Distribution network grounding fault positioning method based on zero-sequence harmonic impedance phase information

Abstract

The invention provides a distribution network grounding fault positioning method based on zero-sequence harmonic impedance phase information, and the method comprises the following steps: 1, obtaining fault transient zero-sequence current data of a plurality of monitoring points on a power distribution network line after a grounding fault occurs; 2, calculating a zero-sequence harmonic impedance phase angle corresponding to each monitoring point based on the fault transient zero-sequence current data of each monitoring point; 3, for a line section formed by adjacent monitoring points, calculating a zero-sequence harmonic impedance phase angle difference of the monitoring points at the two ends of the section; and step 4, performing fault section judgment according to the zero-sequence harmonic impedance phase angle difference: if the phase angle difference of a certain section is greater than a preset threshold value, judging that the section is a fault section. According to the technical scheme, the zero-sequence harmonic impedance phase angle information of the FTU downstream line is obtained by using the transient zero-sequence current recording data generated by the grounding fault, and then the grounding fault section is judged by comparing the phase angle information of the adjacent FTUs, so that the FTU does not need to be configured with a voltage transformer.

Description

Technical Field

[0001] This invention relates to the field of single-phase grounding fault location technology in distribution networks, and in particular to a method for locating grounding faults in distribution networks based on zero-sequence harmonic impedance phase information. Background Technology

[0002] Single-phase grounding faults have the highest incidence rate in medium-voltage distribution networks, accounting for approximately 80% of all faults. Quickly and accurately locating the fault section is crucial for shortening power outage time and improving power supply reliability. Existing fault section location methods are mainly divided into two categories: methods utilizing the fault's own characteristics and methods injecting signals.

[0003] Methods that utilize the characteristics of faults themselves have several limitations: the transient zero-sequence current comparison method has stringent requirements for equipment sampling accuracy and communication synchronization; the transient zero-mode power direction method requires the installation of voltage transformers at each feeder terminal unit, which is costly and prone to ferroresonance; the correlation method is heavily dependent on the quality of communication networks and data transmission, and is not suitable for complex distribution networks; the zero-sequence admittance method will lead to increased positioning errors due to the drop in zero-sequence voltage when grounding at high resistance.

[0004] The signal injection method requires additional signal injection equipment, increasing system complexity. The injected signal has a single characteristic, is susceptible to system harmonic interference, and exhibits weak signal strength and poor anti-interference capability when grounded at high impedance, making it difficult to guarantee accurate positioning in complex distribution network environments.

[0005] Therefore, there is an urgent need in this field for a fault location method that does not rely on voltage transformers, has low requirements for synchronization, requires no additional signal injection equipment, and can reliably locate fault sections under various grounding conditions. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a distribution network grounding fault location method based on zero-sequence harmonic impedance phase information. The method uses transient zero-sequence current recording data generated by the grounding fault to obtain the zero-sequence harmonic impedance phase angle information of the downstream line of the FTU, and then determines the grounding fault section by comparing the phase angle information of adjacent FTUs. This method does not require the FTU to be equipped with a voltage transformer.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a method for locating grounding faults in distribution networks based on zero-sequence harmonic impedance phase information, comprising the following steps:

[0008] Step 1: After a ground fault occurs, acquire fault transient zero-sequence current data from multiple monitoring points on the distribution network line;

[0009] Step 2: Based on the fault transient zero-sequence current data at each monitoring point, calculate the zero-sequence harmonic impedance phase angle corresponding to each monitoring point;

[0010] Step 3: For a line segment consisting of adjacent monitoring points, calculate the zero-sequence harmonic impedance phase angle difference between the monitoring points at both ends of the segment;

[0011] Step 4: Determine the fault section based on the phase angle difference of the zero-sequence harmonic impedance: If the phase angle difference of a certain section is greater than the preset threshold, then the section is determined to be a fault section.

[0012] In a preferred embodiment, in step 4, if no segment has a phase angle difference greater than the preset threshold, the segment where the monitoring point with the smallest zero-sequence harmonic impedance phase angle value is located is selected as the fault segment.

[0013] In a preferred embodiment, in step 1, the acquisition of fault transient zero-sequence current data is achieved by the cycle subtraction method, specifically by subtracting the zero-sequence current sampling point data after the fault occurs from the zero-sequence current sampling point data corresponding to the zero-sequence current entering steady state after 4 power frequency cycles of the fault to obtain the fault transient zero-sequence current sampling point data.

[0014] In a preferred embodiment, the calculation formula in step 1 is: Where i0(h) is the value of the zero-sequence current flowing through a certain feeder terminal unit (FTU) at the h-th sampling point after the fault occurs. Δi0(h) represents the value of the zero-sequence current flowing through a feeder terminal unit (FTU) at the h+4D sampling point after a fault occurs, where h=0 corresponds to the time of the fault occurrence. Δi0(h) represents the value of the fault transient zero-sequence current flowing through the feeder terminal unit (FTU) at the h-th sampling point, and D represents the number of sampling points for one power frequency cycle.

[0015] In a preferred embodiment, in step S2, the zero-sequence harmonic impedance phase angle is the average phase angle calculated by selecting the phase angles of multiple harmonics.

[0016] In a preferred embodiment, the specific calculation process of step S2 is as follows: For the first-end feeder terminal unit (FTU) m and the last-end feeder terminal unit (FTU) n of a certain line section, the calculation is based on their respective fault transient zero-sequence current sampling point data. and Calculate separately and And upload it to the main site;

[0017]

[0018]

[0019] in, This represents the average phase angle of the fault transient zero-sequence current at FTU m. This represents the average phase angle of the fault transient zero-sequence current at FTU n. and They are respectively and The phase angle of the kth harmonic, and the fundamental frequency of the harmonic f0 = 12.5 Hz; , , respectively, are the phase angles of the fault transient zero-sequence currents at FTUs m and n, and k represents the kth harmonic.

[0020] In a preferred embodiment, in step S3, the main station uploads data based on the data uploaded by FTUs m and n. and Calculate the zero-sequence harmonic impedance phase angle difference between the beginning and end of the line section. .

[0021] In a preferred embodiment, the preset threshold is 10°.

[0022] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements a distribution network grounding fault location method based on zero-sequence harmonic impedance phase information as described above.

[0023] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, it implements a distribution network grounding fault location method based on zero-sequence harmonic impedance phase information as described above.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention utilizes only the zero-sequence current data collected by the FTU, eliminating the need to configure voltage transformers at any monitoring point. This significantly reduces hardware costs and system complexity, and avoids the ferroresonance problem caused by voltage transformers.

[0026] By analyzing the stable characteristic quantity of zero-sequence harmonic impedance phase during the transient process of a fault, and using the average value of multiple harmonic phase angles, the influence of weak signal and system harmonic interference during high-impedance grounding is effectively overcome, resulting in high positioning accuracy.

[0027] This method has relatively relaxed requirements for communication synchronization, does not rely on strict clock synchronization, and is more suitable for actual power distribution network environments with complex topologies and diverse communication conditions. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a fault transient zero-sequence current extraction method according to a preferred embodiment of the present invention. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application; as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise; furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0032] This patent utilizes transient zero-sequence current recording data generated by a ground fault to obtain the zero-sequence harmonic impedance phase angle information of the downstream line of the FTU. Then, by comparing this phase angle information with that of adjacent FTUs, the ground fault section is determined. This method does not require a voltage transformer to be configured on the FTU. The specific steps are as follows:

[0033] Step 1: After a ground fault occurs, each FTU extracts the transient zero-sequence current from its own zero-sequence current recording data using a cycle subtraction method. The extraction method is as follows: Figure 1 As shown.

[0034] By subtracting the zero-sequence current sampling point data after the fault occurs from the corresponding zero-sequence current sampling point data after the fault enters steady state four power frequency cycles, the data of each sampling point of the fault transient zero-sequence current are obtained:

[0035]

[0036] Where i0(h) is the value of the h-th sampling point of the zero-sequence current flowing through a certain FTU after the fault occurs, h=0 corresponds to the time when the fault occurs, Δi0(h) is the value of the h-th sampling point of the fault transient zero-sequence current flowing through the FTU, and D is the number of sampling points of 1 power frequency cycle.

[0037] Step 2: The first m-end FTU and the last n-end FTU of a certain line section collect data from their respective fault transient zero-sequence current sampling points. and Calculate separately and And upload it to the main site.

[0038]

[0039]

[0040] in, and They are respectively and The phase angle of the kth harmonic, and the fundamental frequency of the harmonic f0 = 12.5 Hz.

[0041] Step 3: The main site uploads data based on FTUs m and n. and Calculate the zero-sequence harmonic impedance phase angle difference between the beginning and end of this line section:

[0042]

[0043] Step 4: The main station can obtain the zero-sequence harmonic impedance phase angle difference between the beginning and end of each line segment based on the phase angle data uploaded by each FTU. If the zero-sequence harmonic impedance phase angle difference between the beginning and end of a line segment is >10°, then the segment is determined to be a faulty segment.

[0044] Step 5: If no line segment meets the above conditions, select the segment where the FTU with the smallest θav is located as the fault segment.

Claims

1. A method for locating grounding faults in distribution networks based on zero-sequence harmonic impedance phase information, characterized in that, Includes the following steps: Step 1: After a ground fault occurs, acquire fault transient zero-sequence current data from multiple monitoring points on the distribution network line; Step 2: Based on the fault transient zero-sequence current data at each monitoring point, calculate the zero-sequence harmonic impedance phase angle corresponding to each monitoring point; Step 3: For a line segment consisting of adjacent monitoring points, calculate the zero-sequence harmonic impedance phase angle difference between the monitoring points at both ends of the segment; Step 4: Determine the fault section based on the phase angle difference of the zero-sequence harmonic impedance: If the phase angle difference of a certain section is greater than the preset threshold, then the section is determined to be a fault section.

2. The method for locating distribution network grounding faults based on zero-sequence harmonic impedance phase information according to claim 1, characterized in that, In step 4, if no segment has a phase angle difference greater than the preset threshold, the segment where the monitoring point with the smallest zero-sequence harmonic impedance phase angle value is located is selected as the fault segment.

3. The method for locating distribution network grounding faults based on zero-sequence harmonic impedance phase information according to claim 1, characterized in that, In step 1, the fault transient zero-sequence current data is obtained by the cycle subtraction method, specifically: the zero-sequence current sampling point data after the fault occurs is subtracted point by point from the zero-sequence current sampling point data that enters steady state after 4 power frequency cycles of the fault to obtain the fault transient zero-sequence current sampling point data.

4. The method for locating distribution network grounding faults based on zero-sequence harmonic impedance phase information according to claim 3, characterized in that, The calculation formula in step 1 is: Where i0(h) is the value of the zero-sequence current flowing through a certain feeder terminal unit (FTU) at the h-th sampling point after the fault occurs. Δi0(h) represents the value of the zero-sequence current flowing through a feeder terminal unit (FTU) at the h+4D sampling point after a fault occurs, where h=0 corresponds to the time of the fault occurrence. Δi0(h) represents the value of the fault transient zero-sequence current flowing through the feeder terminal unit (FTU) at the h-th sampling point, and D represents the number of sampling points for one power frequency cycle.

5. The method for locating distribution network grounding faults based on zero-sequence harmonic impedance phase information according to claim 1, characterized in that, In step S2, the zero-sequence harmonic impedance phase angle is the average phase angle calculated by selecting the phase angles of multiple harmonics.

6. The method for locating distribution network grounding faults based on zero-sequence harmonic impedance phase information according to claim 5, characterized in that, The specific calculation process of step S2 is as follows: For the first-end feeder terminal unit (FTU) m and the last-end feeder terminal unit (FTU) n of a certain line section, the calculation is based on the fault transient zero-sequence current sampling point data of their respective units. and Calculate separately and And upload it to the main site; in, This represents the average phase angle of the fault transient zero-sequence current at FTU m. This represents the average phase angle of the fault transient zero-sequence current at FTU n. and They are respectively and The phase angle of the kth harmonic, and the fundamental frequency of the harmonic f0 = 12.5 Hz; , , respectively, are the phase angles of the fault transient zero-sequence currents at FTUs m and n, and k represents the kth harmonic.

7. A method for locating distribution network grounding faults based on zero-sequence harmonic impedance phase information according to claim 6, characterized in that, In step S3, the main site uploads data based on FTUs m and n. and Calculate the zero-sequence harmonic impedance phase angle difference between the beginning and end of the line section. .

8. The method for locating distribution network grounding faults based on zero-sequence harmonic impedance phase information according to claim 1, characterized in that, The preset threshold is 10°.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements a distribution network grounding fault location method based on zero-sequence harmonic impedance phase information as described in any one of claims 1 to 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements a distribution network grounding fault location method based on zero-sequence harmonic impedance phase information as described in any one of claims 1 to 8.

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