CN-121978458-A - Distribution network ground fault positioning method based on zero sequence harmonic impedance phase information

CN121978458ACN 121978458 ACN121978458 ACN 121978458ACN-121978458-A

Abstract

The invention provides a distribution network grounding fault positioning method based on zero sequence harmonic impedance phase information, which comprises the following steps of 1, obtaining fault transient zero sequence current data of a plurality of monitoring points on a distribution network line after a grounding fault occurs, 2, calculating zero sequence harmonic impedance phase angles corresponding to the monitoring points based on the fault transient zero sequence current data of the monitoring points, 3, calculating zero sequence harmonic impedance phase angle differences of monitoring points at two ends of a line section formed by adjacent monitoring points, and 4, judging the fault section according to the zero sequence harmonic impedance phase angle differences, wherein if the phase angle difference of a certain section is larger than a preset threshold value, judging the section as a fault section. According to the technical scheme, transient zero sequence current recording data generated by the ground fault are utilized to obtain zero sequence harmonic impedance phase angle information of a downstream line of the FTU, and then the ground fault section is judged by comparing the phase angle information of adjacent FTUs.

Inventors

WU BEN
CHEN CHANG
ZHANG ZHENYU
WANG JUEYING
WANG LIN
WANG JIAN
LUO XIANG
SHENG YUJIE
CAI ZHIPING
GUO ZIYI

Assignees

国网福建省电力有限公司电力科学研究院
国网福建省电力有限公司

Dates

Publication Date: 20260505
Application Date: 20260128

Claims (10)

1. A distribution network ground fault positioning method based on zero sequence harmonic impedance phase information is characterized by comprising the following steps: Step 1, after a ground fault occurs, fault transient state zero sequence current data of a plurality of monitoring points on a power distribution network line are obtained; Step 2, calculating zero sequence harmonic impedance phase angles corresponding to all monitoring points based on the fault transient zero sequence current data of all the monitoring points; Step 3, calculating zero sequence harmonic impedance phase angle differences of monitoring points at two ends of a line section formed by adjacent monitoring points; and 4, judging the fault section according to the zero sequence harmonic impedance phase angle difference, wherein if the phase angle difference of a certain section is larger than a preset threshold value, the section is judged to be the fault section.
2. The method for positioning the ground fault of the distribution network based on the zero sequence harmonic impedance phase information according to claim 1, wherein in the step 4, if the phase angle difference of no section is greater than the preset threshold value, the section where the monitoring point with the minimum zero sequence harmonic impedance phase angle value is located is selected as the fault section.
3. The distribution network grounding fault positioning method based on zero sequence harmonic impedance phase information according to claim 1 is characterized in that in step 1, fault transient zero sequence current data is obtained through cyclic subtraction, specifically, point-by-point subtraction is performed by using zero sequence current sampling point data after fault occurrence and zero sequence current corresponding sampling point data of 4 power frequencies Zhou Bohou of fault occurrence entering a steady state, so as to obtain fault transient zero sequence current sampling point data.
4. The distribution network ground fault locating method based on zero sequence harmonic impedance phase information according to claim 3, wherein the calculation formula in the step 1 is as follows: Wherein i 0 (h) is the value of the h sampling point of the zero sequence current flowing through a feeder terminal unit FTU after the fault occurs, For the value of the h+4D sampling points of the zero sequence current flowing through a feeder terminal unit FTU after the fault occurs, h=0 corresponds to the fault occurrence time, Δi 0 (h) is the value of the h sampling points of the fault transient zero sequence current flowing through the feeder terminal unit FTU, and D is the number of sampling points of 1 power frequency cycle.
5. The method for positioning a distribution network ground fault based on zero sequence harmonic impedance phase information according to claim 1, wherein in step S2, the zero sequence harmonic impedance phase angle is an average phase angle obtained by selecting phase angle calculation of multiple harmonics.
6. The method for positioning a distribution network ground fault based on zero sequence harmonic impedance phase information according to claim 5, wherein the specific calculation process of step S2 is that for a first-end number m feeder terminal unit FTU and a second-end number n feeder terminal unit FTU of a certain line section, according to respective fault transient zero sequence current sampling point data are calculated And Separately calculate And And uploading the master station; Wherein, the Representing the average phase angle of the fault transient zero sequence current at FTU number m, Representing the average phase angle of the fault transient zero sequence current at FTU number n, And Respectively is And The phase angle of the k harmonics of (a), the harmonic fundamental frequency f 0 =12.5 Hz; 、 the phase angles of the fault transient zero sequence currents at the m number and the n number FTU are respectively, and k represents the kth harmonic.
7. The method for positioning a ground fault of a distribution network based on zero sequence harmonic impedance phase information according to claim 6, wherein in step S3, the master station uploads according to the FTU with m number and n number And Calculating the zero sequence harmonic impedance phase angle difference between the head end and the tail end of the line section 。
8. The distribution network ground fault locating method based on zero sequence harmonic impedance phase information according to claim 1, wherein the preset threshold value is 10 °.
9. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements a distribution network ground fault localization method based on zero sequence harmonic impedance phase information according to any one of claims 1 to 8 when executing the computer program.
10. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements a distribution network ground fault localization method based on zero sequence harmonic impedance phase information according to any one of claims 1 to 8.

Description

Distribution network ground fault positioning method based on zero sequence harmonic impedance phase information Technical Field The invention relates to the technical field of distribution network single-phase grounding fault section positioning, in particular to a distribution network grounding fault positioning method based on zero-sequence harmonic impedance phase information. Background The single-phase earth fault occurrence rate of the medium-voltage distribution network is highest, and the single-phase earth fault occurrence rate accounts for about 80% of all faults. The fault section is positioned rapidly and accurately, and is important for shortening the power failure time and improving the power supply reliability. Existing fault section locating methods are mainly divided into two types, namely a method utilizing the characteristics of faults and a method for injecting signals. The method for utilizing the self characteristics of faults has various limitations that the transient zero-sequence current comparison method has strict requirements on equipment sampling precision and communication synchronism, the transient zero-mode power direction method needs to install a voltage transformer at each feeder terminal unit, the cost is high, ferromagnetic resonance is easy to cause, the correlation method has serious dependence on communication network and data transmission quality and is not suitable for complex power distribution networks, and the zero-sequence admittance method can cause the increase of positioning errors due to zero-sequence voltage drop during high-resistance grounding. Whereas the injection signal method requires additional signal injection equipment, increasing system complexity. The signal features of the injection are single, the system harmonic interference is easy to occur, the signal strength is weak when the high-resistance grounding is performed, the anti-interference capability is poor, and the positioning accuracy is difficult to ensure in a complex distribution network environment. Therefore, there is an urgent need in the art for a fault zone locating method that does not rely on a voltage transformer, has low requirements for synchronicity, does not require additional signal injection equipment, and can achieve reliable location under various grounding conditions. Disclosure of Invention Therefore, the invention aims to provide a distribution network ground fault positioning method based on zero sequence harmonic impedance phase information, which utilizes transient zero sequence current recording data generated by a ground fault to acquire zero sequence harmonic impedance phase angle information of a downstream line of an FTU, and further judges a ground fault section by comparing the phase angle information of adjacent FTUs. In order to achieve the purpose, the invention adopts the following technical scheme that the distribution network ground fault positioning method based on zero sequence harmonic impedance phase information comprises the following steps: Step 1, after a ground fault occurs, fault transient state zero sequence current data of a plurality of monitoring points on a power distribution network line are obtained; Step 2, calculating zero sequence harmonic impedance phase angles corresponding to all monitoring points based on the fault transient zero sequence current data of all the monitoring points; Step 3, calculating zero sequence harmonic impedance phase angle differences of monitoring points at two ends of a line section formed by adjacent monitoring points; and 4, judging the fault section according to the zero sequence harmonic impedance phase angle difference, wherein if the phase angle difference of a certain section is larger than a preset threshold value, the section is judged to be the fault section. In a preferred embodiment, in step 4, if the phase angle difference of no segment is greater than the preset threshold, the segment where the monitoring point with the minimum zero sequence harmonic impedance phase angle value is located is selected as the fault segment. In a preferred embodiment, in step 1, the fault transient zero sequence current data is obtained by performing a cyclic subtraction, specifically, the fault transient zero sequence current sampling point data is obtained by performing a point-by-point subtraction between the fault-occurring zero sequence current sampling point data and the fault-occurring zero sequence current corresponding sampling point data of 4 power frequency Zhou Bohou entering a steady state. In a preferred embodiment, the calculation formula in step 1 is: Wherein i 0 (h) is the value of the h sampling point of the zero sequence current flowing through a feeder terminal unit FTU after the fault occurs, For the value of the h+4D sampling points of the zero sequence current flowing through a feeder terminal unit FTU after the fault occurs, h=0 corresponds to the fault occurrence time, Δi 0 (h) is the va