A method and system for fault type identification of an ac transmission line

Abstract

The application discloses a fault type identification method and system of an alternating current transmission line, comprising the following steps: obtaining the primary value of voltage and current on both sides of the alternating current fault line; calculating the line side voltage phasor and the line side current phasor based on the primary value of voltage and current; calculating the fault point voltage phasor and the fault point current phasor based on the line side voltage phasor and the line side current phasor; calculating the average value of transition resistance based on the fault point voltage phasor and the fault point current phasor; calculating the harmonic component and the non-periodic component of the three-phase fault current, and calculating the total harmonic of the three-phase; calibrating the fault stage based on the fault point current phasor, determining the first fault occurrence time, and determining the fault voltage peak time with the shortest interval from the first fault occurrence time and the voltage peak corresponding to the fault voltage peak time; extracting the fault phase data and the reclosing data, obtaining the weather information; performing comprehensive scoring, and identifying the fault type according to the scoring result.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alternating current transmission line relay protection, and more particularly, to a fault type identification method and system for an alternating current transmission line. BACKGROUND

[0002] In recent years, faults of power transmission lines in China caused by severe abnormal weather have accounted for more than half of the total number of faults. Among various types of severe weather, lightning strike faults of alternating current transmission lines account for a high proportion and are the main cause of line faults and outages. China's ultra-high voltage alternating current lines have occurred in N-2 mode multiple times, which has caused certain impact on the safe operation of power grids and reliable power supply. Rapid and accurate analysis of fault causes after lightning strike faults plays an important role in the investigation and repair of staff and the rapid recovery of power supply.

[0003] However, existing lightning strike fault identification methods mainly rely on manual analysis, and the time required from on-site line inspection to system power restoration is relatively long. In particular, for non-breakdown lightning strike faults, when the fault phenomenon is not obvious, the fault identification method based on manual analysis is difficult to accurately distinguish.

[0004] Therefore, there is a need for a fault type identification method for an alternating current transmission line. SUMMARY

[0005] The present application provides a fault type identification method and system for an alternating current transmission line to solve the problem of how to identify the fault type of an alternating current transmission line.

[0006] In order to solve the above problems, according to one aspect of the present application, a fault type identification method for an alternating current transmission line is provided, the method comprising:

[0007] obtaining primary values of voltage and current on both sides of the alternating current fault line;

[0008] calculating line side voltage phasors and line side current phasors on both sides of the alternating current fault line based on the primary values of voltage and current;

[0009] calculating fault point voltage phasors and fault point current phasors at the fault point based on the line side voltage phasors and the line side current phasors;

[0010] calculating instantaneous transition resistance based on the ratio of the fault point voltage phasors and the fault point current phasors, and calculating average transition resistance based on the instantaneous transition resistance;

[0011] calculating each harmonic component and non-periodic component of three-phase fault current based on the line side current phasors and the fault point current phasors, and calculating harmonic sum of each phase and total harmonic of three phases based on the each harmonic component of three-phase fault current;

[0012] determining a first fault occurrence time, and determining a fault voltage peak time interval from the first fault occurrence time and a voltage peak corresponding to the fault voltage peak time;

[0013] extracting fault phase data and reclosing data based on the field recording file, and obtaining weather information of the fault occurrence time based on a meteorological system;

[0014] comprehensive scoring based on the average transition resistance, the non-periodic component, the harmonic three-phase sum of each phase, the total harmonic, the first fault occurrence time, the fault voltage peak time, the voltage peak corresponding to the fault voltage peak time, the fault phase data, the reclosing data and the weather information, and identifying the fault type according to the scoring result.

[0015] Preferably, wherein based on the line side voltage phasor and the line side current phasor, the fault point voltage phasor and the fault point current phasor at the fault point are calculated, including:

[0016]

[0017] Wherein, the fault point voltage phasor and the fault point current phasor are obtained by substituting the line side voltage phasor and the line side current phasor into the above formula and solving; L is the length of the AC transmission line, r, l and c are the resistance, inductance and capacitance per unit length of the AC transmission line; u f , i f and R f are the fault point voltage, the fault point current and the transition resistance; x is the length of the fault point from the M side of the AC transmission line, u m , u n , i m and i n are the line side voltage phasor and the line side current phasor of the M side and the N side of the AC transmission line.

[0018] Preferably, wherein the determination of the first fault occurrence time based on the fault point current phasor includes:

[0019] Based on the fault point current phasor, the phase current mutation method is used to detect the first fault time, if there are continuous preset number of phase current mutations greater than the preset phase current mutation threshold, it is determined that a fault occurs, and the time of the first point in the continuous preset number of sampling points is taken as the first fault occurrence time.

[0020] Preferably, wherein the based on the average value of the transition resistance, non-periodic component, harmonic sum of each phase, three-phase total harmonic, the first fault occurs at the moment, the moment of the fault voltage peak, the voltage peak corresponding to the moment of the fault voltage peak, fault phase data, reclosing data and weather information are comprehensively scored, and the fault type is identified according to the score result, comprising:

[0021] Based on the fault phase data, it is judged whether it is a single-phase ground fault, if yes, the first score is determined as a first preset score, otherwise, the first score is determined as a second preset score;

[0022] If the average value of the transition resistance is greater than the preset transition resistance threshold, it is determined as a metallic fault, and the second score is determined as the first preset score, otherwise, the second score is linearly determined based on the difference between the average value of the transition resistance and the preset transition resistance threshold; wherein the lowest score is 0;

[0023] If the reclosing data is determined to be successful, the third score is determined as the first preset score, otherwise, the third score is determined as 0;

[0024] Based on the non-periodic component, the fourth score is linearly determined; wherein the highest score is the first preset score, and the lowest score is 0;

[0025] Based on the sum of the three-phase total harmonic, the fifth score is linearly determined; wherein the highest score is the first preset score, and the lowest score is 0;

[0026] Based on the first fault occurs at the moment, the moment of the fault voltage peak and the voltage peak corresponding to the moment of the fault voltage peak, it is judged whether the fault moment is at the voltage peak, if yes, the sixth score is determined as the first preset score, otherwise, the sixth score is linearly determined based on the time interval between the fault moment and the moment of the fault voltage peak; wherein the highest score is the first preset score, and the lowest score is 0;

[0027] Based on the weather information, the season of the fault occurrence is determined, and the seventh score is determined based on the season;

[0028] According to each score, the weighted sum is calculated to determine the comprehensive score;

[0029] If the comprehensive score is greater than the preset score threshold, it is determined that the fault type is non-breakdown lightning fault.

[0030] Preferably, wherein the method further comprises:

[0031] If the total harmonic content of any side of the alternating current fault line is greater than the preset total harmonic content threshold, the fault type is directly determined as non-breakdown lightning fault.

[0032] According to another aspect of the present application, there is provided a fault type identification system for an AC transmission line, the system comprising:

[0033] a voltage and current primary value acquisition unit configured to acquire voltage and current primary values on both sides of the AC fault line;

[0034] a line side voltage and current phasor calculation unit configured to calculate line side voltage and current phasors on both sides of the AC fault line based on the voltage and current primary values, respectively;

[0035] a fault point voltage and current phasor calculation unit configured to calculate fault point voltage and current phasors at the fault point based on the line side voltage and current phasors;

[0036] a transition resistance average value calculation unit configured to calculate an instantaneous transition resistance based on a ratio of the fault point voltage and current phasors, and to calculate a transition resistance average value based on the instantaneous transition resistance;

[0037] a harmonic calculation unit configured to calculate harmonic components and non-periodic components of three-phase fault current based on the line side current phasors and the fault point current phasors, and to calculate harmonic sums of each phase and total harmonics of three phases based on the harmonic components of the three-phase fault current;

[0038] a fault calibration unit configured to calibrate a fault stage based on the fault point current phasor, to determine a first fault occurrence time, to determine a fault voltage peak time with the shortest interval from the first fault occurrence time and a voltage peak corresponding to the fault voltage peak time;

[0039] an information acquisition unit configured to extract fault phase data and reclosing data based on a field recording file, and to acquire weather information of the fault occurrence time based on a meteorological system;

[0040] a fault type identification unit configured to comprehensively score the transition resistance average value, the non-periodic components, the harmonic sums of each phase, the total harmonics of three phases, the first fault occurrence time, the fault voltage peak time, the voltage peak corresponding to the fault voltage peak time, the fault phase data, the reclosing data and the weather information, and to identify the fault type according to the scoring result.

[0041] Preferably, the fault point voltage and current phasor calculation unit calculates the fault point voltage and current phasors at the fault point based on the line side voltage and current phasors, comprising:

[0042]

[0043] Wherein, the fault point voltage phasor and the fault point current phasor are obtained by bringing the line side voltage phasor and the line side current phasor into the above formula and solving; L is the length of the AC transmission line, r, l and c are the resistance, inductance and capacitance per unit length of the AC transmission line respectively; u f , f and R f are the fault point voltage, the fault point current and the transition resistance respectively; x is the length of the fault point from the M side of the AC transmission line, u m , u n , i m and i n are the line side voltage phasor and the line side current phasor of the M side and the N side of the AC transmission line respectively.

[0044] Preferably, wherein the fault calibration unit, based on the fault point current phasor, calibrates the fault stage, determines the first fault occurrence time, comprising:

[0045] Based on the fault point current phasor, the phase current mutation quantity detection method is used to detect the first fault time, if there are continuous preset number of phase current mutation quantities greater than the preset phase current mutation quantity threshold, it is determined that a fault occurs, and the time of the first point in the continuous preset number of sampling points is taken as the first fault occurrence time.

[0046] Preferably, wherein the fault type identification unit, based on the transition resistance average, the non-periodic component, the harmonic of each phase, the total harmonic of three phases, the first fault occurrence time, the fault voltage peak time, the voltage peak value corresponding to the fault voltage peak time, the fault phase data, the reclosing data and the weather information Comprehensive scoring, and according to the scoring result, the fault type is identified, comprising:

[0047] Based on the fault phase data, it is judged whether it is a single-phase ground fault, if so, it is determined that the first score is a first preset score, otherwise, it is determined that the first score is a second preset score;

[0048] If the transition resistance average is greater than the preset transition resistance threshold, it is determined to be a metallic fault, and the second score is determined to be a first preset score, otherwise, the second score is linearly determined based on the difference between the transition resistance average and the preset transition resistance threshold; Where the lowest score is 0;

[0049] If it is determined that the reclosing is successful based on the reclosing data, it is determined that the third score is a first preset score, otherwise, it is determined that the third score is 0;

[0050] Based on the non-periodic component, the fourth score is linearly determined; Where the highest score is a first preset score, and the lowest score is 0;

[0051] linearly determine the fifth score based on the sum of the three-phase total harmonics; wherein the highest score is the first preset score and the lowest score is 0;

[0052] linearly determine the sixth score based on the time interval between the fault time and the fault voltage peak time; wherein the highest score is the first preset score and the lowest score is 0;

[0053] determine the seventh score based on the season of the fault occurrence;

[0054] perform weighted summation according to each score to determine a comprehensive score;

[0055] if the comprehensive score is greater than a preset score threshold, determine that the fault type is a non-breakdown lightning fault.

[0056] Preferably, the fault recognition unit is further configured to:

[0057] if the total harmonic content on either side of the AC fault line is greater than a preset total harmonic content threshold, directly determine that the fault type is a non-breakdown lightning fault.

[0058] According to another aspect of the present application, the present application provides a computer readable storage medium having a computer program stored thereon, the program being executed by a processor to implement the steps of any one of the fault type recognition methods of the AC power transmission line.

[0059] According to another aspect of the present application, the present application provides an electronic device comprising:

[0060] the computer readable storage medium described above; and

[0061] one or more processors configured to execute the program in the computer readable storage medium.

[0062] The application provides a fault type identification method and system of an AC transmission line, comprising the following steps: obtaining the primary value of voltage and current on both sides of the AC fault line; calculating the line side voltage phasor and the line side current phasor on both sides of the AC fault line based on the primary value of voltage and current; calculating the fault point voltage phasor and the fault point current phasor at the fault point based on the line side voltage phasor and the line side current phasor; calculating the instantaneous transition resistance based on the ratio of the fault point voltage phasor and the fault point current phasor, and calculating the average value of the transition resistance based on the instantaneous transition resistance; calculating the harmonic component and the non-periodic component of the three-phase fault current based on the line side current phasor and the fault point current phasor, and calculating the harmonic sum of each phase and the total harmonic of three phases based on the harmonic component of the three-phase fault current; calibrating the fault stage based on the fault point current phasor, determining the first fault occurrence time, and determining the fault voltage peak time with the shortest interval from the first fault occurrence time and the voltage peak corresponding to the fault voltage peak time; extracting the fault phase data and the reclosing data based on the field recording file, and obtaining the weather information of the fault occurrence time based on the meteorological system; comprehensively scoring the average value of the transition resistance, the non-periodic component, the harmonic sum of each phase, the total harmonic of three phases, the first fault occurrence time, the fault voltage peak time, the voltage peak corresponding to the fault voltage peak time, the fault phase data, the reclosing data and the weather information, and identifying the fault type according to the scoring result. The method of the application can make full use of various fault characteristic quantities generated when the AC line fault occurs, so as to accurately and quickly identify the fault type, and the required fault information can be accurately obtained in the recording file after the fault occurs, which meets the engineering design requirements and can be popularized and applied in 220kV and 500kV AC lines. BRIEF DESCRIPTION OF DRAWINGS

[0063] The exemplary embodiments of the application can be more completely understood in reference to the following drawings:

[0064] Figure 1 The flow chart of the fault type identification method 100 of the AC transmission line according to the embodiment of the application;

[0065] Figure 2 The flow chart of the identification process according to the embodiment of the application;

[0066] Figure 3 The circuit diagram of the double-ended PI type transmission line according to the embodiment of the application;

[0067] Figure 4 The structural schematic diagram of the fault type identification system 400 of the AC transmission line according to the embodiment of the application. DETAILED DESCRIPTION

[0068] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0069] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0070] Given the shortcomings of existing technologies that cannot identify non-breakdown lightning strike faults by relying solely on line voltage abrupt changes, this invention proposes an AC line fault cause identification method based on fault mechanism and fault electrical characteristics. This method can make full use of the various fault characteristic quantities generated when an AC line fault occurs, thereby accurately and quickly identifying the fault type.

[0071] Figure 1 This is a flowchart of a fault type identification method 100 for AC transmission lines according to an embodiment of the present invention. Figure 1 As shown, the fault type identification method for AC transmission lines provided by this invention can fully utilize the various fault characteristic quantities generated when an AC line fault occurs, thereby accurately and quickly identifying the fault type. The fault information required for calculation can be accurately obtained from the waveform recording file after the fault occurs, meeting engineering design requirements and can be widely applied in 220kV and 500kV AC lines. The fault type identification method 100 for AC transmission lines provided by this invention starts from step 101, where the primary values ​​of voltage and current on both sides of the AC fault line are obtained.

[0072] Combination Figure 2 As shown, in this invention, the data required for fault identification is first obtained based on on-site waveform recording data, including: AC line voltage level, AC line length, AC line resistance per unit length, reactance, inductance and capacitance, distance from the fault point to both sides of the fault, line voltage transformer ratio, line current transformer ratio, etc. Then, data processing is performed based on the obtained readings, and the data collected by the voltage and current transformers is converted into primary values. The two ends of the faulty line are the M side and the N side, respectively. The conversion expression for the M side data is:

[0073]

[0074] In the formula, IAM I BM I CM These are the sampled values ​​of the current transformer in the AC line, I AMP1 I BMP1 I CMP1 These are the primary current values ​​on the M side of the AC line, U AM U BM U CM These are the sampled values ​​of the voltage transformer in the AC line, U AMP1 U BMP1 U CMP1 These are the primary voltage values ​​on the M side of the AC line, I 03MP1 and U 03MP1 These represent the zero-sequence current and zero-sequence voltage at the fault point of the AC fault line, respectively. CT_M and PT_M represent the current and voltage transformer ratio on the M side of the AC line, respectively.

[0075] The reduction expression for the N-side data is:

[0076]

[0077] In the formula, I AN I BN I CN These are the sampled values ​​of the current transformer in the AC line, I ANP1 I BNP1 I CNP1 These are the primary current values ​​on the N side of the AC line, U AN U BN U CN These are the sampled values ​​of the voltage transformer in the AC line, U ANP1 U BNP1 U CNP1 These are the primary voltage values ​​on the N-side of the AC line, I 03NP1 and U 03NP1 These represent the zero-sequence current and zero-sequence voltage at the fault point of the AC fault line, respectively. CT_N and PT_N represent the current and voltage transformer ratio on the N side of the AC line, respectively.

[0078] Additionally, if a high-resistance current exists in the AC line, it is necessary to further calculate the high-resistance current and subtract it from the above data reduction expression to obtain the primary current value. The expression for calculating the high-resistance current is:

[0079]

[0080] In the formula, I GKAMP1 I GKBMP1 I GKCMP1 These are the primary values ​​of the high reactance current on the M side of the AC line, I. GKAM I GKBM, I GKCM are M side high resistance current transformer ratio, I GKANP1 , I GKBNP1 , I GKCNP1 are AC line N side high resistance current primary value, I GKAN , I GKBN , I GKCN are N side high resistance current transformer ratio.

[0081] In step 102, the line side voltage phasor and the line side current phasor on both sides of the AC fault line are calculated based on the voltage and current primary values respectively.

[0082] In the present application, the line side voltage phasor and the line side current phasor on both sides of the AC fault line are calculated based on the voltage and current primary values by using the back Fourier algorithm. In the back Fourier algorithm, 12 points can be sampled in each power frequency cycle.

[0083] In step 103, the fault point voltage phasor and the fault point current phasor at the fault point are calculated based on the line side voltage phasor and the line side current phasor.

[0084] Preferably, wherein the fault point voltage phasor and the fault point current phasor at the fault point are calculated based on the line side voltage phasor and the line side current phasor, comprising:

[0085]

[0086] Wherein, the fault point voltage phasor and the fault point current phasor are obtained by substituting the line side voltage phasor and the line side current phasor into the above formula and solving; L is the length of the AC transmission line, r, l and c are the resistance, inductance and capacitance per unit length of the AC transmission line respectively; u f , i f and R f are the fault point voltage, the fault point current and the transition resistance respectively; x is the length of the fault point from the M side of the AC transmission line, u m , u n , i m and i n are the line side voltage phasor and the line side current phasor on the M side and the N side of the AC transmission line respectively.

[0087] In step 104, the instantaneous transition resistance is calculated based on the ratio of the fault point voltage phasor and the fault point current phasor, and the average value of the transition resistance is calculated based on the instantaneous transition resistance.

[0088] In the present application, based on the line side voltage phasor and the line side current phasor on both sides of the line obtained in step 102, the fault point voltage phasor and the fault point current phasor at the fault point are calculated by solving differential equations, and the instantaneous transition resistance is calculated based on the fault point voltage phasor and the fault point current phasor, and the average transition resistance in the fault stage is calculated based on the instantaneous transition resistance. As shown in the accompanying drawings, a double-ended PI type transmission line is taken as an example. The expressions of the fault point voltage and the fault point current are as follows: Figure 3

[0089]

[0090] In the formula, L is the length of the AC transmission line, r, l and c are the resistance, inductance and capacitance per unit length of the AC transmission line respectively. u f , i f and R f are the fault point voltage, current and transition resistance respectively, x is the length of the fault point from the M side of the AC transmission line, u m , u n , i m and i n are the voltages and currents on the M side and the N side of the AC transmission line respectively.

[0091] By simultaneously solving equations (9)-(11), and bringing the voltage phasor and the current phasor on both sides of the line calculated in step 102 into the above expressions, the fault point voltage u f (t) and the fault point current i f (t) can be solved. Then the instantaneous transition resistance at the fault point can be calculated as:

[0092] R f (t) = u f (t) / i f (t) (12)

[0093] The average transition resistance is calculated based on the instantaneous transition resistance as:

[0094]

[0095] In the formula, R avg is the average transition resistance, N is the total number of sampling points in one power frequency cycle, and R f (i) is the instantaneous value of the transition resistance calculated at each sampling point.

[0096] In step 105, the harmonic components and the non-periodic component of the three-phase fault current are calculated based on the line side current phasor and the fault point current phasor, and the harmonic sum of each phase and the total harmonic of the three phases are calculated based on the harmonic components of the three-phase fault current.

[0097] ​In the present application, based on the AC fault line current phasor obtained in step 102 and the fault point current phasor obtained in step 103, the Fourier algorithm is used to calculate the harmonic components and non-periodic components of the three-phase fault current respectively, and the harmonic sum of each phase and the total harmonic of three phases are calculated.

[0098] In step 106, the fault stage is calibrated based on the fault point current phasor, the first fault occurrence time is determined, and the fault voltage peak time with the shortest interval from the first fault occurrence time and the voltage peak value corresponding to the fault voltage peak time are determined.

[0099] Preferably, wherein the fault stage is calibrated based on the fault point current phasor, the first fault occurrence time is determined, comprising:

[0100] Based on the fault point current phasor, the phase current mutation quantity detection method is used to detect the first fault occurrence time, if there are continuous preset number of phase current mutation quantities greater than the preset phase current mutation quantity threshold, it is determined that a fault occurs, and the time of the first point in the continuous preset number of sampling points is taken as the first fault occurrence time.

[0101] In the present application, the fault stage is calibrated based on the fault point voltage phasor and the fault point current phasor obtained in step 103. Specifically, the phase current mutation quantity detection method is used to detect the first fault occurrence time. In order to avoid the influence of data disturbance, three continuous points are judged. Specifically: if the phase current mutation quantity of the continuous 3 sampling points is greater than the threshold, it is determined that a fault occurs, and the time of the first point in the continuous preset number of sampling points is taken as the first fault occurrence time. Based on the geomagnetic fault occurrence time, the fault voltage peak time closest to the first fault occurrence time and the voltage peak value corresponding to the time are found.

[0102] In addition, the present application can also use the phase current size detection trip time, specifically: in a time window, if more than 95% of the elements are less than the threshold, it is determined that the trip is realized.

[0103] In step 107, the fault phase data and the reclosing data are extracted based on the field recording file, and the weather information of the fault occurrence time is obtained based on the meteorological system.

[0104] In step 108, based on the transition resistance average value, the non-periodic component, the harmonic sum of each phase, the total harmonic of three phases, the first fault occurrence time, the fault voltage peak time, the voltage peak value corresponding to the fault voltage peak time, the fault phase data, the reclosing data and the weather information, a comprehensive score is made, and the fault type is identified according to the score result.

[0105] Preferably, wherein the based on the average value of the transition resistance, non-periodic component, each phase of the sum of the three-phase total harmonic, the first fault occurs at the moment, the moment of the fault voltage peak, the corresponding voltage peak of the moment of the fault voltage peak, fault phase data, reclosing data and weather information are comprehensive score, and according to the score result, the fault type is identified, comprising:

[0106] Based on the fault phase data, it is judged whether it is a single-phase ground fault, if yes, the first score is determined as a first preset score, otherwise, the first score is determined as a second preset score;

[0107] If the average value of the transition resistance is greater than the preset transition resistance threshold, it is determined as a metallic fault, and the second score is determined as the first preset score, otherwise, the second score is linearly determined based on the difference between the average value of the transition resistance and the preset transition resistance threshold; wherein the lowest score is 0;

[0108] If the reclosing data is determined to be successful, the third score is determined as the first preset score, otherwise, the third score is determined as 0;

[0109] Based on the non-periodic component, the fourth score is linearly determined; wherein the highest score is the first preset score, and the lowest score is 0;

[0110] Based on the sum of the three-phase total harmonic, the fifth score is linearly determined; wherein the highest score is the first preset score, and the lowest score is 0;

[0111] Based on the first fault occurs at the moment, the moment of the fault voltage peak and the corresponding voltage peak of the moment of the fault voltage peak, it is judged whether the fault moment is at the voltage peak, if yes, the sixth score is determined as the first preset score, otherwise, the sixth score is linearly determined based on the time interval between the fault moment and the moment of the fault voltage peak; wherein the highest score is the first preset score, and the lowest score is 0;

[0112] Based on the weather information, the season of the fault occurrence is determined, and the seventh score is determined based on the season;

[0113] According to each score, the weighted sum is calculated to determine the comprehensive score;

[0114] If the comprehensive score is greater than the preset score threshold, it is determined that the fault type is a non-breakdown lightning fault.

[0115] Combined Figure 2 As shown in the figure, in the present application, the fault phase and reclosing information are extracted based on the field recording file, and the weather information at the fault occurrence time is extracted in combination with the meteorological system. Then, based on the various information obtained in the above steps, the comprehensive score is calculated to identify the non-breakdown lightning fault.

[0116] In the present application, according to the non-breakage lightning stroke failure mechanism analysis, the failure judgment is divided into 7 items, including:

[0117] The first item is the failure type item; based on the failure phase, if the failure type is single-phase ground fault, the first item is assigned 100 points, if it is other failure, the first item is assigned 10 points;

[0118] The second item is the failure property item; if the transition resistance is greater than the preset resistance threshold, it is determined as the metallic failure property, and the second item is assigned 100 points; otherwise, if it is less than or equal to the preset resistance threshold, it is determined as the non-metallic failure property, and the score is linearly reduced according to the transition resistance value, and the lowest score is 0 points;

[0119] The third item is the reclosing success rate item; if the reclosing success is determined based on the reclosing information obtained in step 107, the third item is assigned 100 points, if the reclosing is unsuccessful, the third item is assigned 0 points;

[0120] The fourth item is the non-periodic component item; the score is linearly determined, the larger the non-periodic component, the higher the score, the highest score is 100 points, and the lowest score is 0 points;

[0121] The fifth item is the harmonic content item; based on the sum of the three-phase total harmonic, the score is linearly determined, the higher the harmonic content, the higher the score, the highest score is 100 points, and the lowest score is 0 points;

[0122] The sixth item is the failure time item; based on the first failure time, the failure voltage peak time and the voltage peak value corresponding to the failure voltage peak time, it is judged whether the failure time is at the voltage peak value, if the failure time is at the voltage peak value, the sixth item is 100 points, and the farther from the peak value, the score is linearly reduced, and the lowest score is 0 points;

[0123] The seventh item is the season item; if the failure occurs in spring and summer, the seventh item is assigned 90 points, if the failure occurs in autumn, the seventh item is assigned 70 points, and if the failure occurs in winter, the seventh item is assigned 10 points.

[0124] Then, according to the weight of the above-mentioned 7 items, weighted sum is respectively carried out, so as to determine the comprehensive score. Among them, the weight of the above-mentioned 7 items can be respectively 0.15, 0.15, 0.1, 0.2, 0.2, 0.1, 0.1.

[0125] Finally, according to the comprehensive score, the failure identification is carried out. The larger the score of the comprehensive score, the higher the non-breakage lightning stroke failure. Therefore, in the present application, if the comprehensive score is greater than the preset score threshold, it is determined that the failure type is non-breakage lightning stroke failure.

[0126] Preferably, wherein the method further comprises:

[0127] If the total harmonic content of any side of the AC fault line is greater than the preset total harmonic content threshold, the fault type is directly determined as non-breakthrough lightning fault.

[0128] In the present application, the fault recognition can also be directly based on the total harmonic content. Specifically, if the total harmonic content of one side of the total harmonic content of the two sides of the fault current is greater than the preset total harmonic content threshold, the fault is immediately identified as a non-breakthrough lightning fault.

[0129] The present application aims at the shortcomings of the existing lightning fault recognition method mainly relying on manual analysis, and the existing technology cannot recognize non-breakthrough lightning fault by using line voltage mutation quantity, and proposes an AC line fault recognition method based on fault mechanism and fault electrical characteristics, which can fully utilize various fault characteristic quantities generated when the AC line fault occurs, thereby accurately and quickly recognizing the fault type.

[0130] Figure 4 The structure schematic diagram of the fault type recognition system 400 of the AC transmission line according to the embodiment of the present application. As shown in Figure 4 The AC transmission line fault type recognition system 400 provided by the embodiment of the present application includes: a voltage and current primary value acquisition unit 401, a line side voltage and current phasor calculation unit 402, a fault point voltage and current phasor calculation unit 403, a transition resistance average value calculation unit 404, a harmonic calculation unit 405, a fault calibration unit 406, an information acquisition unit 407, and a fault type recognition unit 408.

[0131] Preferably, the voltage and current primary value acquisition unit 401 is configured to acquire the voltage and current primary values of the two sides of the AC fault line.

[0132] Preferably, the line side voltage and current phasor calculation unit 402 is configured to calculate the line side voltage phasor and the line side current phasor of the two sides of the AC fault line based on the voltage and current primary values.

[0133] Preferably, the fault point voltage and current phasor calculation unit 403 is configured to calculate the fault point voltage phasor and the fault point current phasor at the fault point based on the line side voltage phasor and the line side current phasor.

[0134] Preferably, the fault point voltage and current phasor calculation unit 403 calculates the fault point voltage phasor and the fault point current phasor at the fault point based on the line side voltage phasor and the line side current phasor, including:

[0135]

[0136] Wherein, the fault point voltage phasor and the fault point current phasor are obtained by bringing the line side voltage phasor and the line side current phasor into the above formula and solving; L is the length of the AC transmission line, r, l and c are the resistance, inductance and capacitance per unit length of the AC transmission line respectively; u f f and R f are the fault point voltage, the fault point current and the transition resistance respectively; x is the length of the fault point from the M side of the AC transmission line, u m n m and i n are the line side voltage phasor and the line side current phasor of the M side and the N side of the AC transmission line respectively.

[0137] Preferably, the transition resistance average value calculation unit 404 is configured to calculate the instantaneous transition resistance based on the ratio of the fault point voltage phasor and the fault point current phasor, and calculate the transition resistance average value based on the instantaneous transition resistance.

[0138] Preferably, the harmonic calculation unit 405 is configured to calculate the harmonic components and the non-periodic component of the three-phase fault current based on the line side current phasor and the fault point current phasor, and calculate the harmonic sum of each phase and the total harmonic of three phases based on the harmonic components of the three-phase fault current.

[0139] Preferably, the fault calibration unit 406 is configured to calibrate the fault stage based on the fault point current phasor, determine the first fault occurrence time, and determine the fault voltage peak time with the shortest interval from the first fault occurrence time and the voltage peak value corresponding to the fault voltage peak time.

[0140] Preferably, the fault calibration unit 406 calibrates the fault stage based on the fault point current phasor to determine the first fault occurrence time, which comprises:

[0141] The first fault occurrence time is detected by using the phase current mutation method based on the fault point current phasor, and if the continuous preset number of phase current mutations are all greater than the preset phase current mutation threshold, it is determined that a fault occurs, and the time of the first point in the continuous preset number of sampling points is taken as the first fault occurrence time.

[0142] Preferably, the information acquisition unit 407 is configured to extract the fault phase data and the reclosing data based on the field recording file, and acquire the weather information of the fault occurrence time based on the meteorological system.

[0143] ​​​Preferably, the fault type identification unit 408 is configured to comprehensively score based on the average transition resistance, the aperiodic component, the harmonic sum of each phase, the total harmonic of three phases, the first fault occurrence time, the fault voltage peak time, the voltage peak corresponding to the fault voltage peak time, the fault phase data, the reclosing data, and the weather information, and identify the fault type according to the scoring result.

[0144] Preferably, the fault type identification unit 408 is configured to comprehensively score based on the average transition resistance, the aperiodic component, the harmonic sum of each phase, the total harmonic of three phases, the first fault occurrence time, the fault voltage peak time, the voltage peak corresponding to the fault voltage peak time, the fault phase data, the reclosing data, and the weather information, and identify the fault type according to the scoring result.

[0145] Based on the fault phase data, it is determined whether it is a single-phase ground fault, if so, the first score is determined as a first preset score, otherwise, the first score is determined as a second preset score;

[0146] If the average transition resistance is greater than a preset transition resistance threshold, it is determined as a metallic fault, and the second score is determined as the first preset score, otherwise, the second score is linearly determined based on the difference between the average transition resistance and the preset transition resistance threshold; wherein the lowest score is 0;

[0147] If it is determined based on the reclosing data that the reclosing is successful, the third score is determined as the first preset score, otherwise, the third score is determined as 0;

[0148] Based on the aperiodic component, the fourth score is linearly determined; wherein the highest score is the first preset score, and the lowest score is 0;

[0149] Based on the sum of the total harmonic of three phases, the fifth score is linearly determined; wherein the highest score is the first preset score, and the lowest score is 0;

[0150] Based on the first fault occurrence time, the fault voltage peak time, and the voltage peak corresponding to the fault voltage peak time, it is determined whether the fault time is at the voltage peak, if so, the sixth score is determined as the first preset score, otherwise, the sixth score is linearly determined based on the time interval between the fault time and the fault voltage peak time; wherein the highest score is the first preset score, and the lowest score is 0;

[0151] Based on the weather information, the season of the fault occurrence is determined, and the seventh score is determined based on the season;

[0152] According to each score, a weighted sum is performed to determine a comprehensive score;

[0153] If the comprehensive score is greater than a preset score threshold, it is determined that the fault type is a non-breakdown lightning stroke fault.

[0154] Preferably, the fault identification unit 408 is further configured to:

[0155] If the total harmonic content on either side of the AC fault line is greater than the pre-set total harmonic content threshold, the fault type is directly determined as non-breakdown lightning fault.

[0156] The fault type identification system 400 of the AC power transmission line corresponds to the fault type identification method 100 of another embodiment of the present application, which will not be described here again.

[0157] Based on another aspect of the present application, the present application provides a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of any one of the fault type identification methods of the AC power transmission line.

[0158] Based on another aspect of the present application, the present application provides an electronic device comprising:

[0159] the computer readable storage medium described above; and

[0160] one or more processors configured to execute the program in the computer readable storage medium.

[0161] The present application has been described by reference to a few embodiments. However, one skilled in the art will understand that other embodiments, which are not explicitly described herein, are equally encompassed by the present application as defined by the appended claims. The specification and drawings are, accordingly, to be regarded simply as an illustration of the embodiment of the application as described by the claims.

[0162] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a" or "an" means "at least one" unless otherwise clearly indicated by the context of the only language "the". The steps of any methods disclosed herein need not be performed in the exact order disclosed, unless explicitly stated.

[0163] Those skilled in the art will appreciate that embodiments of the present application can be devised for use with three-dimensional, quantum-conputing, and optical computing systems. One skilled in the art will further recognize the opportunity for adaptation of the methods and systems described herein to a variety of other applications.

[0164] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 one or more flow or blocks

[0165] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 one or more flow or blocks

[0166] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 one or more flow or blocks

[0167] Finally, it should be noted that the above-mentioned embodiments are merely used to illustrate the technical solutions of the present application, rather than limit the technical solutions of the present application. Although the present application is described in detail with reference to the above embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced, and any modification or replacement without departing from the spirit and scope of the present application should be covered in the protection scope of the claims of the present application.

Claims

1. A method of fault type identification for an AC power transmission line, characterized by, The method includes: Obtain the primary values ​​of voltage and current on both sides of the AC fault line; Based on the primary values ​​of voltage and current, calculate the line-side voltage phasor and line-side current phasor on both sides of the AC fault line respectively. Based on the line-side voltage phasor and the line-side current phasor, calculate the fault point voltage phasor and the fault point current phasor at the fault point. The instantaneous transition resistance is calculated based on the ratio of the fault point voltage phasor to the fault point current phasor, and the average transition resistance is calculated based on the instantaneous transition resistance. Based on the line-side current phasor and the fault point current phasor, calculate the harmonic components and aperiodic components of the three-phase fault current, and calculate the harmonic sum of each phase and the total harmonics of the three phases based on the harmonic components of the three-phase fault current. Based on the fault point current phasor, the fault stage is calibrated to determine the time of the first fault occurrence, and the time of the fault voltage peak with the shortest interval to the time of the first fault occurrence and the voltage peak corresponding to the time of the fault voltage peak are determined. Data on the fault phase and reclosing were extracted from the on-site waveform recording file, and weather information at the time of the fault was obtained from the meteorological system. A comprehensive score is calculated based on the average value of the transition resistance, the non-periodic component, the sum of harmonics for each phase, the total harmonics of the three phases, the time of the first fault occurrence, the time of the peak fault voltage, the peak voltage corresponding to the time of the peak fault voltage, the fault phase data, the reclosing data, and the weather information. The fault type is then identified based on the score results.

2. The method of claim 1, wherein, Based on the line-side voltage phasor and line-side current phasor, calculate the fault-point voltage phasor and fault-point current phasor at the fault point, including: Wherein, the fault point voltage phasor and the fault point current phasor are obtained by bringing the line side voltage phasor and the line side current phasor into the above formula and solving; L is the length of the AC transmission line, r, l and c are the resistance, inductance and capacitance per unit length of the AC transmission line respectively; u f , i f , and R f are the fault point voltage, the fault point current and the transition resistance respectively; x is the length of the fault point from the M side of the AC transmission line, u m , u n , i m , and i n are the line side voltage phasor and the line side current phasor of the M side and the N side of the AC transmission line respectively.

3. The method of claim 1, wherein, The calibration of the fault stage based on the fault point current phasor, and the determination of the time of the first fault occurrence, includes: Based on the fault point current phasor, the phase current mutation detection method is used to detect the first fault time. If there are consecutive preset number of phase current mutations that are all greater than the preset phase current mutation threshold, then a fault is determined to have occurred, and the time of the first point among the consecutive preset number of sampling points is taken as the first fault occurrence time.

4. The method of claim 1, wherein, The system comprehensively scores the fault based on the average value of the transition resistance, the aperiodic component, the sum of harmonics for each phase, the total harmonics of the three phases, the time of the first fault occurrence, the time of the peak fault voltage, the peak voltage corresponding to the peak fault voltage, fault phase data, reclosing data, and weather information. Based on the scoring results, the fault type is identified, including: Based on the fault phase data, determine whether it is a single-phase ground fault. If it is, determine the first score as the first preset score; otherwise, determine the first score as the second preset score. If the average transition resistance is greater than the preset transition resistance threshold, it is determined to be a metallic fault, and the second score is determined to be the first preset score; otherwise, the second score is determined linearly based on the difference between the average transition resistance and the preset transition resistance threshold; the lowest score is 0. If the reclosing is determined to be successful based on the reclosing data, then the third score is set to the first preset score; otherwise, the third score is set to 0. The fourth score is determined linearly based on the non-periodic components; the highest score is the first preset score, and the lowest score is 0. linearly determine the fifth score based on the sum of the three-phase total harmonics; wherein the highest score is a first preset score and the lowest score is 0; linearly determine the sixth score based on the time interval between the fault time and the fault voltage peak time, if the fault time is not at the voltage peak, wherein the highest score is the first preset score and the lowest score is 0; determine the seventh score based on the weather information; perform weighted summation according to each score to determine a comprehensive score; if the comprehensive score is greater than a preset score threshold, determine that the fault type is a non-breakdown lightning fault.

5. The method of claim 1, wherein, The method further comprises: if the total harmonic content of any side of the AC fault line is greater than a preset total harmonic content threshold, directly determine that the fault type is a non-breakdown lightning fault.

6. A fault type identification system for an AC power transmission line, characterized by The system comprises: a voltage and current primary value acquisition unit configured to acquire voltage and current primary values of both sides of the AC fault line; a line side voltage and current phasor calculation unit configured to calculate line side voltage phasors and line side current phasors of both sides of the AC fault line based on the voltage and current primary values; a fault point voltage and current phasor calculation unit configured to calculate fault point voltage phasors and fault point current phasors at the fault point based on the line side voltage phasors and line side current phasors; a transition resistance average value calculation unit configured to calculate an instantaneous transition resistance based on the ratio of the fault point voltage phasors and the fault point current phasors, and calculate a transition resistance average value based on the instantaneous transition resistance; a harmonic calculation unit configured to calculate harmonic components and non-periodic components of three-phase fault currents based on the line side current phasors and the fault point current phasors, and calculate a harmonic sum of each phase and a three-phase total harmonic based on the harmonic components of the three-phase fault currents; a fault calibration unit configured to calibrate a fault stage based on the fault point current phasors, determine a first fault occurrence time, and determine a fault voltage peak time and a voltage peak value corresponding to the fault voltage peak time with the shortest interval from the first fault occurrence time; an information acquisition unit configured to extract fault phase data and reclosing data based on a field recording file, and acquire weather information of the fault time based on a meteorological system; a fault type identification unit configured to perform comprehensive scoring based on the transition resistance average value, the non-periodic components, the harmonic sum of each phase, the three-phase total harmonic, the first fault occurrence time, the fault voltage peak time, the voltage peak value corresponding to the fault voltage peak time, the fault phase data, the reclosing data, and the weather information, and identify the fault type according to the scoring result.

7. The system of claim 6, wherein, The fault point voltage and current phasor calculation unit calculates the fault point voltage phasors and the fault point current phasors at the fault point based on the line side voltage phasors and the line side current phasors, comprising: Wherein, the fault point voltage phasor and the fault point current phasor are obtained by bringing the line side voltage phasor and the line side current phasor into the above formula and solving; L is the length of the AC transmission line, r, l and c are the resistance, inductance and capacitance per unit length of the AC transmission line respectively; u f , i f and R f are the fault point voltage, the fault point current and the transition resistance respectively; x is the length of the fault point from the M side of the AC transmission line, u m , u n , i m and i n are the line side voltage phasor and the line side current phasor of the M side and the N side of the AC transmission line respectively.

8. The system of claim 6, wherein, The fault calibration unit calibrates the fault stage based on the fault point current phasors, determines the first fault occurrence time, comprising: Based on the fault point current phasor, the first fault time detection is performed by using the phase current abrupt change quantity detection method, if there are continuous preset number of phase current abrupt change quantities greater than the preset phase current abrupt change quantity threshold, it is determined that a fault occurs, and the time of the first point in the continuous preset number of sampling points is taken as the first fault occurrence time.

9. The system of claim 6, wherein, The fault type identification unit comprehensively scores based on the transition resistance average value, non-periodic component, harmonic sum of each phase, total harmonic of three phases, first fault occurrence time, fault voltage peak time, voltage peak value corresponding to the fault voltage peak time, fault phase data, reclosing data and weather information, and identifies the fault type according to the scoring result, including: Based on the fault phase data, it is determined whether it is a single-phase ground fault, if yes, it is determined that the first score is a first preset score, otherwise, it is determined that the first score is a second preset score; If the transition resistance average value is greater than the preset transition resistance threshold, it is determined to be a metallic fault, and the second score is determined to be the first preset score, otherwise, the second score is linearly determined based on the difference between the transition resistance average value and the preset transition resistance threshold; wherein the lowest score is 0; If it is determined based on the reclosing data that the reclosing is successful, it is determined that the third score is the first preset score, otherwise, the third score is determined to be 0; Based on the non-periodic component, the fourth score is linearly determined; wherein the highest score is the first preset score, and the lowest score is 0; Based on the sum of the total harmonics of three phases, the fifth score is linearly determined; wherein the highest score is the first preset score, and the lowest score is 0; Based on the first fault occurrence time, the fault voltage peak time and the voltage peak value corresponding to the fault voltage peak time, it is determined whether the fault time is at the voltage peak, if yes, the sixth score is determined to be the first preset score, otherwise, the sixth score is linearly determined based on the time interval between the fault time and the fault voltage peak time; wherein the highest score is the first preset score, and the lowest score is 0; Based on the weather information, the season of the fault occurrence is determined, and the seventh score is determined based on the season; According to each score, weighted summation is performed to determine the comprehensive score; If the comprehensive score is greater than the preset score threshold, it is determined that the fault type is a non-breakdown lightning strike fault.

10. The system of claim 6, wherein, The fault identification unit is also used for: If the total harmonic content of any side of the alternating current fault line is greater than the preset total harmonic content threshold, the fault type is directly determined to be a non-breakdown lightning strike fault.

11. A computer readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to implement the steps of the method of any one of claims 1-5.

12. An electronic device, comprising: Including: The computer readable storage medium of claim 11; And One or more processors for executing the program in the computer readable storage medium.

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