A method and system for determining phase difference of transmission line fault based on analog quantity characteristics

Abstract

The present invention discloses a method and system for determining the phase difference of a power transmission line fault based on analog quantity characteristics, which belongs to the technical field of detecting cable and transmission line faults. The method steps include: determining a fault time window, superimposing a time-scale offset on the basis of the fault time window, calculating the fault current and the fault voltage, setting the initial fault phase difference parameter according to a preset transmission line fault type table, performing a preliminary fault phase difference classification according to the specific values ​​of each phase of the single-phase / three-phase maximum fault current ratio, obtaining a preliminary fault phase difference classification result, strengthening confirmation of the fault phase, and judging and outputting the fault type. The present invention has the characteristics of high accuracy, high efficiency, and good compatibility, is not affected by factors such as transition resistance and induced current, does not rely on the mutual verification of multi-system data, does not rely on manual analysis, and has good compatibility with common problems such as incorrect line impedance parameters of recording data and incomplete access to protection action switch quantity.

Description

Technical Field

[0001] The present invention relates to a method and system for determining phase difference of a power transmission line fault, and in particular to a method and system for determining phase difference of a power transmission line fault based on analog quantity characteristics, and belongs to the technical field of detecting cable and transmission line faults. Background Art

[0002] When a transmission line fails, correct fault phase determination is an important basis for subsequent dispatchers to make decisions on forced power transmission or power outage maintenance. In the field of relay protection, there are two main methods for fault phase determination. The first is to perform fault phase determination based on the relay protection action information and its logical relationship. For example, if the relay protection action information of a certain fault contains: main protection A phase action, main protection single-phase tripping, main protection A phase action, main protection single-phase tripping and other signals, it can be determined as a phase A grounding fault, and other types of faults can be determined by analogy; the second is to perform fault phase determination based on the sequence component of the fault current in the recording data. If there is a zero-sequence current, it indicates a grounding fault. If the angle between the zero-sequence current and the negative-sequence current is less than 30° and the angle between the positive-sequence current and the negative-sequence current is less than 60°, it can be determined as a phase A grounding fault, and other types of faults can be determined by analogy.

[0003] Of the above two methods, the first method has a high reliability of protection action due to the high redundancy of the configuration of the main protection and backup protection, and the differential protection adopts double-end data analysis, so the fault phase judgment based on the protection action information has a high accuracy; the second method has a small fault current amplitude and is easily affected by the interference of the parallel line when the transmission line passes through a high-resistance grounding fault or a double-circuit fault, resulting in a deviation in the fault phase judgment. The advantage of the first method is that it has high accuracy, but the relay protection action information comes from multiple relay protection devices at the power stations on both sides of the transmission line. It is quite time-consuming to collect and organize this information after the fault, averaging more than 20 minutes; the second method has low accuracy, but there are few data sources and fast upload speed, with an average time of less than 5 minutes; therefore, the combination of the first and second methods is currently mainly used, that is, relay protection professionals first manually analyze the recorded data, and then verify it according to the relay protection action information, and improve the accuracy and efficiency of fault analysis through manual intervention. However, as the scale of the power grid continues to expand and the uncertainty of a high proportion of renewable energy increases, dispatchers are faced with problems such as rapid changes in power grid operation methods, a surge in real-time data volumes, and increased requirements for accident handling efficiency. Manual analysis methods can no longer meet the dispatching and management needs of new power systems and are in urgent need of improvement. Summary of the invention

[0004] The purpose of the present invention is to provide a method and system for determining the phase difference of a transmission line fault based on analog quantity characteristics, in view of the characteristics of rapid changes in power grid operation mode, surge in real-time data volume, and increased requirements for accident handling efficiency, to solve the shortcomings of the prior art.

[0005] The present invention provides the following scheme:

[0006] A method for determining the phase difference of a transmission line fault based on analog quantity characteristics, which is applied to determining the phase difference of a transmission line fault, comprises:

[0007] Determine the current sampling value channel and the voltage sampling value channel of each phase in the fault line according to the starting element, extract the time mark of the sampling point, and determine the fault time window, wherein the fault time window includes the fault start time and the fault end time;

[0008] The time-scale offset is superimposed on the fault time window, and the fault current and fault voltage are calculated to obtain the single-phase / three-phase maximum fault current ratio, the three-phase fault voltage attenuation maximum value, and the three-phase fault voltage attenuation minimum value. The single-phase / three-phase maximum fault current ratio is specifically: the ratio of the single-phase maximum fault current to the three-phase maximum fault current;

[0009] According to the preset transmission line fault type table, the initial fault phase discrimination parameters are set, and the fault phase discrimination classification is initially judged according to the specific values ​​of each phase of the single-phase / three-phase maximum fault current ratio to obtain the initial fault phase discrimination classification result;

[0010] According to the different preliminary judgment results, the voltage attenuation and current gain are checked phase by phase to detect whether they meet the single-phase / three-phase fault removal characteristics. According to the relative relationship characteristics of the three-phase fault current gain and the fault voltage attenuation amplitude and ratio, the floating upper and lower limit characteristics are compared to strengthen the confirmation of the fault phase. According to the results of the enhanced confirmation of the fault phase, the fault type is judged and output.

[0011] Furthermore, the step of determining the current sampling value channels and voltage sampling value channels of each phase in the faulty line according to the starting element and extracting the time stamp of the sampling point further includes:

[0012] Parameters related to the fault time window are established on the coordinate system, and the parameters are screened and traversed multiple times to determine the start and end time scales of the fault time window.

[0013] Furthermore, the step of superimposing a time-scale offset on the basis of the fault time window further includes:

[0014] The fault start time t0 is selected as time t0+T / 4 to start calculating the fault current, and the fault end time t1 is selected as time t1-5T / 4, where T is the period;

[0015] On the current sampling value channel, the fault time window is divided into pre-fault current, initial fault current and post-fault current;

[0016] Obtaining a single-phase maximum fault current, comparing the single-phase maximum fault current with a corresponding pre-fault current to obtain a single-phase fault current gain, and taking a maximum value among the single-phase fault current gains to obtain a three-phase maximum fault current;

[0017] The three-phase maximum fault current is compared with the corresponding single-phase maximum fault current to obtain a single-phase / three-phase maximum fault current ratio.

[0018] Furthermore, the method of superimposing a time-scale offset on the basis of the fault time window and calculating the fault current and the fault voltage further includes:

[0019] The fault start time t0 is selected as time t0+T / 4 to start calculating the fault voltage, and the fault end time t1 is selected as time t1-5T / 4, where T is the period;

[0020] On the voltage sampling value channel, the fault voltage is divided into a pre-fault voltage, an initial fault voltage, a final fault voltage and a post-fault voltage;

[0021] Taking the minimum value in the initial fault voltage to obtain the single-phase minimum fault voltage, comparing the single-phase minimum fault voltage with the voltage before the fault to obtain the single-phase fault voltage attenuation;

[0022] The maximum value and the minimum value of the single-phase fault voltage attenuation are taken to obtain the single-phase fault voltage maximum value and the single-phase fault voltage minimum value respectively.

[0023] Further, the initial fault phase classification parameters are set according to the preset transmission line fault type table, and the fault phase classification is initially judged according to the specific values ​​of each phase of the single-phase / three-phase maximum fault current ratio to obtain the initial fault phase classification result, further including:

[0024] Combine the analog current, pre-fault voltage, initial fault voltage, final fault voltage and post-fault voltage to verify phase by phase whether the fault current gain and fault voltage attenuation meet the fault characteristics;

[0025] Verify whether the current after the fault meets the fault removal characteristics and output the corresponding verification fault phase.

[0026] Furthermore, according to the different preliminary judgment results, the voltage attenuation and current gain are checked phase by phase to detect whether the single-phase / three-phase fault removal characteristics are met, and according to the relative relationship characteristics of the three-phase fault current gain and the fault voltage attenuation amplitude and ratio, the floating upper and lower limit characteristics are compared to strengthen the confirmation of the fault phase, further including:

[0027] Define temporary variables in the fault phase reinforcement confirmation process, extract relevant parameters in fault analysis, set corresponding counters, and detect whether specific fault current and voltage thresholds are met;

[0028] Check whether there is a strong fault voltage attenuation in the current phase, and whether the three-phase fault current ratio is higher than the preset lower limit, perform the upper / lower limit check of the floating fault voltage attenuation, and update the temporary variable according to the check result;

[0029] A counter is set and incremented according to the verification result. When the value of the counter is higher than the preset value, it is judged that the enhanced confirmation of the fault phase is completed, and the result of the enhanced confirmation of the fault phase is output.

[0030] Furthermore, the step of comparing the floating upper and lower limit characteristics to strengthen the confirmation of the fault phase further includes:

[0031] Obtain the parameters of the current sampling value channel within the fault time window, analyze all instantaneous sampling values ​​of the current sampling channel, and determine the sampling value with the largest absolute value and its corresponding time scale;

[0032] At the time of the time stamp corresponding to the sampling value with the largest absolute value, the instantaneous sampling values ​​of the three phases are obtained, and the vector sum of the instantaneous sampling values ​​is calculated;

[0033] If the ratio of the vector sum to the sampling value with the largest absolute value meets the preset condition, the current fault is judged to be a ground fault, or: the fault type is judged and output according to the enhanced confirmation result of the fault phase.

[0034] Furthermore, if the ratio of the vector sum to the sampling value with the largest absolute value meets a preset condition, specifically: if the ratio of the vector sum to the sampling value with the largest absolute value is greater than or equal to 0.3, it is determined to be a ground fault.

[0035] Furthermore, judging and outputting the fault type according to the result of the fault phase reinforcement confirmation further includes:

[0036] According to the fault phase difference obtained in the fault phase reinforcement confirmation process, combined with the ground fault code, the fault type is determined according to the preset transmission line fault type table.

[0037] A transmission line fault phase identification determination system based on analog quantity characteristics, used to implement a transmission line fault phase identification determination method based on analog quantity characteristics, comprising:

[0038] A fault time window construction module determines the current sampling value channel and the voltage sampling value channel of each phase in the fault line according to the starting element, extracts the time stamp of the sampling point, and determines the fault time window, wherein the fault time window includes the fault start time and the fault end time;

[0039] A fault current / voltage calculation module, which superimposes a time-scale offset on the basis of the fault time window, calculates the fault current and the fault voltage, and obtains a single-phase / three-phase maximum fault current ratio, a three-phase fault voltage attenuation maximum value, and a three-phase fault voltage attenuation minimum value, wherein the single-phase / three-phase maximum fault current ratio is specifically: a ratio of a single-phase maximum fault current to a three-phase maximum fault current;

[0040] The fault phase classification preliminary judgment module sets the preliminary fault phase judgment parameters according to the preset transmission line fault type table, performs preliminary fault phase classification according to the specific values ​​of each phase of the single-phase / three-phase maximum fault current ratio, and obtains the preliminary fault phase classification result;

[0041] The fault phase enhanced confirmation module verifies the voltage attenuation and current gain phase by phase according to the different preliminary judgment results, detects whether it meets the single-phase / three-phase fault removal characteristics, and compares the relative relationship characteristics of the three-phase fault current gain and the fault voltage attenuation amplitude and ratio through the floating upper and lower limit characteristics to enhance the confirmation of the fault phase. According to the result of the enhanced confirmation of the fault phase, the fault type is judged and output.

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] High precision: The analog quantity features selected by the present invention cover different time periods before, during and after a fault, taking into account the changing laws of various characteristics such as current, voltage and switching quantity, and are not affected by factors such as transition resistance and induced current.

[0044] High efficiency: The present invention fully utilizes the advantage of high efficiency of wave recording data transmission, directly reflects the fault process through the data itself, and uses typical characteristic quantities to complete rapid fault phase judgment. It has small amount of calculation, fast speed, low main station performance consumption, does not rely on mutual verification of multi-system data, and does not rely on manual analysis.

[0045] Good compatibility: the present invention only requires the analog quantity information of the original recording data, and does not require a power grid model. It has good compatibility with common problems such as incorrect line impedance parameters of the recording data and incomplete access to the protection action switch quantity. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0047] Figure 1It is a flow chart of a method for determining the phase difference of a transmission line fault based on analog quantity characteristics.

[0048] Figure 2 This is a schematic diagram of the recording file generated after the fault recorder is started.

[0049] Figure 3 This is a flow chart for determining the fault end time of the fault time window.

[0050] Figure 4 It is a flow chart of the initial fault diagnosis phase.

[0051] Figure 5 It is a flow chart of phase-to-phase fault or three-phase fault verification.

[0052] Figure 6 It is a flow chart of single-phase fault verification.

[0053] Figure 7 It is a flow chart of fault phase reinforcement confirmation.

[0054] Figure 8 This is the architecture diagram of the transmission line fault phase identification system based on analog quantity characteristics. DETAILED DESCRIPTION

[0055] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] The main method flow of the present invention is as follows: determine the fault time window → calculate the fault current → calculate the fault voltage → initial fault phase → fault phase removal verification → fault phase enhanced confirmation → ground fault judgment → output fault type. The key to the above method flow is to perform fault phase judgment and verification completely based on the change characteristics of analog voltage and current. The selected characteristic parameters and methods have strong anti-interference, and do not rely on the circuit breaker tripping information or protection action information of the external system, the switching channel and fixed value of the fault recorder, etc., and can achieve independent, autonomous and rapid fault phase judgment to the greatest extent.

[0057] like Figure 1 The method for determining the phase difference of a transmission line fault based on analog quantity characteristics shown in the figure comprises:

[0058] Step S1, determine the current sampling value channel and voltage sampling value channel of each phase in the faulty line according to the starting element, extract the time stamp of the sampling point, and determine the fault time window, which includes the fault start time and the fault end time; in this step, the starting element refers to the line fault recorder.

[0059] Step S2, superimposing the time-scale offset on the basis of the fault time window, calculating the fault current and the fault voltage, obtaining the single-phase / three-phase maximum fault current ratio, the three-phase fault voltage attenuation maximum value and the three-phase fault voltage attenuation minimum value, wherein the single-phase / three-phase maximum fault current ratio is specifically: the ratio of the single-phase maximum fault current to the three-phase maximum fault current;

[0060] Step S3, according to the preset transmission line fault type table, set the initial fault phase classification parameters, and perform the initial fault phase classification according to the specific values ​​of each phase of the single-phase / three-phase maximum fault current ratio to obtain the initial fault phase classification result;

[0061] Step S4, according to the different preliminary judgment results, the voltage attenuation and current gain are checked phase by phase to detect whether they meet the single-phase / three-phase fault removal characteristics. According to the relative relationship characteristics of the three-phase fault current gain and the fault voltage attenuation amplitude and ratio, the floating upper and lower limit characteristics are compared to strengthen the confirmation of the fault phase. According to the result of the enhanced confirmation of the fault phase, the fault type is judged and output.

[0062] Steps S1 to S4 provide an automated power system fault analysis method, which aims to quickly and accurately determine the fault type by accurately measuring and analyzing the current and voltage data during the fault. Steps S1 to S4 determine the voltage and current sampling channels, determine the fault time window, calculate the fault parameters, perform preliminary fault phase classification, and finally output the fault type through a series of verification and confirmation steps.

[0063] Steps S1 to S4 can quickly and accurately identify the fault type. Since power grid faults may involve different phases and have different characteristics, the fault analysis method of the prior art may not be able to adapt to the complexity and diversity of faults, resulting in inadequate timely or accurate fault handling. In addition, the automation level of fault analysis is insufficient, and a large amount of manual intervention is required during the processing, which is not only inefficient but also prone to errors. Steps S1 to S4 use an automated and intelligent method to determine the current sampling value channel and voltage sampling value channel of each phase in the fault line according to the starting element, determine the fault time window, reduce human intervention, and improve the speed and efficiency of fault analysis. By calculating the fault current and voltage within the fault time window, and obtaining the single-phase / three-phase maximum fault current ratio and fault voltage attenuation value, more accurate fault feature data is provided.

[0064] Based on the preset fault type table and fault current ratio, a quick initial judgment of the fault phase is achieved, which provides a basis for further verification and confirmation. Then, by comparing the amplitude and ratio of the fault current gain and the fault voltage attenuation, and using technical means such as floating upper and lower limit characteristics, the accuracy of fault phase confirmation is improved. Finally, combined with the fault phase to strengthen the confirmation result, the fault type is quickly output, providing timely guidance for fault handling and recovery of the power system.

[0065] The recording data involved in the present invention is a file that complies with the standard of "Common format for transient data exchange, COMTRADE" (GB / T 22386-2008 Power System Transient Data Exchange Common Format). The sampling channel types contained in the COMTRADE file include analog quantity, DC quantity and switch quantity. Among them, the analog quantity channel includes AC voltage channel and AC current channel. In the line fault recorder: the voltage channel is connected to the secondary circuit of the bus voltage transformer (Potential Transformer, PT); the current channel is connected to the secondary circuit of the transmission line current transformer (Current transformer, CT). The DC quantity is a DC voltage channel, which can be connected to the DC voltage circuit of the DC power supply panel or the high-frequency transceiver. The switch quantity is a non-continuous state quantity channel, which can be connected to the auxiliary contacts of equipment such as protection devices, circuit breakers, and switch knives.

[0066] like Figure 2 As shown, the present invention mainly uses the analog channel in the COMTRADE file for calculation, and the calculation parameters involved are Figure 2 It is marked in the figure:

[0067] The horizontal axis t is time, and the vertical axis SV is the sampling value; SVa, SVb, and SVc are the A, B, and C phase voltage sampling value channels of the transmission line associated busbars respectively; SIa, SIb, and SIc are the A, B, and C phase current sampling value channels of the transmission line respectively; t0 is the moment when the fault recorder starts recording, that is, the moment when the fault begins, and the time scale is 0; point o is the moment of the first sampling point, which is generally 100ms or more before t0, and the time scale is ≤-100ms; T is the sampling period, according to domestic standards 1T=20ms;

[0068] t1 is the moment when the fault current disappears and the fault ends. In theory, it is the moment when the fault phase current drops to 0. However, in actual operation, due to factors such as induced current and sampling channel zero drift, there is a delay in the absolute 0 moment. The common practice is to calculate the duration of the fault current, but when the system frequency changes, the cycle time may be biased. Taking the value of t1 too early or too late will affect the calculation of the fault current, thereby affecting the accuracy of the fault phase judgment.

[0069] The types of transmission line faults can be divided into single-phase ground faults (AN, BN, CN), two-phase ground faults (ABN, BCN, CAN), three-phase ground faults (ABCN), two-phase interphase faults (AB, BC, CA) and three-phase interphase faults (ABC). For the convenience of calculation, the fault phases are binary coded, as shown in Table 1 (Transmission Line Fault Type Table).

[0070] Table 1 Transmission line fault phase codes

[0071]

[0072] Preferably, in step S1, the current sampling value channel and the voltage sampling value channel of each phase in the faulty line are determined according to the starting element, the time stamp of the sampling point is extracted, and the fault time window is determined, wherein the fault time window includes the fault start time and the fault end time, and further includes:

[0073] Parameters related to the fault time window are established on the coordinate system, and the parameters are screened and traversed multiple times to determine the start and end time scales of the fault time window.

[0074] Preferably, in step S2, superimposing a time-scale offset on the basis of the fault time window further comprises:

[0075] Step S21, the fault start time t0 is selected as time t0+T / 4 to start calculating the fault current, and the fault end time t1 is selected as time t1-5T / 4, where T is a period;

[0076] Step S22, on the current sampling value channel, dividing the fault time window into pre-fault current, initial fault current and post-fault current;

[0077] Step S23, obtaining a single-phase maximum fault current, comparing the single-phase maximum fault current with the corresponding pre-fault current to obtain a single-phase fault current gain, and taking the maximum value among the single-phase fault current gains to obtain a three-phase maximum fault current;

[0078] Step S24, comparing the three-phase maximum fault current with the corresponding single-phase maximum fault current to obtain a single-phase / three-phase maximum fault current ratio.

[0079] The technical problem addressed by steps S21 to S24 is that, in the power system fault analysis, it is necessary to accurately identify the start and end time of the fault current, eliminate the influence of various transient factors (such as flashover and surge) that may affect the start and end time of the fault current, identify the maximum value of the single-phase fault current in multiple phases, identify the most serious fault condition, and obtain the single-phase / three-phase maximum fault current ratio by calculation.

[0080] The optimization technical solution provided in steps S21 to S24 can avoid the transient effects and the influence of circuit breaker operation in the early stage of the fault, thereby improving the accuracy of current measurement, and dividing the current data within the fault time window into pre-fault, initial fault and post-fault currents, which is helpful for more detailed analysis of the fault development process. By comparing the single-phase maximum fault current with the pre-fault current, the fault current gain is calculated, which helps to identify the severity of the fault. Finally, the maximum value is selected from the single-phase fault current gain as the three-phase maximum fault current, which provides a quantitative indicator for the evaluation of the severity of the fault. By accurately selecting the calculation time and processing the fault current data in segments, the accuracy and reliability of fault analysis are improved, which helps to quickly identify and respond to fault conditions in the power system.

[0081] Preferably, in step S2, the superimposing of the time-scale offset on the basis of the fault time window to calculate the fault current and the fault voltage further comprises:

[0082] Step S25, the fault start time t0 is selected as time t0+T / 4 to start calculating the fault voltage, and the fault end time t1 is selected as time t1-5T / 4, where T is a period;

[0083] Step S26, dividing the fault voltage into pre-fault voltage, initial fault voltage, final fault voltage and post-fault voltage on the voltage sampling value channel;

[0084] Step S27, taking the minimum value in the initial fault voltage to obtain the single-phase minimum fault voltage, and comparing the single-phase minimum fault voltage with the pre-fault voltage to obtain the single-phase fault voltage attenuation;

[0085] Step S28, taking the maximum value and the minimum value of the single-phase fault voltage attenuation to obtain the single-phase fault voltage maximum value and the single-phase fault voltage minimum value respectively.

[0086] The optimization technical scheme of steps S25 to S28 describes the accurate measurement and evaluation of the impact of the fault voltage at specific moments (fault start and end moments), by segmenting the fault voltage data in time and calculating the voltage value of each stage, especially by identifying the minimum fault voltage and comparing it with the pre-fault voltage, to quantify the attenuation of the fault voltage. Since the voltage at the beginning and end of the fault may vary due to various factors (such as circuit breaker operation, system dynamic response, etc.), accurate measurement and evaluation of the fault voltage is one of the important factors for rapid phase judgment.

[0087] The optimization technical solution provided in steps S25 to S28 can reduce the impact of transient effects in the initial stage of the fault and circuit breaker operation on voltage measurement. By dividing the fault voltage, it is helpful to carefully analyze the voltage changes during the fault. By finding the minimum value in the initial fault voltage, the single-phase minimum fault voltage can be determined, which helps to assess the severity of the fault. By comparing the single-phase minimum fault voltage with the pre-fault voltage and calculating the single-phase fault voltage attenuation, it provides a basis for quantifying the impact of the fault. By extracting the maximum and minimum values ​​from the single-phase fault voltage attenuation, the impact range of the fault voltage can be determined, providing more comprehensive information for system protection and fault handling.

[0088] Preferably, in step S3, the initial fault phase classification parameters are set according to the preset transmission line fault type table (Table 1), and the fault phase classification initial judgment is performed according to the specific values ​​of each phase of the single-phase / three-phase maximum fault current ratio to obtain the fault phase classification initial judgment result, which further includes:

[0089] Combine the analog current, pre-fault voltage, initial fault voltage, final fault voltage and post-fault voltage to verify phase by phase whether the fault current gain and fault voltage attenuation meet the fault characteristics;

[0090] Verify whether the current after the fault meets the fault removal characteristics and output the corresponding verification fault phase.

[0091] Preferably, in step S4, the voltage attenuation and current gain are checked phase by phase according to the different preliminary judgment results to detect whether the single-phase / three-phase fault removal characteristics are met, and the relative relationship characteristics of the three-phase fault current gain and the fault voltage attenuation amplitude and ratio are compared through the floating upper and lower limit characteristics to strengthen the confirmation of the fault phase, further comprising:

[0092] Define temporary variables in the fault phase reinforcement confirmation process, extract relevant parameters in fault analysis, set corresponding counters, and detect whether specific fault current and voltage thresholds are met;

[0093] Check whether there is a strong fault voltage attenuation in the current phase, and whether the three-phase fault current ratio is higher than the preset lower limit, perform the upper / lower limit check of the floating fault voltage attenuation, and update the temporary variable according to the check result;

[0094] A counter is set and incremented according to the verification result. When the value of the counter is higher than the preset value, it is judged that the enhanced confirmation of the fault phase is completed, and the result of the enhanced confirmation of the fault phase is output.

[0095] The optimization technical solution of step S4 is used to strengthen the identification process of the fault phase in the power system by defining temporary variables, extracting relevant parameters, setting counters, and performing a series of checks based on the thresholds of fault current and voltage to improve the accuracy of fault phase identification. The technical problems addressed by step S4 are:

[0096] Due to the complexity of the power system, accurately identifying the fault phase in the power system fault analysis is one of the key technologies for taking correct protective measures. In the technical solution, the fault phase may not be determined by relying solely on preliminary judgment. The optimization technical solution provided in step S4 has been improved for the above technical problems. By defining temporary variables and extracting relevant parameters in fault analysis, a more detailed and dynamic way to analyze fault data is provided. By verifying the strong attenuation of the fault voltage and the fault current ratio, and performing the upper / lower limit verification of the floating fault voltage attenuation, the fault characteristics can be more accurately identified. Setting a counter and incrementing it according to the verification result provides a quantitative way to track and confirm the progress of the fault phase identification process, and finally outputting the result of the fault phase reinforcement confirmation, so as to achieve the accuracy of fault phase identification for the fault handling and protection of the power system.

[0097] Exemplarily, the step of comparing the floating upper and lower limit characteristics to strengthen the confirmation of the fault phase further includes:

[0098] Obtain the parameters of the current sampling value channel within the fault time window, analyze all instantaneous sampling values ​​of the current sampling channel, and determine the sampling value with the largest absolute value and its corresponding time scale;

[0099] At the time of the time stamp corresponding to the sampling value with the largest absolute value, the instantaneous sampling values ​​of the three phases are obtained, and the vector sum of the instantaneous sampling values ​​is calculated;

[0100] If the ratio of the vector sum to the sampling value with the largest absolute value meets the preset condition, the current fault is judged to be a ground fault, or: the fault type is judged and output according to the enhanced confirmation result of the fault phase.

[0101] Exemplarily, if the ratio of the vector sum to the maximum sampling value meets a preset condition, specifically: the ratio of the vector sum to the sampling value with the largest absolute value is greater than or equal to 0.3, it is determined to be a ground fault.

[0102] Preferably, in step S4, judging and outputting the fault type according to the result of the fault phase reinforcement confirmation further includes:

[0103] According to the fault phase difference obtained in the fault phase reinforcement confirmation process, combined with the ground fault code, the fault type is determined according to the preset transmission line fault type table.

[0104] like Figure 3As shown, step 1 of determining the fault time window is specifically as follows:

[0105] The specific method is as follows:

[0106] 1) Set the following parameters: SIx is the current sampling value channel containing the starting element; x is the phase difference of the current sampling value channel, x=a or b or c; tp is the time stamp of the sampling point p in the current sampling value channel; SNp is the number of the sampling point p; SN1 is the number of the first sampling point in the current sampling value channel; SNe is the number of the last sampling point; te is the time stamp of the last sampling point; Ixp is the instantaneous sampling value of the sampling point p; Ixpr is the effective sampling value within 1 cycle T after starting from the sampling point p; txl is the current disappearance time of the current sampling value channel; t1 is the fault end time; the relative position relationship of each parameter is as follows Figure 2 shown.

[0107] 2) Take the effective sampling value of the first sampling point SN1 of the SIx sampling value channel in the first cycle T, that is, the current before the fault, recorded as Ix0 (x=a or b or c).

[0108] 3) Initialize tp=t0, SNp=SN(t0), ta1=tb1=tc1=null.

[0109] 4) In order to reduce the amount of calculation, the sampling points that meet the conditions: |Ixp|<Ix0 / 3 or |Ixp|<0.005A are preliminarily screened.

[0110] 5) In the screening results of step 4), the sampling points that meet the conditions: Ixpr<Ix0 / 3 or Ixpr<0.005A are screened again.

[0111] 6) Starting from SN (t0), traverse each sampling point along the time axis, expressed as SNp=SNp+1, until the last sampling period tp+T=te.

[0112] 7) Record the time stamp of the first sampling point that meets the conditions of steps 4) and 5) as tx1=tp (x=a or b or c).

[0113] 8) If there is no sampling point that meets the conditions of steps 4) and 5), let tx1=none (x=a or b or c).

[0114] 9) By querying the values ​​of ta1, tb1, and tc1, select the next sampling value channel to be calculated until ta1≠null, tb1≠null, and tc1≠null.

[0115] 10) If any of the values ​​of ta1, tb1, and tc1 is not none, the minimum value is taken as the fault end time t1, expressed as t1=min(ta1, tb1, tc1);

[0116] 11) When the values ​​of ta1, tb1, and tc1 are all none, then t1=none, indicating that the fault end time is not found, and the COMTRADE file is considered to be a non-fault file or an incomplete fault file, which is not worth further analysis.

[0117] Step 2 of calculating the fault current is as follows:

[0118] Under the premise of determining the fault time window in step 1, step 2 provides a basis for subsequent fault phase determination by calculating the three-phase fault current. The key lies in the selection of the maximum fault current value moment. First, the moment t0+T / 4 is selected to start calculating the fault current. Compared with the traditional method of calculating the fault current from the moment t0, it can avoid the fault recorder sampling distortion caused by flashover, surge and other phenomena in the early stage of the fault; secondly, the moment t1-5T / 4 is added as a comparison. On the one hand, the fault is closer to the maximum value after 1~2 cycles of development at this time, and on the other hand, it can avoid the influence of the circuit breaker breaking current. Through the above method, the influence of realistic interference factors on the calculation accuracy can be effectively reduced.

[0119] The specific method is as follows:

[0120] 1) Set the following parameters:

[0121] SIa, SIb, and SIc are the current sampling value channels of phases a, b, and c of the determined fault time window respectively;

[0122] Ia0, Ib0, Ic0 are the pre-fault currents of SIa, SIb, and SIc respectively, and the method of selecting the values ​​is as in step 1: section 2);

[0123] Iaf1, Ibf1, and Icf1 are the initial fault currents of SIa, SIb, and SIc, respectively, i.e., the effective sampling values ​​within one cycle T after the moment t0+T / 4;

[0124] Iaf2, Ibf2, and Icf2 are the final fault currents of SIa, SIb, and SIc, respectively, i.e., the effective sampling values ​​within one cycle T after the moment t1-5T / 4;

[0125] Ia1, Ib1, Ic1 are the post-fault currents of SIa, SIb, and SIc, respectively, i.e., the effective sampling values ​​within one cycle T after the moment t1+2T;

[0126] Iaf_max, Ibf_max, Icf_max are the maximum fault currents of SIa, SIb, and SIc respectively, and If_max is the maximum fault current of phases a, b, and c compared comprehensively;

[0127] The relative position relationship of each parameter is as follows Figure 2 shown.

[0128] 2) Calculate the maximum single-phase fault current: Iaf_max=max(Iaf1, Iaf2); Ibf_max=max(Ibf1, Ibf2); Icf_max=max(Icf1, Icf2).

[0129] 3) Calculate the single-phase fault current gain (maximum fault current / current before fault): Iag=Iaf_max / Ia0; Ibg=Ibf_max / Ib0; Icg=Icf_max / Ic0.

[0130] 4) Calculate the three-phase maximum fault current If_max=max(Iaf_max, Ibf_max, Icf_max).

[0131] 5) Calculate the ratio of the single-phase maximum fault current to the three-phase maximum fault current: Iaf_r=Iaf_max / If_max; Ibf_r=Ibf_max / If_max; Icf_r=Icf_max / If_max.

[0132] Step 3 of calculating the fault voltage is as follows:

[0133] On the premise that the fault time window is determined in step 1, step 3 provides a basis for subsequent fault phase determination by calculating the three-phase fault voltage. The selection of calculation time is the same as step 2, except that the current will increase and the voltage will decay during a fault. Therefore, the minimum value of the three-phase fault voltage and the decay ratio of the fault voltage to the voltage before the fault will be calculated in step 3. The specific method is as follows:

[0134] 1) Set the following parameters:

[0135] SVa, SVb, SVc are the voltage sampling value channels associated with the current sampling value channels of phases a, b, and c of the determined fault time window respectively;

[0136] Va0, Vb0, and Vc0 are the pre-fault voltages of SVa, SVb, and SVc, respectively, i.e., the effective sampling values ​​within one cycle T starting from the first sampling point of the channel;

[0137] Vaf1, Vbf1, and Vcf1 are the initial fault voltages of SVa, SVb, and SVc, respectively, i.e., the effective sampling values ​​within one cycle T after the moment t0+T / 4;

[0138] Vaf2, Vbf2, and Vcf2 are the final fault voltages of SVa, SVb, and SVc, respectively, i.e., the effective sampling values ​​within one cycle T after the moment t1-5T / 4;

[0139] Va1, Vb1, and VIc1 are the post-fault voltages of SVa, SVb, and SVc, respectively, i.e., the effective sampling values ​​within one cycle T after the moment t1+2T;

[0140] Vaf_min, Vbf_min, and Vcf_min are the minimum fault voltages of SVa, SVb, and SVc, respectively;

[0141] The relative position relationship of each parameter is shown in the schematic diagram of the recording file.

[0142] 2) Calculate the single-phase minimum fault voltage: Vaf_min=min(Vaf1, Vaf2); Vbf_min=min(Vbf1, Vbf2); Vcf_min=min(Vcf1, Vcf2).

[0143] 3) Calculate the single-phase fault voltage attenuation (minimum fault voltage / pre-fault voltage): Vad=Vaf_min / Va0; Vbd=Vbf_min / Vb0; Vcd=Vcf_min / Vc0.

[0144] 4) Calculate the maximum and minimum values ​​of the comprehensive three-phase fault voltage attenuation: Vd_max=max(Vad, Vbd, Vcd): Vd_min=min(Vad, Vbd, Vcd).

[0145] like Figure 4 As shown, step 4 of the initial fault judgment phase is specifically as follows:

[0146] According to the characteristics of the current analog quantity, the fault phases are quickly classified. Different classifications use different verification and confirmation processes in the subsequent process. The specific methods are as follows:

[0147] 1) Set parameter xb1 as the initial fault phase. See Table 1 for the numbering rules. Initialize xb1=0.

[0148] 2) Extract the ratio of the single-phase maximum fault current to the three-phase maximum fault current calculated in step 2: Iaf_r, Ibf_r, Icf_r.

[0149] 3) The fault phases are classified according to the combination of Iaf_r, Ibf_r and Icf_r, and Ifrh is set as the upper limit of the three-phase fault current proportionality coefficient as a reference empirical value for the comparison of the three-phase fault current. In this embodiment, Ifrh is set to 0.9.

[0150] 4) Output the initial fault phase number xb1 to step 5.

[0151] like Figure 5 and Figure 6 As shown, step 5 of the fault phase removal verification is specifically as follows:

[0152] The fault initial judgment phase in step 4 is verified by combining the characteristics of analog current and voltage before, during and after the fault. First, the fault current gain and fault voltage attenuation are verified phase by phase to see if they meet the fault characteristics. Secondly, the current after the fault is verified to see if it meets the fault removal characteristics. Then the fault phase is output for verification. The specific method is as follows:

[0153] 1) Set the following parameters: Ig is the fault current gain coefficient, which is used as a reference empirical value for fault current gain comparison; Vdh and Vdl are the upper and lower limits of the fault voltage attenuation coefficient, respectively, which are used as reference empirical values ​​for fault voltage attenuation comparison; Ifrl is the lower limit of the three-phase fault current proportional coefficient, which is used as a reference empirical value for three-phase fault current comparison; in this embodiment, Ig=9, Vdh=0.85, Vdl=0.55, Ifrl=0.4 are set, which are empirical values ​​obtained through statistical analysis of regionalized fault data. xb2 is the fault phase for verification. The numbering rules refer to Table 1. Initialize xb2=0;

[0154] temp_xb2 is a temporary variable representing the fault phase during the verification process, and temp_xb2 is initialized to 0.

[0155] 2) Extraction step 2: Ia0, Ia1, Iag, Iaf_r, Ib0, Ib1, Ibg, Ibf_r, Ic0, Ic1, Icg, Icf_r; Step 3: Vad, Vbd, Vcd, Vd_max, Vd_min; Step 4: xb1 and other parameters.

[0156] 3) When xb1=3 or xb1=5 or xb1=6 or xb1=7, it means that the initial fault phase is a phase-to-phase fault or a three-phase fault, and the process goes to process 5-A. When xb1=1 or xb1=2 or xb1=4, it means that the initial fault phase is a single-phase fault, and the process goes to process 5-B.

[0157] 4) Phase-to-phase fault or three-phase fault verification process (5-A) Figure 5 As shown, the specific method is as follows:

[0158] 4.1) In case of phase-to-phase fault or three-phase fault, the analog quantity shall comply with the three-phase fault clearing characteristics, which can be expressed as: (Iag>9 or Ia1<Ia0 / 3 or Ia1<0.005A) and (Ibg>9 or Ib1<Ia0 / 3 or Ib1<0.005A) and (Icg>9 or Ic1<Ia0 / 3 or Ic1<0.005A).

[0159] 4.2) Perform voltage attenuation and current gain calibration phase by phase: ① If Vad < 0.85 and Iaf_r > 0.4, perform a compound assignment on temp_xb1, expressed as temp_xb2|=1; ② If Vbd < 0.85 and Ibf_r > 0.4, then temp_xb2|=2; ③ If Vcd < 0.85 and Icf_r > 0.4, then temp_xb2|=4.

[0160] 4.3) If 4.2): Any one of ①②③ is satisfied, then xb2=temp_xb2, otherwise xb2=0.

[0161] 4.4) If xb2>0, output xb2 to step 6.

[0162] 5) Single-phase fault verification process (5-B) Figure 6 As shown, the specific method is as follows:

[0163] 5.1) In case of single-phase fault, three-phase fault removal or single-phase fault removal may be performed according to different protection configurations. Three-phase fault removal is represented by: (Iag>9 or Ia1<Ia0 / 3 or Ia1<0.005A) and (Ibg>9 or Ib1<Ia0 / 3 or Ib1<0.005A) and (Icg>9 or Ic1<Ia0 / 3 or Ic1<0.005A), proceed to step 5.2); otherwise, single-phase fault removal is performed, proceed to step 5.4).

[0164] 5.2) Perform voltage attenuation and current gain calibration phase by phase: ① If Vad < 0.85 and Iaf_r > 0.4, then temp_xb2| = 1; ② If Vbd < 0.85 and Ibf_r > 0.4, then temp_xb2| = 2; ③ If Vcd < 0.85 and Icf_r > 0.4, then temp_xb2| = 4.

[0165] 5.3) If 5.2): Any one of ①②③ is satisfied, then xb2=temp_xb1, otherwise xb2=0.

[0166] 5.4) If xb1=1 and (Ia1<Ia0 / 3 or Ia1<0.005A), then xb2=1; if xb1=2 and (Ib1<Ib0 / 3 or Ib1<0.005A), then xb2=2; if xb1=4 and (Ic1<Ic0 / 3 or Ic1<0.005A), then xb2=4; otherwise xb2=0.

[0167] 5.5) If xb2>0, output xb2 to step 6.

[0168] like Figure 7As shown, step 6 of the fault phase reinforcement confirmation is specifically as follows:

[0169] According to the relative relationship characteristics of the three-phase fault current gain and the fault voltage attenuation amplitude and ratio, the floating upper and lower limit characteristics are repeatedly compared to strengthen the confirmation of the fault phase to avoid the influence of the fault current change on the fault phase judgment accuracy when the transmission line load is small. The specific method is as follows:

[0170] 1) Set the following variables: xb3 is the enhanced confirmation fault phase, the numbering rules are shown in Table 1, initialize xb3 = 0; x, y, z, q are temporary variables representing the phase and number during the enhanced confirmation process; temp_xb3 is a temporary variable representing the fault phase during the enhanced confirmation process, initialize temp_xb3 = 0; i is the fault phase enhanced confirmation counter, initialize i = 0.

[0171] 2) Extraction step 2: Ia0, Ia1, Iag, Iaf_r, Ib0, Ib1, Ibg, Ibf_r, Ic0, Ic1, Icg, Icf_r; Step 3: Vad, Vbd, Vcd, Vd_max, Vd_min, Vdh, Vdl, Ifrl; Step 4: Ifrh; Step 5: xb2 and other parameters.

[0172] 3) If i=0, let x=a, y=b, z=c, q=1; if i=1, let x=b, y=c, z=a, q=2; if i=2, let x=c, y=a, z=b, q=4;

[0173] 4) Determine whether the current phase meets the following conditions: Ix1 < 0.1 and (Ixg > 9 or Ix1 < Ix0 / 3 or Ix1 < 0.005A). If so, proceed to step 5), otherwise proceed to step 9);

[0174] 5) Check whether there is a strong attenuation of the fault voltage in the current phase, that is, it exceeds the lower limit of the fault voltage attenuation Vdl, and the three-phase fault current ratio is higher than the lower limit Ifrl, expressed as: Vxd<0.55 and Ixf_r>0.4. If so, perform a compound assignment on temp_xb3, expressed as temp_xb3|=q, and go to step 9); otherwise, go to step 6);

[0175] 6) Check whether the current phase is a single-phase fault voltage with obvious attenuation, that is, the attenuation of the other two phases is small and does not reach the upper limit of the fault voltage attenuation Vdh, and the three-phase fault current ratio is higher than the upper limit Ifrh, expressed as: Vyd>0.85 and Vzd>0.85 and Ixf_r>0.9. If so, temp_xb3|=q, go to step 9); otherwise go to step 7).

[0176] 7) Check the lower limit of floating fault voltage attenuation, expressed as: Vxd<0.65 and Ixf_r>0.65. If yes, then temp_xb3|=q, go to step 9); otherwise go to step 8).

[0177] 8) Check the upper limit of the floating fault current gain, expressed as: Ixf_r>0.95 and Vxd<0.95. If yes, then temp_xb3|=q, go to step 9); otherwise temp_xb3|=0.

[0178] 9) Counter i=i+1.

[0179] 10) When i=3, it indicates that the fault phase reinforcement confirmation is completed. If temp_xb3>0, then xb3=temp_xb3; otherwise xb3=0.

[0180] 11) If xb3>0, output xb3 to step 7.

[0181] Step 7 of ground fault identification is as follows:

[0182] 1) Read the following parameters in step 1: SIx is the current sampling value channel containing the starting element; x is the phase difference of the current sampling value channel, x=a or b or c; tp is the time stamp of the sampling point p in the current sampling value channel; SNp is the number of the sampling point p; Ixp is the instantaneous sampling value of the sampling point p; t1 is the end time of the fault; n is the ground fault code, see Table 1 for details; the relative position relationship of each parameter is as follows Figure 2 shown.

[0183] 2) Take the instantaneous sampling values ​​of the current sampling channels of phases a, b, and c at all points in the fault time window t0-t1, and record the instantaneous sampling value with the largest absolute value as I1=max(|Ixp|), where tp is the time stamp of the sampling point.

[0184] 3) Take the instantaneous sampling values ​​of phases a, b, and c at time tp and record them as Iap, Ibp, and Icp respectively, and record their vector sum as I0=Iap+Ibp+Icp.

[0185] 4) If |I0| / |I1|≥0.3, it is a ground fault and n=1; otherwise n=0.

[0186] Step 8 to output the fault type:

[0187] According to the enhanced confirmed fault phase xb3 outputted in step 6 and the ground fault code n outputted in step 7, the fault type is obtained according to the coding rules in Table 1, which is expressed as ft=xb3+n.

[0188] like Figure 8The architecture diagram of the transmission line fault phase identification determination system based on analog quantity characteristics shown in the figure is used to implement the transmission line fault phase identification determination method based on analog quantity characteristics, including:

[0189] A fault time window construction module determines the current sampling value channel and the voltage sampling value channel of each phase in the fault line according to the starting element, extracts the time stamp of the sampling point, and determines the fault time window, wherein the fault time window includes the fault start time t0 and the fault end time t1;

[0190] A fault current / voltage calculation module, which superimposes a time-scale offset on the basis of the fault time window, calculates the fault current and the fault voltage, and obtains a single-phase / three-phase maximum fault current ratio, a three-phase fault voltage attenuation maximum value, and a three-phase fault voltage attenuation minimum value, wherein the single-phase / three-phase maximum fault current ratio is specifically: a ratio of a single-phase maximum fault current to a three-phase maximum fault current;

[0191] The fault phase classification preliminary judgment module sets the preliminary fault phase judgment parameters according to the preset transmission line fault type table, performs preliminary fault phase classification according to the specific values ​​of each phase of the single-phase / three-phase maximum fault current ratio, and obtains the preliminary fault phase classification result;

[0192] The fault phase enhanced confirmation module verifies the voltage attenuation and current gain phase by phase according to the different preliminary judgment results, detects whether it meets the single-phase / three-phase fault removal characteristics, and compares the relative relationship characteristics of the three-phase fault current gain and the fault voltage attenuation amplitude and ratio through the floating upper and lower limit characteristics to enhance the confirmation of the fault phase. According to the result of the enhanced confirmation of the fault phase, the fault type is judged and output.

[0193] It is worth noting that although only some basic functional modules are disclosed in the embodiments of the present invention, it does not mean that the composition of the present system is limited to the above basic functional modules. On the contrary, what the present embodiment wants to express is that on the basis of the above basic functional modules, those skilled in the art can arbitrarily add one or more functional modules in combination with the prior art to form an infinite number of embodiments or technical solutions. In other words, the present system is open rather than closed. Just because the present embodiment only discloses individual basic functional modules, it cannot be considered that the protection scope of the claims of the present invention is limited to the disclosed basic functional modules. At the same time, for the convenience of description, the above devices are described in terms of functions and are described separately in various units and modules. Of course, when implementing the present invention, the functions of each unit and module can be implemented in the same or one or more software and / or hardware.

[0194] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. All features disclosed in this specification, or steps in all disclosed methods or processes, except for mutually exclusive features and / or steps, can be combined in any way. Any feature disclosed in this specification, unless otherwise described, can be replaced by other alternative features that are equivalent or have similar purposes. That is, unless otherwise described, each feature is just an example of a series of equivalent or similar features. Throughout the specification, the same figure marks indicate the same elements.

[0195] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the phase difference of a transmission line fault based on analog quantity characteristics, which is applied to the determination of the phase difference of a transmission line fault, and is characterized in that: include: Determine the current sampling value channel and the voltage sampling value channel of each phase in the fault line according to the starting element, extract the time mark of the sampling point, and determine the fault time window, wherein the fault time window includes the fault start time and the fault end time; The time-scale offset is superimposed on the fault time window, and the fault current and fault voltage are calculated to obtain the single-phase / three-phase maximum fault current ratio, the three-phase fault voltage attenuation maximum value, and the three-phase fault voltage attenuation minimum value. The single-phase / three-phase maximum fault current ratio is specifically: the ratio of the single-phase maximum fault current to the three-phase maximum fault current: The step of superimposing a time-scale offset on the basis of the fault time window further comprises: The fault start time t0 is selected as time t0+T / 4 to start calculating the fault current, and the fault end time t1 is selected as time t1-5T / 4, where T is the period; On the current sampling value channel, the fault time window is divided into pre-fault current, initial fault current and post-fault current; Obtaining a single-phase maximum fault current, comparing the single-phase maximum fault current with a corresponding pre-fault current to obtain a single-phase fault current gain, and taking a maximum value among the single-phase fault current gains to obtain a three-phase maximum fault current; Comparing the three-phase maximum fault current with the corresponding single-phase maximum fault current to obtain a single-phase / three-phase maximum fault current ratio; The method of superimposing a time-stamp offset on the basis of the fault time window and calculating the fault current and the fault voltage further includes: The fault start time t0 is selected as time t0+T / 4 to start calculating the fault voltage, and the fault end time t1 is selected as time t1-5T / 4, where T is the period; On the voltage sampling value channel, the fault voltage is divided into a pre-fault voltage, an initial fault voltage, a final fault voltage and a post-fault voltage; Taking the minimum value in the initial fault voltage to obtain the single-phase minimum fault voltage, comparing the single-phase minimum fault voltage with the voltage before the fault to obtain the single-phase fault voltage attenuation; The maximum value and the minimum value of the single-phase fault voltage attenuation are taken to obtain the maximum value and the minimum value of the single-phase fault voltage respectively; according to the preset transmission line fault type table, the initial fault phase difference parameter is set, and the fault phase difference classification is initially judged according to the specific values ​​of each phase of the single-phase / three-phase maximum fault current ratio to obtain the initial fault phase difference classification result, further comprising: Combine the analog current, pre-fault voltage, initial fault voltage, final fault voltage and post-fault voltage to verify phase by phase whether the fault current gain and fault voltage attenuation meet the fault characteristics; Verify whether the current after the fault meets the fault removal characteristics, and output the corresponding verification fault phase; according to the different preliminary judgment results, verify the voltage attenuation and current gain phase by phase to detect whether it meets the single-phase / three-phase fault removal characteristics. According to the relative relationship characteristics of the three-phase fault current gain and the fault voltage attenuation amplitude and ratio, compare the floating upper and lower limit characteristics, strengthen the confirmation of the fault phase, and judge and output the fault type according to the result of the fault phase strengthening confirmation, further including: Define temporary variables in the fault phase reinforcement confirmation process, extract relevant parameters in fault analysis, set corresponding counters, and detect whether specific fault current and voltage thresholds are met; Check whether there is a strong fault voltage attenuation in the current phase, and whether the three-phase fault current ratio is higher than the preset lower limit, perform the upper / lower limit check of the floating fault voltage attenuation, and update the temporary variable according to the check result; A counter is set, and the counter is incremented according to the verification result. When the value of the counter is higher than the preset value, it is judged that the enhanced confirmation of the fault phase is completed, and the result of the enhanced confirmation of the fault phase is output; The step of comparing the floating upper and lower limit characteristics to strengthen the confirmation of the fault phase further includes: Obtain the parameters of the current sampling value channel within the fault time window, analyze all instantaneous sampling values ​​of the current sampling channel, and determine the sampling value with the largest absolute value and its corresponding time scale; At the time of the time stamp corresponding to the sampling value with the largest absolute value, the instantaneous sampling values ​​of the three phases are obtained, and the vector sum of the instantaneous sampling values ​​is calculated; If the ratio of the vector sum to the sampling value with the largest absolute value meets the preset condition, the current fault is judged to be a ground fault, or: the fault type is judged and output according to the enhanced confirmation result of the fault phase.

2. The method for determining the phase difference of a power transmission line fault based on analog quantity characteristics according to claim 1 is characterized in that: The step of determining the current sampling value channels and voltage sampling value channels of each phase in the faulty line according to the starting element and extracting the time stamp of the sampling point further includes: Parameters related to the fault time window are established on the coordinate system, and the parameters are screened and traversed multiple times to determine the start and end time scales of the fault time window.

3. The method for determining the phase difference of a power transmission line fault based on analog quantity characteristics according to claim 1, characterized in that: If the ratio of the vector sum to the sampling value with the largest absolute value meets a preset condition, specifically: the ratio of the vector sum to the sampling value with the largest absolute value is greater than or equal to 0.3, it is determined to be a ground fault.

4. The method for determining the phase difference of a power transmission line fault based on analog quantity characteristics according to claim 1, characterized in that: The method of judging and outputting the fault type according to the result of the fault phase reinforcement confirmation further includes: According to the fault phase difference obtained in the fault phase reinforcement confirmation process, combined with the ground fault code, the fault type is determined according to the preset transmission line fault type table.

5. A transmission line fault phase identification determination system based on analog quantity characteristics, used to implement a transmission line fault phase identification determination method based on analog quantity characteristics, characterized in that: include: A fault time window construction module determines the current sampling value channel and the voltage sampling value channel of each phase in the fault line according to the starting element, extracts the time stamp of the sampling point, and determines the fault time window, wherein the fault time window includes the fault start time and the fault end time; A fault current / voltage calculation module, which superimposes a time-scale offset on the basis of the fault time window, calculates the fault current and the fault voltage, and obtains a single-phase / three-phase maximum fault current ratio, a three-phase fault voltage attenuation maximum value, and a three-phase fault voltage attenuation minimum value, wherein the single-phase / three-phase maximum fault current ratio is specifically: a ratio of a single-phase maximum fault current to a three-phase maximum fault current; The step of superimposing a time-scale offset on the basis of the fault time window further comprises: The fault start time t0 is selected as time t0+T / 4 to start calculating the fault current, and the fault end time t1 is selected as time t1-5T / 4, where T is the period; On the current sampling value channel, the fault time window is divided into pre-fault current, initial fault current and post-fault current; Obtaining a single-phase maximum fault current, comparing the single-phase maximum fault current with a corresponding pre-fault current to obtain a single-phase fault current gain, and taking a maximum value among the single-phase fault current gains to obtain a three-phase maximum fault current; Comparing the three-phase maximum fault current with the corresponding single-phase maximum fault current to obtain a single-phase / three-phase maximum fault current ratio; The method of superimposing a time-stamp offset on the basis of the fault time window and calculating the fault current and the fault voltage further includes: The fault start time t0 is selected as time t0+T / 4 to start calculating the fault voltage, and the fault end time t1 is selected as time t1-5T / 4, where T is the period; On the voltage sampling value channel, the fault voltage is divided into a pre-fault voltage, an initial fault voltage, a final fault voltage and a post-fault voltage; Taking the minimum value in the initial fault voltage to obtain the single-phase minimum fault voltage, comparing the single-phase minimum fault voltage with the voltage before the fault to obtain the single-phase fault voltage attenuation; Taking the maximum value and the minimum value of the single-phase fault voltage attenuation to obtain the single-phase fault voltage maximum value and the single-phase fault voltage minimum value respectively; The fault phase classification preliminary judgment module sets preliminary fault phase judgment parameters according to a preset transmission line fault type table, performs preliminary fault phase classification according to the specific values ​​of each phase of the single-phase / three-phase maximum fault current ratio, and obtains the preliminary fault phase classification result, further comprising: Combine the analog current, pre-fault voltage, initial fault voltage, final fault voltage and post-fault voltage to verify phase by phase whether the fault current gain and fault voltage attenuation meet the fault characteristics; Verify whether the current after the fault meets the fault removal characteristics and output the corresponding verification fault phase; the fault phase enhanced confirmation module, according to the different preliminary judgment results, verifies the voltage attenuation and current gain phase by phase, detects whether it meets the single-phase / three-phase fault removal characteristics, and compares the relative relationship characteristics of the three-phase fault current gain and the fault voltage attenuation amplitude and ratio through the floating upper and lower limit characteristics, and strengthens the confirmation of the fault phase. According to the result of the fault phase enhanced confirmation, judge and output the fault type, further including: Define temporary variables in the fault phase reinforcement confirmation process, extract relevant parameters in fault analysis, set corresponding counters, and detect whether specific fault current and voltage thresholds are met; Check whether there is a strong fault voltage attenuation in the current phase, and whether the three-phase fault current ratio is higher than the preset lower limit, perform the upper / lower limit check of the floating fault voltage attenuation, and update the temporary variable according to the check result; A counter is set, and the counter is incremented according to the verification result. When the value of the counter is higher than the preset value, it is judged that the enhanced confirmation of the fault phase is completed, and the result of the enhanced confirmation of the fault phase is output; The step of comparing the floating upper and lower limit characteristics to strengthen the confirmation of the fault phase further includes: Obtain the parameters of the current sampling value channel within the fault time window, analyze all instantaneous sampling values ​​of the current sampling channel, and determine the sampling value with the largest absolute value and its corresponding time scale; At the time of the time stamp corresponding to the sampling value with the largest absolute value, the instantaneous sampling values ​​of the three phases are obtained, and the vector sum of the instantaneous sampling values ​​is calculated; If the ratio of the vector sum to the sampling value with the largest absolute value meets the preset condition, the current fault is judged to be a ground fault, or: the fault type is judged and output according to the enhanced confirmation result of the fault phase.

Images