Fault type identification method and system for alternating current transmission line

Abstract

The invention discloses a fault type identification method and system for an alternating-current transmission line. The method comprises the following steps: acquiring primary values of voltage and current at two sides of an alternating-current fault line; respectively calculating a line side voltage phasor and a line side current phasor based on the voltage and current primary values; calculating a fault point voltage phasor and a fault point current phasor based on the line side voltage phasor and the line side current phasor; calculating a transition resistance average value based on the fault point voltage phasor and the fault point current phasor; calculating each harmonic component and a non-periodic component of the three-phase fault current, and calculating a three-phase total harmonic wave; performing calibration of a fault stage based on the fault point current phasor, determining a first fault occurrence moment, and determining a fault voltage peak moment with a shortest interval with the first fault occurrence moment and a voltage peak value corresponding to the fault voltage peak moment; extracting fault phase data and reclosing data, and obtaining weather information; and carrying out comprehensive scoring, and carrying out fault type identification according to a scoring result.

Description

Technical Field

[0001] The present invention relates to the technical field of relay protection for AC power transmission lines, and more specifically, to a method and system for identifying the fault type of an AC power transmission line. Background Art

[0002] In recent years, the failures of power transmission lines in my country due to severe abnormal weather have exceeded half of the total number of failures. In various severe weather conditions, AC transmission line lightning failures account for a high proportion and are the main cause of line failures and outages. my country's UHV AC lines have repeatedly experienced N-2 mode, which has a certain impact on the safe operation of the power grid and the reliable supply of electricity. Rapid and accurate fault cause analysis after a lightning fault occurs plays an important role in the staff's investigation and maintenance and the rapid restoration of power supply to the power grid.

[0003] However, existing lightning fault identification methods mainly rely on manual analysis, and it often takes a long time from on-site line inspection to system power supply restoration. Especially for non-breakthrough lightning faults, when the fault phenomenon is not obvious, it is difficult to accurately distinguish the fault based on manual analysis.

[0004] Therefore, a method for identifying the fault type of AC transmission lines is needed. Summary of the invention

[0005] The present invention provides a method and system for identifying the fault type of an AC power transmission line, so as to solve the problem of how to identify the fault type of the AC power transmission line.

[0006] In order to solve the above problem, according to one aspect of the present invention, a method for identifying the fault type of an AC transmission line is provided, the method comprising:

[0007] Obtain the primary values ​​of voltage and current on both sides of the AC fault line;

[0008] Based on the primary values ​​of voltage and current, respectively calculate the line-side voltage phasor and the line-side current phasor on both sides of the AC fault line;

[0009] 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;

[0010] Calculating an instantaneous transition resistance based on a ratio of the fault point voltage phasor to the fault point current phasor, and calculating an average value of the transition resistance based on the instantaneous transition resistance;

[0011] Calculate the harmonic components and non-periodic components 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 three-phase total harmonic based on the harmonic components of the three-phase fault current;

[0012] Calibrate the fault stage based on the fault point current phasor to 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;

[0013] Extract fault phase data and reclosing data based on the on-site recording file, and obtain weather information at the time of fault occurrence based on the meteorological system;

[0014] A comprehensive score is given based on the average value of the transition resistance, the non-periodic component, the sum of harmonics of each phase, the three-phase total harmonics, the time when the first fault occurred, the time of the fault voltage peak, the voltage peak corresponding to the time of the fault voltage peak, the fault phase data, the reclosing data and the weather information, and the fault type is identified based on the scoring result.

[0015] Preferably, 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:

[0016]

[0017] Wherein, the voltage phasor and the current phasor at the fault point are obtained by substituting the line-side voltage phasor and the line-side current phasor into the above formula and solving them; 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, fault point current and transition resistance respectively; x is the distance between the fault point and the M side of the AC transmission line, u m 、u n 、i m and i n They are the line-side voltage phasor and line-side current phasor on the M and N sides of the AC transmission line respectively.

[0018] Preferably, the calibration of the fault stage based on the fault point current phasor to determine the time of occurrence of the first fault includes:

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

[0020] Preferably, the method of performing a comprehensive score based on the transition resistance average value, non-periodic component, harmonic sum of each phase, three-phase total harmonic, first fault occurrence time, fault voltage peak time, voltage peak corresponding to the fault voltage peak time, fault phase data, reclosing data and weather information, and identifying the fault type according to the score result includes:

[0021] Determine whether it is a single-phase grounding fault based on the fault phase data, and if so, determine the first score to be a first preset score, otherwise, determine the first score to be a second preset score;

[0022] If the average value of the 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 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 it is determined based on the reclosing data that the reclosing is successful, the third score is determined to be the first preset score, otherwise, the third score is determined to be 0;

[0024] Based on the non-periodic component, a 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 harmonics, a 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 occurrence time, the fault voltage peak time and the voltage peak corresponding to the fault voltage peak time, determine whether the fault time is at the voltage peak, if so, determine the sixth score to be the first preset score, otherwise, 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;

[0027] determining a season in which the failure occurred based on the weather information, and determining a seventh score based on the season;

[0028] A weighted sum is taken based on each score to determine a composite score;

[0029] If the comprehensive score is greater than a preset score threshold, the fault type is determined to be a non-penetrating lightning fault.

[0030] Preferably, the method further comprises:

[0031] If the total harmonic content on either side of the AC fault line is greater than the preset total harmonic content threshold, the fault type is directly determined to be a non-breakdown lightning fault.

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

[0033] A voltage and current primary value acquisition unit, used to acquire the voltage and current primary values ​​on both sides of the AC fault line;

[0034] A line-side voltage and current phasor calculation unit, used to calculate the line-side voltage phasor and the line-side current phasor on both sides of the AC fault line based on the voltage and current primary values;

[0035] A fault point voltage and current phasor calculation unit, used 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;

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

[0037] A harmonic calculation unit, used for calculating each harmonic component and 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 three-phase total harmonic based on the each harmonic component of the three-phase fault current;

[0038] A fault calibration unit, used 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;

[0039] An information acquisition unit, used to extract fault phase data and reclosing data based on the on-site recording file, and to obtain weather information at the time of fault occurrence based on the meteorological system;

[0040] The fault type identification unit is used to make a comprehensive score based on the transition resistance average value, non-periodic component, harmonic sum of each phase, three-phase total harmonic, time of first fault occurrence, fault voltage peak time, voltage peak corresponding to the fault voltage peak time, fault phase data, reclosing data and weather information, and 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 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:

[0042]

[0043] Wherein, the voltage phasor and the current phasor at the fault point are obtained by substituting the line-side voltage phasor and the line-side current phasor into the above formula and solving them; 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, fault point current and transition resistance respectively; x is the distance between the fault point and the M side of the AC transmission line, u m 、u n 、i m and i n They are the line-side voltage phasor and line-side current phasor on the M and N sides of the AC transmission line respectively.

[0044] Preferably, the fault calibration unit calibrates the fault stage based on the fault point current phasor to determine the time of occurrence of the first fault, including:

[0045] Based on the current phasor at the fault point, a phase current mutation detection method is used to detect the moment of the first fault. If there are a continuous preset number of phase current mutations that are all greater than a preset phase current mutation threshold, it is determined that a fault has occurred, and the moment of the first point in the continuous preset number of sampling points is taken as the moment of occurrence of the first fault.

[0046] Preferably, the fault type identification unit performs comprehensive scoring based on the transition resistance average value, non-periodic component, harmonic sum of each phase, three-phase total harmonic, first fault occurrence time, fault voltage peak time, voltage peak 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:

[0047] Determine whether it is a single-phase grounding fault based on the fault phase data, and if so, determine the first score to be a first preset score, otherwise, determine the first score to be a second preset score;

[0048] If the average value of the 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 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;

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

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

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

[0052] Based on the first fault occurrence time, the fault voltage peak time and the voltage peak corresponding to the fault voltage peak time, determine whether the fault time is at the voltage peak, if so, determine the sixth score to be the first preset score, otherwise, 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] determining a season in which the failure occurred based on the weather information, and determining a seventh score based on the season;

[0054] A weighted sum is taken based on each score to determine a composite score;

[0055] If the comprehensive score is greater than a preset score threshold, the fault type is determined to be a non-penetrating lightning fault.

[0056] Preferably, the fault identification unit is further used for:

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

[0058] According to another aspect of the present invention, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any step of a method for identifying a fault type of an AC transmission line.

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

[0060] The computer-readable storage medium described above; and

[0061] One or more processors are used to execute the program in the computer-readable storage medium.

[0062] The present invention provides a method and system for identifying the fault type of an AC power transmission line, comprising: obtaining the primary values ​​of voltage and current on both sides of the AC fault line; calculating the line-side voltage phasors and the line-side current phasors on both sides of the AC fault line based on the primary values ​​of voltage and current; calculating 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; calculating the instantaneous transition resistance based on the ratio of the fault point voltage phasors to the fault point current phasors, and calculating the average value of the transition resistance based on the instantaneous transition resistance; calculating the harmonic components and non-periodic components of the three-phase fault current based on the line-side current phasors and the fault point current phasors, and calculating the harmonic components of the three-phase fault current based on the harmonic components of the three-phase fault current The sum of harmonics of each phase and the total harmonics of three phases; the calibration of the fault stage is performed based on the fault point current phasor, the time of occurrence of the first fault is determined, and the time of the fault voltage peak with the shortest interval from the time of occurrence of the first fault and the voltage peak corresponding to the time of the fault voltage peak are determined; the fault phase difference data and the reclosing data are extracted based on the on-site recording file, and the weather information at the time of occurrence of the fault is obtained based on the meteorological system; a comprehensive score is performed based on the transition resistance average value, non-periodic component, the sum of harmonics of each phase, the total harmonics of three phases, the time of occurrence of the first fault, the time of the fault voltage peak, the voltage peak corresponding to the time of the fault voltage peak, the fault phase difference data, the reclosing data and the weather information, and the fault type is identified according to the scoring result. The method of the present invention can make full use of the various fault characteristic quantities generated when the AC line fault occurs, so as to accurately and quickly identify the fault type, and the fault information required for calculation can be accurately obtained in the recording file after the fault occurs, which meets the engineering design requirements and can be promoted and applied in 220kV and 500kV AC lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0064] Figure 1 is a flow chart of a method 100 for identifying a fault type of an AC power transmission line according to an embodiment of the present invention;

[0065] Figure 2 is a flow chart of an identification process according to an embodiment of the present invention;

[0066] Figure 3 A circuit diagram of a double-terminal PI type transmission line according to an embodiment of the present invention;

[0067] Figure 4 4 is a schematic diagram of the structure of a fault type identification system 400 for an AC power transmission line according to an embodiment of the present invention. DETAILED DESCRIPTION

[0068] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0069] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0070] In view of the disadvantage that the prior art cannot identify non-breakdown lightning faults by only using line voltage mutation, the present invention proposes an AC line fault cause identification method based on fault mechanism and fault electrical characteristics, which can make full use of a variety of fault characteristic quantities generated when an AC line fault occurs, thereby accurately and quickly identifying the fault type.

[0071] Figure 1 FIG. 1 is a flow chart of a method 100 for identifying a fault type of an AC power transmission line according to an embodiment of the present invention. Figure 1 As shown, the fault type identification method of the AC transmission line provided by the embodiment of the present invention can make full use of the various fault characteristic quantities generated when the AC line fault occurs, so as to accurately and quickly identify the fault type. The fault information required for calculation can be accurately obtained from the recording file after the fault occurs, meeting the engineering design requirements, and can be promoted and applied in 220kV and 500kV AC lines. The fault type identification method 100 of the AC transmission line provided by the embodiment of the present invention starts from step 101. In step 101, the primary values ​​of voltage and current on both sides of the AC fault line are obtained.

[0072] Combination Figure 2 As shown, in the present invention, firstly, the data required for fault identification is obtained based on the field recording data, including: AC line voltage level, AC line length, AC line unit length resistance, reactance, inductance and capacitance, the distance between the fault point and the fault on both sides, line voltage transformer ratio, line current transformer ratio and other information. Then, data processing is performed based on the obtained readings, and the data collected by the voltage and current transformers are reduced to primary values. Among them, the two ends of the fault line are M side and N side respectively, and the reduction expression of the M side data is:

[0073]

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

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

[0076]

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

[0078] In addition, if there is a high-voltage reactor in the AC line, it is necessary to further calculate the AC line high-voltage reactor current and subtract the high-voltage reactor current from the above data reduction expression as the primary current value. The high-voltage reactor current calculation expression is:

[0079]

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

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

[0082] In the present invention, based on the primary values ​​of voltage and current, the backward Fourier algorithm is used to calculate the line-side voltage phasor and the line-side current phasor on both sides of the AC fault line. In the backward Fourier algorithm, 12 points can be sampled in each power frequency cycle.

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

[0084] Preferably, 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 voltage phasor and the current phasor at the fault point are obtained by substituting the line-side voltage phasor and the line-side current phasor into the above formula and solving them; 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, fault point current and transition resistance respectively; x is the distance between the fault point and the M side of the AC transmission line, u m 、u n 、i m and i n They are the line-side voltage phasor and line-side current phasor on the M and N sides of the AC transmission line respectively.

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

[0088] In the present invention, based on the line-side voltage phasors and line-side current phasors on both sides of the line obtained in step 102, the fault point voltage phasors and the fault point current phasors at the fault point are calculated by solving differential equations, and the instantaneous transition resistance is calculated based on the fault point voltage phasors and the fault point current phasors, and then the average value of the transition resistance in the fault stage is calculated based on the instantaneous transition resistance. Figure 3 Take the double-terminal PI type transmission line shown in Figure 2 as an example. The expressions of the voltage and current at the fault point are as follows:

[0089]

[0090] Where 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. f 、i f and R f are the voltage, current and transition resistance at the fault point respectively, x is the distance from the fault point to the M side of the AC transmission line, u m 、u n 、i m and i n are the voltage and current on the M and N sides of the AC transmission line respectively.

[0091] By combining equations (9)-(11) and substituting the voltage phasors and current phasors on both sides of the line calculated in step 102 into the above expression, the fault point voltage u can be obtained. f (t) and fault point current i f (t). Then the instantaneous transition resistance of 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:

[0094]

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

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

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

[0098] In step 106, the fault stage is calibrated based on the fault point current phasor to determine the first fault occurrence time, 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 are determined.

[0099] Preferably, the calibration of the fault stage based on the fault point current phasor to determine the time of occurrence of the first fault includes:

[0100] Based on the current phasor at the fault point, a phase current mutation detection method is used to detect the moment of the first fault. If there are a continuous preset number of phase current mutations that are all greater than a preset phase current mutation threshold, it is determined that a fault has occurred, and the moment of the first point in the continuous preset number of sampling points is taken as the moment of occurrence of the first fault.

[0101] In the present invention, 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 detection method is used to detect the first fault moment. In order to avoid the influence of data disturbance, three consecutive points are judged. Specifically: if there are three consecutive sampling points whose phase current mutations are evenly greater than the threshold, it is judged that a fault has occurred, and the moment of the first point in the continuous preset number of sampling points is taken as the first fault occurrence moment. Based on the geomagnetic fault occurrence moment, find the fault voltage peak moment closest to the first fault occurrence moment and the voltage peak corresponding to this moment.

[0102] In addition, the present invention can also use the phase current magnitude to detect the tripping moment, specifically: within a time window, if more than 95% of the elements are smaller than a threshold value, it is determined that the tripping has been achieved.

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

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

[0105] Preferably, the method of performing a comprehensive score based on the transition resistance average value, non-periodic component, harmonic sum of each phase, three-phase total harmonic, first fault occurrence time, fault voltage peak time, voltage peak corresponding to the fault voltage peak time, fault phase data, reclosing data and weather information, and identifying the fault type according to the score result includes:

[0106] Determine whether it is a single-phase grounding fault based on the fault phase data, and if so, determine the first score to be a first preset score, otherwise, determine the first score to be a second preset score;

[0107] If the average value of the 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 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 it is determined based on the reclosing data that the reclosing is successful, the third score is determined to be the first preset score, otherwise, the third score is determined to be 0;

[0109] Based on the non-periodic component, a 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 harmonics, a 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 occurrence time, the fault voltage peak time and the voltage peak corresponding to the fault voltage peak time, determine whether the fault time is at the voltage peak, if so, determine the sixth score to be the first preset score, otherwise, 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;

[0112] determining a season in which the failure occurred based on the weather information, and determining a seventh score based on the season;

[0113] A weighted sum is taken based on each score to determine a composite score;

[0114] If the comprehensive score is greater than a preset score threshold, the fault type is determined to be a non-penetrating lightning fault.

[0115] Combination Figure 2 As shown, in the present invention, the fault phase and reclosing information are extracted based on the field recording file, and the weather information at the time of the fault is extracted in combination with the meteorological system. Then, a comprehensive score is performed based on the various information obtained in the above steps to identify non-breakthrough lightning faults.

[0116] In the present invention, according to the analysis of the non-penetrating lightning fault mechanism, fault judgment is divided into 7 items, including:

[0117] The first item is the fault type item; it is judged based on the fault phase. If the fault type is a single-phase grounding fault, the first item is assigned 100 points; if it is other faults, the first item is assigned 10 points;

[0118] The second item is the fault property item; if the transition resistance is greater than the preset resistance threshold, it is determined to be a metallic fault 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 to be a non-metallic fault property, and the score is linearly reduced according to the transition resistance value, with the lowest score being 0 points;

[0119] The third item is a reclosing success item; if the reclosing is successful 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 determined linearly, 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; the score is determined linearly based on the sum of the three-phase total harmonics. 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 fault time item; 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 the fault time is at the voltage peak, the sixth item is 100 points, and the scores of other items decrease linearly as they are farther from the peak, with the lowest score being 0 points;

[0123] Item 7 is the season item; if the fault occurs in spring or summer, Item 7 is assigned 90 points; if the fault occurs in autumn, Item 7 is assigned 70 points; if the fault occurs in winter, Item 7 is assigned 10 points.

[0124] Then, according to the weights of the above 7 items, weighted sums are performed to determine the comprehensive score. The weights of the above 7 items can be 0.15, 0.15, 0.1, 0.2, 0.2, 0.1, 0.1 respectively.

[0125] Finally, the fault is identified based on the comprehensive score. The greater the score of the comprehensive score, the higher the non-breakthrough lightning fault. Therefore, in the present invention, if the comprehensive score is greater than the preset score threshold, the fault type is determined to be a non-breakthrough lightning fault.

[0126] Preferably, the method further comprises:

[0127] If the total harmonic content on either side of the AC fault line is greater than the preset total harmonic content threshold, the fault type is directly determined to be a non-breakdown lightning fault.

[0128] In the present invention, fault identification can also be performed directly based on the total harmonic content. Specifically, if the total harmonic content of one side of the total harmonics of the fault current on both sides is greater than a preset total harmonic content threshold, the fault is immediately identified as a non-breakdown lightning fault.

[0129] In view of the shortcomings of the existing lightning fault identification methods that mainly rely on manual analysis and the existing technology that only uses line voltage mutations and cannot identify non-breakdown lightning faults, the present invention proposes an AC line fault identification method based on fault mechanism and fault electrical characteristics, which can make full use of a variety of fault characteristic quantities generated when an AC line fault occurs, thereby accurately and quickly identifying the fault type.

[0130] Figure 4 FIG. 4 is a schematic diagram of a fault type identification system 400 for an AC power transmission line according to an embodiment of the present invention. Figure 4 As shown, the fault type identification system 400 for the AC transmission line provided in the embodiment of the present invention 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 identification unit 408.

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

[0132] Preferably, the line-side voltage and current phasor calculation unit 402 is used to respectively calculate the line-side voltage phasor and the line-side current phasor on both 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 used 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 voltage phasor and the current phasor at the fault point are obtained by substituting the line-side voltage phasor and the line-side current phasor into the above formula and solving them; 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, fault point current and transition resistance respectively; x is the distance between the fault point and the M side of the AC transmission line, u m 、u n 、i m and i n They are the line-side voltage phasor and line-side current phasor on the M and N sides of the AC transmission line respectively.

[0137] Preferably, the transition resistance average value calculation unit 404 is used to calculate the instantaneous transition resistance based on the ratio of the fault point voltage phasor to 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 used to calculate the harmonic components and non-periodic components of the three-phase fault current based on the line-side current phasors and the fault point current phasors, and calculate the harmonic sum of each phase and the three-phase total harmonics based on the harmonic components of the three-phase fault current.

[0139] Preferably, the fault calibration unit 406 is used to calibrate the fault stage based on the fault point current phasor, determine the time when the first fault occurs, and determine the fault voltage peak time with the shortest interval from the time when the first fault occurs and the voltage peak 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 time of occurrence of the first fault, including:

[0141] Based on the current phasor at the fault point, a phase current mutation detection method is used to detect the moment of the first fault. If there are a continuous preset number of phase current mutations that are all greater than a preset phase current mutation threshold, it is determined that a fault has occurred, and the moment of the first point in the continuous preset number of sampling points is taken as the moment of occurrence of the first fault.

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

[0143] Preferably, the fault type identification unit 408 is used to perform a comprehensive score based on the transition resistance average value, non-periodic component, harmonic sum of each phase, three-phase total harmonics, time of first fault occurrence, fault voltage peak time, voltage peak corresponding to fault voltage peak time, fault phase data, reclosing data and weather information, and identify the fault type according to the scoring result.

[0144] Preferably, the fault type identification unit 408 performs comprehensive scoring based on the transition resistance average value, non-periodic component, harmonic sum of each phase, three-phase total harmonic, first fault occurrence time, fault voltage peak time, voltage peak 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:

[0145] Determine whether it is a single-phase grounding fault based on the fault phase data, and if so, determine the first score to be a first preset score, otherwise, determine the first score to be a second preset score;

[0146] If the average value of the 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 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;

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

[0148] Based on the non-periodic component, a 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 three-phase total harmonics, a 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, determine whether the fault time is at the voltage peak, if so, determine the sixth score to be the first preset score, otherwise, 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;

[0151] determining a season in which the failure occurred based on the weather information, and determining a seventh score based on the season;

[0152] A weighted sum is taken based on each score to determine a composite score;

[0153] If the comprehensive score is greater than a preset score threshold, the fault type is determined to be a non-penetrating lightning fault.

[0154] Preferably, the fault identification unit 408 is further used for:

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

[0156] The AC transmission line fault type identification system 400 of the embodiment of the present invention corresponds to the AC transmission line fault type identification method 100 of another embodiment of the present invention, and will not be described in detail herein.

[0157] According to another aspect of the present invention, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any step of a method for identifying a fault type of an AC transmission line.

[0158] According to another aspect of the present invention, the present invention provides an electronic device, including:

[0159] The computer-readable storage medium described above; and

[0160] One or more processors are used to execute the program in the computer-readable storage medium.

[0161] The invention has been described above with reference to a few embodiments. However, it is readily apparent to a person skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the invention, as defined by the appended patent 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 therein. All references to "a / said / the [means, components, etc.]" are to be openly interpreted as at least one instance of said means, components, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily have to be performed in the exact order disclosed, unless explicitly stated otherwise.

[0163] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0164] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0165] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0166] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0167] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for identifying the fault type of an AC transmission line, characterized in that: The method comprises: 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, respectively calculate the line-side voltage phasor and the line-side current phasor on both sides of the AC fault line; 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 an instantaneous transition resistance based on a ratio of the fault point voltage phasor to the fault point current phasor, and calculating an average value of the transition resistance based on the instantaneous transition resistance; Calculate the harmonic components and non-periodic components 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 three-phase total harmonic based on the harmonic components of the three-phase fault current; Calibrate the fault stage based on the fault point current phasor to 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; Extract fault phase data and reclosing data based on the on-site recording file, and obtain weather information at the time of fault occurrence based on the meteorological system; A comprehensive score is given based on the average value of the transition resistance, the non-periodic component, the sum of harmonics of each phase, the three-phase total harmonics, the time when the first fault occurred, the time of the fault voltage peak, the voltage peak corresponding to the time of the fault voltage peak, the fault phase data, the reclosing data and the weather information, and the fault type is identified based on the scoring result.

2. The method according to claim 1, characterized in that 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, including: Wherein, the voltage phasor and the current phasor at the fault point are obtained by substituting the line-side voltage phasor and the line-side current phasor into the above formula and solving them; 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, fault point current and transition resistance respectively; x is the distance between the fault point and the M side of the AC transmission line, u m 、u n 、i m and i n They are the line-side voltage phasor and line-side current phasor on the M and N sides of the AC transmission line respectively.

3. The method according to claim 1, characterized in that The calibrating the fault stage based on the fault point current phasor to determine the time of occurrence of the first fault includes: Based on the current phasor at the fault point, a phase current mutation detection method is used to detect the moment of the first fault. If there are a continuous preset number of phase current mutations that are all greater than a preset phase current mutation threshold, it is determined that a fault has occurred, and the moment of the first point in the continuous preset number of sampling points is taken as the moment of occurrence of the first fault.

4. The method according to claim 1, characterized in that: The method of performing a comprehensive score based on the transition resistance average value, non-periodic component, harmonic sum of each phase, three-phase total harmonic, first fault occurrence time, fault voltage peak time, voltage peak corresponding to the fault voltage peak time, fault phase data, reclosing data and weather information, and identifying the fault type according to the score result includes: Determine whether it is a single-phase grounding fault based on the fault phase data, and if so, determine the first score to be a first preset score, otherwise, determine the first score to be a second preset score; If the average value of the 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 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; If it is determined based on the reclosing data that the reclosing is successful, the third score is determined to be the first preset score, otherwise, the third score is determined to be 0; Based on the non-periodic component, a 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 three-phase total harmonics, a 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 corresponding to the fault voltage peak time, determine whether the fault time is at the voltage peak, if so, determine the sixth score to be the first preset score, otherwise, 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; determining a season in which the failure occurred based on the weather information, and determining a seventh score based on the season; A weighted sum is taken based on each score to determine a composite score; If the comprehensive score is greater than a preset score threshold, the fault type is determined to be a non-penetrating lightning fault.

5. The method according to claim 1, characterized in that The method further comprises: If the total harmonic content on either side of the AC fault line is greater than the preset total harmonic content threshold, the fault type is directly determined to be a non-breakdown lightning fault.

6. A fault type identification system for an AC transmission line, characterized in that: The system comprises: A voltage and current primary value acquisition unit, used to acquire the voltage and current primary values ​​on both sides of the AC fault line; A line-side voltage and current phasor calculation unit, used to calculate the line-side voltage phasor and the line-side current phasor on both sides of the AC fault line based on the voltage and current primary values; A fault point voltage and current phasor calculation unit, used 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; a transition resistance average value calculation unit, configured to calculate an instantaneous transition resistance based on a ratio of the fault point voltage phasor to the fault point current phasor, and calculate an average value of the transition resistance based on the instantaneous transition resistance; A harmonic calculation unit, used for calculating each harmonic component and 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 three-phase total harmonic based on the each harmonic component of the three-phase fault current; A fault calibration unit, used 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; An information acquisition unit, used to extract fault phase data and reclosing data based on the on-site recording file, and to obtain weather information at the time of fault occurrence based on the meteorological system; The fault type identification unit is used to make a comprehensive score based on the transition resistance average value, non-periodic component, harmonic sum of each phase, three-phase total harmonic, time of first fault occurrence, fault voltage peak time, voltage peak corresponding to the fault voltage peak time, fault phase data, reclosing data and weather information, and identify the fault type according to the scoring result.

7. The system according to claim 6, characterized in that The fault point voltage and current phasor calculation unit 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: Wherein, the voltage phasor and the current phasor at the fault point are obtained by substituting the line-side voltage phasor and the line-side current phasor into the above formula and solving them; 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, fault point current and transition resistance respectively; x is the distance between the fault point and the M side of the AC transmission line, u m 、u n 、i m and i n They are the line-side voltage phasor and line-side current phasor on the M and N sides of the AC transmission line respectively.

8. The system according to claim 6, characterized in that The fault calibration unit calibrates the fault stage based on the fault point current phasor to determine the time when the first fault occurs, including: Based on the current phasor at the fault point, a phase current mutation detection method is used to detect the moment of the first fault. If there are a continuous preset number of phase current mutations that are all greater than a preset phase current mutation threshold, it is determined that a fault has occurred, and the moment of the first point in the continuous preset number of sampling points is taken as the moment of occurrence of the first fault.

9. The system according to claim 6, characterized in that The fault type identification unit performs comprehensive scoring based on the transition resistance average value, non-periodic component, harmonic sum of each phase, three-phase total harmonic, first fault occurrence time, fault voltage peak time, voltage peak 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: Determine whether it is a single-phase grounding fault based on the fault phase data, and if so, determine the first score to be a first preset score, otherwise, determine the first score to be a second preset score; If the average value of the 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 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; If it is determined based on the reclosing data that the reclosing is successful, the third score is determined to be the first preset score, otherwise, the third score is determined to be 0; Based on the non-periodic component, a 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 three-phase total harmonics, a 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 corresponding to the fault voltage peak time, determine whether the fault time is at the voltage peak, if so, determine the sixth score to be the first preset score, otherwise, 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; determining a season in which the failure occurred based on the weather information, and determining a seventh score based on the season; A weighted sum is taken based on each score to determine a composite score; If the comprehensive score is greater than a preset score threshold, the fault type is determined to be a non-penetrating lightning fault.

10. The system according to claim 6, characterized in that The fault identification unit is further used for: If the total harmonic content on either side of the AC fault line is greater than the preset total harmonic content threshold, the fault type is directly determined to be a non-breakdown lightning fault.

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

12. An electronic device, characterized in that: include: The computer readable storage medium as claimed in claim 11; as well as One or more processors are used to execute the program in the computer-readable storage medium.

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