A power distribution network fast protection method and device and a computer readable storage medium

Abstract

The application discloses a power distribution network fast protection method and device and a computer readable storage medium, wherein the method comprises the following steps: S1, sequentially calibrating branch lines of a radial power distribution network to determine the grades and numbers of the feeder branch lines; S2, constructing a starting criterion by using transformer low-voltage side currents to calibrate the moment of fault occurrence; S3, according to different fault types, selecting characteristic phases and calculating the amplitude and phase angle of the corresponding characteristic phase mutation current phasor; S4, taking the main transformer low-voltage side phasor as a reference phasor, calculating the inner product of the phasor calculated by other lines and the reference phasor respectively, and marking all the lines with inner product greater than the setting value; and S5, finding the line with the highest number and grade among all the marked lines and marking the line as a fault line. The application can solve the contradiction between the four properties of the traditional power distribution network three-section current protection, and well cope with many problems such as high resistance fault and slow backup protection action.

Description

Technical Field

[0001] This invention relates to the field of power system relay protection technology, specifically to a fast protection method, device, and computer-readable storage medium for distribution networks. Background Technology

[0002] With the expansion of AC distribution networks and the increase in the number of underground cables, the ever-increasing capacitive current in neutral-point-ineffectively-grounded systems is difficult to fully compensate for by resonant grounding devices. Furthermore, resonant grounding devices lead to more complex and unstable transient processes, making fault line identification more difficult and significantly increasing the cost of insulation equipment. Therefore, neutral-point-effectively-grounded systems have been gradually replacing neutral-point-ineffectively-grounded systems in recent years. Distribution networks based on neutral-point-effectively-grounded systems have low overvoltage levels and many advantages; in addition, they exhibit clear fault characteristics, which facilitates fault line selection and protection tripping. However, such distribution networks generate larger short-circuit currents, seriously threatening safe operation. Traditional distribution network current protection encounters the following problems when applied to neutral-point-effectively-grounded distribution networks:

[0003] Firstly, in traditional distribution networks, current protection for tripping short-circuit faults is generally configured according to a three-stage principle. In the case of a single-ended power supply, three-stage current protection with automatic reclosing function performs well in most scenarios, reliably disconnecting faulty feeders, accelerating the restoration of power to non-faulty areas, and improving the power supply reliability of the distribution network. However, the backup protection operating range of three-stage current protection is too large, resulting in insufficient speed of operation, and its performance is severely affected by the grid operating mode.

[0004] Secondly, in distribution networks with effectively grounded neutral points, single-phase faults typically rely on zero-sequence current protection to trip the circuit breaker. Zero-sequence current can be directly measured by a zero-sequence current transformer, but this requires all three phase conductors to pass through the transformer together, which is extremely inconvenient in distribution networks with numerous cable lines and effectively grounded neutral points. If the zero-sequence current is calculated by summing the phase current transformers, the measurement error is extremely large when the zero-sequence current is small. Furthermore, most branch feeders are only equipped with phase current transformers, making the only usable electrical quantity for measurement the three-phase current. Additionally, although zero-sequence current is a natural fault component and theoretically more sensitive than protection principles based on full-sequence current, very few protection principles have been proposed that can withstand excessive resistance up to 2000 ohms.

[0005] Finally, various protection principles have been proposed, which can be categorized into passive and active methods based on their implementation. The basic principle of the passive method is to rely on the steady-state or transient signals generated by the fault itself to locate, isolate, and disconnect the fault feeder. Its advantages include simplicity and ease of implementation, generally requiring no additional signal source injection equipment. However, it suffers from contradictions regarding the "four properties" (signal characteristics, fault characteristics, and fault location) in scenarios where the fault component is not obvious. The basic principle of the active method is to utilize the amplitude or morphological characteristics of the injected signal to achieve fault identification and isolation—a type of protection / fault location method. However, its implementation is more complex and requires additional auxiliary devices. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method, device and computer-readable storage medium for fast protection of distribution networks, so as to improve the selectivity, sensitivity, speed and reliability of current protection for distribution networks with effective neutral grounding.

[0007] To solve the above-mentioned technical problems, the present invention provides a fast protection method for distribution networks, characterized in that it includes:

[0008] Step S1: Sequentially label the branches of the radial distribution network to determine the level and number of each feeder branch;

[0009] Step S2: Construct a start-up criterion using the low-voltage side current of the transformer to determine the time of fault occurrence;

[0010] Step S3: Select characteristic phases according to different fault types and calculate the amplitude and phase angle of the sudden change current phasor of the corresponding characteristic phases;

[0011] Step S4: Using the low-voltage side phasor of the main transformer as the reference phasor, calculate the inner product of the phasors obtained from other lines with it, and mark all lines whose inner product is greater than the setting value.

[0012] Step S5: Locate the line with the highest number among all the marked lines and mark it as the faulty line.

[0013] Preferably, step S1 specifically includes: marking the busbar as L0, and all feeders directly connected to the busbar as primary feeders, the primary feeders being marked as... All feeders connected to the primary feeder are secondary feeders, and these secondary feeders are marked as follows: This process continues until the last feeder.

[0014] Preferably, step S2 specifically includes: setting start-up criteria using the SCADA system, detecting sudden changes in mode space voltage and mode space current using the RTU installed at the bus, and determining the fault occurrence time when the following three conditions are simultaneously satisfied:

[0015]

[0016] Wherein, the subscript 0 indicates the feeder number, and the scenario of e=0 means that only line L0 is used to mark the fault time of the RTU. All other lines with e≠0 are not included in the fault time marking. U0(t) and I0(t) are the mode space voltage and mode space current of the RTU installed at L0, and their calculation methods are as follows:

[0017]

[0018] in, The three-phase voltage measured by the RTU installed at L0; The three-phase current is measured by the RTU installed at L0; T is the period.

[0019] Preferably, step S3 specifically includes: processing the abrupt changes in characteristic phase currents of all lines using a small vector algorithm to obtain the amplitude and phase angle of their fundamental frequency components.

[0020]

[0021] Wherein, the subscript e represents the line number, e = 0, 1, 2, ..., n indicates that the above formula is applied to all lines, e = 0 indicates that the current line is a low-voltage side line of the busbar; e ≠ 0 indicates the line with the corresponding number; f is the characteristic phase marker; P is the number of small vectors, which is taken as P = 4 in this invention; N is the number of sampling points in one power frequency cycle; the superscript ω b α represents the fundamental frequency; p represents the p-th small vector, p≤P; q represents the number of sampling points in each small vector; α represents the original phase angle of each small vector.

[0022] Preferably, step S4 specifically includes: selecting the low-voltage side phasor of the main transformer as the reference phasor, normalizing the fundamental frequency estimate of the characteristic phase current mutation of each feeder, calculating the inner product with the reference phasor, and recording all lines whose inner product is greater than the setting threshold; wherein, the low-voltage side phasor of the main transformer is the amplitude and phase obtained in the scenario of e=0, and the fundamental frequency estimate of the characteristic phase current mutation of each feeder is the amplitude and phase obtained in the scenario of e≠0.

[0023] Preferably, L1 to L2 are denoted as L1 to L2. n The results at each location are respectively L1 to L2 can be obtained using the following formula. n The inner product between the normalized value of the fundamental frequency estimate of the abrupt change in the characteristic phase current at L0 and the normalized value of the fundamental frequency estimate of the abrupt change in the characteristic phase current at L0:

[0024]

[0025] in, They are numbered L0 to Ln Normalized result of the fundamental frequency estimate of the characteristic phase current abrupt change at the line. phasor The corresponding phase angle, D e It is the inner product of the normalized quantity of the fundamental frequency estimate of the characteristic phase current mutation of line e and the normalized quantity of the fundamental frequency estimate of the characteristic phase current mutation of line 0, e = 1, 2, ..., N, e = 0 refers to the low-voltage side line of the main transformer.

[0026] Preferably, the set of suspected faulty lines is determined using the following formula:

[0027]

[0028] The present invention also provides a fast protection device for power distribution networks, comprising:

[0029] The branch calibration module is used to sequentially calibrate the branches of a radial distribution network and determine the level and number of each feeder branch.

[0030] The fault detection start-up module is used to construct a start-up criterion using the low-voltage side current of the transformer and to determine the time of fault occurrence.

[0031] The fault feature extraction module is used to select characteristic phases according to different fault types and to calculate the amplitude and phase angle of the sudden change current phasor of the corresponding characteristic phase.

[0032] The inner product comparison module is used to calculate the inner product of the phasors obtained from other lines with the low-voltage side phasor of the main transformer as the reference phasor, and to mark all lines whose inner product is greater than the setting value.

[0033] The fault location decision module is used to find the line with the highest number among all the marked lines and mark it as the faulty line.

[0034] The present invention also provides a fast protection device for a power distribution network. The electronic device includes a processor and a memory. The memory stores machine-executable instructions that can be executed by the processor. The processor executes the machine-executable instructions to implement the fast protection method for the power distribution network.

[0035] The present invention also provides a computer-readable storage medium comprising a stored computer program; wherein, when the computer program is executed, it controls the device containing the computer-readable storage medium to perform the fast protection method for the power distribution network.

[0036] The present invention offers the following advantages: it provides a highly selective and reliable protection principle for neutral-point effectively grounded distribution networks; it enhances the sensitivity of current protection for neutral-point effectively grounded distribution networks, achieving an anti-transition resistance capability of over 2000 ohms; it does not rely on the acquisition of zero-sequence current, but only needs to extract characteristic phase current to achieve fault identification, avoiding the inconvenience of installing zero-sequence current transformers and the huge measurement error generated when synthesizing zero-sequence current using three-phase currents; it improves the speed of current protection for neutral-point effectively grounded distribution networks, achieving 100% coverage of the main protection and avoiding long delays caused by backup protection operation during faults; and it is unaffected by transformer saturation caused by large fault currents during neutral-point effectively grounded distribution network faults. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0038] Figure 1 This is a flowchart illustrating a fast protection method for a power distribution network according to an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram of the algorithm flow of the fast protection method for distribution networks involved in the embodiments of the present invention.

[0040] Figure 3 This is a schematic diagram of the distribution network feeder numbering method in an embodiment of the present invention.

[0041] Figure 4 This is a schematic diagram illustrating a specific method for numbering distribution network feeders in an embodiment of the present invention.

[0042] Figure 5 This is a schematic diagram of the characteristic phase current in an embodiment of the present invention.

[0043] Figure 6 This is a schematic diagram showing the amplitude and phase angle of the characteristic phase current in an embodiment of the present invention.

[0044] Figure 7 This is a schematic diagram of the fault marker circuit identified in an embodiment of the present invention. Detailed Implementation

[0045] The following description of the embodiments is taken with reference to the accompanying drawings, which illustrate specific embodiments in which the invention can be implemented.

[0046] Please refer to Figure 1As shown, Embodiment 1 of the present invention provides a fast protection method for a distribution network, comprising:

[0047] Step S1: Sequentially label the branches of the radial distribution network to determine the level and number of each feeder branch;

[0048] Step S2: Construct a start-up criterion using the low-voltage side current of the transformer to determine the time of fault occurrence;

[0049] Step S3: Select characteristic phases according to different fault types and calculate the amplitude and phase angle of the sudden change current phasor of the corresponding characteristic phases;

[0050] Step S4: Using the low-voltage side phasor of the main transformer as the reference phasor, calculate the inner product of the phasors obtained from other lines with it, and mark all lines whose inner product is greater than the setting value.

[0051] Step S5: Locate the line with the highest number among all the marked lines and mark it as the faulty line.

[0052] Specifically, please combine Figure 2 As shown, in this embodiment, the power distribution network is equipped with a Supervisory Control and Data Acquisition (SCADA) system and a Remote Terminal Unit (RTU).

[0053] Step S1 sequentially labels the branches of the radial distribution network, determining the level and number of each feeder branch. Specifically, Figure 3 L0 is the busbar, L1-L n These are feeders of various levels. Taking L1 as an example, since it is directly connected to the busbar, it is called a level 1 feeder, and the total number of level 1 feeders is n1; its lower-level branch feeders include... This is called a level 2 feeder, and the total number of level 2 feeders is n2-n1; among them, the directly connected lower-level feeders are... In other words, L1 is Directly connected upstream feeders. Repeat the above process until the last feeder. At this point, no other feeders will be directly connected to the last feeder.

[0054] Based on the above distinction method Figure 3 In this embodiment, each feeder is numbered L1, L2, ..., L 15 Among them, L1, L2, and L3 are level 1 feeders; L4 to L8 are level 2 feeders; L9 to L... 15 It is a level 3 feeder.

[0055] Combination Figure 4As shown, in step S2, when the SCADA determines that the fault judgment condition is met, the fault time is marked, and a phase current recording command is sent to all feeders equipped with RTUs:

[0056] Among them, the RTU installed at the busbar detects sudden changes in the mode space voltage and mode space current, and the moment when the following three conditions are met simultaneously is determined to be the time of fault occurrence:

[0057]

[0058] Where the subscript 0 indicates the feeder number, specifically referring to the scenario where e = 0, meaning that only line L0 is used to mark the fault time for the RTU, and all other lines with e ≠ 0 are not included in the fault time marking. Therefore, the above formula means that only the sudden changes in mode space voltage and mode space current at the bus are checked; U0(t) and I0(t) are the mode space voltage and mode space current of the RTU installed at L0, and their calculation method is as follows:

[0059]

[0060] in, The three-phase voltage measured by the RTU installed at L0; The three-phase current is measured by the RTU installed at L0. T is the period, taken as 20ms.

[0061] right Figure 5 The characteristic phase currents shown are processed using a small vector algorithm to handle the abrupt changes in the characteristic phase currents of all the above lines (e = 0, 1, 2, ..., n), yielding the amplitude and phase angle of their fundamental frequency components. The characteristic phase is determined by the following method: the basic principle is to identify the phase that differs significantly from the other phase currents as the characteristic phase; if the three-phase currents are indistinguishable, then phase C is selected as the characteristic phase.

[0062] 1) In a single-phase fault scenario, the fault phase current increases significantly. Therefore, in the scenario of faults in phases A, B, and C, since the corresponding phase currents increase significantly, phases A, B, and C should be selected as characteristic phases respectively.

[0063] 2) In the scenario of two-phase short circuit or two-phase short circuit to ground, the fault phase current increases significantly. Therefore, in the scenarios of AB phase short circuit, AB phase short circuit to ground, BC phase short circuit, BC phase short circuit to ground, AC phase short circuit, and AC phase short circuit to ground, since the non-fault phase current is basically unchanged and significantly smaller than that of the non-fault phase, C phase, A phase, A phase, B phase, and B phase should be selected as characteristic phases respectively.

[0064] 3) In a three-phase short circuit scenario, the three-phase currents are indistinguishable, so phase C is selected as the characteristic phase.

[0065] Table 1. Methods for determining characteristic phases

[0066]

[0067] Step S3 specifically includes: processing the abrupt changes in characteristic phase currents of all lines using a small vector algorithm to obtain the amplitude and phase angle of their fundamental frequency components.

[0068]

[0069] Wherein, the subscript e represents the line number, e = 0, 1, 2, ..., n indicates that the above formula is applied to all lines, e = 0 indicates that the current line is a low-voltage side line of the busbar; e ≠ 0 indicates the line with the corresponding number; f is the characteristic phase marker; P is the number of small vectors, which is taken as P = 4 in this invention; N is the number of sampling points in one power frequency cycle; the superscript ω b α represents the fundamental frequency; p represents the p-th small vector, p≤P; q represents the number of sampling points in each small vector; α represents the original phase angle of each small vector.

[0070] In this embodiment, the fault is a phase-a ground fault. After processing the 15 lines using the above formula, the result is as follows: Figure 6 As shown. These vectors are normalized using the following formula, denoted as L1~L n The results at each location are respectively And calculate L1~L n The inner product between the normalized value of the fundamental frequency estimate of the abrupt change in the characteristic phase current at L0 and the normalized value of the fundamental frequency estimate of the abrupt change in the characteristic phase current at L0:

[0071]

[0072] in, They are numbered L0 to L n Normalized result of the fundamental frequency estimate of the characteristic phase current abrupt change at the line. phasor The corresponding phase angle, D e It is the inner product of the normalized quantity of the fundamental frequency estimate of the characteristic phase current mutation of line e and the normalized quantity of the fundamental frequency estimate of the characteristic phase current mutation of line 0, e = 1, 2, ..., N, e = 0 refers to the low-voltage side line of the main transformer.

[0073] In this embodiment, the results of these inner products are shown in Table 2:

[0074] Table 2. Normalized inner product results of the estimated fundamental frequency values ​​of characteristic phase abrupt change current.

[0075]

[0076]

[0077] Finally, the set of suspected faulty lines is determined using the following formula:

[0078]

[0079] Therefore, the set of suspected faulty lines is L0, L2, L7, L 13 L 13 It is a level 3 feeder, and the other lines are level 1 and 2 feeders, therefore L 13 If the line is determined to be faulty, such as Figure 7 As shown.

[0080] Corresponding to the aforementioned fast protection method for power distribution networks in Embodiment 1 of the present invention, Embodiment 2 of the present invention also provides a fast protection device for power distribution networks, comprising:

[0081] The branch calibration module is used to sequentially calibrate the branches of a radial distribution network and determine the level and number of each feeder branch.

[0082] The fault detection start-up module is used to construct a start-up criterion using the low-voltage side current of the transformer and to determine the time of fault occurrence.

[0083] The fault feature extraction module is used to select characteristic phases according to different fault types and to calculate the amplitude and phase angle of the sudden change current phasor of the corresponding characteristic phase.

[0084] The inner product comparison module is used to calculate the inner product of the phasors obtained from other lines with the low-voltage side phasor of the main transformer as the reference phasor, and to mark all lines whose inner product is greater than the setting value.

[0085] The fault location decision module is used to find the line with the highest number among all the marked lines and mark it as the faulty line.

[0086] Corresponding to the aforementioned fast protection method for distribution networks in Embodiment 1 of the present invention, Embodiment 3 of the present invention also provides a fast protection device for distribution networks, comprising:

[0087] One or more processors;

[0088] Memory;

[0089] One or more applications, wherein the one or more applications are stored in the memory and configured to be executed by the one or more processors, and the one or more applications are configured to perform the fast protection method for power distribution networks as described in Embodiment 1 of the present invention.

[0090] Corresponding to the aforementioned fast protection method for distribution networks in Embodiment 1 of the present invention, Embodiment 4 of the present invention further provides a computer-readable storage medium, the computer-readable storage medium including a stored computer program; wherein, when the computer program is running, it controls the device where the computer-readable storage medium is located to execute the fast protection method for distribution networks described in Embodiment 1 of the present invention.

[0091] Preferably, the computer program can be divided into one or more modules / units (such as computer program 1, computer program 2, ...), and the one or more modules / units are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing a specific function, and the instruction segments are used to describe the execution process of the computer program in the device.

[0092] The processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor, or the processor can be any conventional processor. The processor is the control center of the device and connects the various parts of the device using various interfaces and lines.

[0093] The memory mainly includes a program storage area and a data storage area. The program storage area can store the operating system, applications required for at least one function, etc., while the data storage area can store related data, etc. Furthermore, the memory can be a high-speed random access memory, or a non-volatile memory, such as a plug-in hard drive, a SmartMedia Card (SMC), a Secure Digital (SD) card, and a Flash Card, or other volatile solid-state storage devices.

[0094] For the working principle and process of the above embodiments, please refer to the description of Embodiment 1 of the present invention, which will not be repeated here.

[0095] As can be seen from the above description, compared with the prior art, the beneficial effects of the embodiments of the present invention are as follows: it improves the selectivity of the neutral point effectively grounded distribution network current protection, reliably distinguishing between internal and external faults; it improves the sensitivity of the neutral point effectively grounded distribution network current protection, and can achieve an anti-transition resistance capability of more than 2000 ohms without relying on the acquisition of zero-sequence current; it improves the speed of the neutral point effectively grounded distribution network current protection, with the coverage of the main protection reaching 100%, avoiding long delays caused by the operation of backup protection during faults; and it is not affected by the saturation of the current transformer caused by the large fault current during neutral point effectively grounded distribution network faults.

[0096] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A fast protection method for power distribution networks, characterized in that, include: Step S1: Sequentially label the branches of the radial distribution network to determine the level and number of each feeder branch; Step S2: Construct a start-up criterion using the low-voltage side current of the transformer to determine the time of fault occurrence; Step S3: Select characteristic phases according to different fault types and calculate the amplitude and phase angle of the sudden change current phasor of the corresponding characteristic phases; Step S4: Using the low-voltage side phasor of the main transformer as the reference phasor, calculate the inner product of the phasors obtained from other lines with it, and mark all lines whose inner product is greater than the setting value. Step S5: Locate the line with the highest number among all the marked lines and mark it as the faulty line.

2. The method according to claim 1, characterized in that, Step S1 specifically includes: marking the busbar as L 0. All feeders directly connected to the busbar are primary feeders, and the primary feeders are marked as follows: - All feeders connected to the primary feeder are secondary feeders, and the secondary feeders are marked as follows: - And so on, until the last feeder.

3. The method according to claim 2, characterized in that, Step S2 specifically includes: setting start-up criteria using the SCADA system, detecting sudden changes in mode space voltage and mode space current using the RTU installed at the bus, and determining the fault occurrence time when the following three conditions are simultaneously satisfied: Here, the subscript 0 represents the feeder number, and the e=0 scenario indicates that only the line is used by the RTU to mark the time of the fault. L 0, and all other lines where e≠0 are not included in the fault time calibration; U0(t) and I0(t) are L The mode space voltage and mode space current of the RTU installed at point 0 are calculated as follows: in, , , for L The three-phase voltage measured by the RTU installed at point 0; , , for L The three-phase current measured by the RTU installed at point 0; T is the period.

4. The method according to claim 3, characterized in that, Step S3 specifically includes: processing the abrupt changes in characteristic phase currents of all lines using a small vector algorithm to obtain the amplitude and phase angle of their fundamental frequency components. Among them, subscript e Indicates the line number. e =0,1,2,…, n means that the above formula is used for all lines. When e=0, it means that the current line is a low-voltage side line of the busbar; when e≠0, it means the line with the corresponding number. f The characteristic phase is marked; P is the number of small vectors, P=4; N is the number of sampling points in one power frequency cycle; superscript The fundamental frequency is represented by q; p represents the p-th small vector, p≤P; q represents the number of sampling points in each small vector. α This represents the original phase angle of each small vector.

5. The method according to claim 4, characterized in that, Step S4 specifically includes: selecting the low-voltage side phasor of the main transformer as the reference phasor, normalizing the fundamental frequency estimate of the characteristic phase current mutation of each feeder, calculating the inner product with the reference phasor, and recording all lines whose inner product is greater than the setting threshold; wherein, the low-voltage side phasor of the main transformer is the amplitude and phase obtained in the scenario of e=0, and the fundamental frequency estimate of the characteristic phase current mutation of each feeder is the amplitude and phase obtained in the scenario of e≠0.

6. The method according to claim 5, characterized in that, remember L 1~ L n The results at each location are respectively ~ The following formula is used to obtain L 1~ L n The normalized quantity of the fundamental frequency estimate of the characteristic phase current mutation of the line and L The inner product between the normalized values ​​of the fundamental frequency estimate of the characteristic phase current abrupt change at point 0: in, ~ They are numbered as follows L 0~ L n Normalized result of the fundamental frequency estimate of the characteristic phase current abrupt change at the line. phasor The corresponding phase angle, D e It is the inner product of the normalized quantity of the fundamental frequency estimate of the characteristic phase current mutation of line e and the normalized quantity of the fundamental frequency estimate of the characteristic phase current mutation of line 0, e=1, 2, …, N, e=0 refers to the low-voltage side line of the main transformer.

7. The method according to claim 6, characterized in that, The following formula can be used to determine the set of suspected faulty lines: 。 8. A fast protection device for power distribution networks, characterized in that, include: The branch calibration module is used to sequentially calibrate the branches of a radial distribution network and determine the level and number of each feeder branch. The fault detection start-up module is used to construct a start-up criterion using the low-voltage side current of the transformer and to determine the time of fault occurrence. The fault feature extraction module is used to select characteristic phases according to different fault types and to calculate the amplitude and phase angle of the sudden change current phasor of the corresponding characteristic phase. The inner product comparison module is used to calculate the inner product of the phasors obtained from other lines with the low-voltage side phasor of the main transformer as the reference phasor, and to mark all lines whose inner product is greater than the setting value. The fault location decision module is used to find the line with the highest number among all the marked lines and mark it as the faulty line.

9. A fast protection device for power distribution networks, characterized in that, It includes a processor and a memory, the memory storing machine-executable instructions that can be executed by the processor, the processor executing the machine-executable instructions to implement the distribution network fast protection method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored computer program; wherein, when the computer program is executed, it controls the device on which the computer-readable storage medium is located to perform the fast protection method for the power distribution network as described in any one of claims 1-7.

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