CN106872855A - One-phase earthing failure in electric distribution network adaptive failure segmentation method based on transient signal - Google Patents

Abstract

The invention relates to the technical field of distribution automation, in particular to a transient signal-based self-adaptive fault segmentation method for a single-phase grounding fault in a distribution network; comprising the following steps: the main station controls the synchronous acquisition work of the distribution line monitoring equipment on the feeder Frequency current data, transmit the collected power frequency current data to the main station for polarity calculation; the main station receives the data of power distribution monitoring equipment, and calculates the transient zero-mode current similarity coefficient for the zero-mode current data of each device on the fault line ; Comparing the polarity and size of the transient zero-mode current similarity coefficient between adjacent power distribution monitoring equipment in each section on the fault line, and comprehensively judging the fault section; this method can be applied to power distribution overhead lines, cable lines and overhead-cable mixed lines , not affected by distributed power sources, compared with existing methods, it can automatically correct the polarity inconsistency of current transformers, and the constructed criterion can deal with situations such as failure to start or abnormality of power distribution monitoring equipment, which has stronger robustness .

Description

Adaptive fault segmentation method for single-phase-to-ground fault in distribution network based on transient signal

technical field

The invention relates to the technical field of distribution automation, in particular to a transient signal-based self-adaptive fault segmentation method for single-phase grounding faults in distribution networks.

Background technique

The neutral point of my country's distribution network widely adopts the method of small current grounding (not grounding or grounding through the arc suppressing coil), and its single-phase ground fault (small current ground fault) is the main fault form of the distribution network, accounting for 10% of the total number of faults. About 80%. Due to the fault quantity is not prominent (generally only a few amperes, far less than the short-circuit current and load current), unstable (arc ground or intermittent grounding account for a considerable proportion) and uncertain (the arc suppression coil compensation effect makes the power frequency current lose the basic fault characteristics) and other issues, there are great difficulties in small current ground fault detection (line selection and positioning) technology, which has always been a problem that plagues field operation.

On-line detection methods for single-phase-to-ground faults are mainly divided into two categories: steady state method and transient state method.

The steady-state method based on the power frequency fault signal has poor field application effect due to the small power frequency fault current amplitude and unstable signal. Especially in the power distribution system where the neutral point is grounded by the arc suppression coil, since the arc suppression coil operates in the overcompensation mode, it overcompensates the capacitive current in the fault line, resulting in the failure of the criterion of the power frequency method.

The transient method based on the fault transient uses the transient signal with high frequency, large amplitude and short duration generated at the moment of the fault, and selects the fault line and fault section by comparing the direction, amplitude and polarity of the transient current. It has the advantages of high sensitivity and no need to install additional high-voltage equipment.

Using the transient current polarity positioning algorithm, the reference directions of the current transformers (TA) on both sides of the section need to be consistent during application. However, reverse polarity or unclear polarity of TA is very likely to occur on site, which will lead to incorrect calculation of polarity results and misjudgment. In addition, the downstream distribution line monitoring equipment at the fault point may not be able to start due to too small transient current. It will lead to misjudgment of the method.

The single-phase grounding of the small current grounding system will not cause power interruption, which is of great significance for reducing power outages caused by faults. If the detection of small current ground faults can be solved, the on-duty personnel can find the ground line or even the fault section in time, and take corresponding measures to reduce or even avoid the adverse effects caused by the ground fault, so that this grounding method continues to be The power supply department plays a role in ensuring the reliability of power supply.

Contents of the invention

In order to solve the deficiencies in the above-mentioned technical problems, the purpose of the present invention is to provide a transient signal-based self-adaptive fault segmentation method for single-phase ground faults in distribution networks, which can real-time check the reference of current transformers on both sides of the section. Direction is used to solve the problem of field polarity inconsistency, and the signal offset calculation method is used to improve the accuracy of the similarity coefficient of transient zero-mode current.

The technical scheme that the present invention adopts for solving its technical problem is:

The self-adaptive fault segmentation method for a single-phase-to-ground fault in a power distribution network based on a transient signal comprises the following steps:

(1) The master station controls the distribution line monitoring equipment on the feeder to collect power frequency current data synchronously, and transmits the collected power frequency current data to the master station for polarity calculation and saves it in the master station;

(2) When a single-phase ground fault occurs on the distribution line, the terminal of the substation starts according to the zero-mode voltage limit, selects the faulty line, and reports the zero-mode current at the outlet of the faulty line to the main station;

(3) The distribution line monitoring equipment starts according to the sudden change of the zero-mode current at the detection point, and reports the fault zero-mode current to the master station;

(4) The master station receives the data of the power distribution monitoring equipment, and calculates the transient zero-mode current similarity coefficient for the zero-mode current data of each device on the fault line;

(5) Compare the polarity and magnitude of the similarity coefficient of transient zero-mode current between adjacent power distribution monitoring equipment in each section on the faulty line, and make a comprehensive judgment of the faulty section. The criterion for the faulty section is:

a. The main station control feeder has only one section where the transient zero-mode current similarity coefficients between the transient currents on both sides have opposite signs, and this section is a fault section;

b. The master station controls the feeder line and the transient zero-mode current similarity coefficients between the transient currents on both sides of more than one section have opposite signs, then compare the absolute values of the transient zero-mode current similarity coefficients of these sections, and the minimum And the section that is smaller than the set threshold value is a faulty section;

c. The master station controls the sign of the similarity coefficient between the transient currents on both sides of the feeder-free section to be opposite, then compare the magnitude of the absolute value of the transient zero-mode current similarity coefficient of these sections, which is the smallest and less than the set threshold value The section is a fault section; if the transient zero-mode current similarity coefficients are greater than the set threshold, the section downstream of the last power distribution monitoring equipment is a fault section.

Further preferably, the master station controls the polarity calculation of the current transformers on both sides of the section of the feeder:

When the distribution line is in normal operation, through the control of the centralized feeder automation master station or the distributed feeder automation master control node, the distribution line monitoring equipment on both sides of the designated section synchronously collects power frequency current data and transmits it to the centralized feeder automation master station Or perform polarity calculation after the distributed feeder automation main control node, the calculation formula is as follows:

In the formula: sgn() is a sign function; i _0,k (t) and i _0,k+1 (t) are adjacent transient zero-mode currents; the reference node is the power frequency at the outlet circuit breaker of the distribution line Current direction, whose direction is 1.

Further preferably, the calculation method of the transient zero-mode current similarity coefficient is:

When calculating the transient zero-mode current similarity coefficient ρ _k,k+1 between two adjacent detection points transient zero-mode current i _0,k (t) and i _0,k+1 (t), one of them The signal is moderately offset to obtain a series of transient zero-mode current similarity coefficients, and the maximum absolute value is taken as the transient zero-mode current similarity coefficient. which is:

In the formula: sgn(ρ _k,k+1 (τ)) is a sign function, corresponding to the sign of the transient zero-mode current similarity coefficient at the maximum absolute value; T _t is the maximum synchronization between power distribution monitoring equipment in adjacent sections Error; for the current data beyond the recording range [0,T], add 0;

The similarity coefficient calculated by formula (2) is multiplied by the polarity (1) of the current transformers on both sides of the main station control feeder section to obtain the final transient zero-mode current similarity coefficient, the formula is as follows:

ρ _k,k+1 = dir _k,k+1 ρ' _k,k+1 (3)

The similarity coefficient ρ _k,k + ₁ satisfies:

-1≤ρk _,k+ 1≤1 (4).

Further preferably, the preset threshold of the transient zero-mode current similarity coefficient is an empirical value, which is set between 0.5 and 0.8.

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

The present invention solves the field polarity inconsistency problem by calculating the polarity of the power frequency current signal when the power distribution line is in normal operation to check the reference direction of the current transformers on both sides of the section in real time, and uses the signal offset calculation method to improve the transient zero The accuracy of the similarity coefficient of the analog current is constructed by comprehensively using the polarity and amplitude of the similarity coefficient to construct the fault section criterion, which fully considers the failure of the fault section at different fault locations, the non-starting or abnormality of the power distribution monitoring equipment, etc., and enhances the the robustness of the method.

In addition, this method can be applied to power distribution overhead lines, cable lines and overhead-cable hybrid lines, and is not affected by distributed power sources. Compared with existing methods, it can automatically correct the polarity inconsistency of current transformers. It can deal with situations such as power distribution monitoring equipment not starting or abnormality, and has stronger robustness.

detailed description

Embodiments of the present invention are further described below:

The self-adaptive fault segmentation method for a single-phase grounding fault in a distribution network based on a transient signal in the present invention is characterized in that it includes the following steps:

(1) During normal operation, the master station controls the distribution line monitoring equipment on the feeder to collect power frequency current data synchronously, and transmits the collected power frequency current data to the master station for polarity calculation and saves it in the master station;

(2) When a single-phase ground fault occurs on the distribution line, the terminal of the substation starts according to the zero-mode voltage limit, selects the faulty line, and reports the zero-mode current at the outlet of the faulty line to the main station;

(3) The distribution line monitoring equipment starts according to the sudden change of the zero-mode current at the detection point, and reports the fault zero-mode current to the master station;

(4) The master station receives the data of the power distribution monitoring equipment, and calculates the transient zero-mode current similarity coefficient for the zero-mode current data of each device on the fault line;

(5) Comparing the polarity and size of the transient zero-mode current similarity coefficient between adjacent power distribution monitoring equipment in each section on the fault line, and making a comprehensive judgment of the fault section, considering that there is only one adjacent power distribution monitoring equipment in the last section and The power distribution monitoring equipment downstream of the fault point may not be able to start because the transient current is too small, and the fault section criterion is:

a. The main station control feeder has only one section where the transient zero-mode current similarity coefficients between the transient currents on both sides have opposite signs, and this section is a fault section;

b. The master station controls the feeder line and the transient zero-mode current similarity coefficients between the transient currents on both sides of more than one section have opposite signs, then compare the absolute values of the transient zero-mode current similarity coefficients of these sections, and the minimum And the section that is smaller than the set threshold value is a fault section, and the preset threshold of the transient zero-mode current similarity coefficient is an empirical value, which is set between 0.5 and 0.8;

c. The master station controls the sign of the similarity coefficient between the transient currents on both sides of the feeder-free section to be opposite, then compare the magnitude of the absolute value of the transient zero-mode current similarity coefficient of these sections, which is the smallest and less than the set threshold value The section is a fault section; if the transient zero-mode current similarity coefficients are greater than the set threshold, the section downstream of the last power distribution monitoring equipment is a fault section.

The calculation of the polarity of the current transformers on both sides of the section of the main station control feeder:

When the distribution line is in normal operation, through the control of the centralized feeder automation master station or the distributed feeder automation master control node, the distribution line monitoring equipment on both sides of the designated section synchronously collects power frequency current data and transmits it to the centralized feeder automation master station Or perform polarity calculation after the distributed feeder automation main control node, the calculation formula is as follows:

In the formula: sgn() is a sign function; i _0,k (t) and i _0,k+1 (t) are adjacent transient zero-mode currents; the reference node is the power frequency at the outlet circuit breaker of the distribution line Current direction, whose direction is 1.

The calculation method of the transient zero-mode current similarity coefficient is:

In the project, it is difficult to record the transient current signal accurately and synchronously between the power distribution monitoring equipment. When calculating the transient zero-mode current i _0,k (t) and i _0,k+1 (t) of two adjacent detection points When the state zero-mode current similarity coefficient ρ _k,k+1 is used, due to the synchronous sampling error of the power distribution monitoring equipment, the calculation of the similarity coefficient ρ _k,k+1 will be deviated, so it is necessary to correct the deviation to obtain an accurate similarity coefficient. The method is Moderately offset one of the signals to obtain a series of transient zero-mode current similarity coefficients, and take the maximum absolute value as its transient zero-mode current similarity coefficient. which is:

In the formula: sgn(ρ _k,k+1 (τ)) is a sign function, corresponding to the sign of the transient zero-mode current similarity coefficient at the maximum absolute value; T _t is the maximum synchronization between power distribution monitoring equipment in adjacent sections Error; for the current data beyond the recording range [0,T], add 0;

The similarity coefficient calculated by formula (2) is multiplied by the polarity (1) of the current transformers on both sides of the main station control feeder section to obtain the final transient zero-mode current similarity coefficient, the formula is as follows:

ρ _k,k+1 = dir _k,k+1 ρ' _k,k+1 (3)

The similarity coefficient ρ _k,k+1 satisfies:

-1≤ρk _,k+ 1≤1 (4).

Wherein, the algorithm in the method of the present invention runs on the distribution main station in the centralized feeder automation mode or the master control node in the distributed feeder automation mode.

Claims (4)

1. A single-phase-to-ground fault adaptive fault segmentation method for distribution network based on transient signal, is characterized in that, comprises the following steps: (1) The master station controls the distribution line monitoring equipment on the feeder to collect power frequency current data synchronously, and transmits the collected power frequency current data to the master station for polarity calculation and saves it in the master station; (2) When a single-phase ground fault occurs on the distribution line, the terminal of the substation starts according to the zero-mode voltage limit, selects the faulty line, and reports the zero-mode current at the outlet of the faulty line to the main station; (3) The distribution line monitoring equipment starts according to the sudden change of the zero-mode current at the detection point, and reports the fault zero-mode current to the master station; (4) The master station receives the data of the power distribution monitoring equipment, and calculates the transient zero-mode current similarity coefficient for the zero-mode current data of each device on the fault line; (5) Compare the polarity and magnitude of the similarity coefficient of transient zero-mode current between adjacent power distribution monitoring equipment in each section on the faulty line, and make a comprehensive judgment of the faulty section. The criterion for the faulty section is: a. The main station control feeder has only one section where the transient zero-mode current similarity coefficients between the transient currents on both sides have opposite signs, and this section is a fault section; b. The master station controls the feeder line and the transient zero-mode current similarity coefficients between the transient currents on both sides of more than one section have opposite signs, then compare the absolute values of the transient zero-mode current similarity coefficients of these sections, and the minimum And the section that is smaller than the set threshold value is a faulty section; c. The master station controls the sign of the similarity coefficient between the transient currents on both sides of the feeder-free section to be opposite, then compare the magnitude of the absolute value of the transient zero-mode current similarity coefficient of these sections, which is the smallest and less than the set threshold value The section is a fault section; if the transient zero-mode current similarity coefficients are greater than the set threshold, the section downstream of the last power distribution monitoring equipment is a fault section. 2. the distribution network single-phase-to-ground fault adaptive fault segmentation method based on transient signal according to claim 1, it is characterized in that, the polarity calculation of the section both sides current transformer of main station control feeder: When the distribution line is in normal operation, through the control of the centralized feeder automation master station or the distributed feeder automation master control node, the distribution line monitoring equipment on both sides of the designated section synchronously collects power frequency current data and transmits it to the centralized feeder automation master station Or perform polarity calculation after the distributed feeder automation main control node, the calculation formula is as follows: ${\mathrm{<span\; class="notranslate">\; dir</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; g</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$ In the formula: sgn() is a sign function; i _0,k (t) and i _0,k+1 (t) are adjacent transient zero-mode currents; the reference node is the power frequency at the outlet circuit breaker of the distribution line Current direction, whose direction is 1. 3. the distribution network single-phase-to-ground fault self-adaptive fault segmentation method based on transient signal according to claim 1, is characterized in that, the calculation method of transient zero-mode current similarity coefficient is: When calculating the transient zero-mode current similarity coefficient ρ _k,k+1 between two adjacent detection points transient zero-mode current i _0,k (t) and i _0,k+1 (t), one of them The signal is moderately offset to obtain a series of transient zero-mode current similarity coefficients, and the maximum absolute value is taken as the transient zero-mode current similarity coefficient. which is: $\begin{array}{c}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; sgn</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\underset{\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; \&Element;</span><span\; class="notranslate">\; \&lsqb;</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; \&rsqb;</span>}{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; sgn</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\underset{\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; \&Element;</span><span\; class="notranslate">\; \&lsqb;</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; \&rsqb;</span>}{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}}\frac{<span\; class="notranslate">\; |</span>{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; |</span>}{\sqrt{{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}}}\end{array}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$ In the formula: sgn(ρ _k,k+1 (τ)) is a sign function, corresponding to the sign of the transient zero-mode current similarity coefficient at the maximum absolute value; T _t is the maximum synchronization between power distribution monitoring equipment in adjacent sections Error; for the current data beyond the recording range [0,T], add 0; The similarity coefficient calculated by formula (2) is multiplied by the polarity (1) of the current transformers on both sides of the main station control feeder section to obtain the final transient zero-mode current similarity coefficient, the formula is as follows: ρ _k,k+1 = dir _k,k+1 ρ' _k,k+1 (3) The similarity coefficient ρ _k,k+1 satisfies: -1≤ρk _,k+ 1≤1 (4). 4. The self-adaptive fault segmentation method for single-phase-to-ground faults in distribution network based on transient signals according to claim 1, wherein the preset threshold of the transient zero-mode current similarity coefficient is an empirical value, which is set at 0.5 ~0.8.