Fault line selection method, system and equipment based on bus zero-sequence current neutral point ungrounded device and medium

Abstract

The invention relates to the technical field of power distribution network fault line selection, and discloses a fault line selection method, system and equipment based on a bus zero sequence current neutral point ungrounded device and a medium. Fault judgment is carried out according to phase comparison of the zero-sequence current of the two buses associated with each line; and for the edge distribution line, calculating the zero-sequence current of the edge line, respectively comparing the zero-sequence current with the starting current, and carrying out fault judgment by combining the phase and amplitude comparison of the bus zero-sequence current. Based on the bus zero-sequence current formed by converging the line zero-sequence current, the fault line identification method based on phase comparison is provided according to the access mode of the bus zero-sequence current, the method does not depend on zero-sequence current information of all lines in the system and does not need to test alternate cutting lines; whether the line is a fault line or not can be quickly judged only depending on the bus zero-sequence current information related to the line.

Description

Technical Field

[0001] This invention relates to the field of fault location technology in power distribution networks, and in particular to a fault location method, system, device and medium based on a bus zero-sequence current neutral point ungrounded device. Background Technology

[0002] Neutral point ungrounded system devices are generally used in 6kV to 66kV distribution networks, especially in places where the power supply continuity requirement is extremely high. Traditional low current grounding line selection devices mainly rely on the zero-sequence current transformers of each outgoing line to directly collect the zero-sequence current of the line, and use a variety of principles such as steady-state power frequency component comparison, amplitude comparison, active component, transient high-frequency component, fifth harmonic, and wavelet energy for comprehensive discrimination; some devices also combine multiple rounds of sampling and group amplitude comparison algorithms to improve the accuracy of line selection.

[0003] Since the total zero-sequence current of all lines in a neutral-point ungrounded system generally does not exceed 20A, when a single-phase ground fault occurs, the zero-sequence current of the line is generally small, making it difficult for protection devices to effectively measure the zero-sequence current and effectively identify faulty and non-faulty lines. Specifically, the zero-sequence current of the faulty line is only the remainder after deducting its own portion from the sum of the system's ground capacitance current, and the actual value is still very small. This results in extremely low signal-to-noise ratio and large amplitude and phase measurement errors for zero-sequence current transformers. Generally, it is necessary to configure a special low-current ground fault location device in this type of distribution network system or to adopt a method of alternating line disconnection tests to select and disconnect the faulty line. Therefore, there is an urgent need for a method that does not rely on the accuracy of zero-sequence current measurement, can quickly select the faulty line, and does not require line tripping. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a fault selection method and system based on a busbar zero-sequence current neutral point ungrounded device to solve the current problem of difficulty in effectively measuring zero-sequence current and effectively identifying faulty and non-faulty lines.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a fault location method based on a busbar zero-sequence current neutral point ungrounded device, comprising: the method being applied to a busbar zero-sequence current neutral point ungrounded device, the device having a total of A power distribution line, of which the line The faulty line; the zero-sequence current transformer is located on the bus side; For the non-edge distribution lines of the device, the relay protection device introduces the zero-sequence current of the two adjacent bus zero-sequence current transformers at the bus connection point of the line; for the edge distribution lines of the device, the same bus zero-sequence current is introduced as the adjacent non-edge lines. The method includes: For any non-edge distribution line, compare it with the starting current, and determine the fault based on the phase comparison of the zero-sequence currents of the two buses associated with each line; For edge distribution lines, calculate the zero-sequence current of the edge lines and compare it with the starting current. Combine the phase and amplitude comparison of the zero-sequence current of the bus to determine the fault.

[0007] As a preferred embodiment of the fault selection method based on a busbar zero-sequence current neutral point ungrounded device described in this invention, the method includes: for any non-edge distribution line, comparing it with the starting current, and performing fault judgment based on the phase comparison of the two busbar zero-sequence currents associated with each line, including: Based on non-edge lines Calculate the zero-sequence current of the busbars on both sides of the busbar connection point for non-edge lines. zero-sequence current ; If zero-sequence current If the current is less than the starting current, then it is determined to be a non-edge circuit. It is a non-faulty line.

[0008] As a preferred embodiment of the fault selection method based on a busbar zero-sequence current neutral point ungrounded device described in this invention, the method further includes: for any non-edge distribution line, comparing it with the starting current, and determining the fault based on the phase comparison of the two busbar zero-sequence currents associated with each line; Based on non-edge lines Calculate the zero-sequence current of the busbars on both sides of the busbar connection point for non-edge lines. zero-sequence current ; If zero-sequence current If the current is greater than the starting current, then the zero-sequence current is determined. Does it meet the first criterion? If so, it is determined to be a non-edge line. It is a faulty line; if it does not meet the criteria, it is determined to be a non-edge line. It is a non-faulty line; The first criterion is based on the directional characteristics of the zero-sequence current in the faulty and non-faulty lines, determined by the phase difference angle between the zero-sequence currents of the two busbars. Determine non-edge lines Is it malfunctioning?

[0009] As a preferred embodiment of the fault location method based on a busbar zero-sequence current neutral point ungrounded device described in this invention, the first criterion is based on the directional characteristics of the zero-sequence currents of the faulty line and the non-faulty line, determined by the phase difference angle between the two busbar zero-sequence currents. Determine non-edge lines Whether it is a malfunction, specifically: when When the angle is ≥90°, it is determined to be a non-edge line. The zero-sequence currents on both sides of the busbars are reversed, and the non-edge lines are not affected. The faulty line; when When the angle is less than 90°, it is determined to be a non-edge line. The zero-sequence currents on both sides of the busbar are in the same direction, and the non-edge lines are not in the same direction. This is a non-faulty line.

[0010] The beneficial effects of this preferred technical solution are: for non-edge lines, whether there is a fault can be accurately determined simply by the phase relationship of the zero-sequence currents of two adjacent busbars at the connection point of the busbar, and the criterion is simple and fast.

[0011] As a preferred embodiment of the fault location method based on a busbar zero-sequence current neutral point ungrounded device described in this invention, the method includes: for edge distribution lines, calculating the zero-sequence current of the edge lines and comparing it with the starting current, and combining the phase and amplitude comparison of the busbar zero-sequence current to determine the fault, including: Calculate edge distribution line 1 and edge distribution line zero-sequence current and ; If zero-sequence current If the current is less than the starting current, then edge distribution line 1 is determined to be a non-faulty line; If zero-sequence current If the current is less than the starting current, then it is determined to be an edge distribution line. It is a non-faulty line.

[0012] As a preferred embodiment of the fault location method based on a busbar zero-sequence current neutral point ungrounded device described in this invention, the method further includes: for edge distribution lines, calculating the zero-sequence current of the edge lines and comparing it with the starting current, and combining the phase and amplitude comparison of the busbar zero-sequence current to determine the fault, and further comprising: Calculate the zero-sequence current of edge distribution line 1 ; If zero-sequence current If the starting current is greater than or equal to the starting current, then the zero-sequence current is determined. Whether the second criterion is met, if it is met, then the edge distribution line 1 is determined to be a faulty line; if it is not met, then the edge distribution line 1 is determined to be a non-faulty line. The second criterion includes: Assuming only one line fault exists, the phase difference angle of the zero-sequence currents of the two busbars connected through distribution line 2 is... To determine whether edge distribution line 1 is faulty, the specific steps are as follows: like The current amplitude flowing through the zero-sequence current transformer of the first busbar shared by Line 1 and Line 2 is ≤90° and is greater than the current amplitude flowing through the zero-sequence current transformer of the second busbar shared by Line 2 and Line 3 and the difference between the two. When the sum of the values ​​is multiples of the given values, edge line 1 is determined to be a faulty line.

[0013] As a preferred embodiment of the fault location method based on a busbar zero-sequence current neutral point ungrounded device described in this invention, the method further includes: for edge distribution lines, calculating the zero-sequence current of the edge lines and comparing it with the starting current, and combining the phase and amplitude comparison of the busbar zero-sequence current to determine the fault, and further comprising: Calculate edge distribution lines zero-sequence current ; If zero-sequence current If the starting current is greater than or equal to the starting current, then the zero-sequence current is determined. Does it meet the third criterion? If so, then the edge distribution line... If the condition is not met, then it is determined to be a peripheral distribution line. It is a non-faulty line; The third criterion includes, If the line The phase angle difference between the zero-sequence currents of the two associated buses ≤90°, and flows through the line With the line The current amplitude of the zero-sequence current transformer on the shared terminal bus is greater than the current flowing through the line. With the line The current amplitude of the shared preceding bus zero-sequence current transformer and the difference between the two When the sum of the times is multiples, the edge distribution lines are determined. Faulty circuit.

[0014] The beneficial effects of this preferred technical solution are as follows: For edge lines, by reusing the phase discrimination results already completed by adjacent non-edge lines as a prerequisite, and supplemented by the comparison of the bus zero-sequence current amplitude, fault identification with the same reliability as that of non-edge lines can be achieved.

[0015] Secondly, the present invention provides a fault location system based on a busbar zero-sequence current neutral point ungrounded device, comprising: The first judgment module is used to compare the starting current with any non-edge distribution line and to make fault judgment based on the phase comparison of the zero-sequence currents of the two buses associated with each line. The second judgment module is used to calculate the zero-sequence current of the edge distribution line and compare it with the starting current. It also combines the phase and amplitude comparison of the zero-sequence current of the bus to make fault judgment.

[0016] Thirdly, the present invention provides a computer device, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of a fault selection method based on a bus zero-sequence current neutral point ungrounded device.

[0017] Fourthly, the present invention provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the fault location method based on a busbar zero-sequence current neutral point ungrounded device.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The method of the present invention is based on the neutral point ungrounded device of bus zero-sequence current. It uses the bus zero-sequence current formed by the convergence of line zero-sequence current. The zero-sequence current is large and easy to detect. Based on this, a fault line identification method based on phase comparison is proposed according to the access method of bus zero-sequence current. The effectiveness of this method does not depend on the zero-sequence current information of all lines in the system, nor does it require test switching of lines. It can quickly determine whether the line is a fault line by relying solely on the bus zero-sequence current information related to the line. It is particularly suitable for neutral point ungrounded distribution network systems connected to important loads such as data centers. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall process of a fault location method based on a busbar zero-sequence current neutral point ungrounded device, according to an embodiment of the present invention.

[0021] Figure 2This is a schematic diagram of the zero-sequence current of a single-phase grounding fault in a neutral-point ungrounded system, as described in an embodiment of the present invention, in a fault selection method based on a busbar zero-sequence current neutral-point ungrounded device.

[0022] Figure 3 This is a schematic diagram of the connection method of zero-sequence current in the relay protection device in a fault selection method based on a busbar zero-sequence current neutral point ungrounded device according to an embodiment of the present invention.

[0023] Figure 4 This is a schematic diagram of the fault selection process for non-edge lines in a fault selection method based on a busbar zero-sequence current neutral point ungrounded device, according to an embodiment of the present invention.

[0024] Figure 5 This is a schematic diagram of the fault selection process for edge lines in a fault selection method based on a busbar zero-sequence current neutral point ungrounded device, according to an embodiment of the present invention. Detailed Implementation

[0025] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0026] Example 1, referring to Figures 2-3 As an embodiment of the present invention, a fault location method based on a busbar zero-sequence current neutral point ungrounded device is provided. The method is applied to the busbar zero-sequence current neutral point ungrounded device, which has a total of... A power distribution line, of which the line The faulty line; the zero-sequence current transformer is located on the bus side; For the non-edge distribution lines of the device, the relay protection device introduces the zero-sequence current of the two adjacent bus zero-sequence current transformers at the bus connection point of the line; for the edge distribution lines of the device, the same bus zero-sequence current is introduced as the adjacent non-edge lines. Specifically, the zero-sequence current distribution of the busbar zero-sequence current neutral point ungrounded device during a single-phase ground fault is as follows: Figure 2 As shown.

[0027] The zero-sequence current transformer is installed on the busbar side. The current flowing through is Its positive direction is as follows Figure 2 As indicated by the middle arrow, This refers to the zero-sequence capacitance to ground for each line. They are respectively The zero-sequence current of the line, For grounding resistance, This is the voltage of the faulty phase.

[0028] The connection method of zero-sequence current in relay protection is as follows: Figure 3 As shown, in order to accurately determine the faulty line, for non-edge lines 2 to 3 in the power distribution system... The relay protection device needs to introduce the zero-sequence current from the zero-sequence current transformers of the two adjacent busbars at the busbar connection point; for example, for line 2, the protection device needs to collect the zero-sequence current. and The other non-edge lines are similar; for edge lines, i.e., line 1 and line... ,because and Both are 0. To ensure the correct operation of the edge line relay protection device, this invention uses the same bus zero-sequence current for edge line 1 and non-edge line 2. Non-edge lines A scheme that connects to the same zero-sequence current. Figure 3 RP1 to RPm represent the lines respectively Relay protection devices.

[0029] Example 2, refer to Figures 1-5 As an embodiment of the present invention, based on the above embodiment, a fault location method based on a busbar zero-sequence current neutral point ungrounded device is provided. (Refer to...) Figure 1 The method includes: S100: For any non-edge distribution line, compare it with the starting current and determine the fault based on the phase comparison of the zero-sequence currents of the two buses associated with each line; S200: For edge distribution lines, calculate the zero-sequence current of the edge line and compare it with the starting current. Combine the phase and amplitude comparison of the zero-sequence current of the bus to determine the fault.

[0030] In this embodiment of the application, step S100 compares the starting current with the fault current for any non-edge distribution line, and performs fault determination based on the phase comparison of the zero-sequence currents of the two buses associated with each line, including the following steps A1-A2-1: A1: Based on non-edge lines Calculate the zero-sequence current of the busbars on both sides of the busbar connection point for non-edge lines. zero-sequence current ; Specifically, by Figure 2 It can be seen that for non-edge lines The formula for calculating zero-sequence current is: ; according to Figure 2 The direction of the zero-sequence current. and The lines are respectively The zero-sequence current of the busbars on both sides of the connection point.

[0031] A2-1: If zero-sequence current If the current is less than the starting current, then it is determined to be a non-edge circuit. It is a non-faulty line.

[0032] In the embodiments of this application, reference is made to Figure 4 In step S100, for any non-edge distribution line, the starting current is compared, and fault identification is performed based on the phase comparison of the zero-sequence currents of the two busbars associated with each line. The steps A1-A2-2 are also included: A1: Based on non-edge lines Calculate the zero-sequence current of the busbars on both sides of the busbar connection point for non-edge lines. zero-sequence current ; A2-2: If zero-sequence current If the current is greater than the starting current, then the zero-sequence current is determined. Does it meet the first criterion? If so, it is determined to be a non-edge line. It is a faulty line; if it does not meet the criteria, it is determined to be a non-edge line. It is a non-faulty line; The first criterion is based on the directional characteristics of the zero-sequence current in the faulty and non-faulty lines, determined by the phase difference angle between the zero-sequence currents of the two busbars. Determine non-edge lines Is it malfunctioning?

[0033] In the embodiments of this application, reference is made to Figure 4 In step S100, the first criterion is based on the directional characteristics of the zero-sequence current of the faulty line and the non-faulty line, and is determined by the phase difference angle of the zero-sequence current of the two busbars. Determine non-edge lines Whether it is a malfunction, specifically: when When the angle is ≥90°, it is determined to be a non-edge line. The zero-sequence currents on both sides of the busbars are reversed, and the non-edge lines are not affected. The faulty line; when When the angle is less than 90°, it is determined to be a non-edge line. The zero-sequence currents on both sides of the busbar are in the same direction, and the non-edge lines are not in the same direction. This is a non-faulty line.

[0034] Specifically, for non-edge lines 2 to m in the system, faults can be identified by comparing the phase of the zero-sequence currents of the two buses associated with each line; When the zero-sequence currents of the two busbars are in the same direction, the line is determined to be a non-faulty line. When the zero-sequence currents of the two busbars are reversed, the line is determined to be a faulty line. Therefore, for non-edge lines The first criterion formula can be expressed as: It should be noted that the physical basis for fault criterion of non-edge lines is that when a single-phase ground fault occurs, the zero-sequence current directions of the faulty line and the non-faulty line are opposite.

[0035] The calculation is for the phase difference between two complex currents. Taking the absolute value means taking the absolute value of the phase difference, that is, not considering the lead-lag state, but only focusing on the direction difference.

[0036] For a non-faulty line, it is itself a capacitor, generating only capacitive current, which flows from the busbar to the line. (Reference) Figure 2 For line 2 (assuming it is not faulty), the current is... and The positive directions of both currents point towards line 2. In actual physical processes, these two currents flow in the same direction (both flow into line 2), therefore, their phase difference is very small, close to 0 degrees. <90°.

[0037] For a faulty line, it carries not only its own capacitive current, but also the sum of the capacitive currents of all other non-faulty lines (i.e., the total grounding current at the fault point). This total grounding current flows from the faulty line to the busbar, and then is distributed to other non-faulty lines through the busbar. This results in zero-sequence currents on both sides of the faulty line, one of which has the same actual direction as the defined "positive direction," while the other has the opposite direction.

[0038] Assuming line 3 is a faulty line, then The actual direction may be the same as the positive direction (inflow line), while The actual direction is opposite to the positive direction (flowing out of the line), and the two currents are almost out of phase. Therefore, their phase difference will be large. ≥90°.

[0039] It should also be noted that the first criterion relies entirely on the directional characteristics of the zero-sequence current in the faulty and non-faulty lines. This characteristic is very significant and stable, and is not affected by the magnitude of the current, thus enabling fast and reliable fault line selection.

[0040] In the embodiments of this application, reference is made to Figure 5 In step S200, for edge distribution lines, the zero-sequence current of the edge lines is calculated and compared with the starting current. Fault identification is performed by combining the phase and amplitude comparison of the zero-sequence current of the busbar, including the following steps: B1: Calculate edge distribution line 1 and edge distribution line zero-sequence current and ; Specifically, refer to Figure 2 For edge line 1, the formula for calculating its zero-sequence current is: ; Specifically, refer to Figure 2 For edge lines The formula for calculating its zero-sequence current is: .

[0041] B2-1: If zero-sequence current If the current is less than the starting current, then edge distribution line 1 is determined to be a non-faulty line; B3-1: If zero-sequence current If the current is less than the starting current, then it is determined to be an edge distribution line. It is a non-faulty line.

[0042] In the embodiments of this application, reference is made to Figure 5 In step S200, for edge distribution lines, the zero-sequence current of the edge line is calculated and compared with the starting current. Fault identification is performed by combining the phase and amplitude comparison of the zero-sequence current of the bus. The steps also include: C1: Calculate the zero-sequence current of edge distribution line 1 For details, please refer to the calculation formula in B1.

[0043] C2: If zero-sequence current If the starting current is greater than or equal to the starting current, then the zero-sequence current is determined. Whether the second criterion is met, if it is met, then the edge distribution line 1 is determined to be a faulty line; if it is not met, then the edge distribution line 1 is determined to be a non-faulty line. The second criterion includes: Assuming only one line fault exists, the phase difference angle of the zero-sequence currents of the two busbars connected through distribution line 2 is... To determine whether edge distribution line 1 is faulty, the specific steps are as follows: like The current amplitude flowing through the zero-sequence current transformer of the first busbar shared by Line 1 and Line 2 is ≤90° and is greater than the current amplitude flowing through the zero-sequence current transformer of the second busbar shared by Line 2 and Line 3 and the difference between the two. When the sum of the values ​​is multiples of the given values, edge line 1 is determined to be a faulty line.

[0044] Specifically, for edge line 1, the fault criterion is as follows: in, As a scaling factor, it can be taken as... It is 0.5. In the above formula, Line 2 is considered a non-faulty line because this invention assumes that it is impossible for two lines to fail simultaneously; the second equation indicates... Greater than If this formula is satisfied, then line 1 is determined to be a faulty line; otherwise, line 1 is determined to be a non-faulty line.

[0045] It should be noted that, It is electric current Compared to The phase angle; this condition requires the phase angle to be less than or equal to 90 degrees, indicating that the two currents are approximately in phase or have a small phase difference. In the system, if line 2 is a non-faulty line, the zero-sequence currents of its two adjacent buses ( and The phases of the two components should be in the same direction. Therefore, A value ≤90° indicates that line 2 is a non-faulty line. Since it is assumed that only one line is faulty, this means that line 1 may be a faulty line.

[0046] And the amplitude condition, when When the value is 0.5, the condition simplifies to That is, current The amplitude is greater than The amplitude; if line 1 is a faulty line, the fault current will flow from the bus to line 1, causing the zero-sequence current near line 1 to increase. The amplitude is relatively large, while the adjacent ones The amplitude is relatively small. Therefore, when the amplitude relationship is satisfied, support line 1 is a faulty line.

[0047] Line 1 is determined to be a faulty line only when both the phase condition and the amplitude condition are met; otherwise, line 1 is determined to be a non-faulty line. This criterion utilizes the characteristic that edge lines and adjacent non-edge lines share the zero-sequence current of the bus, eliminating the need to directly measure the zero-sequence current of all lines, thus enabling rapid fault line selection.

[0048] In the embodiments of this application, reference is made to Figure 5In step S200, for edge distribution lines, the zero-sequence current of the edge line is calculated and compared with the starting current. Fault identification is performed by combining the phase and amplitude comparison of the zero-sequence current of the bus. The steps also include: D1: Calculate the edge distribution lines zero-sequence current For details, please refer to the calculation formula in B1.

[0049] D2: If zero-sequence current If the starting current is greater than or equal to the starting current, then the zero-sequence current is determined. Does it meet the third criterion? If so, then the edge distribution line... If the condition is not met, then it is determined to be a peripheral distribution line. It is a non-faulty line; The third criterion includes, If the line The phase angle difference between the zero-sequence currents of the two associated buses ≤90°, and flows through the line With the line The current amplitude of the zero-sequence current transformer on the shared terminal bus is greater than the current flowing through the line. With the line The current amplitude of the shared preceding bus zero-sequence current transformer and the difference between the two When the sum of the times is multiples, the edge distribution lines are determined. Faulty circuit.

[0050] Specifically, for edge lines The fault criterion is: Among them, take The value is 0.5. If this formula is satisfied, the circuit is considered complete. If it is a faulty line, otherwise determine the line. This is a non-faulty line.

[0051] It should be noted that, It is electric current Compared to The phase angle; this condition requires the phase angle to be less than or equal to 90 degrees, indicating that the two currents are approximately in phase. This indicates that the circuit It is a non-faulty line, because if the line If it's a faulty line, its phase relationship will be different; since the system only has one faulty line, this means the line... It may be a faulty circuit.

[0052] And the amplitude condition, when When the value is 0.5, the condition simplifies to That is, current The amplitude is greater than The amplitude. If the line It's a faulty line; the fault current will flow from the busbar to the line. This caused the line to be close to Bus zero-sequence current The amplitude is relatively large, while the adjacent ones The amplitude is relatively small. Therefore, when the amplitude relationship is satisfied, the supporting line... The line is faulty.

[0053] The line is determined only when both the phase condition and the amplitude condition are met. The line is faulty; otherwise, the line is determined to be faulty. This is a non-faulty line.

[0054] It should also be noted that, considering the special location of edge lines, the problem of difficult zero-sequence current measurement for edge lines is overcome by introducing the zero-sequence current information of the busbars of adjacent non-edge lines and combining it with phase and amplitude comparison. This method does not require switching lines in turn or relying on the zero-sequence current information of all lines, thus improving the speed and reliability of fault location, and is particularly suitable for neutral point ungrounded systems containing important loads.

[0055] In summary, the line selection method of the present invention eliminates the direct dependence on the zero-sequence current of the line and shifts the judgment basis to the zero-sequence current of the bus. Since the zero-sequence current of all non-faulty lines eventually converges to the bus, the amplitude of the zero-sequence current of the bus is significantly greater than that of any line, thereby greatly improving the reliability of the measurement signal-to-noise ratio and phase identification.

[0056] Specifically, for non-edge lines, faults can be accurately determined simply by the phase relationship of the zero-sequence currents of two adjacent buses at the connection point. The criteria are simple and do not require complex algorithms or multiple sampling. For edge lines, by reusing the phase discrimination results already completed by adjacent non-edge lines as a prerequisite, and then comparing the amplitude of the zero-sequence current of the bus, fault identification with the same reliability as that of non-edge lines can be achieved without adding additional hardware.

[0057] The entire line selection process relies solely on information collected by the zero-sequence current transformer on the bus side, eliminating the need for specific ground capacitance parameters of each outgoing line, line tripping tests, or waiting for transient decay. Furthermore, because the judgment logic does not depend on the accuracy of small current amplitude measurements, it exhibits stronger robustness to complex situations such as uneven capacitive current distribution.

[0058] This method can directly improve the single-phase grounding fault location performance of existing neutral point ungrounded system relay protection devices, or it can be embedded as an independent fault location module into existing low-current fault location devices to improve the overall fault location accuracy and operating speed.

[0059] Example 3 illustrates a fault location method based on a busbar zero-sequence current neutral point ungrounded device. It should be noted that the technical solution of this fault location system based on a busbar zero-sequence current neutral point ungrounded device is based on the same concept as the aforementioned fault location method based on a busbar zero-sequence current neutral point ungrounded device. Details not described in detail in this example of the fault location system based on a busbar zero-sequence current neutral point ungrounded device can be found in the description of the aforementioned fault location method based on a busbar zero-sequence current neutral point ungrounded device.

[0060] This embodiment also provides another fault location system based on a busbar zero-sequence current neutral point ungrounded device, including: The first judgment module is used to compare the starting current with any non-edge distribution line and to make fault judgment based on the phase comparison of the zero-sequence currents of the two buses associated with each line. The second judgment module is used to calculate the zero-sequence current of the edge distribution line and compare it with the starting current. It also combines the phase and amplitude comparison of the zero-sequence current of the bus to make fault judgment.

[0061] This embodiment also provides a computer device applicable to a fault selection method based on a busbar zero-sequence current neutral point ungrounded device, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the fault selection method based on a busbar zero-sequence current neutral point ungrounded device as proposed in the above embodiment.

[0062] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements a fault selection method based on a busbar zero-sequence current neutral point ungrounded device as proposed in the above embodiments.

[0063] The storage medium proposed in this embodiment and the fault location method based on the bus zero-sequence current neutral point ungrounded device proposed in the above embodiment belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0064] From the above description of the implementation methods, those skilled in the art will clearly understand that the present invention can be implemented using software and necessary general-purpose hardware. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0065] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A fault location method based on a busbar zero-sequence current neutral point ungrounded device, characterized in that, The method is applied to a busbar zero-sequence current neutral point ungrounded device, which has a total of A power distribution line, of which the line The faulty line; the zero-sequence current transformer is located on the bus side; For the non-edge distribution line of the device, the relay protection device introduces the zero-sequence current of the two adjacent bus zero-sequence current transformers at the bus connection point of the line. For the edge distribution lines of the device, the same bus zero-sequence current is connected to the adjacent non-edge lines. The method includes: For any non-edge distribution line, compare it with the starting current, and determine the fault based on the phase comparison of the zero-sequence currents of the two buses associated with each line; For edge distribution lines, calculate the zero-sequence current of the edge lines and compare it with the starting current. Combine the phase and amplitude comparison of the zero-sequence current of the bus to determine the fault.

2. The fault location method based on a busbar zero-sequence current neutral point ungrounded device as described in claim 1, characterized in that, For any non-edge distribution line, the fault is determined by comparing it with the starting current and by comparing the phase of the zero-sequence currents of the two buses associated with each line, including: Based on non-edge lines Calculate the zero-sequence current of the busbars on both sides of the busbar connection point for non-edge lines. zero-sequence current ; If zero-sequence current If the current is less than the starting current, then it is determined to be a non-edge circuit. It is a non-faulty line.

3. The fault location method based on a busbar zero-sequence current neutral point ungrounded device as described in claim 2, characterized in that, For any non-edge distribution line, the fault determination is performed by comparing the starting current with the fault current and by comparing the phase of the zero-sequence currents of the two buses associated with each line. This also includes: Based on non-edge lines Calculate the zero-sequence current of the busbars on both sides of the busbar connection point for non-edge lines. zero-sequence current ; If zero-sequence current If the current is greater than the starting current, then the zero-sequence current is determined. Does it meet the first criterion? If so, it is determined to be a non-edge line. It is a faulty line; if it does not meet the criteria, it is determined to be a non-edge line. It is a non-faulty line; The first criterion is based on the directional characteristics of the zero-sequence current in the faulty and non-faulty lines, determined by the phase difference angle between the zero-sequence currents of the two busbars. Determine non-edge lines Is it malfunctioning? 4. The fault location method based on a busbar zero-sequence current neutral point ungrounded device as described in claim 3, characterized in that, The first criterion is based on the directional characteristics of the zero-sequence current in the faulty and non-faulty lines, determined by the phase difference angle between the zero-sequence currents of the two busbars. Determine non-edge lines Whether it is a malfunction, specifically: when When the angle is ≥90°, it is determined to be a non-edge line. The zero-sequence currents on both sides of the busbars are reversed, and the non-edge lines are not affected. The faulty line; when When the angle is less than 90°, it is determined to be a non-edge line. The zero-sequence currents on both sides of the busbar are in the same direction, and the non-edge lines are not in the same direction. This is a non-faulty line.

5. A fault location method based on a busbar zero-sequence current neutral point ungrounded device as described in claim 1 or 4, characterized in that, For peripheral distribution lines, calculate the zero-sequence current of the peripheral lines and compare it with the starting current. Fault identification is then performed by combining the phase and amplitude comparison of the bus zero-sequence current, including: Calculate edge distribution line 1 and edge distribution line zero-sequence current and ; If zero-sequence current If the current is less than the starting current, then edge distribution line 1 is determined to be a non-faulty line; If zero-sequence current If the current is less than the starting current, then it is determined to be an edge distribution line. It is a non-faulty line.

6. The fault location method based on a busbar zero-sequence current neutral point ungrounded device as described in claim 5, characterized in that, For peripheral distribution lines, the zero-sequence current of the peripheral lines is calculated and compared with the starting current. Fault identification is performed by combining the phase and amplitude comparison of the zero-sequence current of the busbar. This also includes: Calculate the zero-sequence current of edge distribution line 1 ; If zero-sequence current If the starting current is greater than or equal to the starting current, then the zero-sequence current is determined. Whether the second criterion is met, if it is met, then the edge distribution line 1 is determined to be a faulty line; if it is not met, then the edge distribution line 1 is determined to be a non-faulty line. The second criterion includes: Assuming only one line fault exists, the phase difference angle of the zero-sequence currents of the two busbars connected through distribution line 2 is... To determine whether edge distribution line 1 is faulty, the specific steps are as follows: like The current amplitude flowing through the zero-sequence current transformer of the first busbar shared by Line 1 and Line 2 is ≤90° and is greater than the current amplitude flowing through the zero-sequence current transformer of the second busbar shared by Line 2 and Line 3 and the difference between the two. When the sum of the values ​​is multiples of the given values, edge line 1 is determined to be a faulty line.

7. The fault location method based on a busbar zero-sequence current neutral point ungrounded device as described in claim 5, characterized in that, For peripheral distribution lines, the zero-sequence current of the peripheral lines is calculated and compared with the starting current. Fault identification is performed by combining the phase and amplitude comparison of the zero-sequence current of the busbar. This also includes: Calculate edge distribution lines zero-sequence current ; If zero-sequence current If the starting current is greater than or equal to the starting current, then the zero-sequence current is determined. Does it meet the third criterion? If so, then the edge distribution line... If the condition is not met, then it is determined to be a peripheral distribution line. It is a non-faulty line; The third criterion includes, If the line The phase angle difference between the zero-sequence currents of the two associated buses ≤90°, and flows through the line With the line The current amplitude of the zero-sequence current transformer on the shared terminal bus is greater than the current flowing through the line. With the line The current amplitude of the shared preceding bus zero-sequence current transformer and the difference between the two When the sum of the times is multiples, the edge distribution lines are determined. Faulty circuit.

8. A fault location system based on a busbar zero-sequence current neutral point ungrounded device, using the method described in any one of claims 1-7, characterized in that, include: The first judgment module is used to compare the starting current with any non-edge distribution line and to make fault judgment based on the phase comparison of the zero-sequence currents of the two buses associated with each line. The second judgment module is used to calculate the zero-sequence current of the edge distribution line and compare it with the starting current. It also combines the phase and amplitude comparison of the zero-sequence current of the bus to make fault judgment.

9. A computer device, characterized in that, include: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the fault selection method based on the bus zero-sequence current neutral point ungrounded device as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It stores computer-executable instructions, which, when executed by a processor, implement the steps of the fault location method based on a busbar zero-sequence current neutral point ungrounded device as described in any one of claims 1 to 7.

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