Recording file synchronization method and system for line multi-terminal differential protection joint debugging

Abstract

The present invention discloses a recording file synchronization method and system for multi-terminal differential protection co-adjustment of a line. The method comprises: obtaining recording files at both ends of a faulty line, extracting the three-phase voltages from the recording files at each end and performing wavelet decomposition, then reconstructing each layer after the wavelet decomposition to obtain a reconstructed signal layer, and finally selecting sampling points at the moment of the fault mutation in each reconstructed signal layer and calculating the average value of the sampling points at the moment of the fault mutation corresponding to the same end to obtain the fault moment at both ends of the faulty line; if the error in the fault moment at both ends of the faulty line is greater than a preset threshold, calculating a compensation value based on the difference in distance from the two ends of the faulty line to the fault point, the propagation speed of the fault traveling wave, and the sampling frequency of the recording file, and using the compensation value to compensate for the fault moment at the end with a relatively delayed fault moment. The present invention can effectively reduce the synchronization error of the recording files obtained at both ends of the line during multi-terminal differential protection co-adjustment of the line.

Description

Technical Field

[0001] The present invention relates to the technical field of power system protection, and in particular to a recording file synchronization method and system for line multi-terminal differential protection joint debugging. Background Art

[0002] In modern power systems, safety and reliability are key factors in ensuring power supply quality. With the increase in transmission line length and power demand, multi-terminal differential protection (MTDP) has become widely used as a key protection mechanism. Its basic principle is to detect faults by comparing currents measured at multiple terminals and promptly disconnect the faulty portion, effectively preventing the escalation of the incident.

[0003] The fundamental principle of multi-terminal differential protection is the law of conservation of current. Under normal operating conditions, the currents flowing into and out of the protection zone should be equal. However, when a fault occurs, this current balance is disrupted, resulting in a differential current. The differential protection device detects this difference to determine the presence and nature of the fault.

[0004] To ensure the reliability and accuracy of multi-terminal differential protection for power lines, systematic joint commissioning of protection devices is necessary. This joint commissioning not only verifies the performance of the protection devices but also ensures their responsiveness under various operating and fault conditions. Effective joint commissioning can reduce false trips and missed trips, improving overall system safety.

[0005] A common method for coordinating multi-terminal differential protection on a line is to utilize the relay protection instrument's own output current signal, with controllable amplitude and phase, for coordinating and verifying. This method can create various virtual fault scenarios, simulating actual current fluctuations, and thus testing the protection device's response under different conditions. By controlling the instrument's output, a comprehensive assessment of the protection characteristics can be performed.

[0006] In addition to using the relay protection device's own output current with controllable amplitude and phase for joint commissioning and verification, another important method is to invert and output the waveform file of the on-site fault recording. This method is of great significance for analyzing the on-site protection action behavior and has the following advantages:

[0007] Based on real data: By analyzing the recorded data under real fault conditions, the performance of the protection device can be evaluated more accurately.

[0008] Acquisition of two-terminal electrical quantities: For longitudinal current differential protection requiring two-terminal electrical quantities, waveform files recorded simultaneously at both ends of the line must be used. This data provides more comprehensive current information, enabling more accurate fault analysis and protection action determination.

[0009] However, fault recording usually uses fault current to start. When the system parameters at both ends are inconsistent and the fault conditions change, the magnitude of the fault current will also be different, so there will be synchronization errors at the starting time. Summary of the Invention

[0010] The technical problem to be solved by the present invention is as follows: In view of the above-mentioned problems in the prior art, a method and system for synchronizing recording files for multi-terminal differential protection joint debugging of lines are provided, which can effectively reduce the synchronization error of the recording files obtained at both ends of the line during the multi-terminal differential protection joint debugging of the line.

[0011] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0012] A recording file synchronization method for line multi-terminal differential protection joint debugging includes the following steps:

[0013] Obtain the recording files at both ends of the fault line, extract the three-phase voltages from the recording files at each end and perform wavelet decomposition. Then, reconstruct each layer after the wavelet decomposition to obtain each layer of reconstructed signals. Finally, select the sampling points at the fault mutation moment in each layer of the reconstructed signals and calculate the average value of the sampling points at the fault mutation moment corresponding to the same end to obtain the fault moment at both ends of the fault line.

[0014] If the fault time error at both ends of the faulty line is greater than a preset threshold, a compensation value is calculated based on the difference in distance from the two ends of the faulty line to the fault point, the propagation speed of the fault traveling wave, and the sampling frequency of the recording file. The compensation value is used to compensate for the fault time of the end with the relatively delayed fault time.

[0015] Furthermore, when extracting the three-phase voltage from the recording file at each end and performing wavelet decomposition, the following steps are included:

[0016] Extract the three-phase voltage from the recording file and decompose it into zero-mode voltage and line-mode voltage;

[0017] If the zero-mode voltage is not 0, the zero-mode voltage is subjected to wavelet decomposition; if the zero-mode voltage is 0, the line-mode voltage is subjected to wavelet decomposition.

[0018] Furthermore, when selecting the sampling point at the moment of fault mutation in each layer of the reconstructed signal, the following steps are specifically included:

[0019] Perform square operations on each layer of reconstructed signals to obtain the corresponding mutation coefficient sequence, and calculate the maximum value of each mutation coefficient sequence;

[0020] In each mutation coefficient sequence, the value of each sampling point is compared with the corresponding maximum value in turn, and the sampling point corresponding to the first value that exceeds the specified proportion of the maximum value is taken as the sampling point of the fault mutation moment.

[0021] Furthermore, when extracting the three-phase voltage in the recording file and decomposing it to obtain the zero-mode voltage and the line-mode voltage, specifically, Karenbauer transformation is performed on the three-phase voltage to obtain the zero-mode voltage and the line-mode voltage.

[0022] Furthermore, when performing wavelet decomposition on the zero mode voltage and the line mode voltage, the Haar wavelet basis is used to perform a two-layer wavelet decomposition on the zero mode voltage or the line mode voltage. The expression is as follows:

[0023] [c,l]=wavedec(u i ,2,'haar')

[0024] Among them, wavedec represents the wavelet decomposition mathematical operation function, haar is the wavelet transform basis, c, l are the high-frequency and low-frequency coefficients after wavelet transform, u i Indicates the decomposed voltage, i indicates the type of decomposed voltage, when i is 0, it indicates zero-mode voltage, and when i is 1, it indicates line-mode voltage.

[0025] Furthermore, each layer after wavelet decomposition is reconstructed, specifically the high-frequency wavelet coefficients of the first and second layers are reconstructed. The signal expression of each layer after reconstructing is as follows:

[0026]

[0027] Among them, waverco represents the wavelet reconstruction function, du01 and du02 are the decomposed voltage u i The reconstructed first layer and the reconstructed second layer signals, d represents the reconstruction of high-frequency wavelet coefficients.

[0028] Furthermore, when using the compensation value to compensate for the fault moments at both ends of the faulty line, specifically, using the compensation value to compensate for the fault moment at the end with a relatively delayed fault moment, the expression is as follows:

[0029]

[0030] Where TFindex is the sampling point corresponding to the fault moment after compensation, Findex1 is the sampling point corresponding to the fault moment at one end that is relatively delayed, ΔL is the difference in distance from the two ends of the fault line to the fault point, v is the line mode or zero mode propagation velocity of the fault traveling wave in the line, and f s The sampling frequency of the recording file.

[0031] The present invention also proposes a recording file synchronization system for multi-terminal differential protection coordination of lines, comprising a microprocessor and a memory connected to each other, wherein the microprocessor is programmed or configured to execute any one of the recording file synchronization methods for multi-terminal differential protection coordination of lines.

[0032] The present invention also proposes a computer-readable storage medium, which stores a computer program or instruction. The computer program or instruction is programmed or configured to execute any one of the recording file synchronization methods for line multi-terminal differential protection coordination through a processor.

[0033] The present invention also proposes a computer program product, including a computer program or instructions, which are programmed or configured to execute any one of the recording file synchronization methods for line multi-terminal differential protection coordination through a processor.

[0034] Compared with the prior art, the advantages of the present invention are:

[0035] The present invention performs wavelet decomposition on the three-phase voltage in the recording file at both ends of the fault line and performs signal reconstruction, and selects the sampling points of the fault mutation moment in the reconstructed signal to calculate the fault time at both ends of the line, which can effectively reduce the fault time error at both ends of the fault line.

[0036] When the fault moment error still does not meet the requirements, the present invention calculates a compensation value based on the difference in distances from the two ends of the fault line to the fault point, the propagation speed of the fault traveling wave, and the sampling frequency of the recording file. The compensation value is used to compensate for the fault moment of the end with a relatively delayed fault moment. This dynamic compensation mechanism allows real-time adjustment according to different environments and conditions, can more flexibly adapt to different fault scenarios, can effectively eliminate or reduce the impact of errors caused by time asynchrony, helps to improve the reliability of multi-terminal differential protection, and reduces the risks of false operation and missed protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Flowchart of a method in an embodiment of the present invention.

[0038] Figure 2 Schematic diagram of power transmission system simulation in an embodiment of the present invention.

[0039] Figure 3 Schematic diagram of three-phase current waveforms at the S end of the protection installation when a single-phase grounding fault occurs in an embodiment of the present invention.

[0040] Figure 4 Schematic diagram of three-phase current waveforms at the R end of the protection installation when a single-phase grounding fault occurs in an embodiment of the present invention.

[0041] Figure 5Schematic diagram of two layers of signals after reconstruction of the zero-mode voltage at the S end of the protection installation and the R end of the protection installation when a single-phase grounding fault occurs in an embodiment of the present invention, wherein (a) is a schematic diagram of the first layer of signals after reconstruction of the zero-mode voltage at the S end of the protection installation, (b) is a schematic diagram of the second layer of signals after reconstruction of the zero-mode voltage at the S end of the protection installation, (c) is a schematic diagram of the first layer of signals after reconstruction of the zero-mode voltage at the R end of the protection installation, and (d) is a schematic diagram of the second layer of signals after reconstruction of the zero-mode voltage at the R end of the protection installation.

[0042] Figure 6 Schematic diagram of two layers of signals after reconstruction of the line mode voltage at the S end and the R end of the protection installation when a phase-to-phase fault occurs in an embodiment of the present invention, wherein (a) is a schematic diagram of the first layer of signals after reconstruction of the line mode voltage at the S end of the protection installation, (b) is a schematic diagram of the second layer of signals after reconstruction of the line mode voltage at the S end of the protection installation, (c) is a schematic diagram of the first layer of signals after reconstruction of the line mode voltage at the R end of the protection installation, and (d) is a schematic diagram of the second layer of signals after reconstruction of the line mode voltage at the R end of the protection installation. DETAILED DESCRIPTION

[0043] The present invention will be further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the scope of protection of the present invention is not limited thereby.

[0044] In order to reduce the synchronization error caused by starting the recording files at different times, this embodiment proposes a recording file synchronization method for line multi-terminal differential protection joint adjustment, which calibrates the zero-mode and line-mode voltage Haar wavelet coefficients based on fault location compensation. Figure 1 As shown, the following steps are included:

[0045] S101) obtaining recording files at both ends of the fault line, extracting the three-phase voltages from the recording files at each end and performing wavelet decomposition, then reconstructing each layer after the wavelet decomposition to obtain each layer of reconstructed signals, finally selecting sampling points at the moment of fault mutation in each layer of the reconstructed signals and calculating the average value of the sampling points at the moment of fault mutation corresponding to the same end to obtain the fault moments at both ends of the fault line;

[0046] S102) If the error in the fault moments at both ends of the faulty line is greater than a preset threshold, a compensation value is calculated based on the difference in distances from the two ends of the faulty line to the fault point, the propagation speed of the fault traveling wave, and the sampling frequency of the recording file, and the compensation value is used to compensate for the fault moment of the end with the relatively delayed fault moment.

[0047] The main steps are described in detail below.

[0048] In step S101 of this embodiment, the three-phase voltages (u a 、ub 、u c ) is used to perform Karenbauer transformation to obtain the zero-mode voltage (u0) and line-mode voltage (u1). For faults with both zero-mode voltage and line-mode voltage components, the zero-mode voltage component is preferentially selected for analysis, while for faults without zero-mode voltage components, the line-mode voltage is used for analysis.

[0049] Correspondingly, in step S101, extracting the three-phase voltage from the recording file of each end and performing wavelet decomposition includes the following steps:

[0050] S201) extracting the three-phase voltage in the recording file and decomposing it to obtain zero-mode voltage and line-mode voltage;

[0051] S202) If the zero mode voltage is not 0, then performing wavelet decomposition on the zero mode voltage; if the zero mode voltage is 0, then performing wavelet decomposition on the line mode voltage.

[0052] It should be noted that how to perform Karenbauer transformation on the three-phase voltage to obtain the zero-mode voltage and the line-mode voltage is well known to those skilled in the art and will not be described in detail in this embodiment.

[0053] In step S202 of this embodiment, when performing wavelet decomposition on the zero mode voltage and the line mode voltage, specifically, a two-layer wavelet decomposition is performed on the zero mode voltage or the line mode voltage using a Haar wavelet basis, and the expression is as follows:

[0054] [c,l]=wavedec(u i ,2,'haar') (1)

[0055] Among them, wavedec represents the wavelet decomposition mathematical operation function, haar is the wavelet transform basis, c, l are the high-frequency and low-frequency coefficients after wavelet transform, u i Indicates the decomposed voltage, i indicates the type of decomposed voltage, when i is 0, it indicates zero-mode voltage, and when i is 1, it indicates line-mode voltage.

[0056] Correspondingly, in this embodiment, the reconstruction of each layer after wavelet decomposition is specifically the reconstruction of the high-frequency wavelet coefficients of the first layer and the second layer. The expression of the reconstructed signal of each layer is as follows:

[0057]

[0058] Among them, waverco represents the wavelet reconstruction function, du01 and du02 are the decomposed voltage u i The reconstructed first layer and the reconstructed second layer signals, d represents the reconstruction of high-frequency wavelet coefficients.

[0059] In step S101 of this embodiment, selecting the sampling point at the moment of the fault mutation in each layer of the reconstructed signal specifically includes the following steps:

[0060] S301) To avoid the influence of noise and highlight the sudden change part of the fault voltage signal, square the reconstructed signals du01 and du02 in each layer to obtain the corresponding sudden change coefficient sequences du01s and du02s, and calculate the maximum values ​​dmax1 and dmax2 in each sudden change coefficient sequence respectively;

[0061] S302) In each mutation coefficient sequence du01s and du02s, starting from the first sampling point, the value of each sampling point is compared with the corresponding maximum value dmax1 or dmax2, and the sampling point corresponding to the first value exceeding the maximum value by a specified proportion is used as the sampling point of the fault mutation moment.

[0062] In this embodiment, the specified ratio is set to 20%. When the value of the mutation coefficient of a sampling point exceeds 20% of the corresponding maximum value, the sampling point is considered to be a sampling point near the fault mutation. Since the reconstructed first-layer signal du01 and the sampling points in the corresponding mutation coefficient sequence du01s have a one-to-one correspondence, if the value of the mutation coefficient of the sampling point is the value in the mutation coefficient sequence du01s, the sampling point with the same sequence number in the reconstructed first-layer signal du01 is used as the sampling point at the fault mutation moment and is marked as index1. Similarly, the reconstructed second-layer signal du02 and the sampling point in the corresponding mutation coefficient sequence du02s have a one-to-one correspondence. If the value of the mutation coefficient of the sampling point is the value in the mutation coefficient sequence du02s, the sampling point with the same sequence number in the reconstructed second-layer signal du02 is used as the sampling point at the fault mutation moment and is marked as index2.

[0063] In this embodiment, when calculating the average value of the sampling points at the time of the sudden fault corresponding to the same end, specifically, the average value of the sampling point sequence numbers is calculated. After obtaining the sampling point index1 at the time of the sudden fault in the reconstructed first-layer signal du01 and the sampling point index2 at the time of the sudden fault in the reconstructed second-layer signal du02 corresponding to the same end, the fault time of this end is:

[0064]

[0065] Among them, Findex represents the sampling point corresponding to the fault moment.

[0066] Since the fault moment obtained by formula (3) is determined by the high-frequency component of the fault, it takes a certain amount of time for the high-frequency component to propagate from the fault point to the protection installation, which is related to the fault distance. Specifically, when the distances between the two ends of the fault line and the fault point are inconsistent, the fault mutation moment detected at the end farther from the fault point will be relatively delayed, causing the fault moment obtained by calculating the average fault mutation moment to also be relatively delayed. In this embodiment, the sampling point corresponding to the fault moment at the end with the relatively earlier fault moment at the two ends of the fault line is marked as Findex0, and the sampling point corresponding to the fault moment at the end with the relatively later fault moment is marked as Findex1.

[0067] In step S102 of this embodiment, the preset threshold is 3. That is, when |Findex1-Findex0|≤3, it is considered that the fault time error at both ends of the fault line meets the requirement and no subsequent compensation is required. However, when |Findex1-Findex0|>3, that is, the fault time error at both ends of the fault line does not meet the requirement, the following formula is used to use the compensation value to compensate for the fault time of the end with the relatively delayed fault time:

[0068]

[0069] Among them, TFindex is the sampling point corresponding to the fault moment after compensation, Findex1 is the sampling point corresponding to the fault moment at one end of the relatively delayed fault moment, is the compensation value. Specifically, ΔL is the difference in distance from the two ends of the fault line to the fault point, which can be obtained through the subsequent analysis report of the fault recording file. v is the line mode or zero mode propagation speed of the fault traveling wave in the line, which can be calculated based on the corresponding line parameters. f s The sampling frequency of the recording file.

[0070] The above method is further illustrated below through specific examples.

[0071] like Figure 2 As shown in Figure 2, when a single-phase grounding fault occurs at 0.2s (corresponding to sampling point 2000) between the transmission line SR and the busbar S at a distance of 90km, Figure 3 and Figure 4 The three-phase current waveforms of the busbars at the S and R terminals of the protection installation are shown, with the sampling frequency set to 10kHz. It can be seen that when the protection setting at both terminals is 2kA, the fault initiation point at the S terminal is at sampling point 2056, while the fault initiation point at the R terminal is at sampling point 2027. Therefore, the recording files at both terminals will start at different times, with a difference of 28 sampling points. This will result in a synchronization error of approximately 3ms when the inherent recording files are used to play back the relay protection instrument.

[0072] Through step S101, the recording files are obtained for the S end and the R end respectively, and the sampling points of the fault mutation moment in each layer of the signal after the zero-mode voltage reconstruction at both ends are calculated, such as Figure 5 As shown, from Figure 5 (a) and Figure 5 As can be seen in (b), since the S end is far away from the fault point, the fault mutation time detected is relatively delayed. The first layer detects the fault mutation time at sampling point 2012, and the second layer detects the fault mutation time at sampling point 2005. Therefore, the average of the uncompensated fault time is at sampling point 2008. Figure 5 (c) and Figure 5 (d) It can be seen that the moment when the fault mutation is detected by the first layer at the R end is at sampling point 2001, and the moment when the fault mutation is detected by the second layer is at sampling point 2004. Therefore, the sampling point corresponding to the fault moment is obtained by taking the average as sampling point 2002.

[0073] It can be seen that after step S101, the synchronization error between the recording files of terminals S and R has been reduced to 6 sampling points, but it does not meet the requirement of less than or equal to 3 sampling points. Therefore, step S102 is executed again. Based on the 80km difference in fault distance between the two terminals, the average speed of the zero-mode traveling wave of approximately 2.5e5km / s, and the sampling frequency of 10kHz, the compensation value is calculated to be 3.2. This compensation value is then used to compensate for the fault time of terminal S, which is relatively delayed. The sampling point corresponding to the fault time of terminal S after compensation is sampling point 2005. Therefore, after the final synchronization calibration, the synchronization error between the two terminals is approximately 3 sampling points, which is much smaller than the initial synchronization error of 28 sampling points.

[0074] Assuming that a phase-to-phase fault occurs under the aforementioned conditions, similarly, since the position of the fault point has not changed, without applying the method of this embodiment, the S-end and R-end recording files differ by 28 sampling points because they are started at different times.

[0075] Since there is no zero-mode component in the phase-to-phase fault, the waveform files are obtained for the S and R terminals respectively in step S101 and the sampling points of the fault mutation moment in each layer of the signal after the line mode voltage at both ends is reconstructed are calculated, such as Figure 6 As shown, from Figure 6 (a) and Figure 6 As can be seen from (b), the first layer detected fault mutation at the S end is at sampling point 2003, and the second layer detected fault mutation at sampling point 2001. Therefore, the average of the uncompensated fault is at sampling point 2002. Figure 6 (c) and Figure 6(d) It can be seen that the moment when the fault mutation is detected by the first layer at the R end is at sampling point 2001, and the moment when the fault mutation is detected by the second layer is also at sampling point 2001. Therefore, the sampling point corresponding to the fault moment is obtained by taking the average as sampling point 2001.

[0076] It can be seen that after step S101, the synchronization error between the recording files at terminals S and R has been reduced to 1 sampling point, meeting the requirement of less than or equal to 3 sampling points and significantly less than the initial synchronization error of 28 sampling points. If step S102 is executed again, the compensation value is calculated to be 2.6 based on the 80km difference in fault distance between the two terminals, the average speed of the line-mode traveling wave of approximately 3.5e5km / s, and the sampling frequency of 10kHz. This compensation value is then used to compensate for the fault time at the terminal S, which is relatively delayed. After compensation, the sampling point corresponding to the fault time at terminal S is sampling point 2000. Finally, after synchronization calibration, the synchronization error between the two terminals is also around 1 sampling point.

[0077] Example 2

[0078] This embodiment proposes a recording file synchronization system for line multi-terminal differential protection coordination, including a microprocessor and a memory connected to each other, and the microprocessor is programmed or configured to execute the recording file synchronization method for line multi-terminal differential protection coordination described in Example 1.

[0079] This embodiment also proposes a computer-readable storage medium, which stores a computer program or instruction. The computer program or instruction is programmed or configured to execute the recording file synchronization method for line multi-terminal differential protection coordination described in Example 1 through a processor.

[0080] This embodiment also proposes a computer program product, including a computer program or instructions, which are programmed or configured to execute the recording file synchronization method for line multi-terminal differential protection joint debugging described in Example 1 through a processor.

[0081] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A recording file synchronization method for line multi-terminal differential protection joint debugging, characterized in that: The following steps are involved: Obtain the recording files at both ends of the fault line, extract the three-phase voltages from the recording files at each end and perform wavelet decomposition. Then, reconstruct each layer after the wavelet decomposition to obtain each layer of reconstructed signals. Finally, select the sampling points at the fault mutation moment in each layer of the reconstructed signals and calculate the average value of the sampling points at the fault mutation moment corresponding to the same end to obtain the fault moment at both ends of the fault line. If the fault time error at both ends of the faulty line is greater than a preset threshold, a compensation value is calculated based on the difference in distance from the two ends of the faulty line to the fault point, the propagation speed of the fault traveling wave, and the sampling frequency of the recording file. The compensation value is used to compensate for the fault time of the end with the relatively delayed fault time.

2. The recording file synchronization method for line multi-terminal differential protection joint debugging according to claim 1 is characterized in that: Extracting the three-phase voltage from the recording file at each end and performing wavelet decomposition includes the following steps: Extract the three-phase voltage from the recording file and decompose it into zero-mode voltage and line-mode voltage; If the zero-mode voltage is not 0, the zero-mode voltage is subjected to wavelet decomposition; if the zero-mode voltage is 0, the line-mode voltage is subjected to wavelet decomposition.

3. The recording file synchronization method for line multi-terminal differential protection joint debugging according to claim 1 is characterized in that: When selecting the sampling point at the moment of fault mutation in each layer of the reconstructed signal, the following steps are specifically included: Perform square operations on each layer of reconstructed signals to obtain the corresponding mutation coefficient sequence, and calculate the maximum value of each mutation coefficient sequence; In each mutation coefficient sequence, the value of each sampling point is compared with the corresponding maximum value in turn, and the sampling point corresponding to the first value that exceeds the specified proportion of the maximum value is taken as the sampling point of the fault mutation moment.

4. The recording file synchronization method for line multi-terminal differential protection joint debugging according to claim 2 is characterized in that: When extracting the three-phase voltage in the recording file and decomposing it to obtain the zero-mode voltage and the line-mode voltage, specifically performing Karenbauer transformation on the three-phase voltage to obtain the zero-mode voltage and the line-mode voltage.

5. The recording file synchronization method for line multi-terminal differential protection joint debugging according to claim 2 is characterized in that: When performing wavelet decomposition on the zero-mode voltage and the line-mode voltage, the Haar wavelet basis is used to perform a two-layer wavelet decomposition on the zero-mode voltage or the line-mode voltage. The expression is as follows: [c,l]=wavedec(u i ,2,'her') Among them, wavedec represents the wavelet decomposition mathematical operation function, haar is the wavelet transform basis, c, l are the high-frequency and low-frequency coefficients after wavelet transform, u i Indicates the decomposed voltage, i indicates the type of decomposed voltage, when i is 0, it indicates zero-mode voltage, and when i is 1, it indicates line-mode voltage.

6. The recording file synchronization method for line multi-terminal differential protection joint debugging according to claim 5, characterized in that: Reconstructing each layer after wavelet decomposition is specifically reconstructing the high-frequency wavelet coefficients of the first and second layers. The signal expression of each layer after reconstruction is as follows: Among them, waverco represents the wavelet reconstruction function, du01 and du02 are the decomposed voltage u i The reconstructed first layer and the reconstructed second layer signals, d represents the reconstruction of high-frequency wavelet coefficients.

7. The recording file synchronization method for line multi-terminal differential protection joint debugging according to claim 1 is characterized in that: When using the compensation value to compensate for the fault moment at one end that is relatively delayed, the expression is as follows: Where TFindex is the sampling point corresponding to the fault moment after compensation, Findex1 is the sampling point corresponding to the fault moment at one end that is relatively delayed, ΔL is the difference in distance from the two ends of the fault line to the fault point, v is the line mode or zero mode propagation velocity of the fault traveling wave in the line, and f s The sampling frequency of the recording file.

8. A recording file synchronization system for line multi-terminal differential protection joint debugging, comprising a microprocessor and a memory connected to each other, characterized in that: The microprocessor is programmed or configured to execute the recording file synchronization method for line multi-terminal differential protection joint debugging as described in any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program or instruction stored therein, characterized in that: The computer program or instruction is programmed or configured to execute the recording file synchronization method for line multi-terminal differential protection joint debugging as described in any one of claims 1 to 7 through a processor.

10. A computer program product comprising a computer program or instructions, characterized in that The computer program or instruction is programmed or configured to execute the recording file synchronization method for line multi-terminal differential protection joint debugging as described in any one of claims 1 to 7 through a processor.

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