A method and system for synchronizing the modulus of dual-end traveling wave ranging based on differential current judgment

Abstract

This invention discloses a method and system for synchronizing the modulus of dual-end traveling wave ranging based on differential current judgment. The method includes: acquiring power frequency current data and traveling wave current data; obtaining power frequency current phasors from the power frequency current data and obtaining traveling wave current moduli from the traveling wave current data; calculating the inter-phase current differential current using the power frequency current phasors and performing preliminary screening of the differential currents; selecting the optimal inter-phase current containing the fault phase based on a comprehensive comparison of the selected differential current amplitude characteristics; selecting the corresponding traveling wave current modulus based on the optimal inter-phase current; performing wavelet transform on the selected corresponding traveling wave current modulus to obtain the initial traveling wave front time, thus completing dual-end traveling wave ranging. Advantages: This invention acquires power frequency current data from both sides, performs comprehensive judgment on the inter-phase current differential current, and achieves strict synchronization of modulus selection on both sides based on the judgment results, thereby effectively improving the accuracy of dual-end traveling wave ranging under multi-phase non-simultaneous fault conditions.

Description

Technical Field

[0001] This invention relates to a method and system for synchronizing the modulus of dual-end traveling wave ranging based on differential current judgment, belonging to the field of transmission line fault location technology. Background Technology

[0002] Two-end traveling wave ranging (TWR) of transmission lines is a fault location technology that uses the initial traveling wave front times at both ends of the line and precise time synchronization via fiber optic channels and satellites to determine the distance. TWR has advantages such as not needing to identify the reflected wave at the fault point and high ranging accuracy. Ideally, the initial traveling wave front times of all modulus currents are the same, allowing TWR to arbitrarily select modulus currents for calculation. However, actual fault conditions are often very complex; for example, a single-phase fault may rapidly develop into a multi-phase fault, causing significant differences in the initial traveling wave front times of various modulus currents. In such cases, if the modulus currents on both sides of the line are not selected consistently, the difference in the initial traveling wave front times on both sides will not accurately reflect the fault distance, leading to incorrect ranging results.

[0003] Achieving consistency in modulus selection on both sides of the line requires exchanging current data. However, traveling wave current has a very high sampling rate, and exchanging traveling wave current data would consume a large amount of bandwidth, making it less than optimal. Power frequency current has a lower sampling rate, and traditional line protection devices already implement the exchange of power frequency current data on both sides. Therefore, collecting power frequency current data from both sides to provide a reference for modulus selection in dual-end traveling wave ranging is a more feasible solution. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology in terms of low accuracy of dual-end traveling wave ranging under multiphase non-simultaneous fault conditions, and to provide a method and system for synchronizing the modulus of dual-end traveling wave ranging based on differential current judgment.

[0005] To solve the above technical problems, this invention provides a method for synchronizing the modulus of dual-end traveling wave ranging based on differential current judgment, comprising:

[0006] The power frequency current data and traveling wave current data of the line are obtained. The power frequency current phasor is obtained by performing phasor calculation on the power frequency current data, and the traveling wave current modulus is obtained by performing modulus calculation on the traveling wave current data.

[0007] The phase-to-phase current difference is calculated using power frequency current phasors, and the difference current is initially screened.

[0008] Based on the differential current amplitude characteristics after screening, the optimal interphase current containing the faulty phase is selected through comprehensive comparison;

[0009] Select the corresponding traveling wave current modulus based on the optimal phase-to-phase current, perform wavelet transform on the selected traveling wave current modulus to obtain the initial traveling wave front time, and complete the double-ended traveling wave ranging.

[0010] Furthermore, the modulus calculation includes the AB line modulus, BC line modulus, and CA line modulus, and the calculation formula is as follows:

[0011]

[0012] Where, m AB m BC m CA These are the linear moduli of traveling waves AB, BC, and CA, respectively; m A m B m C This contains the traveling wave current data for phases A, B, and C.

[0013] Furthermore, the formula for calculating the interphase current differential is as follows:

[0014]

[0015] φφ=AB、BC、CA

[0016] in, This refers to the phase-to-phase differential current. This refers to the phase-to-phase current on the M side of the line; This refers to the phase-to-phase current on the N side of the line;

[0017] The preliminary screening refers to the phase-to-phase current difference that meets the following conditions:

[0018]

[0019]

[0020] Among them, I set Let be the adjustable threshold; k is an adjustable coefficient that satisfies 0. <k<1。

[0021] Furthermore, the process of comprehensively comparing and selecting the optimal interphase current including the faulty phase includes:

[0022] If only one phase-to-phase current differential current meets the preliminary screening criteria, then that phase-to-phase current shall be taken as the optimal phase-to-phase current.

[0023] If two phase-to-phase current differential currents meet the preliminary screening conditions, then the phase-to-phase current differential current formed by the common phase of the two phase-to-phase current differential currents and the next phase is taken as the optimal phase-to-phase current.

[0024] If three phase-to-phase current differential currents meet the preliminary screening criteria, then the phase-to-phase current differential current with the largest amplitude is taken as the optimal phase-to-phase current.

[0025] If no phase-to-phase current differential current meets the preliminary screening criteria, the selection of the optimal phase-to-phase current will fail.

[0026] Furthermore, the process of selecting the corresponding traveling wave current modulus based on the optimal interphase current includes:

[0027] If the optimal phase-to-phase current selection fails, the linear modulus with the largest amplitude of the wavelet transform result is used as the current modulus for the two-end traveling wave ranging; otherwise, the linear modulus corresponding to the optimal phase-to-phase current is used as the current modulus for the two-end traveling wave ranging.

[0028] A dual-end traveling wave ranging modulus synchronization system based on differential current judgment includes:

[0029] The acquisition unit is used to acquire line power frequency current data and traveling wave current data;

[0030] The analog quantity calculation unit is used to obtain the power frequency current phasor by performing phasor calculation on the power frequency current data and to obtain the traveling wave current modulus by performing modulus calculation on the traveling wave current data.

[0031] The differential current calculation and screening unit is used to calculate the phase-to-phase differential current using power frequency current phasors, perform preliminary screening of the differential current, and select the optimal phase-to-phase current containing the fault phase based on the amplitude characteristics of the screened differential current and comprehensive comparison.

[0032] The traveling wave ranging unit is used to select the corresponding traveling wave current modulus according to the optimal phase-to-phase current, perform wavelet transform to obtain the initial traveling wave front time, and complete the double-ended traveling wave ranging.

[0033] The communication unit is connected to the acquisition unit and the traveling wave ranging unit, and is used to exchange power frequency current data and initial traveling wave head time with the other side of the line.

[0034] Furthermore, the analog quantity calculation unit includes a modulus calculation module.

[0035] Used to calculate the linear modulus of AB, BC, and CA according to the following formula;

[0036] The formula for obtaining this is:

[0037]

[0038] Where, m AB m BC m CA These are the linear moduli of traveling waves AB, BC, and CA, respectively; m A m B m C This contains the traveling wave current data for phases A, B, and C.

[0039] Furthermore, the differential current calculation and filtering unit includes an inter-phase current differential current calculation module and a filtering module.

[0040] The formula is used to calculate the phase-to-phase current difference according to the following formula:

[0041]

[0042] φφ=AB、BC、CA

[0043] in, This refers to the phase-to-phase differential current. This refers to the phase-to-phase current on the M side of the line; This refers to the phase-to-phase current on the N side of the line;

[0044] The filtering module is used to filter interphase current differential currents that meet the following conditions:

[0045]

[0046]

[0047] Among them, I set Let be the adjustable threshold; k is an adjustable coefficient that satisfies 0. <k<1。

[0048] Furthermore, the differential flow calculation and filtering unit includes a comparison module for performing the following comparisons:

[0049] If only one phase-to-phase current differential current meets the preliminary screening criteria, then that phase-to-phase current shall be taken as the optimal phase-to-phase current.

[0050] If two phase-to-phase current differential currents meet the preliminary screening conditions, then the phase-to-phase current differential current formed by the common phase of the two phase-to-phase current differential currents and the next phase is taken as the optimal phase-to-phase current.

[0051] If three phase-to-phase current differential currents meet the preliminary screening criteria, then the phase-to-phase current differential current with the largest amplitude is taken as the optimal phase-to-phase current.

[0052] If no phase-to-phase current differential current meets the preliminary screening criteria, the selection of the optimal phase-to-phase current will fail.

[0053] Furthermore, the traveling wave ranging unit includes a judgment module for making the following judgments:

[0054] If the optimal phase-to-phase current selection fails, the linear modulus with the largest amplitude of the wavelet transform result is used as the current modulus for the two-end traveling wave ranging; otherwise, the linear modulus corresponding to the optimal phase-to-phase current is used as the current modulus for the two-end traveling wave ranging.

[0055] The beneficial effects achieved by this invention are as follows:

[0056] This invention acquires power frequency current data from both sides, performs a comprehensive judgment on the phase-to-phase current differential current, and achieves strict synchronization of the selection of the modulus on both sides based on the judgment result, thereby effectively improving the accuracy of dual-end traveling wave ranging under multi-phase non-simultaneous fault conditions. Attached Figure Description

[0057] Figure 1 This is one of the flowcharts of an embodiment of the dual-end traveling wave ranging modulus synchronization method based on differential current judgment in this application;

[0058] Figure 2 This is a second flowchart of an embodiment of the dual-end traveling wave ranging modulus synchronization method based on differential current judgment in this application;

[0059] Figure 3 This is a schematic diagram of an embodiment of a dual-end traveling wave ranging modulus synchronization system based on differential current judgment according to this application. Detailed Implementation

[0060] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0061] like Figure 1 As shown, an embodiment of a dual-end traveling wave ranging modulus synchronization method based on differential current judgment includes the following steps:

[0062] S11: Obtain line power frequency current data and traveling wave current data; perform phasor calculation on the power frequency current data to obtain the power frequency current phasor; and perform modulus calculation on the traveling wave current data to obtain the traveling wave current modulus.

[0063] S12: Calculate the phase-to-phase current difference using power frequency current phasors and perform preliminary screening of the difference current;

[0064] S13: Based on the differential current amplitude characteristics after screening, select the optimal interphase current containing the faulty phase through comprehensive comparison;

[0065] S14: Select the corresponding traveling wave current modulus based on the optimal phase-to-phase current, perform wavelet transform on the selected corresponding traveling wave current modulus to obtain the initial traveling wave front time, and complete the double-ended traveling wave ranging.

[0066] like Figure 2 Another embodiment of the dual-end traveling wave ranging modulus synchronization method based on differential current judgment, as shown, includes the following steps:

[0067] Step 1: Obtain the line power frequency current data and traveling wave current data, perform phasor calculation on the power frequency current data, and perform modulus calculation on the traveling wave current data;

[0068] Preferably, the modulus calculation includes the AB line modulus, BC line modulus, and CA line modulus, and the calculation formula is as follows:

[0069]

[0070] Where, m AB mBC m CA These are the linear moduli of traveling waves AB, BC, and CA, respectively; m A m B m C This contains the traveling wave current data for phases A, B, and C.

[0071] Step 2: Calculate the phase-to-phase current difference using power frequency current phasors and perform preliminary screening of the difference current;

[0072] Preferably, the formula for calculating the phase-to-phase differential current is:

[0073]

[0074] φφ=AB、BC、CA

[0075] in, This refers to the phase-to-phase differential current. This refers to the phase-to-phase current on the M side of the line; This represents the phase-to-phase current on the N side of the line.

[0076] Preferably, the preliminary screening specifically refers to the phase-to-phase current difference that meets the following conditions:

[0077]

[0078]

[0079] Among them, I set Let be the adjustable threshold; k is an adjustable coefficient that satisfies 0. <k<1。

[0080] Step 3: Based on the differential current amplitude characteristics after screening, select the optimal interphase current containing the faulty phase through comprehensive comparison;

[0081] Preferably, the specific method for selecting the optimal interphase current including the faulty phase through comprehensive comparison is as follows:

[0082] If only one phase-to-phase current differential current meets the preliminary screening criteria, then that phase-to-phase current shall be taken as the optimal phase-to-phase current.

[0083] If two phase-to-phase current differential currents meet the preliminary screening conditions, then the phase-to-phase current differential current formed by the common phase of the two phase-to-phase current differential currents and the next phase is taken as the optimal phase-to-phase current.

[0084] If three phase-to-phase current differential currents meet the preliminary screening criteria, then the phase-to-phase current differential current with the largest amplitude is taken as the optimal phase-to-phase current.

[0085] If no phase-to-phase current differential current meets the preliminary screening criteria, the selection of the optimal phase-to-phase current will fail.

[0086] Step 4: Select the corresponding traveling wave current modulus based on the optimal phase-to-phase current, perform wavelet transform to obtain the initial traveling wave front time, and complete the double-ended traveling wave ranging.

[0087] Preferably, the specific method for selecting the corresponding traveling wave current modulus based on the optimal interphase current is as follows:

[0088] If the optimal phase-to-phase current selection fails, the linear modulus with the largest amplitude of the wavelet transform result is used as the current modulus for the two-end traveling wave ranging; otherwise, the linear modulus corresponding to the optimal phase-to-phase current is used as the current modulus for the two-end traveling wave ranging.

[0089] like Figure 3 The figure shown is an embodiment of a dual-end traveling wave ranging modulus synchronization system based on differential current judgment provided in this application, including an acquisition unit, an analog quantity calculation unit, a differential current calculation and filtering unit, a traveling wave ranging unit, and a communication unit, wherein:

[0090] The acquisition unit is used to acquire line power frequency current data and traveling wave current data;

[0091] The analog quantity calculation unit is connected to the acquisition unit and is used to perform phasor calculation on the power frequency current data and modulus calculation on the traveling wave current data.

[0092] The differential current calculation and screening unit is connected to the analog quantity calculation unit. It is used to calculate the phase-to-phase current differential current using the power frequency current phasor, perform preliminary screening of the differential current, and select the optimal phase-to-phase current containing the fault phase based on the amplitude characteristics of the screened differential current and comprehensive comparison.

[0093] The traveling wave ranging unit is connected to the differential current calculation and screening unit. It is used to select the corresponding traveling wave current modulus according to the optimal phase-to-phase current, perform wavelet transform to obtain the initial traveling wave front time, and complete the double-end traveling wave ranging.

[0094] The communication unit is connected to the acquisition unit and the traveling wave ranging unit, and is used to exchange power frequency current data and initial traveling wave head time with the other side of the line.

[0095] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0096] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0097] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0098] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0099] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for synchronizing the modulus of a two-end traveling wave ranging system based on differential current judgment, characterized in that, include: The power frequency current data and traveling wave current data of the line are obtained. The power frequency current phasor is obtained by performing phasor calculation on the power frequency current data, and the traveling wave current modulus is obtained by performing modulus calculation on the traveling wave current data. The phase-to-phase differential current is calculated using power frequency current phasors, and the differential current is initially screened; the calculation formula for the phase-to-phase differential current is: ； in, This refers to the phase-to-phase differential current. This refers to the phase-to-phase current on the M side of the line; This refers to the phase-to-phase current on the N side of the line; The preliminary screening refers to the phase-to-phase current difference that meets the following conditions: ； Among them, I set Let be the adjustable threshold; k is an adjustable coefficient that satisfies 0. <k<1; Based on the differential current amplitude characteristics after screening, the optimal interphase current containing the faulty phase is selected through comprehensive comparison, including: if only one interphase current differential current meets the preliminary screening conditions, then that interphase current is selected as the optimal interphase current; if two interphase current differential currents meet the preliminary screening conditions, then the interphase current differential current formed by the common phase of the two interphase current differential currents and the next phase is selected as the optimal interphase current; if three interphase current differential currents meet the preliminary screening conditions, then the interphase current differential current with the largest amplitude is selected as the optimal interphase current; if no interphase current differential current meets the preliminary screening conditions, then the selection of the optimal interphase current fails. The corresponding traveling wave current modulus is selected based on the optimal interphase current, including: if the optimal interphase current selection fails, the linear modulus with the largest amplitude of the wavelet transform result is used as the current modulus of the two-end traveling wave ranging; otherwise, the linear modulus corresponding to the optimal interphase current is used as the current modulus of the two-end traveling wave ranging. Wavelet transform is performed on the selected corresponding traveling wave current modulus to obtain the initial traveling wave front time, thus completing the double-ended traveling wave ranging.

2. The method for synchronizing the modulus of dual-end traveling wave ranging based on differential current judgment according to claim 1, characterized in that, The modulus calculation includes the AB line modulus, BC line modulus, and CA line modulus, and the formula is as follows: ； in, m AB , m BC , m CA These are the linear moduli of the traveling waves AB, BC, and CA, respectively. m A , m B , m C This contains the traveling wave current data for phases A, B, and C.

3. A dual-end traveling wave ranging modulus synchronization system based on differential current judgment, characterized in that, include: The acquisition unit is used to acquire line power frequency current data and traveling wave current data; The analog quantity calculation unit is used to obtain the power frequency current phasor by performing phasor calculation on the power frequency current data and to obtain the traveling wave current modulus by performing modulus calculation on the traveling wave current data. The differential current calculation and screening unit is used to calculate the phase-to-phase differential current using power frequency current phasors, perform preliminary screening of the differential current, and select the optimal phase-to-phase current containing the fault phase based on the amplitude characteristics of the screened differential current and comprehensive comparison. The traveling wave ranging unit is used to select the corresponding traveling wave current modulus according to the optimal phase-to-phase current, perform wavelet transform to obtain the initial traveling wave front time, and complete the double-ended traveling wave ranging. The communication unit is connected to the acquisition unit and the traveling wave ranging unit, and is used to exchange power frequency current data and initial traveling wave head time with the other side of the line. The differential current calculation and filtering unit includes an inter-phase current differential current calculation module and a filtering module. The formula is used to calculate the phase-to-phase current difference according to the following formula: ； in, This refers to the phase-to-phase differential current. This refers to the phase-to-phase current on the M side of the line; This refers to the phase-to-phase current on the N side of the line; The preliminary screening refers to the phase-to-phase current difference that meets the following conditions: ； Among them, I set Let be the adjustable threshold; k is an adjustable coefficient that satisfies 0. <k<1; The differential flow calculation and filtering unit includes a comparison module for performing the following comparisons: If only one phase-to-phase current differential current meets the preliminary screening criteria, then that phase-to-phase current shall be taken as the optimal phase-to-phase current. If two phase-to-phase current differential currents meet the preliminary screening conditions, then the phase-to-phase current differential current formed by the common phase of the two phase-to-phase current differential currents and the next phase is taken as the optimal phase-to-phase current. If three phase-to-phase current differential currents meet the preliminary screening criteria, then the phase-to-phase current differential current with the largest amplitude is taken as the optimal phase-to-phase current. If no phase-to-phase current differential current meets the preliminary screening criteria, the selection of the optimal phase-to-phase current will fail. The traveling wave ranging unit includes a judgment module, used to make the following judgments: If the optimal phase-to-phase current selection fails, the linear modulus with the largest amplitude of the wavelet transform result is used as the current modulus for the two-end traveling wave ranging; otherwise, the linear modulus corresponding to the optimal phase-to-phase current is used as the current modulus for the two-end traveling wave ranging.

4. The dual-end traveling wave ranging modulus synchronization system based on differential current judgment according to claim 3, characterized in that, The analog quantity calculation unit includes a modulus calculation module. Used to calculate the linear modulus of AB, BC, and CA according to the following formula; The formula for obtaining this is: ； in, m AB , m BC , m CA These are the linear moduli of the traveling waves AB, BC, and CA, respectively. m A , m B , m C This contains the traveling wave current data for phases A, B, and C.

Images