A method and system for online monitoring of full current of parallel lightning arrester at high voltage cable terminal

Abstract

The invention discloses a method and system for online monitoring of the full current of a parallel lightning arrester at a high-voltage cable terminal, and relates to the technical field of power grid equipment. The method comprises the following steps: in a test phase, obtaining the cable coupling coefficient of each cable terminal to a current lightning arrester under single-phase action, and obtaining the phase-to-phase coupling coefficient between the current lightning arrester and the remaining lightning arresters under single-phase action; in actual operation, using a leakage current detection module to online obtain the leakage current sensing value of the current lightning arrester; using a power frequency calibration coefficient to calibrate the leakage current sensing value to obtain the leakage current calibration value of the current lightning arrester; based on the leakage current calibration value, the cable coupling coefficient and the phase-to-phase coupling coefficient, obtaining the actual leakage current value of the current lightning arrester; in the scheme of the invention, the coupling interference caused by the spatial distribution is fully considered, and the interference caused by the spatial distribution parameters is eliminated by correction based on the cable coupling coefficient and the phase-to-phase coupling coefficient, so as to accurately monitor the current leakage amount of the lightning arrester.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid equipment, and in particular to a method and system for online monitoring of the full current of a high-voltage cable terminal parallel lightning arrester. Background Art

[0002] The high-voltage cable terminal parallel arrester is a gapless arrester, which needs to withstand the power frequency operating voltage, instantaneous operation overvoltage, and lightning overvoltage for a long time during operation. At the same time, unlike the porcelain bushing arrester in the station, the composite sleeve arrester used in the terminal parallel arrester has relatively poorer pollution resistance and corrosion resistance, and is prone to deformation under complex working conditions, which in turn affects the internal valve plate. These factors will cause arrester defects and endanger the safety and stability of the power grid. In addition, the terminal parallel arrester is installed on the outdoor terminal tower. In addition to regular appearance inspections and infrared thermal imaging inspections, there is usually no other live detection, and it is impossible to perceive its internal conditions in time. Therefore, the online monitoring device of the arrester is particularly necessary.

[0003] In the prior art, the arrester online monitoring system has the following major problems: inconvenient installation and maintenance. During installation, the primary grounding wire of the arrester needs to be disassembled and modified in a power outage, which generally requires power outage and disassembly, resulting in difficulty in the installation and maintenance of the online monitoring device, and it is difficult to repair and replace faults in a timely manner; it is impossible to judge the validity of the monitoring result data. The online monitoring device is installed on the outdoor terminal together with the arrester and is in a state of being unable to operate and maintain for a long time. Under complex working conditions, the validity of the test results of the online monitoring device cannot be verified; phase-to-phase interference is difficult to eliminate. When testing the leakage current by inducing the arrester grounding wire, there will be induced current between the phases, which will affect the arrester leakage current monitoring results.

[0004] In view of this, it is necessary to propose a method and system for online monitoring of the full current of a high-voltage cable terminal parallel lightning arrester to solve or at least partially solve the above technical problems. Summary of the invention

[0005] The main purpose of the present invention is to provide a method and system for online monitoring of the full current of a parallel lightning arrester at a high-voltage cable terminal, aiming to solve the technical problem of inaccurate monitoring result data of the existing online monitoring system for lightning arresters.

[0006] To achieve the above object, the present invention provides a method for online monitoring of the full current of a high-voltage cable terminal parallel lightning arrester, comprising the steps of:

[0007] S100, in the test phase, obtaining the cable coupling coefficient of each cable terminal to the current leaking arrester under the single-phase action, and obtaining the phase coupling coefficient between the current arrester and the remaining arresters under the single-phase action;

[0008] S200, using the leakage current detection module to obtain the current sensing value of the arrester online;

[0009] S300, calibrating the leakage current sensing value using the power frequency calibration coefficient to obtain a current leakage current calibration value of the arrester;

[0010] S400, obtaining a current actual value of the leakage current of the arrester based on the leakage current calibration value, the cable coupling coefficient, and the phase-to-phase coupling coefficient;

[0011] Among them, the step of obtaining the power frequency calibration coefficient includes: injecting multiple different target frequency standard signals into the calibration lead, the target frequency standard signal is not equal to the power frequency; using the leakage current detection module to obtain the target signal pickup value corresponding to each target frequency standard signal; obtaining the deviation value between the target frequency standard signal and the corresponding target signal pickup value; if the absolute value of the deviation value is greater than the preset deviation, fitting each target signal pickup value to form a calibration curve; interpolating the calibration curve to obtain the power frequency calibration coefficient corresponding to the power frequency; if the absolute value of the deviation value is less than the preset deviation, the power frequency calibration coefficient is 1.

[0012] Furthermore, the multiple different target frequency standard signals include a high-frequency calibration signal of X times the power frequency and a low-frequency calibration signal within a 20 Hz difference from the power frequency, wherein X is a positive integer greater than or equal to 2.

[0013] Furthermore, the preset deviation is 2%.

[0014] Furthermore, in the test phase, the cable coupling coefficient of each cable terminal j to the current arrester i under single-phase action is obtained: ; ;in, Indicates the cable body current detected by the cable core current detection module corresponding to the cable terminal j, It indicates the lightning protection monitoring leakage current detected by the leakage current detection module corresponding to the current lightning arrester i, represents the coupling capacitance of the cable terminal j to the current arrester i, Indicates the cable impedance value corresponding to the cable terminal j, is the power frequency; i=1, 2, 3, ..., M, j=1, 2, 3, ..., N, M is the total number of cable terminals, N is the total number of lightning arresters, and the total number of cable terminals is the same as the total number of lightning arresters.

[0015] During the test phase, the phase coupling coefficient between the current arrester i and the remaining arrester k under single-phase action is obtained. , ,in, It represents the leakage current detected by the leakage current detection module corresponding to the remaining lightning arrester k, represents the leakage current detected by the cable core current detection module corresponding to the current arrester i to which voltage is applied, It indicates the resistance of the current arrester i at rated voltage and frequency, Represents the phase-to-phase coupling capacitance between the current arrester i and the remaining arrester k, k∈N.

[0016] Furthermore, using the formula Calculate and obtain the actual value of the leakage current of the current arrester i ,in, is the cable coupling coefficient of the cable terminal j to the current arrester i, is the leakage current calibration value of arrester i, is the phase-to-phase coupling coefficient between the current arrester i and the remaining arrester j, is the online current of the cable body at cable terminal i, and the phase-to-phase coupling coefficient of the arrester's influence on itself is 1.

[0017] Furthermore, using the formula

[0018] Calculate the actual value of leakage current of each item in the three-phase power grid , , , , , They are the leakage current calibration values ​​of each lightning arrester in the three-phase power grid.

[0019] Furthermore, using the formula Calculate the actual value of leakage current of each item in the two-phase power grid , , , They are the leakage current calibration values ​​of each lightning arrester in the two-phase power grid.

[0020] The present invention also provides a full-current online monitoring system for parallel lightning arresters at high-voltage cable terminals, including online monitoring devices arranged in one-to-one correspondence with the lightning arresters, the lightning arresters are connected to the corresponding cable terminals, and each lightning arrester is correspondingly arranged with a lightning protection grounding down conductor, including an electrically connected cable core current detection module, a leakage current detection module, a calibration signal injection module, a current sensor power supply module and a monitoring host, the cable core current detection module is used to obtain the current of the cable terminal, the leakage current detection module is used to obtain the current of the lightning protection grounding down conductor, the calibration signal injection module is used to inject multiple different target frequency standard signals, the current sensor power supply module is used to inductively obtain power from the cable terminal, and the monitoring host is used to implement the steps of the above-mentioned full-current online monitoring method for parallel lightning arresters at high-voltage cable terminals.

[0021] Compared with the prior art, the method for online monitoring of full current of a high-voltage cable terminal parallel lightning arrester provided by the present invention has the following beneficial effects:

[0022] The present invention provides a method for online monitoring of the full current of a parallel lightning arrester at a high-voltage cable terminal. When the power grid is not working (power outage state or infrastructure construction or power outage maintenance), the method can be in a testing phase to obtain the cable coupling coefficient of each cable terminal to the current lightning arrester under unidirectional action and the phase-to-phase coupling coefficient between the current lightning arrester and the remaining lightning arresters under single-phase action; then in the working phase, the leakage current calibration value of the current lightning arrester is obtained online, and the current leakage current actual value is calculated based on the cable coupling coefficient, the phase-to-phase coupling coefficient and the leakage current calibration value of the current lightning arrester obtained online, so as to realize accurate online monitoring of the leakage current of the lightning arrester; the corresponding power frequency calibration coefficient under the power frequency is used to calibrate the leakage current induction value to reduce the influence of overvoltage The accuracy of the leakage current detection module detection is affected, and the cable coupling coefficient and the phase-to-phase coupling coefficient are used to further correct the leakage current calibration value to reduce the coupling interference during detection. The steps of obtaining the power frequency calibration coefficient include: injecting multiple different target frequency standard signals into the calibration lead, and the target frequency standard signal is not equal to the power frequency; using the leakage current detection module to obtain the target signal pickup value corresponding to each target frequency standard signal; obtaining the deviation value between the target frequency standard signal and the corresponding target signal pickup value; if the absolute value of the deviation value is greater than the preset deviation, fitting the calibration curve formed by the target signal pickup value; interpolating the calibration curve to obtain the power frequency calibration coefficient corresponding to the power frequency; if the absolute value of the deviation value is less than the preset deviation, the power frequency calibration coefficient is 1. The method of the present invention uses multiple different target frequency standard signals outside the power frequency range to obtain the calibration curve, and uses interpolation processing to obtain the power frequency calibration coefficient corresponding to the power frequency, fully considering the coupling interference caused by the spatial distribution, and correcting based on the cable coupling coefficient and the phase-to-phase coupling coefficient to eliminate the interference caused by the spatial distribution parameters, and can accurately monitor the current leakage of the lightning arrester. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] 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 the structures shown in these drawings without paying creative work.

[0024] Figure 1 It is a flow chart of the full current online monitoring method of the high-voltage cable terminal parallel lightning arrester of the present invention;

[0025] Figure 2 It is a structural schematic diagram of the full current online monitoring system of the high-voltage cable terminal parallel lightning arrester of the present invention;

[0026] Figure 3 It is the equivalent circuit principle diagram of the cable coupling coefficient of the cable terminal to the arrester in the present invention;

[0027] Figure 4 It is the equivalent circuit principle diagram of the coupling coefficient between phases of the lightning arrester in the present invention.

[0028] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0029] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0032] Please refer to Figure 1 and Figure 2 The present invention provides a method for online monitoring of the full current of a high-voltage cable terminal parallel lightning arrester, comprising the steps of:

[0033] S100, in the test phase, obtaining the cable coupling coefficient of each cable terminal to the current lightning arrester under the single-phase action, and obtaining the phase coupling coefficient between the current lightning arrester and the remaining lightning arresters under the single-phase action;

[0034] S200, using a leakage current detection module to obtain the current leakage current sensing value of the arrester online;

[0035] S300, calibrating the leakage current sensing value using the power frequency calibration coefficient to obtain a current leakage current calibration value of the arrester;

[0036] S400, obtaining a current actual value of the leakage current of the arrester based on the leakage current calibration value, the cable coupling coefficient, and the phase-to-phase coupling coefficient;

[0037] Among them, the step of obtaining the power frequency calibration coefficient includes: injecting multiple different target frequency standard signals into the calibration lead, the target frequency standard signal is not equal to the power frequency; using the leakage current detection module to obtain the target signal pickup value corresponding to each target frequency standard signal; obtaining the deviation value between the target frequency standard signal and the corresponding target signal pickup value; if the absolute value of the deviation value is greater than the preset deviation, fitting each target signal pickup value to form a calibration curve; interpolating the calibration curve to obtain the power frequency calibration coefficient corresponding to the power frequency; if the absolute value of the deviation value is less than the preset deviation, the power frequency calibration coefficient is 1.

[0038] The present invention provides a method for online monitoring of the full current of a parallel lightning arrester at a high-voltage cable terminal. When the power grid is not working (power outage state or infrastructure construction or power outage maintenance), the method can be in a testing phase to obtain the cable coupling coefficient of each cable terminal to the current lightning arrester under unidirectional action and the phase-to-phase coupling coefficient between the current lightning arrester and the remaining lightning arresters under single-phase action; then in the working phase, the leakage current calibration value of the current lightning arrester is obtained online, and the current leakage current actual value is calculated based on the cable coupling coefficient, the phase-to-phase coupling coefficient and the leakage current calibration value of the current lightning arrester obtained online, so as to realize accurate online monitoring of the leakage current of the lightning arrester; the corresponding power frequency calibration coefficient under the power frequency is used to calibrate the leakage current induction value to reduce the influence of overvoltage The accuracy of the leakage current detection module detection is affected, and the cable coupling coefficient and the phase-to-phase coupling coefficient are used to further correct the leakage current calibration value to reduce the coupling interference during detection. The steps of obtaining the power frequency calibration coefficient include: injecting multiple different target frequency standard signals into the calibration lead, and the target frequency standard signal is not equal to the power frequency; using the leakage current detection module to obtain the target signal pickup value corresponding to each target frequency standard signal; obtaining the deviation value between the target frequency standard signal and the corresponding target signal pickup value; if the absolute value of the deviation value is greater than the preset deviation, fitting the calibration curve formed by the target signal pickup value; interpolating the calibration curve to obtain the power frequency calibration coefficient corresponding to the power frequency; if the absolute value of the deviation value is less than the preset deviation, the power frequency calibration coefficient is 1. The method of the present invention uses multiple different target frequency standard signals outside the power frequency range to obtain the calibration curve, and uses interpolation processing to obtain the power frequency calibration coefficient corresponding to the power frequency, fully considering the coupling interference caused by the spatial distribution, and correcting based on the cable coupling coefficient and the phase-to-phase coupling coefficient to eliminate the interference caused by the spatial distribution parameters, and can accurately monitor the current leakage of the lightning arrester.

[0039] Please refer to Figure 2 In the scheme of the present invention, a wire with resistance parallel to the grounding down conductor of the lightning arrester is inserted into the ring current transformer of the leakage current detection module as a calibration lead; during calibration, a selected voltage is added to the calibration lead to obtain a corresponding standard current signal, thereby realizing the calibration of the leakage current detection module.

[0040] Further, a plurality of different target frequency standard signals include a high frequency calibration signal of X times the power frequency and a low frequency calibration signal within a range of 20 Hz from the power frequency, wherein X is a positive integer greater than or equal to 2. In a specific embodiment, the high frequency calibration signal includes a 100 Hz calibration signal, a 150 Hz calibration signal, a 200 Hz calibration signal, and a 250 Hz calibration signal, etc., and the low frequency calibration signal includes a 45 Hz calibration signal, a 48 Hz calibration signal, a 52 Hz calibration signal, and a 55 Hz calibration signal, etc. In a specific implementation, a plurality of different target frequency standard signals are injected into the calibration lead to implement calibration.

[0041] Furthermore, the preset deviation is 2%. Specifically, if the ratio of the absolute value of the deviation between the target frequency standard signal and the corresponding target signal pickup value divided by the target frequency standard signal is greater than 2%, it is greater than the preset deviation.

[0042] Furthermore, in the test phase, the cable coupling coefficient of each cable terminal j to the current arrester i under single-phase action is obtained: ; ;in, Indicates the cable body current detected by the cable core current detection module corresponding to the cable terminal j, It indicates the lightning protection monitoring leakage current detected by the leakage current detection module corresponding to the current lightning arrester i, represents the coupling capacitance of the cable terminal j to the current arrester i, Indicates the cable impedance value corresponding to the cable terminal j, is the power frequency; i=1, 2, 3, ..., M, j=1, 2, 3, ..., N, M is the total number of cable terminals, N is the total number of lightning arresters, and the total number of cable terminals is the same as the total number of lightning arresters. It can be understood that in a two-phase power grid, i=1, 2, j=1, 2; in a three-phase power grid, i=1, 2, 3, j=1, 2, 3.

[0043] It can be understood that in the present invention, in the test phase before the online test, the cable coupling coefficient generated by each cable terminal j on the arrester i is obtained in advance. , pre-obtain the phase coupling coefficient between arrester i and arrester k .

[0044] It is understandable that the power frequency calibration coefficient is obtained before the online test or during the first test. In the present invention, the power frequency calibration coefficient can be obtained once at intervals of a preset time period, or after a strong overvoltage occurs.

[0045] Furthermore, the phase coupling coefficient between the current arrester i and the remaining arrester k under single-phase action is obtained during the test phase. , ,in, It represents the leakage current detected by the leakage current detection module corresponding to the remaining lightning arrester k, represents the leakage current detected by the cable core current detection module corresponding to the current arrester i to which voltage is applied, It indicates the resistance of the current arrester i at rated voltage and frequency, Represents the phase-to-phase coupling capacitance between the current arrester i and the remaining arrester k, k∈N.

[0046] Furthermore, using the formula

[0047]

[0048] Calculate and obtain the actual value of the leakage current of the current arrester i ,in, is the cable coupling coefficient of the cable terminal j to the current arrester i, is the leakage current calibration value of arrester i, is the phase-to-phase coupling coefficient between the current arrester i and the remaining arrester j, is the online current of the cable body at the cable terminal i, and the phase coupling coefficient of the arrester's influence on itself is 1. =1.

[0049] Understandably, is the current leakage current calibration value of arrester 1, The current leakage current calibration value of the arrester M, is the online current of the cable body at cable terminal 1, is the online current of the cable body at the cable terminal M, is the phase-to-phase coupling coefficient between the current arrester M and the remaining arrester 1.

[0050] Furthermore, using the formula

[0051] Calculate the actual value of leakage current of each item in the three-phase power grid , , , , , are the leakage current calibration values ​​of each arrester in the three-phase power grid. is the cable coupling coefficient of the cable terminal 1 to the current arrester 1, is the phase-to-phase coupling coefficient between the current lightning arrester 1 and the remaining lightning arrester 2.

[0052] Furthermore, using the formula Calculate the actual value of leakage current of each item in the two-phase power grid , , , They are the leakage current calibration values ​​of each lightning arrester in the two-phase power grid.

[0053] The present invention also provides a full-current online monitoring system for parallel lightning arresters at high-voltage cable terminals, including online monitoring devices arranged in one-to-one correspondence with the lightning arresters, the lightning arresters are connected to the corresponding cable terminals, and each lightning arrester is correspondingly arranged with a lightning protection grounding down conductor, including an electrically connected cable core current detection module, a leakage current detection module, a calibration signal injection module, a current sensor power supply module and a monitoring host, the cable core current detection module is used to obtain the current of the cable terminal, the leakage current detection module is used to obtain the current of the lightning protection grounding down conductor, the calibration signal injection module is used to inject multiple different target frequency standard signals, the current sensor power supply module is used to inductively obtain power from the cable terminal, and the monitoring host is used to implement the steps of the above-mentioned full-current online monitoring method for parallel lightning arresters at high-voltage cable terminals.

[0054] In the specific implementation, the calibration signal injection module is arranged close to the arrester, and the leakage current detection module is located on the side of the calibration signal injection module away from the arrester. The current sensor power supply module is used to inductively draw power from the cable terminal to realize power supply for various modules such as the monitoring host.

[0055] Furthermore, the full current online monitoring system of the high-voltage cable terminal parallel lightning arrester also includes a lightning strike counter, which is arranged at the end of the lightning protection grounding down conductor.

[0056] The present invention provides a method for online monitoring of full current of a high-voltage cable terminal parallel lightning arrester, and the implementation method is as follows:

[0057] The current sensor power supply module adopts a high-precision open-type CT, which is easy to install on site; the cable coupling coefficient and the phase-to-phase coupling coefficient can assist in the calculation of spatial distribution parameters, and automatically eliminate the influence of coupling interference in data processing. In specific implementation, it only needs to be carried out when the cable line is put into operation, routine power outage tests, and coordinated power outages, and the test data is transmitted to the monitoring background. By comparing the relationship between the currents, the coupling coefficient of the cable and terminal to the lightning arrester and the coupling coefficient between the phases of the lightning arrester can be calculated.

[0058] The specific implementation process is:

[0059] The first step is to obtain the cable coupling coefficient and the phase-to-phase coupling coefficient: During the test phase, the rated power frequency voltage and high-order harmonic signals are applied to the arrester and cable terminal (high-voltage cable / cable body) in phases (the process of applying voltage to the high-voltage cable can be carried out simultaneously during the cable withstand voltage test); during the pressurization process, the phase-to-phase coupling coefficient of the arrester phases and the coupling coefficient of the cable and terminal to the cable arrester are calculated through the monitoring host.

[0060] In specific operation, when the high-voltage cable is subjected to voltage in phase The circuit between the cable terminal and the arrester is open, and the current of the cable body is measured by the battery current detection module installed on the cable body. , combined with the leakage current detection module to measure the arrester leakage current , the cable part has coupling capacitance to the arrester , please refer to the attached Figure 3 The cable impedance is , and The relationship is:

[0061] .

[0062] The coupling coefficient of the cable terminal to the arrester is : When voltage is applied to the arrester in phases , the circuit between the cable terminal and the arrester is open, and the arrester leakage current with applied voltage is , and the other two phase arrester leakage currents are , , is the resistance of the arrester at rated voltage and frequency, , is the coupling capacitor between lightning arresters. Figure 4 , then the coupling coefficient between the phases of the arrester under single-phase action is , They are:

[0063] .

[0064] The second step is to eliminate interference: When the cable and lightning arrester are operating normally, the detected leakage current sensing value includes the actual leakage current of the lightning arrester, the accuracy interference of the leakage current detection module, and the current value generated by the coupling interference. Among them, the current value generated by the coupling interference consists of 5 parts, which are the interference of the remaining two-phase lightning arrester and the interference of the three-phase cable terminal. Therefore, the leakage current value detection value of the three-phase lightning arrester It can be expressed as:

[0065]

[0066] in, Indicates the leakage current calibration value, , , Indicates the online current of each cable body, , , Indicates the actual value of each leakage current.

[0067] In the specific operation of eliminating the interference of the accuracy of the leakage current detection module, it comes with a calibration module, which can verify the validity of the data of the leakage current detection module. The calibration module has a built-in standard variable frequency current source, and the calibration procedure is started regularly or as needed. During the calibration process, the standard variable frequency current source outputs a calibration current signal. The leakage current detection module collects the current signal and processes it through Fourier transform and other processing techniques to extract the corresponding standard current signal pickup value (target signal pickup value). The target signal pickup value is compared with the calibration current signal value output by the standard variable frequency current source. The calibration deviation results at different frequencies are used to obtain the frequency-related calibration coefficient, so as to calibrate the measurement value of the leakage current detection module to ensure the accuracy and reliability of its measurement. The specific principle is as follows. When the calibration module is not added, the leakage current is , the calibration current signal input to the calibration module is ,because , then the actual measured current value .adjust The frequency of the monitoring device is close to the power frequency. and If there is a deviation between them, the following formula can be listed to obtain the power frequency calibration coefficient: :

[0068]

[0069] By adjusting the frequency and input current value , the calibration coefficient can be obtained At the same time, for more accurate measurement results, you can use and The vector synthesis calculation method is Make corrections.

[0070] The current sensor power supply module is used to power the system after power is taken. It adopts the current transformer power supply method to provide power. The back end of the CT power supply device (current sensor power supply module) is connected to a group of small-capacity lithium batteries. When working, the CT power supply device charges the lithium battery. At the same time, the lithium battery and the CT power supply device form a dual channel to supply power to the full current measurement unit to ensure the safe and stable operation of the system. At the same time, a flexible coil sensor is integrated in the power supply unit, which can measure the main body current and transmit it to the data upload unit.

[0071] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0072] The open current sensor power supply module is adopted. Compared with the closed current transformer and the direct connection method of the lightning arrester grounding wire, this method can support live installation and avoid the power outage problem during device installation. At the same time, it is convenient for maintenance and replacement. The built-in calibration module overcomes the technical difficulties of the coordination between the leakage current detection module and the calibration module and the difficulty of inputting built-in high-precision current signals, providing reliable support for the accuracy of the measurement data. The device can assist in the calculation of spatial distribution parameters through the three steps of "pressurization-calculation-interference elimination", and can eliminate the influence of coupling interference when there is no obvious abnormality in the surrounding live equipment.

[0073] Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application can take the form of a computer program product implemented on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes 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 produce 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 process Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process in 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.

[0074] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for online monitoring of the full current of a high-voltage cable terminal parallel lightning arrester, characterized in that: Includes steps: S100, in the test phase, obtaining the cable coupling coefficient of each cable terminal to the current lightning arrester under the single-phase action, and obtaining the phase coupling coefficient between the current lightning arrester and the remaining lightning arresters under the single-phase action; S200, using a leakage current detection module to obtain the current leakage current sensing value of the arrester online; S300, calibrating the leakage current sensing value using the power frequency calibration coefficient to obtain a current leakage current calibration value of the arrester; S400, obtaining a current actual value of the leakage current of the arrester based on the leakage current calibration value, the cable coupling coefficient, and the phase-to-phase coupling coefficient; Among them, the step of obtaining the power frequency calibration coefficient includes: injecting a plurality of different target frequency standard signals into the calibration lead, the target frequency standard signal is not equal to the power frequency; using the leakage current detection module to obtain the target signal pickup value corresponding to each target frequency standard signal; obtaining the deviation value between the target frequency standard signal and the corresponding target signal pickup value; if the absolute value of the deviation value is greater than the preset deviation, fitting the calibration curve formed by each target signal pickup value; interpolating the calibration curve to obtain the power frequency calibration coefficient corresponding to the power frequency; if the absolute value of the deviation value is less than the preset deviation, the power frequency calibration coefficient is 1; Using formula Calculate and obtain the actual value of the leakage current of the current arrester i ,in, is the cable coupling coefficient of the cable terminal j to the current arrester i, is the leakage current calibration value of arrester i, is the phase-to-phase coupling coefficient between the current arrester i and the remaining arrester j, is the online current of the cable body at cable terminal i, and the phase-to-phase coupling coefficient of the arrester's influence on itself is 1.

2. The method for online monitoring of full current of parallel lightning arrester at high-voltage cable terminal according to claim 1 is characterized in that: The multiple different target frequency standard signals include a high frequency calibration signal of X times the power frequency and a low frequency calibration signal within a 20 Hz range from the power frequency, wherein X is a positive integer greater than or equal to 2.

3. The method for online monitoring of full current of parallel lightning arrester at high-voltage cable terminal according to claim 1 is characterized in that: The preset deviation is 2%.

4. The method for online monitoring of full current of a high-voltage cable terminal parallel lightning arrester according to any one of claims 1 to 3, characterized in that: During the test phase, the cable coupling coefficient of each cable terminal j to the current arrester i under single-phase action is obtained. ; ;in, Indicates the cable body current detected by the cable core current detection module corresponding to the cable terminal j, It indicates the lightning protection monitoring leakage current detected by the leakage current detection module corresponding to the current lightning arrester i, represents the coupling capacitance of the cable terminal j to the current arrester i, Indicates the cable impedance value corresponding to the cable terminal j, is the power frequency; i=1, 2, 3, ..., M, j=1, 2, 3, ..., N, M is the total number of cable terminals, N is the total number of lightning arresters, and the total number of cable terminals is the same as the total number of lightning arresters.

5. The method for online monitoring of full current of parallel lightning arrester at high voltage cable terminal according to claim 4 is characterized in that: During the test phase, the phase coupling coefficient between the current arrester i and the remaining arrester k under single-phase action is obtained. , ,in, It represents the leakage current detected by the leakage current detection module corresponding to the remaining lightning arrester k, represents the leakage current detected by the cable core current detection module corresponding to the current arrester i to which voltage is applied, It indicates the resistance of the current arrester i at rated voltage and frequency, Represents the phase-to-phase coupling capacitance between the current arrester i and the remaining arrester k, k∈N.

6. The method for online monitoring of full current of parallel lightning arrester at high-voltage cable terminal according to claim 1 is characterized in that: Using formula Calculate the actual value of leakage current of each item in the three-phase power grid , , , , , They are the leakage current calibration values ​​of each lightning arrester in the three-phase power grid.

7. The method for online monitoring of full current of parallel lightning arrester at high voltage cable terminal according to claim 1 is characterized in that: Using formula Calculate the actual value of leakage current of each item in the two-phase power grid , , , They are the leakage current calibration values ​​of each lightning arrester in the two-phase power grid.

8. A full current online monitoring system for parallel lightning arresters at high-voltage cable terminals, comprising online monitoring devices arranged one-to-one with the lightning arresters, the lightning arresters are connected to the corresponding cable terminals, and each lightning arrester is correspondingly arranged with a lightning protection grounding down conductor, characterized in that: It includes an electrically connected cable core current detection module, a leakage current detection module, a calibration signal injection module, a current sensor power supply module and a monitoring host. The cable core current detection module is used to obtain the current at the cable terminal. The leakage current detection module is used to obtain the current of the lightning protection grounding down conductor. The calibration signal injection module is used to inject a plurality of different target frequency standard signals. The current sensor power supply module is used to induct power from the cable terminal. The monitoring host is used to implement the steps of the method for online monitoring of the full current of a high-voltage cable terminal shunt arrester as described in any one of claims 1 to 7.

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