Distribution line protection method, device and equipment with magnetizing inrush current identification function and storage medium

Abstract

The invention discloses a distribution line protection method, device and equipment with an excitation inrush current identification function, and a storage medium. The method comprises the following steps: collecting a current signal and a voltage signal of a distribution line in real time; the current signal is used for harmonic component extraction, and the voltage signal is used for constructing an auxiliary criterion variable; the position state of the circuit breaker is monitored in real time, the current closing / tripping state of the circuit breaker is judged to trigger a closing event, and an inrush current recognition mode is started; and on the basis of the inrush current identification mode, the excitation inrush current condition is judged in combination with a multi-feature criterion, and the distribution line is protected. On the basis of existing over-current protection function configuration, secondary harmonic content judgment logic is added, based on the characteristics that the secondary harmonic content of magnetizing inrush current is high, bus voltage is normal and waveform is asymmetric, line misoperation caused by the magnetizing inrush current is prevented through the secondary harmonic content, meanwhile, a voltage criterion is added to avoid faults and inrush current, and therefore the over-current protection function is achieved. While the overcurrent protection action is ensured to quickly cut off the fault, the protection misoperation caused by inrush current during switching on can be prevented.

Description

Technical Field

[0001] This invention relates to the technical field of power distribution line protection, and in particular to a power distribution line protection method, device, equipment and storage medium with inrush current identification function. Background Technology

[0002] With increasing electricity demand, the number and total capacity of distribution transformers are constantly increasing. However, when power is restored to distribution lines after no-load closing or fault clearing, each distribution transformer may generate a large inrush current due to core saturation, leading to accidents such as line protection malfunction, closing failure, or feeder automation failure, threatening the safe operation of the distribution network.

[0003] Currently, there are two common methods to avoid inrush current. One is to appropriately increase the instantaneous overcurrent protection setting during the setting calculation, provided it matches the main transformer backup protection setting. To prevent maloperation of the protection due to inrush current, the setting of the first-stage instantaneous overcurrent protection device can be increased and the operating time extended to avoid inrush current. Typically, a delay of 0.15–0.2 seconds is added to the first-stage instantaneous overcurrent protection circuit. The biggest advantage of this method is that it does not require extensive modification of the protection device; only a simple modification of the setting is needed to effectively avoid maloperation of the instantaneous overcurrent protection. However, increasing the setting of the first-stage instantaneous overcurrent protection device will affect sensitivity; extending the operating time, shortening the protection range, and increasing the fault clearing time will cause significant damage to the transformer and 10kV line equipment during line outgoing faults. Secondly, when restoring power to a 10kV distribution line after maintenance, if protection trips or line fault reclosing fails, the recommended measure is to open the 10kV line branch switches. After the line is energized, each branch switch is energized separately. By rationally segmenting and distributing the load, the initial energizing capacity is controlled, and energizing is performed in stages, allowing the instantaneous overcurrent protection of stage I to avoid the impact of inrush current. However, in actual operation, opening the branch switches and energizing separately requires a large number of workers to cooperate, which is wasteful of manpower and unsafe. Summary of the Invention

[0004] In view of the aforementioned existing problems, this invention is proposed. Therefore, this invention provides a method, device, equipment, and storage medium for protecting power distribution lines with inrush current identification function, solving the problem that when power distribution lines are restored to operation after maintenance or power outages, inrush current during closing causes overcurrent protection to activate and switches to trip, preventing normal power restoration.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] In a first aspect, embodiments of the present invention provide a power distribution line protection method with inrush current identification function, comprising: real-time acquisition of current signals and voltage signals of the power distribution line; the current signals are used for harmonic component extraction, and the voltage signals are used to construct auxiliary criterion variables;

[0007] Real-time monitoring of the circuit breaker's position status determines the current closed / tripped state of the circuit breaker, triggering a closing event and activating the inrush current identification mode.

[0008] Based on the inrush current identification mode, and combined with multiple feature criteria, the excitation inrush current situation is judged, and the power distribution line is protected.

[0009] As a preferred embodiment of the power distribution line protection method with inrush current identification function described in this invention, the multi-feature criteria include: harmonic content, voltage level, and waveform characteristics.

[0010] As a preferred embodiment of the power distribution line protection method with inrush current identification function described in this invention, the following steps are included: determining the current closed / tripped state of the circuit breaker to trigger a closing event and activating the inrush current identification mode:

[0011] When the circuit breaker position changes from tripped to closed, or when the current in any phase rises from no current to more than 5% of its secondary rated current, a closing event is triggered, and the inrush current identification mode is activated.

[0012] As a preferred embodiment of the power distribution line protection method with inrush current identification function described in this invention, the current signal for harmonic component extraction includes: performing Fourier transform on the acquired current signal, performing spectrum analysis on the current signal, separating the fundamental component and the second harmonic component, and calculating the second harmonic content of each phase.

[0013] The second harmonic content is expressed as:

[0014]

[0015] Among them, K 2A K represents the percentage of the second harmonic content in phase A current. 2B K represents the percentage of the second harmonic content in the B-phase current. 2C I represents the percentage of the second harmonic content in the C-phase current. A I is the amplitude of the fundamental component of the phase A current. B I is the amplitude of the fundamental component of the B-phase current. C I is the amplitude of the fundamental component of the C-phase current. A2 I is the amplitude of the second harmonic component in phase A current. B2 I is the amplitude of the second harmonic component in the B-phase current. C2 This represents the amplitude of the second harmonic component in the C-phase current.

[0016] The beneficial effect of this preferred technical solution is that by adding a second harmonic content judgment logic, based on multiple characteristics such as high second harmonic content of inrush current, normal bus voltage, and waveform asymmetry, the second harmonic content is used to prevent line malfunction caused by inrush current.

[0017] As a preferred embodiment of the distribution line protection method with inrush current identification function described in this invention, the voltage signal used to construct auxiliary criterion variables includes: calculating the line voltage U in real time using the three-phase phase voltage. AB U BC U CA And negative sequence voltage U2; when a closing event is identified, the line voltage and negative sequence voltage are used as voltage criteria to identify inrush current.

[0018] The beneficial effects of this preferred technical solution are that by adding voltage criteria to avoid faults and inrush currents, it ensures that the overcurrent protection can quickly clear faults while preventing inrush currents from causing malfunctions during closing.

[0019] As a preferred embodiment of the distribution line protection method with inrush current identification function described in this invention, the protection of the distribution line includes: based on the inrush current identification mode, combining multiple feature criteria to determine the inrush current situation, and performing protection of the distribution line includes:

[0020] When the inrush current identification mode is activated, if the amplitude of the fundamental component of any phase current is greater than the current threshold of the line protection device and its second harmonic content is greater than the preset second harmonic content threshold, then the line voltage and negative sequence voltage are used as voltage criteria to identify the excitation inrush current.

[0021] When the amplitude of the fundamental component of any phase current is greater than the current threshold of the line protection device and its second harmonic content is greater than the preset second harmonic content threshold, if the voltage of any phase line is less than the voltage threshold or the negative sequence voltage is greater than the negative sequence voltage threshold, it is judged as a real fault and the overcurrent protection is opened; if the voltage of any phase line is not less than the voltage threshold or the negative sequence voltage is not greater than the negative sequence voltage threshold, it is judged as an inrush current and the overcurrent protection is blocked.

[0022] As a preferred embodiment of the power distribution line protection method with inrush current identification function described in this invention, it further includes: identifying inrush current characteristics using waveform asymmetry; during a fault, the following expression holds:

[0023] S + ≤K b *S -

[0024] Numerical value.

[0025] Secondly, the present invention provides a power distribution line protection device with inrush current identification function, comprising:

[0026] The data acquisition module is used to acquire current and voltage signals of the power distribution line in real time; the current signal is used for harmonic component extraction, and the voltage signal is used to construct auxiliary criterion variables.

[0027] The monitoring module is used to monitor the circuit breaker's position status in real time, determine the current closed / tripped status of the circuit breaker, trigger a closing event, and start the inrush current identification mode.

[0028] The overcurrent protection module is used to determine the inrush current situation based on the inrush current identification mode and combined with multiple feature criteria, and to protect the power distribution line.

[0029] Thirdly, the present invention provides an electronic device, comprising:

[0030] Memory and processor;

[0031] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the power distribution line protection method with inrush current identification function.

[0032] Fourthly, the present invention provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the power distribution line protection method with inrush current identification function.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: Based on the existing overcurrent protection function configuration of the power distribution line protection device, the present invention adds second harmonic content judgment logic. Based on multiple characteristics such as high second harmonic content of excitation inrush current, normal bus voltage, and waveform asymmetry, the second harmonic content is used to prevent the line from malfunctioning due to excitation inrush current. At the same time, voltage criteria are added to avoid faults and inrush currents. This ensures that the overcurrent protection action can quickly clear faults while preventing inrush current from causing protection malfunctions when closing the circuit. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0035] Figure 1 This is a schematic flowchart of a power distribution line protection method with inrush current identification function according to an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the line protection process of a power distribution line protection method with inrush current identification function according to an embodiment of the present invention;

[0037] Figure 3 This is a line protection control logic diagram of a power distribution line protection method with inrush current identification function according to an embodiment of the present invention. Detailed Implementation

[0038] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0039] Example 1, referring to Figures 1-3 As one embodiment of the present invention, this embodiment provides a power distribution line protection method with inrush current identification function, including:

[0040] S100: Real-time acquisition of current and voltage signals of power distribution lines; current signals are used for harmonic component extraction, and voltage signals are used to construct auxiliary criterion variables;

[0041] S200: Real-time monitoring of circuit breaker position status, determining the current closed / tripped status of the circuit breaker, triggering a closing event, and activating inrush current identification mode;

[0042] S300: Based on inrush current identification mode, it combines multiple feature criteria to judge the excitation inrush current situation and protect the power distribution line.

[0043] It should be noted that, in order to avoid inrush current, the setting value of the instantaneous overcurrent protection can be appropriately increased during the setting calculation, provided it matches the setting value of the main transformer backup protection. To prevent maloperation of the protection caused by inrush current, the setting value of the first-stage instantaneous overcurrent protection device can be increased and the operating time extended to avoid inrush current. Typically, a delay of 0.15 to 0.2 seconds is added to the first-stage instantaneous overcurrent protection circuit. The biggest advantage of this method is that it does not require extensive modification of the protection device; only a simple modification of the setting value is needed to effectively avoid maloperation of the instantaneous overcurrent protection. However, increasing the setting value of the first-stage instantaneous overcurrent protection device will affect sensitivity; extending the operating time, shortening the protection range, and increasing the fault clearing time will cause significant damage to the transformer and 10kV line equipment during line outlet faults. When restoring power to a 10kV distribution line after maintenance, if protection trips or line fault reclosing fails, the usual procedure is to open the 10kV line branch switches. After energizing the line, each branch switch is energized separately. By rationally segmenting and distributing the load, the initial energizing capacity is controlled, and energizing is performed in stages to allow the instantaneous overcurrent protection of stage I to avoid the impact of inrush current. However, in actual operation, opening the branch switches and energizing separately requires a large number of personnel to cooperate, which is wasteful of manpower and unsafe.

[0044] This invention adds second harmonic content judgment logic to the existing overcurrent protection function configuration of power distribution line protection devices. Based on multiple characteristics such as high second harmonic content of inrush current, normal bus voltage, and waveform asymmetry, it prevents line maloperation caused by inrush current by judging the second harmonic content. At the same time, it adds voltage criteria to avoid faults and inrush currents. This ensures that the overcurrent protection can quickly clear faults while preventing maloperation of the protection due to inrush current during closing. It can effectively solve the problem that the overcurrent protection will trip and the switch will not be able to be restored normally when the power distribution line is restored after maintenance or power restriction. It provides a guarantee for the normal operation of the 10kV power distribution system and ensures the stable and reliable operation of the power system.

[0045] In this embodiment of the invention, step S100, using the current signal for harmonic component extraction, includes: performing a Fourier transform on the acquired current signal, performing spectral analysis on the current signal, separating the fundamental component and the second harmonic component, and calculating the second harmonic content of each phase; the second harmonic content is expressed as:

[0046]

[0047] Among them, K 2A K represents the percentage of the second harmonic content in phase A current. 2B K represents the percentage of the second harmonic content in the B-phase current. 2C I represents the percentage of the second harmonic content in the C-phase current. A I is the amplitude of the fundamental component of the phase A current. BI is the amplitude of the fundamental component of the B-phase current. C I is the amplitude of the fundamental component of the C-phase current. A2 I is the amplitude of the second harmonic component in phase A current. B2 I is the amplitude of the second harmonic component in the B-phase current. C2 This represents the amplitude of the second harmonic component in the C-phase current.

[0048] Furthermore, a Fourier transform is performed on the acquired current signal. An orthogonal current signal is used as the standard current signal. The standard current signal and the current signal to be processed are subjected to corresponding integral transforms to obtain the real axis component and imaginary axis component in the current signal to be processed that have the same frequency as the standard current signal. The effective value of the frequency component in the current signal to be processed can be obtained using the real and imaginary axis components.

[0049] The formula for the full-cycle Fourier algorithm is:

[0050]

[0051] Where N is the number of sampling points per cycle, k is the nth sampling point, n is the harmonic order, and I A For the real part, I B This is the imaginary part.

[0052] The second harmonic can be represented by Fourier decomposition as:

[0053] X2(t)=X 2s sin2ωt+X 2c cos2ωt

[0054] Where X2 is the effective value of the second harmonic component, X 2s X 2c These are the coefficients of the sine and cosine components of the m-th harmonic, respectively.

[0055] It should be noted that in this embodiment of the invention, a sampling frequency of 12kHz is used, that is, 12,000 data points are collected per second to obtain the harmonic components of the three-phase current of the power distribution line, so as to ensure that the current harmonic components are more accurate.

[0056] In this embodiment of the invention, step S100, in which the voltage signal is used to construct auxiliary criterion variables, includes: calculating the line voltage U in real time using the three-phase phase voltage. AB U BC U CA And negative sequence voltage U2; when a closing event is identified, the line voltage and negative sequence voltage are used as voltage criteria to identify inrush current.

[0057] The line voltage is expressed as: U AB =UA-UB,U BC =UB-UC,UCA =UC-UA;

[0058] Negative sequence voltage is represented as:

[0059]

[0060] in, These represent the complex voltages of phases A, B, and C, respectively, with 'a' being the complex operation factor.

[0061] In this embodiment of the invention, step S200, which involves determining the current closed / tripped state of the circuit breaker to trigger a closing event and activate the inrush current identification mode, includes:

[0062] When the circuit breaker position changes from tripped to closed, or when the current in any phase rises from no current to more than 5% of its secondary rated current, a closing event is triggered, and the inrush current identification mode is activated.

[0063] It should be noted that the secondary rated current of the current transformer in the line is generally 1A or 5A.

[0064] In this embodiment of the invention, the multi-feature criteria in step S300 include: harmonic content, voltage level, and waveform characteristics.

[0065] In this embodiment of the invention, step S300, which involves determining the inrush current situation based on the inrush current identification mode and combining multiple feature criteria to protect the power distribution line, includes:

[0066] When the inrush current identification mode is activated, if the amplitude of the fundamental component of any phase current is greater than the current threshold of the line protection device and its second harmonic content is greater than the preset second harmonic content threshold, then the line voltage and negative sequence voltage are used as voltage criteria to identify the excitation inrush current.

[0067] When the amplitude of the fundamental component of any phase current is greater than the current threshold of the line protection device and its second harmonic content is greater than the preset second harmonic content threshold, if the voltage of any phase line is less than the voltage threshold or the negative sequence voltage is greater than the negative sequence voltage threshold, it is judged as a real fault and the overcurrent protection is opened; if the voltage of any phase line is not less than the voltage threshold or the negative sequence voltage is not greater than the negative sequence voltage threshold, it is judged as an inrush current and the overcurrent protection is blocked.

[0068] Specifically, when I A I greater than the setting of the line protection device set When the inrush current identification function has been activated, determine the current second harmonic content K of phase A. 2A Is it greater than the preset second harmonic content K? 2set .

[0069] When I B I greater than the device setting setWhen the inrush current identification function has been activated, determine the current second harmonic content K of phase B. 2B Is it greater than the preset second harmonic content K? 2set .

[0070] When I C I greater than the device setting set When the inrush current identification function has been activated, determine the current C-phase second harmonic content K. 2C Is it greater than the preset second harmonic content K? 2set .

[0071] Furthermore, when both the phase A current and the phase A second harmonic content are large, the previously determined voltage U... AB U BC U CA If the voltage criterion is not met (e.g., less than 80V or greater than 8V), then inrush current is considered to occur, and overcurrent protection is blocked.

[0072] Furthermore, when both the phase B current and the phase B second harmonic content are large, the previously determined voltage U... AB U BC U CA If the voltage criterion is not met (e.g., less than 80V or greater than 8V), then inrush current is considered to occur, and overcurrent protection is blocked.

[0073] Furthermore, when both the C-phase current and the C-phase second harmonic content are large, the previously determined voltage U... AB U BC U CA If the voltage criterion is not met (e.g., U2 is less than 80V or U2 is greater than 8V), then inrush current is considered to occur, and overcurrent protection is blocked.

[0074] It should be noted that the line protection device also has waveform recognition capabilities. It can determine that differential current is basically a power frequency sine wave, while inrush current contains a large number of harmonic components, causing waveform distortion, discontinuity, and asymmetry. When the algorithm identifies such distortion exceeding 20%, inrush current can be detected.

[0075] In this embodiment of the invention, step S300 further includes: identifying inrush current characteristics using waveform asymmetry; during a fault, the following expression holds:

[0076] S + ≤K b *S -

[0077] Numerical value.

[0078] It should be noted that the waveform asymmetry coefficient is fixed at 0.2 internally.

[0079] Example 2 is an embodiment of the present invention. This embodiment differs from the first embodiment in that it provides a power distribution line protection device with inrush current identification function, comprising:

[0080] The data acquisition module is used to acquire current and voltage signals of power distribution lines in real time; the current signal is used for harmonic component extraction, and the voltage signal is used to construct auxiliary criterion variables.

[0081] The monitoring module is used to monitor the circuit breaker's position status in real time, determine the current closed / tripped status of the circuit breaker, trigger a closing event, and start the inrush current identification mode.

[0082] The overcurrent protection module is used to protect the power distribution line by judging the excitation inrush current situation based on the inrush current identification mode and combined with multiple feature criteria.

[0083] It should be noted that the line protection device has an independent harmonic data acquisition module, which is used to acquire the harmonic components of the three-phase current of the distribution line and transmit this data to the overcurrent protection module. Unlike the normal data acquisition module, the harmonic data acquisition module uses a 12KHZ sampling frequency to acquire high-precision current sampling, that is, to acquire 120 data points per second, so as to ensure that the current harmonic components are more accurate.

[0084] Specifically, each module of the distribution line protection device with inrush current identification function in this embodiment implements the steps of the distribution line protection method with inrush current identification function in Embodiment 1 when it is executed, for example:

[0085] In one embodiment, a power line protection device with inrush current identification function can perform the following steps:

[0086] The acquired current signal is subjected to Fourier transform and spectrum analysis to separate the fundamental component and the second harmonic component, and the second harmonic content of each phase is calculated.

[0087] The second harmonic content is expressed as:

[0088]

[0089] Among them, K 2A K represents the percentage of the second harmonic content in phase A current. 2B K represents the percentage of the second harmonic content in the B-phase current. 2C I represents the percentage of the second harmonic content in the C-phase current. A I is the amplitude of the fundamental component of the phase A current. B I is the amplitude of the fundamental component of the B-phase current. C I is the amplitude of the fundamental component of the C-phase current. A2I is the amplitude of the second harmonic component in phase A current. B2 I is the amplitude of the second harmonic component in the B-phase current. C2 This represents the amplitude of the second harmonic component in the C-phase current.

[0090] Real-time calculation of line voltage U using three-phase phase voltage AB U BC U CA And negative sequence voltage U2; when a closing event is identified, the line voltage and negative sequence voltage are used as voltage criteria to identify inrush current.

[0091] When the circuit breaker position changes from tripped to closed, or when the current in any phase rises from no current to more than 5% of its secondary rated current, a closing event is triggered, and the inrush current identification mode is activated.

[0092] When the inrush current identification mode is activated, if the amplitude of the fundamental component of any phase current is greater than the current threshold of the line protection device and its second harmonic content is greater than the preset second harmonic content threshold, then the line voltage and negative sequence voltage are used as voltage criteria to identify the excitation inrush current.

[0093] When the amplitude of the fundamental component of any phase current is greater than the current threshold of the line protection device and its second harmonic content is greater than the preset second harmonic content threshold, if the voltage of any phase line is less than the voltage threshold or the negative sequence voltage is greater than the negative sequence voltage threshold, it is judged as a real fault and the overcurrent protection is opened; if the voltage of any phase line is not less than the voltage threshold or the negative sequence voltage is not greater than the negative sequence voltage threshold, it is judged as an inrush current and the overcurrent protection is blocked.

[0094] The characteristics of inrush current can be identified by utilizing waveform asymmetry. During a fault, the following expression holds true:

[0095] S + ≤K b *S -

[0096]

[0097] Numerical value.

[0098] Example 3: This example provides an electronic device applicable to power distribution line protection methods with inrush current identification function, including:

[0099] The system includes a memory and a processor. The memory stores computer-executable instructions, and the processor executes these instructions to implement the power distribution line protection method with inrush current identification function as proposed in the above embodiments.

[0100] This embodiment also provides a storage medium storing a computer program, which, when executed by a processor, implements the power distribution line protection method with inrush current identification function as proposed in the above embodiments.

[0101] The storage medium proposed in this embodiment and the power distribution line protection method with inrush current identification function proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0102] From the above description of the embodiments, those skilled in the art will clearly understand that the embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can 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. The solutions in the embodiments of this application can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0103] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0104] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0105] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0106] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0107] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

[0108] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for protecting distribution lines with inrush current identification function, characterized in that, include: Real-time acquisition of current and voltage signals of power distribution lines; the current signal is used for harmonic component extraction, and the voltage signal is used to construct auxiliary criterion variables; Real-time monitoring of the circuit breaker's position status determines the current closed / tripped state of the circuit breaker, triggering a closing event and activating the inrush current identification mode. Based on the inrush current identification mode, and combined with multiple feature criteria, the excitation inrush current situation is judged, and the power distribution line is protected.

2. The power distribution line protection method with inrush current identification function as described in claim 1, characterized in that, The multi-feature criteria include: harmonic content, voltage level, and waveform characteristics.

3. The power distribution line protection method with inrush current identification function as described in claim 2, characterized in that, Determine the current closed / tripped state of the circuit breaker to trigger a closing event and activate the inrush current identification mode, including: When the circuit breaker position changes from tripped to closed, or when the current in any phase rises from no current to more than 5% of its secondary rated current, a closing event is triggered, and the inrush current identification mode is activated.

4. The power distribution line protection method with inrush current identification function as described in claim 3, characterized in that, The use of current signals for harmonic component extraction includes: performing Fourier transform on the acquired current signal, performing spectrum analysis on the current signal, separating the fundamental component and the second harmonic component, and calculating the second harmonic content of each phase. The second harmonic content is expressed as: Among them, K 2A K represents the percentage of the second harmonic content in phase A current. 2B K represents the percentage of the second harmonic content in the B-phase current. 2C I represents the percentage of the second harmonic content in the C-phase current. A I is the amplitude of the fundamental component of the phase A current. B I is the amplitude of the fundamental component of the B-phase current. C I is the amplitude of the fundamental component of the C-phase current. A2 I is the amplitude of the second harmonic component in phase A current. B2 I is the amplitude of the second harmonic component in the B-phase current. C2 This represents the amplitude of the second harmonic component in the C-phase current.

5. The power distribution line protection method with inrush current identification function as described in claim 4, characterized in that, Voltage signals are used to construct auxiliary criterion variables, including: real-time calculation of line voltage U using three-phase phase voltages. AB U BC U CA And negative sequence voltage U2; when a closing event is identified, the line voltage and negative sequence voltage are used as voltage criteria to identify inrush current.

6. The power distribution line protection method with inrush current identification function as described in claim 5, characterized in that, Based on inrush current identification mode, and combined with multiple feature criteria to determine the inrush current situation, the protection of power distribution lines includes: When the inrush current identification mode is activated, if the amplitude of the fundamental component of any phase current is greater than the current threshold of the line protection device and its second harmonic content is greater than the preset second harmonic content threshold, then the line voltage and negative sequence voltage are used as voltage criteria to identify the excitation inrush current. When the amplitude of the fundamental component of any phase current is greater than the current threshold of the line protection device and its second harmonic content is greater than the preset second harmonic content threshold, if the voltage of any phase line is less than the voltage threshold or the negative sequence voltage is greater than the negative sequence voltage threshold, it is judged as a real fault and the overcurrent protection is opened; if the voltage of any phase line is not less than the voltage threshold or the negative sequence voltage is not greater than the negative sequence voltage threshold, it is judged as an inrush current and the overcurrent protection is blocked.

7. The power distribution line protection method with inrush current identification function as described in claim 6, characterized in that, It also includes: identifying inrush current characteristics using waveform asymmetry; during a fault, the following expression holds true: S + ≤K b *S - Among them, S + for The half-wave integral value, S - for The half-wave integral value, k b I is the waveform asymmetry coefficient. i ′ represents the value of the differential derivative at a certain point in the first half of the wave. This represents the value of the point corresponding to the second half-wave of the differential derivative.

8. A power distribution line protection device with inrush current identification function, applied to the method described in any one of claims 1-7, characterized in that, include: The data acquisition module is used to acquire current and voltage signals of the power distribution line in real time; the current signal is used for harmonic component extraction, and the voltage signal is used to construct auxiliary criterion variables. The monitoring module is used to monitor the circuit breaker's position status in real time, determine the current closed / tripped status of the circuit breaker, trigger a closing event, and start the inrush current identification mode. The overcurrent protection module is used to determine the inrush current situation based on the inrush current identification mode and combined with multiple feature criteria, and to protect the power distribution line.

9. An electronic device, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the power distribution line protection method with inrush current identification function as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the power distribution line protection method with inrush current identification function as described in any one of claims 1 to 7.

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