Distributed route selection and positioning method and system

Abstract

The application provides a distributed line selection and positioning method, which synchronously and high-speed collects zero sequence voltage, zero sequence current and / or three-phase current on each power supply section, carries out zero sequence transient energy method and / or three-phase current transient correlation method analysis, determines a grounding line and positions a grounding fault section; each power supply section on the grounding line is differentially delayed and tripped by a power receiving end phase power supply end, when the fault section is tripped and the fault disappears, all power supply sections before the fault section stop timing, after the fault section isolation time reaches, the power supply of the fault section is restored through reclosing, if the fault is a transient fault, the power supply of the line on the fault section can be restored; if the fault is a permanent fault, the fault section is removed again through post-acceleration, and the permanent isolation of the fault is realized. The application realizes accurate positioning and reliable isolation of a single-phase grounding fault section, guarantees the reliability and safety of power supply, and improves the stability of power distribution network operation.

Description

Technical Field

[0001] This invention relates to the field of power line fault detection technology, specifically to a distributed fault selection and location method and system. Background Technology

[0002] In my country's 6-66kV power grid, the neutral point is generally ungrounded or grounded via an arc suppression coil; these two methods are collectively referred to as low-current grounding systems. In low-current grounding systems, single-phase grounding faults are among the most common faults in the power grid, accounting for over 80% of all faults.

[0003] The existence of a single-phase ground fault can have many adverse effects on the operation of the entire power grid:

[0004] After a single-phase grounding fault occurs, the phase-to-ground voltage of the two non-faulty phases will rise to √3 times the normal value. This may cause the weakest link in the insulation of the entire network to break down, causing the grounding fault to develop into a phase-to-phase short circuit, resulting in the expansion of the accident, affecting the normal power supply of users, and reducing the reliability of power supply.

[0005] If intermittent arcing grounding occurs, it can also cause resonant overvoltage in the entire power grid, which can damage power supply equipment and disrupt the safe operation of the system.

[0006] For people around a single-phase grounding fault, it can cause step voltage electric shock, resulting in personal injury or death.

[0007] When a single-phase ground fault occurs, a large amount of electrical energy is lost because the grounded phase discharges directly or indirectly to the ground.

[0008] Therefore, when a single-phase ground fault occurs, the faulty line must be located in a timely manner and disconnected as soon as possible to prevent the single-phase ground fault from spreading further and to ensure the safety of equipment and personnel.

[0009] Conventional fault location devices, installed inside substations, can monitor the entire length of power supply lines. A ground fault at any point on the line can be detected by the device. However, because they only monitor the main outgoing line, they can only indicate or disconnect the entire faulty line, but cannot pinpoint or isolate the specific faulty section. This negatively impacts the safe and reliable operation of the distribution network.

[0010] The inability to accurately locate the faulty section increases the difficulty and workload of line inspection work to find the fault point. Often, the result is that the fault point cannot be found, and the fault continues to exist, causing the accident to escalate.

[0011] If the faulty section cannot be accurately isolated, the entire line can only be disconnected, resulting in an expanded power outage area and reduced power supply reliability; or if the fault is not isolated, the fault will persist, causing the accident to escalate and reducing power supply safety.

[0012] The inability to quickly locate and isolate faults, even when fault points are found through line inspections and isolation is possible, often results in prolonged fault persistence or incorrect fault isolation due to untimely or inaccurate location and isolation processes. This reduces the stability and reliability of the distribution network operation.

[0013] Therefore, when a single-phase ground fault occurs, it is of great practical significance to accurately locate and reliably isolate the faulty section as soon as possible to ensure the safe and reliable operation of the distribution network and to improve the operation level of the distribution network.

[0014] To address the aforementioned problems, a distributed fault location technology has been proposed in this field. This technology enables rapid and accurate location of faulty sections and subsequent reliable and timely isolation. However, existing distributed fault location technologies typically suffer from the following technical drawbacks:

[0015] Existing distributed line selection methods mostly adopt the directional zero-sequence overcurrent method commonly used in relay protection. This method is based on low-frequency steady-state signals. First, when there is an arc suppression coil in the power grid, the current direction changes due to the compensation of the arc suppression coil, causing the algorithm to fail and incorrectly identify the grounding line. Second, it uses an absolute current action value, which often fails to initiate grounding detection due to insufficient current in high-resistance grounding.

[0016] In addition, there is a distributed line selection and positioning method that does not collect zero-sequence current but instead uses three-phase current and then synthesizes zero-sequence current by software. This method is difficult to guarantee the timing synchronization of the three independent three-phase current acquisition modules, resulting in poor accuracy of the synthesized zero-sequence current acquisition and affecting the accuracy of line selection.

[0017] Meanwhile, most existing distributed fault selection devices are only used as alarm devices and cannot isolate faulty areas, let alone achieve self-recovery from transient faults or permanent isolation from permanent faults. Summary of the Invention

[0018] To address the aforementioned shortcomings in the prior art, this invention provides a distributed route selection and positioning method and system.

[0019] According to one aspect of the present invention, a distributed route selection and positioning method is provided, comprising:

[0020] Each power supply line is divided into multiple power supply sections from the power supply end to the power receiving end. The zero-sequence voltage, zero-sequence current and / or three-phase current on each power supply section are collected synchronously at high speed. The zero-sequence transient energy method and / or three-phase current transient correlation method are used for analysis to determine the grounding line and locate the grounding fault section.

[0021] The zero-sequence transient energy method integrates the zero-sequence voltage and zero-sequence current of all power supply sections of all power supply lines, and performs digital filtering of the integration result in the transient frequency band to filter out the transient energy signal that characterizes the fault characteristics when a ground fault occurs, thereby determining the grounding line; after determining the grounding line, the zero-sequence transient energy method is applied to the grounding line to find the grounding transient energy section closest to the power receiving end, which is the ground fault section;

[0022] The three-phase current transient correlation method is used to determine the transient correlation of the three-phase currents of each line. When the three-phase currents of a certain line are strongly uncorrelated in the transient frequency band, the line with strong transient uncorrelatedness is determined to be a grounding line. The three-phase current transient correlation method is then used on the grounding line to find the section with strong transient uncorrelatedness closest to the power receiving end, which is the grounding fault section.

[0023] Differential time-delay tripping is performed on each power supply section of the grounding line from the power receiving end to the power supply end. When a certain power supply section trips, the grounding fault disappears, thus isolating the grounding fault section. At the same time, all normal sections before the fault section stop timing to ensure the power supply operation of the normal sections.

[0024] For ground fault sections, perform self-recovery of transient faults and permanent isolation of permanent faults.

[0025] Preferably, the zero-sequence transient energy method integrates the zero-sequence voltage and zero-sequence current of all power supply sections of all power supply lines, and performs digital filtering of the integration result in the transient frequency band to filter out the transient energy signal characterizing the fault features when a ground fault occurs, thereby determining the grounding line; after determining the grounding line, the zero-sequence transient energy method is applied again on the grounding line to find the grounding transient energy section closest to the receiving end, which is the ground fault section; including:

[0026] The integral operation is as follows:

[0027]

[0028] in, It is the zero-sequence voltage. S0 represents the zero-sequence current, and S0 is the integral result of the zero-sequence voltage and zero-sequence current; the digital filtering operation for the transient frequency band is as follows:

[0029]

[0030] The transient characteristic frequency band range is f1 to f2, where f1 and f2 are determined by the pair. The maximum amplitude signal frequency obtained from the FFT analysis is the center frequency, which is then spread. S0 is the result of the integration of zero-sequence voltage and zero-sequence current, and S is the grounding characteristic transient energy after digital filtering within the transient characteristic frequency band. When S<0, it indicates grounding; when S>0, it indicates normal operation.

[0031] On a normal line, the zero-sequence transient energy of the grounding characteristic is positive in all power supply sections; while on a grounded line, there are power supply sections with negative zero-sequence transient energy of the grounding characteristic. Therefore, the grounding characteristic transient energy can be used to distinguish between normal lines and grounded lines, thus enabling grounded line identification.

[0032] On the identified grounding line, the grounding characteristic zero-sequence transient energy obtained by all power supply sections before the grounding fault point is negative, and the grounding characteristic zero-sequence transient energy obtained by all power supply sections after the grounding fault point is positive. Therefore, the last power supply section on the grounding line with negative grounding characteristic zero-sequence transient energy is the grounding fault section, thus realizing the location of the grounding section.

[0033] Preferably, the three-phase current transient correlation method determines the transient correlation of the three-phase currents of each line. When the three-phase currents of a certain line are strongly uncorrelated in the transient frequency band, the line with strong transient uncorrelatedity is determined to be a grounding line. The three-phase current transient correlation method is then applied to the grounding line to find the section with strong transient uncorrelatedity closest to the receiving end, which is the grounding fault section. Wherein:

[0034] The digital filtering operation for the transient frequency band is as follows:

[0035]

[0036] Among them, I′ ak I b ′ k I c ′ k The original sampled values ​​of the three-phase current of each line, I ak I bk I ck The transient signal is filtered; the transient characteristic frequency band range is f1~f2, which is obtained by taking the maximum amplitude signal frequency as the center frequency from the FFT analysis of the zero-sequence voltage U0 of the bus and spreading it.

[0037] The Pearson correlation coefficient is calculated as follows:

[0038]

[0039] Among them: I ak Ibk I ck The transient data sequence of the three-phase current of each line, r ab r bc r ca These are the correlation coefficients between the three-phase currents in phases AB, BC, and CA, respectively.

[0040] When the three correlation coefficients r of the three-phase current of a certain line ab r bc r ca Two of them are strongly positively uncorrelated, meaning the correlation coefficient is 0. <r p If the value is less than 0.2, then the line is a grounded line; other lines that do not meet the strong positive correlation requirement are ungrounded lines.

[0041] On a grounding line, the power supply section before the grounding fault point has three correlation coefficients that satisfy the grounding characteristics, that is, two of them are strongly positive and uncorrelated; while the power supply section after the grounding fault point does not satisfy the characteristic that two of the three correlation coefficients are strongly positive and uncorrelated. Therefore, the last section of the power supply section of the grounding line that satisfies the grounding characteristics is the grounding fault section.

[0042] Preferably, the high-speed acquisition is performed using a sampling rate of not less than 12K / S, which is used to retain complete transient frequency band information of the zero-sequence voltage, zero-sequence current, and three-phase current signals when applying the zero-sequence transient energy method and / or the three-phase current transient correlation method; the synchronous high-speed acquisition is performed to simultaneously acquire the zero-sequence voltage, zero-sequence current, and / or three-phase current at the 10-microsecond level, which is used to ensure that the zero-sequence voltage, zero-sequence current, and three-phase current signals retain consistent transient frequency band information when applying the zero-sequence transient energy method and / or the three-phase current transient correlation method.

[0043] Preferably, the differential time-delay tripping method, which performs differential time-delay tripping from the power receiving end to the power supply end for each power supply section on the grounding line to achieve fault section isolation, includes:

[0044] On the same power supply line, the tripping delay is set in progressively decreasing order from the first segment to the last segment. After a ground fault occurs, the faulty segment on the grounded line and all the normal power supply segments preceding it start tripping timers simultaneously. The faulty segment with the shortest tripping time among these segments trips first. When the ground fault disappears after the faulty segment trips, the tripping timers for the normal segments preceding the faulty segment stop, thus isolating the ground faulty segment and ensuring continuous power supply to the normal segments. No tripping timers are set for the normal segments on the normal line and the normal segments following the faulty segment on the grounded line.

[0045] Preferably, a voltage-detection method is used for the self-recovery of transient faults in the ground fault section, and a post-acceleration method is used for the permanent isolation of permanent faults in the ground fault section; including:

[0046] When the automatic isolation time of the ground fault section expires, if it is detected that there is power at the upstream power supply terminal of this section, it indicates that the power grid is normal, and this section will automatically close the circuit to realize the automatic restoration of power supply to the section.

[0047] If the ground fault does not recur after power is restored, it indicates that the ground fault was transient and normal power supply can be restored after the circuit breaker is closed.

[0048] If the ground fault recurs after power is restored, it indicates that the ground fault is permanent. In this case, the ground fault section will be immediately disconnected again with a post-acceleration method and a 0-second delay, and the circuit will not be automatically closed again to achieve permanent isolation of the ground fault section and ensure the normal power supply of other normal parts of the power grid.

[0049] Preferably, the method further includes any one or more of the following:

[0050] - The ground fault analysis results of the faulty section are sent to the upper-level terminal for corresponding processing of the ground fault;

[0051] - Based on the ground fault analysis results of the faulty section, output the corresponding alarm information.

[0052] According to another aspect of the present invention, a distributed line selection and positioning system is provided, comprising: a plurality of distributed line selection modules, wherein each of the plurality of distributed line selection modules divides each power supply line into a plurality of power supply sections; wherein:

[0053] Each of the distributed route selection modules includes:

[0054] The voltage and current acquisition unit divides each power supply line from the power supply end to the power receiving end into multiple power supply sections, and synchronously and at high speed acquires the zero-sequence voltage, zero-sequence current and / or three-phase current on each power supply section.

[0055] The fault section location unit uses the zero-sequence transient energy method and / or the three-phase current transient correlation method to analyze the zero-sequence voltage, zero-sequence current, and / or three-phase current to determine the grounding line and locate the grounding fault section. Specifically, the zero-sequence transient energy method integrates the zero-sequence voltage and zero-sequence current of all power supply sections of all power supply lines, and performs digital filtering of the integration result in the transient frequency band to filter out the zero-sequence transient energy signal that characterizes the fault characteristics when the grounding fault occurs, thereby determining the grounding line. After identifying the grounding line, the zero-sequence transient energy method is applied to the grounding line to find the grounding transient energy section closest to the power receiving end, which is the grounding fault section. The three-phase current transient correlation method is used to determine the transient correlation of the three-phase currents of each line. When the three-phase currents of a certain line are strongly uncorrelated in the transient frequency band, the line with strong transient uncorrelatedness is identified as the grounding line. After identifying the grounding line, the three-phase current transient correlation method is applied to the grounding line to find the strongly uncorrelated transient section closest to the power receiving end, which is the grounding fault section.

[0056] The switch control unit performs differential delay tripping on each power supply section of the grounding line from the receiving end to the supply end. When a power supply section trips, the grounding fault disappears, thus isolating the grounding fault section. At the same time, all normal sections before the fault section stop timing to ensure the power supply operation of the normal sections. It also performs self-recovery of instantaneous faults and permanent isolation of permanent faults in the grounding fault section.

[0057] Preferably, the system further includes any one or more of the following:

[0058] - Real-time status monitoring unit, which is used to monitor the grounding fault analysis results of the fault section and the power supply switch status of the fault section in real time;

[0059] - Bluetooth unit, which is used to implement Bluetooth wireless function, including: local wireless data monitoring function, debugging and operation function and module upgrade function of the distributed line selection module;

[0060] - Positioning unit, which is used to implement the positioning function, transmit signals with the positioning system, and provide the location of the fault section;

[0061] - Network and SMS unit, which is used to implement wireless network function and send the ground fault analysis results of the fault section and the power supply switch status of the fault section to the upper-level monitoring system;

[0062] - Alarm unit, which is used to output corresponding alarm information based on the ground fault analysis results of the fault section and the power supply switch status of the fault section.

[0063] Preferably, the system further includes: a remote monitoring backend system, wherein the remote monitoring backend system includes any one or more of the following:

[0064] - Real-time monitoring of the operating status of each distributed line selection module, receiving and displaying the operating status data uploaded in real time by each distributed line selection module, the operating status data including: zero-sequence voltage value, zero-sequence current value and / or three-phase current value, and switch opening and closing status;

[0065] - Locate the grounded power supply line and the grounded power supply section. Based on the positive and negative values ​​of the zero-sequence transient energy S of the grounding characteristic at each point and / or the three-phase correlation coefficient immediately uploaded by each distributed line selection module after the grounding, determine the power supply line where the grounding occurred and the power supply section where the grounding is located. That is, the line containing the negative zero-sequence transient energy S of the grounding characteristic or the line containing two strong positive uncorrelated coefficients is the grounded line; the last power supply section on the grounded line with the negative zero-sequence transient energy S of the grounding characteristic or the last strong positive uncorrelated power supply section is the grounded section.

[0066] - Remotely control the isolation of incoming line grounding faults of each distributed line selection module. Based on the identified power supply line and the power supply section where the grounding occurs, remotely control the distributed line selection module in the grounded section of the power supply line to trip directly, tripping before the tripping delay of the distributed line selection module, thereby isolating the fault section and reducing the duration of the fault. At the same time, remotely lock the tripping function of the distributed line selection module in the normal line and the non-grounded section of the grounded line to prevent false tripping. The lockout will be automatically released after the grounding disappears.

[0067] - Real-time display of GIS information for each distributed routing module. Each distributed routing module is identified according to the actual power supply line route and the geographic coordinates uploaded by the distributed routing module, and the overall information of each distributed routing module on the power supply line is displayed.

[0068] - Adopts a B / S architecture and supports wireless 4G / 5G networks as well as wired networks.

[0069] By adopting the above technical solution, the present invention has at least one of the following beneficial effects compared with the prior art:

[0070] The distributed line selection and location method and system provided by this invention have flexible working modes. They can work independently or work in conjunction with existing segmented monitoring equipment in the distribution network to realize real-time monitoring of the power supply status of line segments and location and isolation of grounding faults.

[0071] The distributed fault location and positioning method and system provided by this invention can promptly locate and disconnect faulty lines, thereby effectively preventing the further expansion of single-phase grounding faults and ensuring the safety of equipment and personnel.

[0072] The distributed route selection and positioning method and system provided by this invention can accurately locate faulty sections. The working method is simple and effective, avoiding the problem of accident escalation caused by the continued existence of faults.

[0073] The distributed fault location and positioning method and system provided by this invention can accurately isolate faulty sections, ensuring the reliability and safety of power supply and improving the stability of power distribution network operation. Attached Figure Description

[0074] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0075] Figure 1 This is a flowchart illustrating the process of a distributed route selection and positioning method in one embodiment of the present invention.

[0076] Figure 2 This is a schematic diagram of the composition structure of a distributed route selection and positioning system in a preferred embodiment of the present invention.

[0077] Figure 3 This is a schematic diagram of transient energy detected after grounding at any point on the line in a preferred embodiment of the present invention.

[0078] Figure 4 This is a schematic diagram of fault isolation based on differential delay in a preferred embodiment of the present invention.

[0079] Figure 5 This is a control flowchart for implementing grounding tripping, reclosing, and subsequent accelerated tripping in a fault section according to a preferred embodiment of the present invention.

[0080] Figure 6 This is a block diagram of the distributed line selection module and DTU / FTU collaboration in a preferred embodiment of the present invention.

[0081] Figure 7 This is a schematic diagram illustrating the working principle of a distributed route selection and positioning system in a specific application example of the present invention.

[0082] Figure 8 This is a grounding waveform diagram recorded by the distributed line selection module of the fault section in a specific application example of the present invention.

[0083] Figure 9 This is a grounding waveform diagram recorded by the distributed line selection module in the normal section in a specific application example of the present invention.

[0084] Figure 10 (a) and (b) are the original three-phase current diagram and the three-phase current diagram of the transient frequency band of the three-phase current transient correlation method of the grounding line in another embodiment of the present invention; Detailed Implementation

[0085] The embodiments of the present invention are described in detail below: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

[0086] Figure 1 This is a flowchart illustrating the distributed route selection and positioning method provided in an embodiment of the present invention.

[0087] like Figure 1 As shown, the distributed route selection and positioning method provided in this embodiment may include the following steps:

[0088] S100 divides each power supply line into multiple power supply sections from front to back (from the power supply end to the power receiving end). It synchronously and at high speed collects zero-sequence voltage, zero-sequence current, and / or three-phase current in each power supply section, and performs zero-sequence transient energy method and / or three-phase current transient correlation method analysis to determine the grounding line and locate the grounding fault section; where:

[0089] The zero-sequence transient energy method integrates the zero-sequence voltage and zero-sequence current of all power supply sections of all power supply lines, and performs digital filtering on the transient frequency band of the integration result to filter out the transient energy signal that characterizes the fault characteristics when a ground fault occurs, thereby determining the grounding line. After determining the grounding line, the zero-sequence transient energy method is applied to the grounding line to find the grounding transient energy section closest to the receiving end, which is the grounding fault section.

[0090] The three-phase current transient correlation method is used to determine the transient correlation of the three-phase currents of each line. When the three-phase currents of a certain line are strongly uncorrelated in the transient frequency band, the line with strong transient uncorrelatedness is determined to be a grounding line. The three-phase current transient correlation method is then used on the grounding line to find the section with strong transient uncorrelatedness closest to the power receiving end, which is the grounding fault section.

[0091] S200 performs differential time-delay tripping on each power supply section of the grounding line from back to front, that is, from the power receiving end to the power supply end. When a power supply section trips and the grounding fault disappears, the grounding fault section can be isolated. At the same time, all normal sections before the fault section stop timing to ensure the normal power supply operation of the normal sections.

[0092] S300 enables self-recovery of transient faults and permanent isolation of permanent faults in ground fault sections.

[0093] In a preferred embodiment of S100, high-speed acquisition can be performed using a sampling rate of not less than 12K / S to ensure that the zero-sequence voltage, zero-sequence current, and / or three-phase current signals can retain complete transient frequency band information when applying the zero-sequence transient energy method and / or the three-phase current transient correlation method; synchronous acquisition is performed by simultaneously acquiring the zero-sequence voltage, zero-sequence current, and / or three-phase current at the 10-microsecond level to ensure that the zero-sequence voltage, zero-sequence current, and / or three-phase current signals can retain consistent transient frequency band information when applying the zero-sequence transient energy method and / or the three-phase current transient correlation method.

[0094] In a preferred embodiment of S100, the zero-sequence transient energy method integrates the zero-sequence voltage and zero-sequence current of all power supply sections of all power supply lines, and performs digital filtering of the integration result in the transient frequency band to filter out the transient energy signal characterizing the fault features when a ground fault occurs, thereby determining the grounding line; after determining the grounding line, the zero-sequence transient energy method is applied again on the grounding line to find the grounding transient energy section closest to the receiving end, which is the ground fault section; including:

[0095] Integration is performed as follows:

[0096]

[0097] in, It is the zero-sequence voltage. S0 is the integral result of the zero-sequence voltage and zero-sequence current, where S is the zero-sequence current. The digital filtering operation for the transient frequency band is as follows:

[0098]

[0099] The transient characteristic frequency band range is f1 to f2, where f1 and f2 are determined by the pair. The maximum amplitude signal frequency obtained from the FFT analysis is the center frequency, which is then spread. S0 is the result of the integration of zero-sequence voltage and zero-sequence current, and S is the grounding characteristic transient energy after digital filtering within the transient characteristic frequency band. When S<0, it indicates grounding; when S>0, it indicates normal operation.

[0100] On a normal line, the zero-sequence transient energy of the grounding characteristic is positive in all power supply sections; while on a grounded line, there are power supply sections with negative zero-sequence transient energy of the grounding characteristic. Therefore, the grounding characteristic transient energy can be used to distinguish between normal lines and grounded lines, thus enabling the identification of grounded lines.

[0101] On the identified grounding line, the grounding characteristic zero-sequence transient energy obtained by all power supply sections before the grounding fault point is negative, and the grounding characteristic zero-sequence transient energy obtained by all power supply sections after the grounding fault point is positive. Therefore, the last power supply section on the grounding line with negative grounding characteristic zero-sequence transient energy is the grounding fault section, thus realizing the location of the grounding section.

[0102] In a preferred embodiment of S100, the three-phase current transient correlation method is used to determine the transient correlation of the three-phase currents of each line. When the three-phase currents of a certain line are strongly uncorrelated in the transient frequency band, the line with strong transient uncorrelatedity is determined to be a grounding line. The three-phase current transient correlation method is then applied to the grounding line to find the section with strong transient uncorrelatedity closest to the receiving end, which is the grounding fault section. Wherein:

[0103] The digital filtering operation for the transient frequency band is as follows:

[0104]

[0105] Among them, I′ ak I b ′ k I c ′ k The original sampled values ​​of the three-phase current of each line, I ak I bk I ck The transient signal is filtered; the transient characteristic frequency band range is f1~f2, which is obtained by taking the maximum amplitude signal frequency as the center frequency from the FFT analysis of the zero-sequence voltage U0 of the bus and spreading it.

[0106] The Pearson correlation coefficient is calculated as follows:

[0107]

[0108] Among them: I ak I bk I ck The transient data sequence of the three-phase current of each line, r ab r bc r ca These are the correlation coefficients between the three-phase currents in phases AB, BC, and CA, respectively.

[0109] When the three correlation coefficients r of the three-phase current of a certain line ab r bc r ca Two of them are strongly positively uncorrelated, meaning the correlation coefficient is 0. <r p If the value is less than 0.2, then the line is a grounded line; other lines that do not meet the strong positive correlation requirement are ungrounded lines.

[0110] On a grounding line, the power supply section before the grounding fault point has three correlation coefficients that satisfy the grounding characteristics, that is, two of them are strongly positive and uncorrelated; while the power supply section after the grounding fault point does not satisfy the characteristic that two of the three correlation coefficients are strongly positive and uncorrelated. Therefore, the last section of the power supply section of the grounding line that satisfies the grounding characteristics is the grounding fault section.

[0111] In practical line selection algorithms, depending on the input current signal, zero-sequence transient energy method and / or three-phase current transient correlation method can be used. However, when only zero-sequence voltage and zero-sequence current are collected, only the zero-sequence transient energy method is used; when only zero-sequence voltage and three-phase current are collected, only the three-phase current transient correlation method is used; when zero-sequence voltage, zero-sequence current, and three-phase current are collected simultaneously, one or more of the zero-sequence transient energy method and the three-phase current transient correlation method can be used.

[0112] In a preferred embodiment of S200, a differential time-delay tripping method is used to perform differential time-delay tripping on each power supply section of the grounding line from back to front, i.e. from the power receiving end to the power supply end, to achieve fault section isolation, including:

[0113] On the same power supply line, the tripping delay is set in progressively decreasing order from the first segment to the last segment. After a ground fault occurs, the faulty segment on the grounded line and all the normal power supply segments preceding it start tripping timers simultaneously. The tripping time of the faulty segment is the shortest among these segments, so it will trip first. When the ground fault disappears after the faulty segment trips, the tripping timers for the normal segments preceding it stop, thus isolating the ground faulty segment and ensuring continuous power supply to the normal segments. No tripping timers are set for the normal segments on the normal line, or for the normal segments following the faulty segment on the grounded line, and no tripping occurs.

[0114] In a preferred embodiment of S300, the self-recovery of transient faults in the ground fault section is performed using a voltage detection method, and the permanent isolation of permanent faults in the ground fault section is performed using a post-acceleration method, including:

[0115] When the automatic isolation time of the ground fault section expires, if it is detected that there is power at the upstream power supply terminal of this section, it indicates that the power grid is normal, and this section will automatically close the circuit to realize the automatic restoration of power supply to the section.

[0116] If the ground fault does not recur after power is restored, it indicates that the ground fault was transient and normal power supply can be restored after the circuit breaker is closed.

[0117] If the ground fault recurs after power is restored, it indicates that the ground fault is permanent. In this case, a post-acceleration method is used to immediately disconnect the ground fault section again with a 0-second delay, and the circuit breaker will not be automatically closed again to achieve permanent isolation of the ground fault section; thus ensuring the normal power supply to the power lines of other normal parts of the power grid.

[0118] In a preferred embodiment of this example, the method may further include the following steps:

[0119] The S500 sends the ground fault analysis results of the faulty section to the upper-level terminal for corresponding processing of the ground fault.

[0120] In a preferred embodiment of this example, the method may further include the following steps:

[0121] S600 outputs corresponding alarm information based on the ground fault analysis results of the faulty section.

[0122] Figure 2 This is a schematic diagram of the composition structure of a distributed route selection and positioning system provided in an embodiment of the present invention.

[0123] like Figure 2 As shown, the distributed line selection and positioning system provided in this embodiment can include multiple distributed line selection modules, each of which divides each power supply line into multiple power supply sections; wherein, each distributed line selection module can include the following units:

[0124] The voltage and current acquisition unit divides each power supply line from the power supply end to the power receiving end into multiple power supply sections, and synchronously and at high speed acquires the zero-sequence voltage, zero-sequence current and / or three-phase current on each power supply section.

[0125] The fault section location unit uses the zero-sequence transient energy method and / or the three-phase current transient correlation method to analyze the zero-sequence voltage, zero-sequence current, and / or three-phase current to determine the grounding line and locate the grounding fault section. Specifically, the zero-sequence transient energy method integrates the zero-sequence voltage and zero-sequence current of all power supply sections of all power supply lines, and performs digital filtering of the integration results in the transient frequency band to filter out the zero-sequence transient energy signal that characterizes the fault characteristics when the grounding fault occurs, thereby determining the grounding line. After identifying the grounding line, the zero-sequence transient energy method is applied to the grounding line to find the grounding transient energy section closest to the receiving end, which is the grounding fault section. The three-phase current transient correlation method is used to determine the transient correlation of the three-phase currents of each line. When the three-phase currents of a certain line are strongly uncorrelated in the transient frequency band, the line with strong transient uncorrelatedness is identified as the grounding line. After identifying the grounding line, the three-phase current transient correlation method is applied to the grounding line to find the section with strong transient uncorrelatedness closest to the receiving end, which is the grounding fault section.

[0126] The switch control unit performs differential time-delay tripping on each power supply section of the grounding line from the receiving end to the supply end. When a power supply section trips, the grounding fault disappears, thus isolating the grounding fault section. At the same time, all normal sections before the fault section stop timing to ensure the power supply operation of the normal sections. It also performs instantaneous fault self-recovery and permanent fault permanent isolation on the grounding fault section.

[0127] In a preferred embodiment, the system may further include the following units:

[0128] The real-time status monitoring unit is used to monitor the grounding fault analysis results and the power supply switch status of the faulty section in real time.

[0129] In a preferred embodiment, the system may further include the following units:

[0130] The Bluetooth unit is used to implement Bluetooth wireless functionality, enabling local wireless data monitoring, debugging, and module upgrades for the distributed line selection module.

[0131] In a preferred embodiment, the system may further include the following units:

[0132] The positioning unit is used to implement the positioning function, transmit signals with the positioning system, and provide the location of the faulty section.

[0133] In a preferred embodiment, the system may further include the following units:

[0134] The network and SMS unit is used to implement wireless network functionality and send the ground fault analysis results of the faulty section and the power supply switch status of the faulty section to the upper-level monitoring system.

[0135] In a preferred embodiment, the system may further include the following units:

[0136] The alarm unit is used to output corresponding alarm information based on the ground fault analysis results of the faulty section and the status of the power supply switch of the faulty section.

[0137] In a preferred embodiment, the system may further include: a remote monitoring backend system; the remote monitoring backend system includes any one or more of the following:

[0138] - Real-time monitoring of the operating status of each distributed line selection module, receiving and displaying the real-time operating status data uploaded by each distributed line selection module, including: zero-sequence voltage value, zero-sequence current value and / or three-phase current value, as well as the switch opening and closing status;

[0139] - Locate the grounded power supply line and the grounded power supply section. Based on the positive and negative values ​​of the zero-sequence transient energy S of the grounding characteristic at each point and / or the three-phase correlation coefficient immediately uploaded by each distributed line selection module after the grounding, determine the power supply line where the grounding occurred and the power supply section where the grounding is located. That is, the line containing the negative zero-sequence transient energy S of the grounding characteristic or the line containing two strong positive uncorrelated coefficients is the grounded line; the last power supply section on the grounded line with the negative zero-sequence transient energy S of the grounding characteristic or the last strong positive uncorrelated power supply section is the grounded section.

[0140] - Remotely control the isolation of incoming line grounding faults of each distributed line selection module. Based on the identified power supply line and the power supply section where the grounding occurs, remotely control the distributed line selection module in the grounded section of the power supply line to trip directly, tripping before the tripping delay of the distributed line selection module, thereby isolating the fault section and reducing the duration of the fault. At the same time, remotely lock the tripping function of the distributed line selection module in the normal line and the non-grounded section of the grounded line to prevent false tripping. The lockout will be automatically released after the grounding disappears.

[0141] - Real-time display of GIS information for each distributed routing module. Each distributed routing module is identified according to the actual power supply line route and the geographic coordinates uploaded by the distributed routing module, and the overall information of each distributed routing module on the power supply line is displayed.

[0142] - Adopts a B / S architecture and supports wireless 4G / 5G networks as well as wired networks.

[0143] It should be noted that the steps in the method provided by the present invention can be implemented using corresponding modules, devices, units, etc. in the system. Those skilled in the art can refer to the technical solution of the method to realize the composition of the system. That is, the embodiments in the method can be understood as preferred examples for building the system, and will not be elaborated here.

[0144] The distributed fault location and positioning method and system provided in the above embodiments of the present invention are designed to achieve rapid and accurate location of faulty sections and subsequent reliable and timely isolation. Specifically, several sets of distributed fault location modules are installed along each power supply line, with each module responsible for fault identification in a specific power supply section. When a ground fault occurs at a point in the power grid, all distributed fault location modules simultaneously detect the fault and perform ground fault analysis. When a distributed fault location module identifies that the ground fault occurs in its monitored section, it can clearly indicate the faulty section. After the fault clearing delay is reached, the distributed fault location module in the faulty section can disconnect the power supply switch of that section, achieving fault isolation. Other distributed fault location modules not belonging to the ground faulty section will remain inactive, ensuring continuous fault-free power supply operation.

[0145] After the faulty section is cleared and isolated, the power grid returns to normal. At this time, the distributed fault location module can close the section power supply switch to restore power to the faulty section. If the ground fault is transient, it will automatically disappear and power will be restored. If the ground fault recurs, it indicates a permanent ground fault, and the distributed fault location module can again disconnect the section power supply switch without delay and will not reclose it. This achieves permanent isolation of the faulty section, ensuring power supply to other normal parts of the power grid.

[0146] The technical solutions provided by the above embodiments of the present invention will be further described below.

[0147] The distributed route selection and positioning method and system provided in the above embodiments of the present invention can mainly achieve the following functions:

[0148] To achieve the acquisition of zero-sequence voltage and zero-sequence current of the line.

[0149] It enables the opening and closing control of line sectionalizing switches and the acquisition of the opening and closing positions of the sectionalizing switches.

[0150] To enable the analysis and judgment of segmented grounding faults in the line.

[0151] It enables grounding alarm, grounding trip, reclosing, and accelerated tripping for segmented grounding faults on the line.

[0152] In addition to the main functions mentioned above, the following extended functions can also be implemented based on practical applications:

[0153] The Bluetooth function enables wireless control, monitoring, and upgrades of the cable selection module.

[0154] The positioning function can locate the position of the line selection module, making it easier to reach the fault site in a timely manner.

[0155] The network and SMS functions can monitor the electrical status of each line selection module section in real time and promptly notify maintenance personnel after a grounding fault occurs.

[0156] To achieve the above functions, the method and system provided in the above embodiments of the present invention mainly adopt the following technical means:

[0157] I. High-speed, synchronous acquisition of zero-sequence voltage and zero-sequence current.

[0158] When a single-phase ground fault occurs, a high-frequency transient signal containing complete fault information is generated instantaneously. Because these transient signals have a very high frequency, according to the Nyquist sampling theorem, a sufficiently high sampling rate is required to accurately reconstruct the signal at the time of the ground fault. Therefore, a sampling rate of no less than 12 K / s is used to acquire the zero-sequence voltage and current signals.

[0159] Meanwhile, after a ground fault occurs, the direction relationship of current and voltage in the grounded line is different from that in the ungrounded line. Specifically: for the ungrounded line, its zero-sequence current leads the zero-sequence voltage by 90°; for the grounded line, before the ground fault point, its zero-sequence current lags the zero-sequence voltage by 90°; and after the ground fault point, the current shows that the zero-sequence current leads the zero-sequence voltage by 90°.

[0160] Because the phase relationship between zero-sequence voltage and zero-sequence current after grounding can indicate the location of the fault, it is essential to accurately acquire the phase of voltage and current. Due to the high-frequency characteristics of grounding transient signals, voltage and current must be acquired synchronously to accurately reflect the phase relationship between voltage and current, thus providing accurate data for grounding fault diagnosis.

[0161] Furthermore, since the amplitudes of zero-sequence voltage and zero-sequence current are relatively small after grounding, especially when grounding with high resistance, in order to accurately acquire these tiny grounding voltage and current signals, in a specific application example, a differential circuit (high-speed multi-channel synchronous differential converter ADC module) can be used during sampling to achieve high-speed and synchronous acquisition of voltage and current, thereby effectively improving the sampling accuracy and anti-interference capability.

[0162] II. Line selection algorithm based on transient method.

[0163] Since low-current grounding systems include ungrounded neutral grids and neutral grids grounded via arc suppression coils, the direction of the zero-sequence current in the final steady state will change due to the compensation effect of the arc suppression coil. Transient signals, however, are unaffected because they are outside the compensation range of the arc suppression coil. Therefore, a transient method is used for grounding fault detection. This allows for automatic adaptation to various low-current grounding systems.

[0164] In a specific application example, the zero-sequence transient energy method is used for ground fault detection. Specifically, the zero-sequence voltage and zero-sequence current of all power supply sections of all power lines are integrated, and the integration result is digitally filtered in the transient frequency band to extract the transient energy signal characterizing the fault features when a ground fault occurs, thereby identifying the grounding line. After identifying the grounding line, the zero-sequence transient energy method is further applied to the grounding line to determine the ground fault section.

[0165] As previously stated, in the section before the grounding point of the grounding line, the direction of the zero-sequence current lags behind the zero-sequence voltage by 90°. After integration, its transient energy is negative, indicating that it is absorbing energy. In contrast, in the ungrounded line and the section after the grounding point of the grounding line, the direction of the zero-sequence current leads the zero-sequence voltage by 90°. After integration and filtering, its grounding characteristic transient energy is positive, indicating that it is releasing energy.

[0166] Therefore, the section where the transient energy of the grounding characteristic is negative is the section where the grounding fault is located, thus realizing the identification of the faulty line and the faulty section.

[0167] Integration is performed as follows:

[0168]

[0169] The digital filtering operation for the transient frequency band is as follows:

[0170]

[0171] S<0 indicates grounding; S>0 indicates normal operation.

[0172] After grounding at any point on the line, the detected grounding characteristic transient energy is as follows: Figure 3 As shown.

[0173] Depend on Figure 3 It can be seen that on a grounded line, the grounding characteristic transient energy of all sections before the grounding fault point is negative, while the grounding characteristic transient energy of all sections after the grounding point is positive. Therefore, the real fault section should be the last section on the line with negative grounding characteristic transient energy.

[0174] In another specific application example, the three-phase current transient correlation method is used to perform digital filtering of the transient frequency band of the three-phase current of each line to extract the transient signal. Then, the Pearson correlation coefficient is calculated sequentially using the transient signals of the three-phase current of each line to determine the transient correlation. The line with a strong positive uncorrelated correlation coefficient is the grounded line.

[0175] The digital filtering operation for the transient frequency band is as follows:

[0176]

[0177] Among them, I′ ak I b ′ k I c ′ k The original sampled values ​​of the three-phase current of each line, I ak I bk I ck The transient signal is filtered; the transient characteristic frequency band range is f1~f2, which is obtained by taking the maximum amplitude signal frequency as the center frequency from the FFT analysis of the zero-sequence voltage U0 of the bus and spreading it.

[0178] The Pearson correlation coefficient is calculated as follows:

[0179]

[0180] Among them: I ak Ibk I ck The transient data sequence of the three-phase current of each line, r ab r bc r ca These are the correlation coefficients between the three-phase currents in phases AB, BC, and CA, respectively.

[0181] When the three correlation coefficients r of the three-phase current of a certain line ab r bc r ca Two of them are strongly positively uncorrelated, meaning the correlation coefficient is 0. <r p If the value is less than 0.2, then the line is a grounded line; other lines that do not meet the strong positive correlation requirement are ungrounded lines.

[0182] On a grounding line, the power supply section before the grounding fault point has three correlation coefficients that satisfy the grounding characteristics, that is, two of them are strongly positive and uncorrelated; while the power supply section after the grounding fault point does not satisfy the characteristic that two of the three correlation coefficients are strongly positive and uncorrelated. Therefore, the last section of the power supply section of the grounding line that satisfies the grounding characteristics is the grounding fault section.

[0183] III. Fault Segment Isolation and Self-Recovery Based on Differential Delay

[0184] As previously mentioned, on a grounded line, all sections before the ground fault point receive negative grounding characteristic transient energy. Only the last section with negative energy is the faulty section; all sections before it are normal. Therefore, if all sections on the line trip at the same time, all sections with negative grounding characteristic transient energy will trip simultaneously, resulting in the incorrect disconnection of normal sections. Therefore, selective grounding fault handling is necessary, disconnecting only the faulty sections while ensuring the operation of normal sections.

[0185] Therefore, a differential delay method is used to achieve accurate isolation of ground fault sections. On the same line, tripping delays are sequentially set from the beginning to the end of the line, with the longest tripping delay at the beginning and the shortest at the end. The difference between these delays can be set as needed, typically with the same delay for each section. In this way, after a ground fault occurs, the faulty section and all preceding normal sections will detect the ground fault and begin their tripping delays. However, because the delay of the faulty section's selection module is the shortest compared to the preceding modules, the faulty section's delay arrives first, and it trips first. After tripping, the ground fault disappears, and the timing of the selection modules in the preceding normal sections stops, preventing further tripping. This achieves precise fault section isolation.

[0186] Fault isolation based on differential delay is an example such as... Figure 4 As shown.

[0187] Most actual ground faults are transient and self-recovering. That is, after the faulty section is disconnected by tripping, most ground faults will automatically disappear and return to normal. Therefore, after the fault is disconnected, there will be a certain delay before the sectionalizing switch is closed to restore power supply to the faulty section and all subsequent sections, thus restoring the entire line to normal power supply operation. This realizes the reclosing and self-recovery functions of the faulty section in the power distribution system.

[0188] Besides most transient faults, a small number of ground faults are permanent and cannot be automatically recovered. That is, after the sectionalizing switch trips, the fault is restored; but when the sectionalizing switch is closed again via the reclosing function, the fault recurs. In this case, the faulty section that was just reclosed is immediately disconnected with zero delay and will not be reclosed again, thus permanently disconnecting the faulty section. This achieves the post-acceleration function for faulty sections in the power distribution system.

[0189] The trip-reclosing-acceleration function enables different isolation and recovery functions for various grounding faults, thereby maximizing the reliability of power supply to the line and power grid. The control flowchart for the trip-reclosing-acceleration function is shown below. Figure 5 As shown.

[0190] The technical solutions provided in the above embodiments of the present invention have flexible working methods:

[0191] In some embodiments of the present invention, the distributed line selection module has a flexible operating mode. It can work automatically as an independent module, or it can be used as a component of the DTU / FTU in the distribution network, working in conjunction with the DTU / FTU.

[0192] In a typical power grid, the distributed line selection module can be used as an independent measurement and control module to realize real-time monitoring of the power supply status of line sections, and to locate and isolate grounding faults.

[0193] In urban power distribution networks, segmented monitoring equipment such as DTUs / FTUs are typically already in place. In this case, the distributed fault location module can function as a sub-module of the DTU / FTU, acquiring voltage and current data from the grid and outputting control commands to the DTU / FTU when tripping or closing is required. The DTU / FTU then performs the final switching control and fault isolation. A collaborative block diagram of the distributed fault location module and DTU / FTU is shown below. Figure 6 As shown.

[0194] The technical solution provided by the above embodiments of the present invention has a complete monitoring function:

[0195] Distributed line selection modules are typically installed on power line towers, high above the ground. Therefore, direct parameter setting and data monitoring are difficult. In some embodiments of this invention, a Bluetooth unit is also included, enabling short-range wireless monitoring and control below the tower. Furthermore, the Bluetooth function of the unit can be used to upgrade and maintain the line selection module when needed, greatly improving the convenience of on-site maintenance.

[0196] In some embodiments of this invention, the distributed line selection modules are installed segment by segment along the power supply line, with their installation locations being highly dispersed. Monitoring of these modules utilizes 4G / 5G wireless network communication, GPS positioning, and SMS functionality. 4G / 5G wireless network communication enables remote monitoring of the electrical status of each section of the line; GPS positioning allows for rapid location of each module's installation position, facilitating quick location of the line selection modules by maintenance personnel; and SMS functionality allows for immediate transmission of fault information to maintenance personnel upon the occurrence of a grounding fault, significantly improving fault handling efficiency.

[0197] The technical solution provided by the above embodiments of the present invention will be further explained below with reference to a specific application example.

[0198] In this specific implementation example, the distributed line selection module operates as a sub-module of the distribution network FTU. The distributed line selection module receives zero-sequence voltage U0, zero-sequence current signal I0, and sectionalizing switch trip position node signal TWJ from the FTU, resets the signal input command RESET, and outputs the sectionalizing switch trip control signal TZ, closing control signal HZ, and alarm signal ALARM via the FTU. Its principle block diagram is as follows: Figure 7 As shown.

[0199] When a single-phase ground fault occurs in the distribution network, all installed distributed fault location modules detect the ground fault and simultaneously perform ground fault determination. For fault location modules on the line where the ground fault occurs, the calculated ground transient energy S is negative, indicating that the ground fault exists in these sections. After a set trip delay, the last fault location module with a negative S trips, disconnects the ground fault, and issues an alarm signal. For other fault location modules, the ground transient energy S is positive, indicating that these sections are normal, and the fault location modules do not issue alarms or trip.

[0200] In this specific application example, approximately 5 seconds after the fault location module trips, it issues a closing command, which is transmitted via the FTU to the sectionalizing switch, which then closes. Power is restored. The grounding waveform recorded by the fault location module in the fault section shows that the current lags the voltage by 90°, and the transient energy S is negative. Figure 8 As shown; the grounding waveform recorded by the line selection module in the normal section shows that the current leads the voltage by 90°, and the transient energy S is positive, as shown. Figure 9 As shown.

[0201] Figure 10 (a) and (b) are the original three-phase current diagram and the three-phase current diagram of the transient frequency band of the three-phase current transient correlation method of the grounding line in another embodiment of the present invention;

[0202] like Figure 10 As shown in (b), at the peak of the transient frequency band, the waveform of phase A in the three-phase current of the grounding line is almost completely uncorrelated with the other two phases. The correlation coefficient r is calculated. ab =0.08<0.2, r bc =0.88>0.2, r ca =0.08 < 0.2, indicating that the line is grounded;

[0203] The distributed fault location and positioning method and system provided in the above embodiments of the present invention can work independently or in conjunction with existing segmented monitoring equipment in the distribution network to achieve real-time monitoring of the power supply status of line segments, location and isolation of grounding faults; it can promptly locate and disconnect faulty lines, thereby effectively preventing the further expansion of single-phase grounding faults and ensuring the safety of equipment and personnel; it can accurately locate faulty sections, and the working method is simple and effective, avoiding the problem of accident expansion caused by the continued existence of faults; it can accurately isolate faulty sections, ensuring the reliability and safety of power supply and improving the stability of distribution network operation.

[0204] Any matters not covered in the above embodiments of the present invention are well-known in the art.

[0205] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A distributed route selection and positioning method, characterized in that, include: Each power supply line is divided into multiple power supply sections from the power supply end to the power receiving end. The zero-sequence voltage, zero-sequence current and / or three-phase current on each power supply section are collected synchronously at high speed. The zero-sequence transient energy method and / or three-phase current transient correlation method are used for analysis to determine the grounding line and locate the grounding fault section. The zero-sequence transient energy method integrates the zero-sequence voltage and zero-sequence current of all power supply sections of all power supply lines, and performs digital filtering of the integration result in the transient frequency band to filter out the transient energy signal that characterizes the fault characteristics when a ground fault occurs, thereby determining the grounding line. After determining the grounding line, continue to apply the zero-sequence transient energy method on the grounding line to find the grounding transient energy section closest to the power receiving end, which is the grounding fault section; The three-phase current transient correlation method is used to determine the transient correlation of the three-phase currents of each line. When the three-phase currents of a certain line are strongly uncorrelated in the transient frequency band, the line with strong transient uncorrelatedness is determined to be a grounded line. Continue to use the three-phase current transient correlation method on the grounding line to find the transient strongly uncorrelated section closest to the power receiving end, which is the grounding fault section; Differential time-delay tripping is performed on each power supply section of the grounding line from the power receiving end to the power supply end. When a power supply section trips, the grounding fault disappears, thus isolating the grounding fault section. At the same time, all normal sections before the fault section stop timing to ensure the power supply operation of the normal sections. For ground fault sections, perform self-recovery of transient faults and permanent isolation of permanent faults; The method employs a differential time-delay tripping technique, performing differential time-delay tripping on each power supply section of the grounding line from the receiving end to the supply end to isolate the faulty section. This includes: On the same power supply line, the tripping delay is set in progressively decreasing order from the first segment to the last segment. After a ground fault occurs, the faulty segment on the grounded line and all the normal power supply segments preceding it start tripping timers simultaneously. The faulty segment with the shortest tripping time among these segments trips first. When the ground fault disappears after the faulty segment trips, the tripping timers for the normal segments preceding the faulty segment stop, thus isolating the ground faulty segment and ensuring continuous power supply to the normal segments. No tripping timers are set for the normal segments on the normal line and the normal segments following the faulty segment on the grounded line.

2. The distributed route selection and positioning method according to claim 1, characterized in that, The zero-sequence transient energy method integrates the zero-sequence voltage and zero-sequence current of all power supply sections of all power supply lines, and performs digital filtering of the integration result in the transient frequency band to filter out the transient energy signal that characterizes the fault characteristics when a ground fault occurs, thereby determining the grounding line. After identifying the grounding line, the zero-sequence transient energy method is applied along the grounding line to find the grounding transient energy section closest to the receiving end, which is the grounding fault section; including: The integral operation is as follows: ； in It is the zero-sequence voltage. It is the zero-sequence current. This is the result of the integral calculation of zero-sequence voltage and zero-sequence current; The digital filtering operation for the transient frequency band is as follows: ； The transient characteristic frequency band range is f1~f2, where f1 and f2 are determined by the pair The frequency of the signal with the largest amplitude obtained from the FFT analysis is the center frequency, which is then spread. S represents the integral result of zero-sequence voltage and zero-sequence current, and S represents the grounding characteristic transient energy after digital filtering within the transient characteristic frequency band. When S < 0, it indicates grounding; when S > 0, it indicates normal operation. On a normal line, the zero-sequence transient energy of the grounding characteristic is positive in all power supply sections; while on a grounded line, there are power supply sections with negative zero-sequence transient energy of the grounding characteristic. Therefore, the grounding characteristic transient energy can be used to distinguish between normal lines and grounded lines, thus enabling the identification of grounded lines. On the identified grounding line, the grounding characteristic zero-sequence transient energy obtained by all power supply sections before the grounding fault point is negative, and the grounding characteristic zero-sequence transient energy obtained by all power supply sections after the grounding fault point is positive. Therefore, the last power supply section on the grounding line with negative grounding characteristic zero-sequence transient energy is the grounding fault section, thus realizing the location of the grounding section.

3. The distributed route selection and positioning method according to claim 1, characterized in that: The three-phase current transient correlation method is used to determine the transient correlation of the three-phase currents of each line. When the three-phase currents of a line are strongly uncorrelated in the transient frequency band, the line with strong transient uncorrelation is determined to be a ground fault line. The three-phase current transient correlation method is then applied to the ground fault line to find the section with strong transient uncorrelation closest to the receiving end, which is the ground fault section. Wherein: The digital filtering operation for the transient frequency band is as follows: ； in, The original sampled values ​​of the three-phase current of each line, This is the filtered transient signal; the transient characteristic frequency band ranges from f1 to f2, determined by the zero-sequence voltage of the bus. The frequency of the signal with the largest amplitude obtained by FFT analysis is the center frequency, which is then spread. The Pearson correlation coefficient is calculated as follows: ； Among them: I ak I bk I ck The transient data sequence of the three-phase current of each line, r ab r bc r ca These are the correlation coefficients between the three-phase currents in phases AB, BC, and CA, respectively. When the three correlation coefficients r of the three-phase current of a certain line ab r bc r ca Two of them are strongly positively uncorrelated, meaning the correlation coefficient is 0. <r p If the value is less than 0.2, then the line is a grounded line; other lines that do not meet the strong positive correlation requirement are ungrounded lines. On a grounding line, the power supply section before the grounding fault point has three correlation coefficients that satisfy the grounding characteristics, that is, two of them are strongly positive and uncorrelated; while the power supply section after the grounding fault point does not satisfy the characteristic that two of the three correlation coefficients are strongly positive and uncorrelated. Therefore, the last section of the power supply section of the grounding line that satisfies the grounding characteristics is the grounding fault section.

4. The distributed route selection and positioning method according to claim 1, characterized in that, The high-speed acquisition refers to acquiring data at a sampling rate of not less than 12K / S, which is used to retain complete transient frequency band information of the zero-sequence voltage, zero-sequence current, and / or three-phase current signals when applying the zero-sequence transient energy method and / or the three-phase current transient correlation method. The synchronous high-speed acquisition refers to the simultaneous acquisition of zero-sequence voltage, zero-sequence current, and / or three-phase current at the 10-microsecond level, which is used to ensure that the zero-sequence voltage, zero-sequence current, and / or three-phase current signals retain consistent transient frequency band information when applying the zero-sequence transient energy method and / or the three-phase current transient correlation method.

5. The distributed route selection and positioning method according to claim 1, characterized in that, The system employs a voltage-detection method for self-recovery of transient faults in the grounding fault section and a post-acceleration method for permanent isolation of permanent faults in the grounding fault section; including: When the automatic isolation time of the ground fault section expires, if it is detected that there is power at the upstream power supply terminal of this section, it indicates that the power grid is normal, and this section will automatically close the circuit to realize the automatic restoration of power supply to the section. If the ground fault does not recur after power is restored, it indicates that the ground fault was transient and normal power supply can be restored after the circuit breaker is closed. If the ground fault recurs after power is restored, it indicates that the ground fault is permanent. In this case, the ground fault section will be immediately disconnected again with a post-acceleration method and a 0-second delay, and the circuit will not be automatically closed again to achieve permanent isolation of the ground fault section and ensure the normal power supply of other normal parts of the power grid.

6. The distributed route selection and positioning method according to any one of claims 1-5, characterized in that, It also includes any one or more of the following: - Send the ground fault analysis results of the faulty section to the upper-level terminal for corresponding processing of the ground fault; - Based on the ground fault analysis results of the faulty section, output the corresponding alarm information.

7. A distributed route selection and positioning system, characterized in that, include: Multiple distributed line selection modules, each of which divides each power supply line into multiple power supply sections; wherein: Each of the distributed route selection modules includes: The voltage and current acquisition unit divides each power supply line from the power supply end to the power receiving end into multiple power supply sections, and synchronously and at high speed acquires the zero-sequence voltage, zero-sequence current and / or three-phase current on each power supply section. The fault section location unit uses the zero-sequence transient energy method and / or the three-phase current transient correlation method to analyze the zero-sequence voltage, zero-sequence current, and / or three-phase current to determine the grounding line and locate the grounding fault section. Specifically, the zero-sequence transient energy method integrates the zero-sequence voltage and zero-sequence current of all power supply sections of all power supply lines, and performs digital filtering of the integration result in the transient frequency band to filter out the zero-sequence transient energy signal that characterizes the fault characteristics when the grounding fault occurs, thereby determining the grounding line. After identifying the grounding line, the zero-sequence transient energy method is applied to the grounding line to find the grounding transient energy section closest to the power receiving end, which is the grounding fault section. The three-phase current transient correlation method is used to determine the transient correlation of the three-phase currents of each line. When the three-phase currents of a certain line are strongly uncorrelated in the transient frequency band, the line with strong transient uncorrelatedness is identified as the grounding line. After identifying the grounding line, the three-phase current transient correlation method is applied to the grounding line to find the strongly uncorrelated transient section closest to the power receiving end, which is the grounding fault section. The switch control unit performs differential time-delay tripping on each power supply section of the grounding line from the receiving end to the supply end. When a power supply section trips, the ground fault disappears, thus isolating the ground fault section. Simultaneously, all normal sections preceding the fault section stop timing to ensure power supply operation in the normal sections. The unit performs self-recovery for transient faults and permanent isolation for permanent faults in the ground fault section. Specifically, the differential time-delay tripping method, performing differential time-delay tripping on each power supply section of the grounding line from the receiving end to the supply end to achieve fault section isolation, includes: On the same power supply line, the tripping delay is set in progressively decreasing order from the first segment to the last segment. After a ground fault occurs, the faulty segment on the grounded line and all the normal power supply segments preceding it start tripping timers simultaneously. The faulty segment with the shortest tripping time among these segments trips first. When the ground fault disappears after the faulty segment trips, the tripping timers for the normal segments preceding the faulty segment stop, thus isolating the ground faulty segment and ensuring continuous power supply to the normal segments. No tripping timers are set for the normal segments on the normal line and the normal segments following the faulty segment on the grounded line.

8. The distributed route selection and positioning system according to claim 7, characterized in that, It also includes any one or more of the following: - Real-time status monitoring unit, which is used to monitor the grounding fault analysis results of the fault section and the power supply switch status of the fault section in real time; - Bluetooth unit, which is used to implement Bluetooth wireless function, including: local wireless data monitoring function, debugging and operation function and module upgrade function of the distributed line selection module; - Positioning unit, which is used to implement the positioning function, transmit signals with the positioning system, and provide the location of the faulty section; - Network and SMS unit, which is used to implement wireless network function and send the ground fault analysis results of the fault section and the power supply switch status of the fault section to the upper-level monitoring system; - Alarm unit, which is used to output corresponding alarm information based on the ground fault analysis results of the fault section and the power supply switch status of the fault section.

9. The distributed route selection and positioning system according to claim 7 or 8, further characterized in that, It also includes: a remote monitoring backend system, wherein the remote monitoring backend system includes any one or more of the following: - Monitor the operating status of each distributed line selection module in real time, receive and display the operating status data uploaded by each distributed line selection module in real time, the operating status data includes: zero-sequence voltage value, zero-sequence current value and / or three-phase current value, and switch opening and closing status; - Locate the grounded power supply line and the grounded power supply section. Based on the positive and negative values ​​of the zero-sequence transient energy S of the grounding characteristic at each point and / or the three-phase correlation coefficient uploaded immediately by each distributed line selection module after the grounding, determine the power supply line where the grounding occurred and the power supply section where the grounding is located. That is, the line containing the negative zero-sequence transient energy S of the grounding characteristic or the line containing two strong positive uncorrelated coefficients is the grounded line; the last power supply section on the grounded line with the negative zero-sequence transient energy S of the grounding characteristic or the last strong positive uncorrelated power supply section is the grounded section. - Remotely control the isolation of incoming line grounding faults of each distributed line selection module. Based on the identified power supply line and the power supply section where the grounding occurs, remotely control the distributed line selection module in the grounded section of the power supply line to trip directly, tripping before the tripping delay of the distributed line selection module, thereby isolating the fault section and reducing the duration of the fault. At the same time, remotely lock the tripping function of the distributed line selection module in the normal line and the non-grounded section of the grounded line to prevent false tripping. The lockout is automatically released after the grounding disappears. - Display the GIS information of each distributed route selection module in real time. Identify each distributed route selection module according to the actual power supply line route and the geographic coordinates uploaded by the distributed route selection module, and display the overall information of each distributed route selection module on the power supply line. - It adopts a B / S architecture and supports wireless 4G / 5G networks as well as wired networks.

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