Single-phase grounding fault section location method and system based on zero-sequence characteristic coefficient

Abstract

The present disclosure relates to the technical field of power grid fault location, and proposes a single-phase grounding fault section location method and system based on zero-sequence characteristic coefficients. The method includes: judging whether a fault occurs according to the acquired zero-sequence voltage of the distribution network system and the zero-sequence current data of each node; when a fault occurs, controlling the active arc extinguishing device to inject different currents, obtaining the change of the zero-sequence voltage of the distribution network system and the zero-sequence current of each node relative to the normal operation of the system, and calculating the zero-sequence characteristic coefficient of each node; distinguishing the fault section from the non-fault section according to the zero-sequence characteristic coefficient of each node and its downstream node. The fault section can be located in the active arc extinguishing distribution network, can be adapted to the active arc extinguishing device, further shorten the fault location range, and can eliminate the influence of the three-phase asymmetry of the distribution network on the section location result, and is still applicable in the three-phase asymmetric distribution network.

Description

Technical Field

[0001] The present disclosure relates to the technical field related to power grid fault location, and in particular, to a method and system for locating a single-phase grounding fault section based on a zero-sequence characteristic coefficient. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] The structure of the distribution network is complex, and single-phase grounding faults account for more than 80%, posing a great threat to the safety of electrical equipment and personal safety. When a single-phase grounding fault occurs in the distribution network, since the three-phase line voltage of the system is still symmetrical, it can generally be allowed to continue to operate for 1 to 2 hours. However, when the distribution network is operating with a single-phase grounding fault, the non-fault phase voltage operates at a higher voltage to the ground, which will threaten the line insulation and thus there is a risk of re-fault. The processing of single-phase grounding faults in the distribution network requires safe arc extinguishing of instantaneous faults and rapid isolation of permanent faults to reduce the hazards of single-phase grounding faults in the distribution network. Therefore, in order to reduce the time and danger of the distribution network operating with faults and ensure the reliability of system power supply, it is necessary to select the section where the fault point is as quickly as possible for permanent grounding faults in the distribution network, so as to achieve rapid isolation of the fault section and restore the normal operation of the system.

[0004] Traditional methods generally use methods such as manual test line pulling or special grounding line selection devices to select fault lines, and locate faults by manual line searching, which is time-consuming and labor-intensive and will affect power supply reliability. To this end, scholars have conducted in-depth research on the line selection and location methods of single-phase grounding faults in distribution networks, and proposed a series of single-phase grounding fault line selection and location methods, which are mainly divided into two categories according to different characteristic signals, namely, line selection methods based on transient signals and line selection methods based on steady-state signals.

[0005] Since my country's distribution network is generally a neutral point non-effective grounding system, the neutral point is generally ungrounded or grounded through an arc suppression coil. Therefore, the existing distribution network single-phase grounding fault line selection and location methods generally revolve around these two distribution networks. However, due to the expansion of the distribution network scale and the widespread application of various nonlinear elements, the harmonic components and active components in the single-phase grounding fault current of the distribution network have increased accordingly, and the problem that the arc suppression coil can only compensate for the reactive fundamental component in the fault current has been exposed. Therefore, the active arc suppression method based on power electronic converters has begun to be applied. However, there is currently little research on how to achieve line selection and location of the fault point in the active arc suppression distribution network. Therefore, it is necessary to analyze the fault characteristics of the single-phase grounding fault in the active arc suppression distribution network, and study and propose a single-phase grounding fault line selection and location method and system that can be adapted to the active arc suppression method. Summary of the invention

[0006] In order to solve the above problems, the present disclosure proposes a single-phase grounding fault section positioning method and system based on zero-sequence characteristic coefficient, which can realize single-phase grounding fault line selection and positioning adapted to the active arc extinguishing method. The zero-sequence characteristic coefficient is constructed by active injection current, system zero-sequence voltage and zero-sequence current of each node, and the position relationship of each node relative to the fault point is judged according to the calculated value of the zero-sequence characteristic coefficient, thereby realizing accurate positioning of the section where the single-phase grounding fault point is located in the active arc extinguishing distribution network, and the method is not affected by the asymmetry of the three-phase admittance of the distribution network.

[0007] In order to achieve the above objectives, the present disclosure adopts the following technical solutions:

[0008] One or more embodiments provide a method for locating a single-phase grounding fault section based on a zero-sequence characteristic coefficient, comprising the following steps:

[0009] Determine whether a fault occurs based on the acquired zero-sequence voltage of the distribution network system and zero-sequence current data of each node;

[0010] When a fault occurs, the active arc extinguishing device is controlled to inject different currents to obtain the changes of the zero-sequence voltage of the distribution network system and the zero-sequence current of each node relative to the normal operation of the system, and the zero-sequence characteristic coefficient of each node is calculated;

[0011] According to the zero-sequence characteristic coefficient of each node and its downstream nodes, the fault section and the non-fault section are distinguished.

[0012] One or more embodiments provide a single-phase grounding fault section location system based on a zero-sequence characteristic coefficient, including:

[0013] Fault judgment module: configured to judge whether a fault occurs according to the acquired zero-sequence voltage of the distribution network system and zero-sequence current data of each node;

[0014] Zero-sequence characteristic coefficient determination module: configured to control the active arc extinguishing device to inject different currents when a fault occurs, obtain the change of the zero-sequence voltage of the distribution network system and the zero-sequence current of each node relative to the normal operation of the system, and calculate the zero-sequence characteristic coefficient of each node;

[0015] Fault section determination module: configured to distinguish fault sections from non-fault sections according to the zero-sequence characteristic coefficients of each node and its downstream nodes.

[0016] An electronic device comprises a memory and a processor, and computer instructions stored in the memory and executed on the processor. When the computer instructions are executed by the processor, the steps described in the above method are completed.

[0017] A computer-readable storage medium is used to store computer instructions, and when the computer instructions are executed by a processor, the steps described in the above method are completed.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The fault section locating method disclosed in the present invention can directly select the fault section through the calculated zero-sequence characteristic coefficient, further shortening the fault position locating range; it can adapt to the influence of active arc extinguishing device on the fault characteristics of distribution network, and realize the fault section locating of new active arc extinguishing distribution network; at the same time, this method can eliminate the asymmetric current component caused by the asymmetry of the three-phase to ground admittance parameters of the distribution network, effectively eliminating the influence of the asymmetry of three-phase parameters on the section locating result.

[0020] The advantages of the present disclosure and the advantages of additional aspects will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The exemplary embodiments of the present disclosure and the description thereof are used to explain the present disclosure but do not constitute a limitation of the present disclosure.

[0022] Figure 1 This is a flow chart of a method for locating a single-phase grounding fault section of an active arc-extinguishing distribution network based on a zero-sequence characteristic coefficient in Embodiment 1 of the present disclosure;

[0023] Figure 2 A schematic diagram of a single-phase grounding fault in an active arc suppression distribution network in Embodiment 1 of the present disclosure;

[0024] Figure 3 This is a schematic diagram of a single-phase grounded zero-sequence equivalent circuit of an active arc-extinguishing distribution network in Embodiment 1 of the present disclosure;

[0025] Figure 4 This is the related measured admittance phasor diagram of the N and S nodes when the simulation experiment of Embodiment 1 of the present disclosure is grounded through a 10Ω transition resistor;

[0026] Figure 5 This is the related measured admittance phasor diagram of the N and S nodes when the simulation experiment of Example 1 of the present disclosure is grounded through a 100Ω transition resistor. DETAILED DESCRIPTION

[0027] The present disclosure is further described below in conjunction with the accompanying drawings and embodiments.

[0028] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present disclosure belongs.

[0029] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof. It should be noted that, in the absence of conflict, the various embodiments in the present disclosure and the features in the embodiments can be combined with each other. The embodiments will be described in detail below in conjunction with the accompanying drawings.

[0030] Example 1

[0031] In the technical solutions disclosed in one or more embodiments, Figure 1-Figure 5 As shown, the single-phase grounding fault section location method based on zero-sequence characteristic coefficient includes the following steps:

[0032] Step 1: Determine whether a fault occurs based on the acquired zero-sequence voltage of the distribution network system and the zero-sequence current data of each node;

[0033] Step 2: When a fault occurs, the active arc extinguishing device is controlled to inject different currents to obtain the change of the zero-sequence voltage of the distribution network system and the zero-sequence current of each node relative to the normal operation of the system, and the zero-sequence characteristic coefficient of each node is calculated;

[0034] Step 3: Distinguish the fault section from the non-fault section according to the zero-sequence characteristic coefficient of each node and its downstream node.

[0035] Compared with the traditional distribution network single-phase grounding fault line selection method, the method of this embodiment can directly select the fault section through the calculated zero-sequence characteristic coefficient, further shortening the fault location positioning range; it can adapt to the influence of active arc extinguishing devices on the fault characteristics of the distribution network, and realize the fault section positioning of the new active arc extinguishing distribution network; at the same time, this method can eliminate the asymmetric current component caused by the asymmetry of the three-phase to ground admittance parameters of the distribution network, effectively eliminating the influence of the asymmetry of the three-phase parameters on the section positioning results.

[0036] In step 1, the method for determining whether a fault occurs is to first determine whether a single-phase grounding fault occurs, and then determine whether the single-phase fault is a transient fault or a permanent fault.

[0037] Optionally, the method for judging a single-phase grounding fault is:

[0038] Step 11: When the distribution network is operating normally, measure the system zero-sequence voltage in real time And the zero-sequence current of each node The data is collected and saved, and whether a single-phase grounding fault occurs in the system is determined based on the system zero-sequence voltage.

[0039] Furthermore, when a single-phase grounding fault occurs in the distribution network system, an active arc extinguishing device is put into operation to inject current into the distribution network or control the system zero-sequence voltage to extinguish the arc.

[0040] The method for determining whether it is a transient fault or a permanent fault includes the following steps:

[0041] Step 12: If it is determined that a single-phase grounding fault occurs in the distribution network system, the active arc extinguishing device is put into use to extinguish the arc, and the phasor values ​​of the active injection current, the zero-sequence voltage and the zero-sequence current of each node are measured, and the change of the zero-sequence voltage and the change of the zero-sequence current of each node relative to normal operation are calculated and saved;

[0042] Specifically, it is determined that a single-phase grounding fault occurs in the distribution network system, and the active arc extinguishing device is put into use to extinguish the arc. At this time, the active injection current is measured. Zero sequence voltage And the zero-sequence current of each node The phasor value of the zero-sequence voltage is calculated relative to the normal operation as follows: The change of zero-sequence current at each node is

[0043] by Figure 2 Take the active arc suppression distribution network shown in the figure as an example, where a phase A ground fault occurs. There are n feeders in the distribution network. Assume that the fault point is located on feeder L n In the section NS.

[0044] When the distribution network operates normally, the feeder L1~L n-1 Nodes in (such as Figure 2 Nodes P, Q in the fault point) and downstream nodes (such as Figure 2 The node S in the figure is node i. At this time, the zero-sequence current caused by the asymmetry of the three-phase admittance of the distribution network can be obtained at this type of node:

[0045]

[0046] in, is the three-phase power supply voltage, It is the zero-sequence voltage caused by load or parameter asymmetry during normal system operation (if the system is completely symmetrical, its value is zero). is the zero-sequence current at node i when the system is operating normally, Y ai , Y bi , Y ci is the three-phase ground admittance of the line from node i to the end of the feeder, Y i =Y ai +Y bi +Y ci and They are respectively the zero-sequence admittance of the line from node i to the end of the feeder and the inherent asymmetric component of the zero-sequence current at node i.

[0047] Therefore, according to Kirchhoff's current law, for the node j upstream of the fault point (such as Figure 2 When the system is operating normally, the zero-sequence current flowing through this type of node is:

[0048]

[0049] When the active arc suppression device injects current When the non-fault feeder L1~L n-1 The derivation of the zero-sequence current expression at the node on the fault point and the node downstream of the fault point of the fault feeder is the same as that when the system is operating normally, which is:

[0050]

[0051] in, and Active injection current The zero-sequence voltage of the system and the zero-sequence current at node i, and the inherent asymmetric component of the zero-sequence current at node i are the same as those when the system is operating normally.

[0052] Therefore, according to Kirchhoff's current law, the active injection current is When , the zero-sequence current at the node j upstream of the fault point is:

[0053]

[0054] Among them, Y L is the admittance of the arc suppression coil, and node k represents the feeder line L k Therefore, each node is used to inject current into the active The difference between the zero-sequence current when the system is operating normally and the zero-sequence current when the system is operating normally can be obtained by sorting out the relationship between the change in zero-sequence current and the change in zero-sequence voltage as follows:

[0055]

[0056]

[0057] Step 13, after controlling the active arc extinguishing device to be put into operation for the set first time length, continuously change the reference voltage of the active arc extinguishing device according to the set number of times, and maintain the set second time length each time. If the measured system zero-sequence voltage and the change of the injected current of the active arc extinguishing device are linearly related, it is determined to be a transient fault. Otherwise, it is considered that the fault still exists and the fault is determined to be a permanent fault.

[0058] Specifically, in this embodiment, the first time length can be set to 10 seconds or more, the number of times the reference voltage is changed can be set to 3 times, and the second time length maintained at each reference voltage can be set to 40 milliseconds.

[0059] After the active arc extinguishing device is put into operation for 10 seconds, the reference voltage of the active arc extinguishing device is changed three times in succession, each time lasting 40ms. If the measured system zero-sequence voltage is linearly related to the change of the injected current of the active arc extinguishing device, it is determined to be a transient fault. Otherwise, it is considered that the fault still exists and is determined to be a permanent fault.

[0060] by Figure 3 The single-phase grounding zero-sequence equivalent circuit of the active arc suppression distribution network is used as an example to illustrate that when a single-phase grounding fault occurs in the distribution network and active arc suppression is performed, if the fault point has not disappeared, the fault point can be equivalent to a zero-sequence voltage source.

[0061] For transient faults, the fault disappears after 10s of arc extinguishing. There is only one power source, the active arc extinguishing device, in the system zero-sequence equivalent circuit. Therefore, according to the homogeneity theorem, the system zero-sequence voltage is linearly related to the active injection current. For permanent faults, the fault point still exists after 10s of arc extinguishing. There is a voltage source (fault point) and a current source (active arc extinguishing device) in the system zero-sequence equivalent circuit. The system zero-sequence voltage is not linearly related to the active injection current. This can be used to determine whether the fault in the system is a permanent fault. If it is a permanent fault, the fault point needs to be segmented.

[0062] In step 2, when the distribution network system is in a permanent fault, the active injection current, zero-sequence voltage and the phasor value of the zero-sequence current of each node are measured at this time, and the change of the zero-sequence voltage and the change of the zero-sequence current of each node relative to normal operation are calculated and saved;

[0063] Specifically, when the system is in permanent fault, the active injection current is measured The zero sequence voltage is And the zero-sequence current of each node The phasor value of the zero-sequence voltage is calculated relative to the normal operation as follows:

[0064]

[0065] The change of zero-sequence current at each node is:

[0066]

[0067] With the injected current The calculation process is similar to that of When the system is operating normally, the relationship between the change in zero-sequence current and the change in zero-sequence voltage at each node is:

[0068]

[0069]

[0070] The calculation method of the zero-sequence characteristic coefficient of each node is as follows: control the active arc extinguishing device to inject currents of different magnitudes twice, calculate the zero-sequence voltage change and the zero-sequence current change of each node relative to normal operation twice, and the calculation method of the zero-sequence characteristic coefficient ε is as follows: when different currents are injected twice, the first difference of the ratio of the change of the zero-sequence current of each node relative to the normal operation state of the system to the change of the zero-sequence voltage relative to the normal operation state of the system The second difference between the ratio of the injected current and the zero-sequence voltage change relative to the normal operation of the system when different currents are injected twice The zero-sequence characteristic coefficient ε is the ratio of the first difference to the second difference.

[0071] The calculation formula of zero-sequence characteristic coefficient ε is as follows:

[0072]

[0073] in, and is the injection current twice. and is the change in zero-sequence voltage relative to the normal operation of the system when different currents are injected. and It is the change in zero-sequence current of each node relative to the normal operation of the system when different currents are injected, so as to determine the positional relationship between each node and the fault point.

[0074] For example, the zero-sequence characteristic coefficients at points i and j are:

[0075]

[0076]

[0077] According to the zero-sequence characteristic coefficient of each node and its downstream node, the method of distinguishing the fault section from the non-fault section is as follows:

[0078] Step 31, when the calculation result of the node zero-sequence characteristic coefficient is 0, it indicates that the node is a non-fault feeder node or a node downstream of the fault point; when the calculation result of the node zero-sequence characteristic coefficient is 1, it indicates that the node is an upstream node of the fault feeder fault point;

[0079] That is: when ε=0, it is determined to be a non-fault feeder node or a node downstream of the fault point; when ε=1, it is determined to be an upstream node of the fault point.

[0080] Step 32, obtain the calculated value of the zero-sequence characteristic coefficient of each node and its downstream node. When the zero-sequence characteristic coefficient of the node itself is 1 and the zero-sequence characteristic coefficient of its downstream node is 0, the node is determined to be the head-end node of the faulty section. For the end section of the line, if the zero-sequence characteristic coefficient of its head-end node is 1, the section can be determined to be a faulty section.

[0081] According to the calculation results of the zero-sequence characteristic coefficients of the head and end nodes of the section, the fault section and the non-fault section are distinguished, specifically including: when the head node ε=1 and the end node ε=0 of the section, it is determined to be a fault section, and in other cases it is determined to be a non-fault section.

[0082] Through the above steps, the section where the single-phase grounding fault point is located can be selected to isolate the fault point.

[0083] In this embodiment, by subtracting the zero-sequence current of each node when different currents are injected from the zero-sequence current of the system during normal operation, the asymmetric component in the current can be eliminated, thereby eliminating the influence of the asymmetric three-phase admittance of the distribution network on the section positioning result.

[0084] In order to illustrate the effect of this embodiment, a simulation is performed to verify the single-phase grounding fault section locating method of this embodiment.

[0085] 1) Build the model

[0086] The simulation model can be Figure 2 As shown in the figure, the system voltage level in the simulation model is 10kV, and there are 5 feeders L1~L5 in the distribution network, of which L1 and L2 are overhead lines with lengths of 9km and 7km respectively, L3 is a cable-overhead line mixed line, and the cable and overhead line lengths are 5km and 4km respectively, L4 and L5 are cables with lengths of 7km and 10km respectively, the load size of each line is 2MVA, the power factor is 0.9, and the cable line parameters are set as follows: positive sequence resistance is 0.270Ω / km, positive sequence inductance is 0.255mH / km, positive sequence capacitance is 0.339uF / km, zero sequence resistance is 2.700Ω / km, zero sequence inductance is 1.019mH / km, zero sequence capacitance is 0.280uF / km; overhead line parameters are: positive sequence resistance is 0.125Ω / km, positive sequence inductance is 1.300mH / km, positive sequence capacitance is 0.010uF / km, zero sequence resistance is 0.275Ω / km, zero sequence inductance is 4.600mH / km, zero sequence capacitance is 0.005uF / km, and the distribution network damping rate is 0.08. Figure 2 The feeder L5 is set to three sections: MN, NS, and SL, with lengths of 3 km, 3 km, and 4 km respectively. The head node of the feeder L1 is the node P. A phase grounding fault is set to occur in the section NS, and the transition resistance is 10Ω, 100Ω, and 1000Ω.

[0087] When a single-phase grounding fault occurs in the distribution network, the active arc extinguishing device is put into operation to control the zero-sequence voltage of the system Arc extinguishing is performed, and the active injection current with transition resistance of 10Ω, 100Ω, and 1000Ω is measured. They are 44.65∠-116.27°A, 47.49∠-98.75°A, and 48.23∠-96.07°A respectively; 10s after the fault occurs, the reference voltage of the active arc extinguishing device is changed to At this time, the active injection current when the transition resistance is 10Ω, 100Ω, and 1000Ω is measured. They are 49.39∠-52.90°A, 42.18∠-88.75°A, and 43.05∠-95.07°A respectively. In addition, the injected current and The simulation results of zero-sequence voltage and current changes when the transition resistance is different are shown in Table 1, from which the relevant measured admittance at each node when the single-phase grounding is carried out through different transition resistances can be obtained. The phasor value of point N and point S is as follows: Figure 4 and Figure 5 shown.

[0088] Table 1 Simulation results of three-phase symmetrical distribution network

[0089]

[0090] It can be seen that when a single-phase grounding fault occurs in section NS, the zero-sequence characteristic coefficients at the upstream nodes M and N of the fault point in the fault feeder L5 are close to 1, while the zero-sequence characteristic coefficients at the downstream node S of the fault point and the node P of the non-fault feeder are close to 0. Among them, in section NS, the zero-sequence characteristic coefficients of the first and end nodes of the section are 1 and 0 respectively. It is judged to be a fault section, and the other sections are non-fault sections, which is the same as the actual situation and the judgment is correct.

[0091] In order to verify the impact of three-phase asymmetry of the distribution network on the positioning results, capacitors of 1.4μF, 1.6μF, and 1.2μF are added to the A, B, and C phases of the distribution network feeder to simulate an asymmetric distribution network. At this time, the asymmetry of the distribution network is 1.5%, and the fault point is also set in section NS. At this time, the active injection current when the transition resistance is 10Ω, 100Ω, and 1000Ω is measured. They are 53.46∠-111.99°A, 58.01∠-97.61°A, and 58.96∠-95.44°A respectively; the reference voltage is The injected current under the conditions of 10Ω, 100Ω, and 1000Ω transition resistance They are 49.39∠-52.90°A, 42.18∠-88.75°A, and 43.05∠-95.07°A respectively. The simulation results of the system zero-sequence voltage and the change of zero-sequence current of each node when different currents are injected are shown in Table 2.

[0092] Table 2 Simulation results of three-phase asymmetric distribution network

[0093]

[0094] It can be seen that the simulation results obtained when the three-phase admittance of the distribution network is asymmetric are not much different from those when the three-phase admittance of the distribution network is symmetric. Therefore, the asymmetry of the three-phase admittance of the distribution network does not affect the accuracy of the section positioning method. This method has a strong adaptability to the asymmetry of the three-phase distribution network.

[0095] This embodiment uses the active arc extinguishing device to inject different currents, and calculates the zero-sequence characteristic coefficient of each node based on the change in the system zero-sequence voltage and the zero-sequence current of each node relative to the normal operation of the system. Based on the calculation results of the zero-sequence characteristic coefficient of each node and its downstream nodes, the fault section and the non-fault section are distinguished.

[0096] According to the simulation results, in a distribution network using an active arc extinguishing device for arc extinguishing, regardless of whether the three-phase to ground admittance of the system is symmetrical, this embodiment can correctly select the fault section and has a strong tolerance to transition resistance.

[0097] Example 2

[0098] Based on Embodiment 1, this embodiment provides a single-phase grounding fault section locating system based on zero-sequence characteristic coefficient, including:

[0099] Fault judgment module: configured to judge whether a fault occurs based on the acquired zero-sequence voltage of the distribution network system and zero-sequence current data of each node;

[0100] Zero-sequence characteristic coefficient determination module: configured to control the active arc extinguishing device to inject different currents when a fault occurs, obtain the change of the zero-sequence voltage of the distribution network system and the zero-sequence current of each node relative to the normal operation of the system, and calculate the zero-sequence characteristic coefficient of each node;

[0101] Fault section determination module: configured to distinguish fault sections from non-fault sections according to the zero-sequence characteristic coefficients of each node and its downstream nodes.

[0102] It should be noted here that the various modules in this embodiment correspond one-to-one to the various steps in Example 1, and the specific implementation process is the same, which will not be repeated here.

[0103] Example 3

[0104] This embodiment provides an electronic device, including a memory and a processor, and computer instructions stored in the memory and running on the processor. When the computer instructions are run by the processor, the steps described in the method of Embodiment 1 are completed.

[0105] Example 4

[0106] This embodiment provides a computer-readable storage medium for storing computer instructions. When the computer instructions are executed by a processor, the steps described in the method of Embodiment 1 are completed.

[0107] The electronic devices proposed in the present disclosure can be mobile terminals and non-mobile terminals. Non-mobile terminals include desktop computers, and mobile terminals include smart phones (such as Android phones, IOS phones, etc.), smart glasses, smart watches, smart bracelets, tablet computers, laptops, personal digital assistants, and other mobile Internet devices that can communicate wirelessly.

[0108] It should be understood that in the present disclosure, the processor may be a central processing unit CPU, and the processor may also be other general-purpose processors, digital signal processors DSP, application-specific integrated circuits ASIC, off-the-shelf programmable gate arrays FPGA or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0109] The memory may include a read-only memory and a random access memory, and provide instructions and data to the processor, and a portion of the memory may also include a non-volatile random access memory. For example, the memory may also store information about the device type.

[0110] In the implementation process, each step of the above method can be completed by an integrated logic circuit of hardware in a processor or an instruction in the form of software. The steps of the method disclosed in the present disclosure can be directly embodied as being executed by a hardware processor, or being executed by a combination of hardware and software modules in a processor. The software module can be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. The storage medium is located in a memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware. To avoid repetition, it is not described in detail here. A person of ordinary skill in the art can appreciate that the units of each example described in combination with the embodiments disclosed herein, i.e., the algorithm steps, can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present disclosure.

[0111] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0112] In the several embodiments provided in the present disclosure, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a division of logical functions. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0113] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present disclosure, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present disclosure. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0114] The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

[0115] Although the above describes the specific implementation methods of the present disclosure in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present disclosure. Technical personnel in the relevant field should understand that on the basis of the technical solution of the present disclosure, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present disclosure.

Claims

1. A single-phase grounding fault section location method based on zero-sequence characteristic coefficient is characterized by: The steps include: Determine whether a fault occurs based on the acquired zero-sequence voltage of the distribution network system and zero-sequence current data of each node; When a fault occurs, the active arc extinguishing device is controlled to inject different currents to obtain the changes of the zero-sequence voltage of the distribution network system and the zero-sequence current of each node relative to the normal operation of the system, and the zero-sequence characteristic coefficient of each node is calculated; Distinguish the fault section from the non-fault section according to the zero-sequence characteristic coefficient of each node and its downstream node; The calculation method of the zero-sequence characteristic coefficient of each node is: control the active arc extinguishing device to inject currents of different magnitudes twice, calculate the zero-sequence voltage change relative to normal operation and the zero-sequence current change of each node twice, and the calculation method of the zero-sequence characteristic coefficient is: inject different currents twice, and the difference of the ratio of the change of the zero-sequence current of each node relative to the normal operation state of the system to the change of the zero-sequence voltage relative to the normal operation state of the system is taken as the first difference; Different currents are injected twice, and the difference between the ratio of the injected current and the zero-sequence voltage change relative to the normal operation of the system is taken as the second difference. The zero-sequence characteristic coefficient is the ratio of the first difference to the second difference.

2. The single-phase grounding fault section location method based on zero-sequence characteristic coefficient according to claim 1 is characterized in that: The method for determining whether a fault occurs is to first determine whether a single-phase grounding fault occurs, and then determine whether the single-phase fault is a transient fault or a permanent fault.

3. The single-phase grounding fault section location method based on zero-sequence characteristic coefficient according to claim 2 is characterized in that: The method to distinguish between transient faults and permanent faults is: If it is determined that a single-phase grounding fault occurs in the distribution network system, the active arc extinguishing device is put into use to extinguish the arc, and the phasor values ​​of the active injection current, zero-sequence voltage and zero-sequence current of each node are measured, and the change in zero-sequence voltage and the change in zero-sequence current of each node relative to normal operation are calculated; After the active arc extinguishing device is controlled to be put into operation for the set first time period, the reference voltage of the active arc extinguishing device is continuously changed according to the set number of times, and the set second time period is maintained each time. If the measured system zero-sequence voltage and the change of the injected current of the active arc extinguishing device are linearly related, it is determined to be a transient fault. Otherwise, it is considered that the fault still exists and the fault is determined to be a permanent fault.

4. The method for locating a single-phase grounding fault section based on a zero-sequence characteristic coefficient according to claim 3, characterized in that: The first time length is set to be no less than 10 seconds, the number of times the reference voltage is changed is set to 3 times, and the second time length maintained at each reference voltage is set to 40 milliseconds.

5. The method for locating a single-phase grounding fault section based on a zero-sequence characteristic coefficient according to claim 2, characterized in that: When a single-phase grounding fault occurs in the distribution network system, an active arc extinguishing device is used to inject current into the distribution network or control the system zero-sequence voltage to extinguish the arc.

6. The method for locating a single-phase grounding fault section based on a zero-sequence characteristic coefficient according to claim 1, characterized in that: According to the zero-sequence characteristic coefficient of each node and its downstream node, the method of distinguishing the fault section from the non-fault section is as follows: When the calculation result of the node zero-sequence characteristic coefficient is 0, it means that the node is a non-fault feeder node or a node downstream of the fault point; when the calculation result of the node zero-sequence characteristic coefficient is 1, it means that the node is an upstream node of the fault feeder fault point; Obtain the calculated value of the zero-sequence characteristic coefficient of each node and its downstream node. When the zero-sequence characteristic coefficient of the node itself is 1 and the zero-sequence characteristic coefficient of its downstream node is 0, the node is determined to be the head node of the faulty section. For the end section of the line, if the zero-sequence characteristic coefficient of its head node is 1, the section can be determined to be a faulty section.

7. A single-phase grounding fault section location system based on zero-sequence characteristic coefficient, characterized in that: include: Fault judgment module: configured to judge whether a fault occurs according to the acquired zero-sequence voltage of the distribution network system and zero-sequence current data of each node; Zero-sequence characteristic coefficient determination module: configured to control the active arc extinguishing device to inject different currents when a fault occurs, obtain the change of the zero-sequence voltage of the distribution network system and the zero-sequence current of each node relative to the normal operation of the system, and calculate the zero-sequence characteristic coefficient of each node; Fault section determination module: configured to distinguish the fault section from the non-fault section according to the zero-sequence characteristic coefficient of each node and its downstream node; The calculation method of the zero-sequence characteristic coefficient of each node is: control the active arc extinguishing device to inject currents of different magnitudes twice, calculate the zero-sequence voltage change relative to normal operation and the zero-sequence current change of each node twice, and the calculation method of the zero-sequence characteristic coefficient is: inject different currents twice, and the difference of the ratio of the change of the zero-sequence current of each node relative to the normal operation state of the system to the change of the zero-sequence voltage relative to the normal operation state of the system is taken as the first difference; Different currents are injected twice, and the difference between the ratio of the injected current and the zero-sequence voltage change relative to the normal operation of the system is taken as the second difference. The zero-sequence characteristic coefficient is the ratio of the first difference to the second difference.

8. An electronic device, characterized in that: The method comprises a memory and a processor and computer instructions stored in the memory and executed on the processor, wherein when the computer instructions are executed by the processor, the steps described in any one of the methods of claims 1 to 6 are completed.

9. A computer-readable storage medium, characterized in that: Used to store computer instructions, which, when executed by a processor, complete the steps described in any one of claims 1 to 6.

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