corresponding weights according to the operating load values ​​of the long cables; Determine the residual current background mean value according to the weight and the residual current value; Specifically, I n Indicates the background current value of the nth long cable, which is the average value measured by the CT monitoring devices at both ends of the cable, n = 1...N; Then, the weight p is assigned based on the line load current or the station operating load at that time; The residual current background mean value I0 of each long cable in the substation area is obtained: According to the calculation formula σ=|I n -I0| Calculate the maximum error value σ between the residual current background value of each long cable and the residual current background mean value; The characteristic parameters include: the voltage level of the substation, the length of the long cable, the number of historical operating failures and the historical operating years; the corresponding residual current correction coefficient is determined according to the characteristic parameters of the long cable, including: Determining the importance of the long cable according to the voltage level; Determining the influence range of the long cable according to the length; Determine the residual current correction coefficient according to the number of historical operating failures, the historical operating years, the importance and the impact scope; Wherein, the residual current value includes: a vector value of the cable head end and a vector value of the cable end; the real-time residual current value of the long cable is determined according to the residual current correction coefficient and the residual current value, including: Determine the vector sum of the residual current according to the vector value of the cable head end and the vector value of the cable end; Determining a vector difference of the residual current according to the vector sum of the residual current and the residual current background mean; Determining the real-time residual current value according to the residual current vector difference and the residual current correction coefficient; Specifically, according to the calculation formula: Get the real-time residual current value of each long cable, where I A ,I B are the residual current vectors at the beginning and end of the long cable, I0 is the residual current background mean, K is the residual current correction coefficient, It is the real-time residual current value.

2. The insulation fault judgment method of a low-voltage AC long cable according to claim 1 is characterized in that: The determining whether the long cable has an insulation fault according to the real-time residual current value and the maximum current error threshold comprises: Comparing the real-time residual current value with the maximum current error threshold, if the real-time residual current value is greater than the maximum current error threshold, the long cable has the insulation fault; The real-time residual current value is compared with the maximum current error threshold. If the real-time residual current value is less than or equal to the maximum current error threshold, the insulation fault does not exist in the long cable.

3. A device for judging insulation fault of a low-voltage AC long cable, characterized in that: include: An error threshold determination unit, used to determine a maximum current error threshold of the long cable according to the acquired residual current value of the long cable in the substation area; A residual current determination unit, used to determine a real-time residual current value of the long cable according to the characteristic parameters of the long cable and the residual current value; A fault judgment unit, used for judging whether the long cable has an insulation fault according to the real-time residual current value and the maximum current error threshold; Wherein, the residual current determination unit includes: A correction coefficient determination module, used to determine a corresponding residual current correction coefficient according to characteristic parameters of the long cable; A real-time current determination module, used to determine the real-time residual current value of the long cable according to the residual current correction coefficient and the residual current value; Wherein, the insulation fault judgment device for the low-voltage AC long cable further includes: A load weight determination unit, used to determine a corresponding weight according to the operating load value of each of the long cables; A background mean value determining unit, configured to determine a residual current background mean value according to the weight and the residual current value; Specifically, I n Indicates the background current value of the nth long cable, which is the average value measured by the CT monitoring devices at both ends of the cable, n = 1...N; Then, the weight p is assigned based on the line load current or the station operating load at that time; The residual current background mean value I0 of each long cable in the substation area is obtained: According to the calculation formula σ=|I n -I0| Calculate the maximum error value σ between the residual current background value of each long cable and the residual current background mean value; The characteristic parameters include: the voltage level of the substation, the length of the long cable, the number of historical operating failures and the historical operating years; the correction coefficient determination module includes: An importance determination submodule, used to determine the importance of the long cable according to the voltage level; An influence range determination submodule, used to determine the influence range of the long cable according to the length; A correction coefficient determination submodule, used to determine the residual current correction coefficient according to the number of historical operating failures, the historical operating years, the importance and the impact range; Wherein, the residual current value includes: a cable head end vector value and a cable end vector value; the real-time current determination unit includes: A vector sum determination module, used to determine the vector sum of the residual current according to the vector value of the cable head end and the vector value of the cable end; A vector difference determination module, used for determining the vector difference of the residual current according to the vector sum of the residual current and the residual current background mean value; A real-time current determination module, used to determine the real-time residual current value according to the residual current vector difference and the residual current correction coefficient; Specifically, according to the calculation formula: Get the real-time residual current value of each long cable, where I A ,I B are the residual current vectors at the beginning and end of the long cable, I0 is the residual current background mean, K is the residual current correction coefficient, It is the real-time residual current value.

4. The insulation fault judgment device for a low-voltage AC long cable according to claim 3, characterized in that: The fault judgment unit comprises: A fault determination module, used for comparing the real-time residual current value with the maximum current error threshold, if the real-time residual current value is greater than the maximum current error threshold, the long cable has the insulation fault; The fault elimination module is used to compare the real-time residual current value with the maximum current error threshold. If the real-time residual current value is less than or equal to the maximum current error threshold, the insulation fault does not exist in the long cable.

5. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the insulation fault judgment method for a low-voltage AC long cable according to any one of claims 1 to 2 are implemented.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the insulation fault judgment method for a low-voltage AC long cable according to any one of claims 1 to 2 are implemented.

7. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instruction is executed by a processor, the steps of the insulation fault judgment method for a low-voltage AC long cable as described in any one of claims 1 to 2 are implemented.

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