A method and device for handling abnormal differential current in high-voltage transmission lines

Abstract

The present invention belongs to the technical field of power systems and discloses a method and device for handling differential current anomalies in high-voltage transmission lines. The method comprises: obtaining analog data from line protection devices installed on both sides of the line, the analog data comprising at least the three-phase voltage, three-phase current, zero-sequence current, and three-phase differential current of the line protection devices; in the presence of a load current in the line protection devices, if it is determined that the maximum value of the three-phase currents meets a preset condition, calculating a differential current warning threshold for current differential protection; if the three-phase differential current is greater than the differential current warning threshold, initiating a differential current anomaly warning, and processing the analog data and recorded waveform data. This method solves the problems of low diagnostic accuracy of differential current anomalies and untimely fault warnings in current differential protection systems in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a method and device for processing differential current anomalies in high-voltage transmission lines. Background Art

[0002] Current differential protection is the primary protection method for high-voltage transmission lines. Its reliable and normal operation is crucial for rapidly clearing faults, ensuring the safety of transmission lines, and ensuring the security of the power grid. Abnormal differential current is a major cause of improper current differential operation. Line current differential protection requires current data from both sides of the line, so its reliable operation is affected by the status of the devices on both sides. The causes of abnormal differential current are numerous and complex to analyze. Traditional methods primarily utilize sampled data from single-side protection devices, resulting in low diagnostic accuracy and precision, making it difficult to meet the needs of precise on-site response. Summary of the Invention

[0003] Embodiments of the present invention provide a method and apparatus for handling differential current anomalies in high-voltage transmission lines to address the problems of low diagnostic accuracy and untimely fault warnings in current differential protection systems in the prior art. To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is provided below. This summary is not intended to be a general review, nor is it intended to identify key / important components or delineate the scope of protection of these embodiments. Its sole purpose is to present some concepts in a simple form as a prelude to the detailed description that follows.

[0004] According to a first aspect of an embodiment of the present invention, a method for handling a differential current anomaly in a high-voltage transmission line is provided.

[0005] In some embodiments, the method comprises:

[0006] Acquire analog data of line protection devices disposed on both sides of the line, respectively, the analog data including at least three-phase voltage, three-phase current, zero-sequence current, and three-phase differential current of the line protection devices; the line protection devices disposed on both sides of the line include a line protection device on the local side and a line protection device on the opposite side;

[0007] In the case where there is a load current in the line protection device, if it is determined that the maximum value of the three-phase current meets a preset condition, calculating a differential current warning threshold of the current differential protection;

[0008] When the three-phase differential current is greater than the differential current warning threshold, the differential current abnormality warning is activated, and the analog data and the recorded waveform data are processed.

[0009] In some embodiments, obtaining analog data of a line protection device specifically includes:

[0010] The analog data is obtained by using an online monitoring device for secondary equipment in the substation through a preset calling strategy.

[0011] In some embodiments, the preset summoning strategy is any one of the following:

[0012] Regularly summon data based on a pre-set summon cycle;

[0013] In response to the fault recording pushed by the line protection device, the analog data is called.

[0014] In some embodiments, when it is determined that the maximum value among the three-phase currents meets a preset condition, the preset condition is: max(Ia, Ib, Ic)>0.05In;

[0015] Wherein, In is the rated secondary current of the line protection device, Ia, Ib, and Ic are the current amplitudes of phase a, phase b, and phase c respectively collected by the line protection device on this side.

[0016] In some embodiments, a first preset formula is used to calculate a differential current warning threshold value Icdyj of the current differential protection;

[0017] Among them, the first preset formula is:

[0018] Icdyj=K*max(Ia,Ib,Ic)

[0019] Where K is the threshold coefficient, Ia, Ib, and Ic are the current amplitudes of phase a, phase b, and phase c collected by the line protection device on this side, respectively.

[0020] In some embodiments, when the three-phase differential current is greater than the differential current warning threshold, a differential current abnormality warning is initiated, and the analog data and the recorded waveform data are processed, specifically including:

[0021] The three-phase current amplitude difference Icda is calculated according to the second preset formula ht 、Icdb ht 、Icdc ht and phase difference Anga ht Angb ht Angc ht ;

[0022] The second preset formula includes:

[0023] Icda ht =Ia-Iar

[0024] Anga ht =AngIa-AngIar-180°

[0025] Icdb ht =Ib-Ibr

[0026] Angb ht =AngIb-AngIbr-180°

[0027] Icdc ht =Ic-Icr

[0028] Angc ht =AngIc-AngIcr-180°

[0029] Wherein, Ia, Ib, and Ic are the current amplitudes of phase a, phase b, and phase c collected by the line protection device on this side, respectively; Iar, Ibr, and Icr represent the current amplitudes of phase a, phase b, and phase c collected by the line protection device on the opposite side; AngIa, AngIb, and AngIc represent the current phase angles of phase a, phase b, and phase c collected by the line protection device on this side; AngIar, AngIbr, and AngIcr represent the current phase angles of phase a, phase b, and phase c collected by the line protection device on the opposite side.

[0030] In some embodiments, when the three-phase differential current is greater than the differential current warning threshold, a differential current abnormality warning is initiated, and the analog data and the recorded waveform data are processed, specifically including:

[0031] Extract the three-phase current sequence on the local and opposite sides from the fault waveform or the most recent startup waveform. Taking the recording startup time as the benchmark, calculate the similarity coefficient ρ of the corresponding phase current sequence on the local and opposite sides (Xi (i = a, b, c) and the current sequence on the opposite side (Yi (i = a, b, c)) using the third preset formula, one cycle before the start time and three cycles after the start time. xy ;

[0032] Wherein, the third preset formula is:

[0033]

[0034] Where Cov(X,Y) represents the covariance of the phase current sequence on this side and the phase current sequence on the opposite side, represents the variance of the phase current sequence on this side, represents the variance of the contralateral phase current series.

[0035] In some embodiments, when the three-phase differential current is greater than the differential current warning threshold, a differential current abnormality warning is initiated, and the analog data and the recorded waveform data are processed, specifically including:

[0036] The Fourier analysis method is used to calculate the second harmonic content THD2i (i = a, b, c) of the three-phase current sequence on this side in the waveform.

[0037] In some embodiments, the process of initiating a differential flow abnormality warning further includes:

[0038] Perform differential flow abnormality diagnosis according to preset rules to obtain and store diagnostic results.

[0039] In some embodiments, differential flow anomaly diagnosis is performed according to preset rules to obtain and store diagnostic results, specifically including:

[0040] When the three-phase current amplitude differences do not exceed the threshold and the current phase difference exceeds the threshold, the diagnosis result of the line protection device is determined to be a time parameter or communication delay abnormality, and the diagnosis result is recorded in the patrol record.

[0041] In some embodiments, differential flow anomaly diagnosis is performed according to preset rules to obtain and store diagnostic results, specifically including:

[0042] In the analog data obtained twice in a row, if the three-phase current amplitude difference exceeds the threshold and the current phase difference does not exceed the threshold, the diagnosis result of the line protection device is determined to be an amplitude parameter abnormality or a secondary circuit shunt, and the diagnosis result is recorded in the patrol record.

[0043] In some embodiments, differential flow anomaly diagnosis is performed according to preset rules to obtain and store diagnostic results, specifically including:

[0044] In one phase, the waveform satisfies |ρ xy |>0.98, THD2<1%, and at least one phase waveform data meets |ρ xy |<0.98, THD2>1%, the diagnosis result of the target side protection device is determined to be a neutral line circuit abnormality or multiple neutral line grounding, and the diagnosis result is recorded in the patrol record;

[0045] Among them, |ρ xy | represents the absolute value of the similarity coefficient, and THD2 represents the second harmonic content.

[0046] In some embodiments, analog data of line protection devices disposed on both sides of the line are obtained respectively, and then the method further includes:

[0047] In the case where there is a load current in the line protection device, if it is determined that the maximum value of the three-phase current does not meet the preset conditions, the diagnosis result is pushed to the centralized control station or the dispatching master station.

[0048] In some embodiments, calculating the differential current warning threshold of the current differential protection further includes:

[0049] When the three-phase differential current is less than the differential current warning threshold, the diagnosis result is pushed to the centralized control station or the dispatching master station.

[0050] According to a second aspect of an embodiment of the present invention, a device for handling abnormal differential current in a high-voltage transmission line is provided.

[0051] In some embodiments, the apparatus comprises:

[0052] a data acquisition unit, configured to respectively acquire analog data of line protection devices disposed on both sides of the line, the analog data including at least three-phase voltage, three-phase current, zero-sequence current, and three-phase differential current of the line protection devices; the line protection devices disposed on both sides of the line include a line protection device on the local side and a line protection device on the opposite side;

[0053] a threshold calculation unit, configured to calculate a differential current warning threshold of a current differential protection when a load current exists in the line protection device and if it is determined that the maximum value of the three-phase current satisfies a preset condition;

[0054] The result generating unit is used to start the differential current abnormal warning when the three-phase differential current is greater than the differential current warning threshold, and to process the analog data and the recorded waveform data.

[0055] According to a third aspect of an embodiment of the present invention, a computer device is provided.

[0056] In some embodiments, the computer device includes a memory and a processor, the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0057] The technical solution provided by the embodiment of the present invention may have the following beneficial effects:

[0058] The method for handling differential current anomalies in high-voltage transmission lines provided by the present invention obtains analog data from line protection devices installed on both sides of the line, wherein the analog data includes at least the three-phase voltage, three-phase current, zero-sequence current, and three-phase differential current of the line protection device; when there is a load current in the line protection device, if it is determined that the maximum value of the three-phase current meets the preset conditions, the differential current warning threshold of the current differential protection is calculated; when the three-phase differential current is greater than the differential current warning threshold, the differential current anomaly warning is activated, and the analog data and recorded waveform data are processed. In this line current differential protection differential current anomaly warning and diagnosis method, the three-phase current and waveform data of the local side and the opposite side are used to diagnose differential current anomalies, which overcomes the errors caused by unilateral current data diagnosis and improves the accuracy of diagnosis. It is suitable for deployment of station control layer equipment or master station acquisition systems. It solves the problems of low diagnostic accuracy of differential current anomalies and untimely fault warnings in current differential protection systems in the prior art.

[0059] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0061] Figure 1 This is one of the flow charts of a method for handling abnormal differential current in a high-voltage transmission line according to an exemplary embodiment;

[0062] Figure 2 This is a second flow chart of a method for handling abnormal differential current in a high-voltage transmission line according to an exemplary embodiment;

[0063] Figure 3 This is an example diagram of analog data pushed by the line protection device in this usage scenario;

[0064] Figure 4 This is an example diagram of the recorded waveform pushed by the line protection device in this usage scenario;

[0065] Figure 5 This is a flow chart of the method for handling abnormal differential current in high-voltage transmission lines provided by the present invention in this usage scenario;

[0066] Figure 6 This is a structural diagram of a device for handling abnormal differential current in a high-voltage transmission line according to an exemplary embodiment;

[0067] Figure 7 The figure is a schematic diagram showing the structure of a computer device according to an exemplary embodiment.

[0068] Reference numerals:

[0069] 601-data acquisition unit, 602-threshold calculation unit, 603-result generation unit. DETAILED DESCRIPTION

[0070] The following description and accompanying drawings sufficiently illustrate the specific embodiments herein to enable those skilled in the art to practice them. Portions and features of some embodiments may be included in or substituted for portions and features of other embodiments. The scope of the embodiments herein includes the entire scope of the claims, including all available equivalents thereof. Herein, the terms "first," "second," and the like are used solely to distinguish one element from another and do not require or imply any actual relationship or order between these elements. In practice, the first element can also be referred to as the second element, and vice versa. Furthermore, the terms "comprise," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a structure, device, or apparatus comprising a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such structure, device, or apparatus. Without further limitation, an element defined by the phrase "comprising a..." does not preclude the presence of other identical elements in the structure, device, or apparatus comprising the element. The various embodiments herein are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Similar or identical parts between the various embodiments can be referenced to each other.

[0071] The terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like used herein to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are intended only to facilitate the description of this document and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention. In the description herein, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, they can be mechanical or electrical connections, or they can be internal connections between two elements, they can be directly connected, or they can be indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0072] As used herein, unless otherwise specified, the term "plurality" means two or more.

[0073] In this document, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B.

[0074] In this article, the term "and / or" is used to describe the association relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or, A and B.

[0075] In the absence of conflict, the embodiments of the present invention and the features thereof may be combined with each other.

[0076] Please refer to Figure 1 , Figure 1 This is one of the flow charts of a method for handling a differential current anomaly in a high-voltage transmission line according to an exemplary embodiment.

[0077] In a specific embodiment, the method for handling abnormal differential current in a high-voltage transmission line provided by the present invention includes the following steps:

[0078] S110: Acquire analog data from line protection devices installed on both sides of the line, the analog data including at least three-phase voltage, three-phase current, zero-sequence current, and three-phase differential current of the line protection devices. The line protection devices installed on both sides of the line include a line protection device on the local side and a line protection device on the opposite side.

[0079] Specifically, when obtaining analog data from the line protection device, the analog data can be obtained by utilizing an online monitoring device for secondary equipment in the substation through a preset calling strategy.

[0080] The preset calling strategy is any one of the following:

[0081] First, data can be regularly summoned based on a pre-set summoning cycle. This means that data can be summoned regularly at a manually set interval to meet the real-time requirements of data acquisition and ensure the timeliness of calculations. For example, data can be summoned weekly or daily depending on the scenario.

[0082] Secondly, in response to the fault recording pushed by the line protection device, the analog data is called. In a specific usage scenario, the analog data of the protection device can be called when the fault recording pushed by the protection device is received. That is to say, data is obtained only when a fault push is received, which reduces the system's computational complexity.

[0083] S120: When there is load current in the line protection device, if it is determined that the maximum value of the three-phase current meets the preset conditions, the differential current warning threshold of the current differential protection is calculated; if it is determined that the maximum value of the three-phase current does not meet the preset conditions, the diagnosis result is pushed to the centralized control station or the dispatching master station.

[0084] Among them, the preset condition is: max(Ia, Ib, Ic)>0.05In; where In is the rated secondary current of the line protection device, Ia, Ib, and Ic are the a-phase current amplitude, b-phase current amplitude, and c-phase current amplitude collected by the line protection device on this side, respectively.

[0085] S130: When the three-phase differential current is greater than the differential current warning threshold, the differential current abnormality warning is started, and the analog data and recorded waveform data are processed; when the three-phase differential current is less than the differential current warning threshold, the diagnosis result is pushed to the centralized control station or the dispatching master station.

[0086] In step S120, a first preset formula is used to calculate a differential current warning threshold value Icdyj of the current differential protection;

[0087] Among them, the first preset formula is:

[0088] Icdyj=K*max(Ia,Ib,Ic)

[0089] Where K is the threshold coefficient, Ia, Ib, and Ic are the current amplitudes of phase a, phase b, and phase c collected by the line protection device on this side, respectively.

[0090] In step S130, the following strategy may be used to process the analog data and the recorded waveform data.

[0091] In some embodiments, when the three-phase differential current is greater than the differential current warning threshold, a differential current abnormality warning is initiated, and the analog data and the recorded waveform data are processed, specifically including:

[0092] The three-phase current amplitude difference Icda is calculated according to the second preset formula ht 、Icdb ht 、Icdc ht and phase difference Anga ht Angb ht Angc ht ;

[0093] The second preset formula includes:

[0094] Icda ht =Ia-Iar

[0095] Anga ht =AngIa-AngIar-180°

[0096] Icdb ht =Ib-Ibr

[0097] Angbht =AngIb-AngIbr-180°

[0098] Icdc ht =Ic-Icr

[0099] Angc ht =AngIc-AngIcr-180°

[0100] Wherein, Ia, Ib, and Ic are the current amplitudes of phase a, phase b, and phase c collected by the line protection device on this side, respectively; Iar, Ibr, and Icr represent the current amplitudes of phase a, phase b, and phase c collected by the line protection device on the opposite side; AngIa, AngIb, and AngIc represent the current phase angles of phase a, phase b, and phase c collected by the line protection device on this side; AngIar, AngIbr, and AngIcr represent the current phase angles of phase a, phase b, and phase c collected by the line protection device on the opposite side.

[0101] In other embodiments, when the three-phase differential current is greater than the differential current warning threshold, a differential current abnormality warning is initiated, and the analog data and the recorded waveform data are processed, specifically including:

[0102] Extract the three-phase current sequence on the local and opposite sides from the fault waveform or the most recent startup waveform. Taking the recording startup time as the benchmark, calculate the similarity coefficient ρ of the corresponding phase current sequence on the local and opposite sides (Xi (i = a, b, c) and the current sequence on the opposite side (Yi (i = a, b, c)) using the third preset formula, one cycle before the start time and three cycles after the start time. xy ;

[0103] Wherein, the third preset formula is:

[0104]

[0105] Where Cov(X,Y) represents the covariance of the phase current sequence on this side and the phase current sequence on the opposite side, represents the variance of the phase current sequence on this side, represents the variance of the contralateral phase current series.

[0106] In other embodiments, when the three-phase differential current is greater than the differential current warning threshold, a differential current abnormality warning is initiated, and the analog data and the recorded waveform data are processed, specifically including:

[0107] The Fourier analysis method is used to calculate the second harmonic content THD2i (i = a, b, c) of the three-phase current sequence on this side in the waveform.

[0108] Furthermore, in the method provided by the present invention, Figure 2 As shown, after starting the differential flow abnormality warning, the following steps are also included:

[0109] S140: Perform differential flow abnormality diagnosis according to preset rules to obtain and store the diagnosis result.

[0110] Specifically, a variety of strategies can be used to obtain abnormal diagnostic results.

[0111] First, perform differential flow anomaly diagnosis according to preset rules to obtain and store diagnostic results, including:

[0112] When the three-phase current amplitude differences do not exceed the threshold and the current phase difference exceeds the threshold, the diagnosis result of the line protection device is determined to be a time parameter or communication delay abnormality, and the diagnosis result is recorded in the patrol record.

[0113] Second, perform differential flow anomaly diagnosis according to preset rules to obtain and store the diagnosis results, including:

[0114] In the analog data obtained twice in a row, if the three-phase current amplitude difference exceeds the threshold and the current phase difference does not exceed the threshold, the diagnosis result of the line protection device is determined to be an amplitude parameter abnormality or a secondary circuit shunt, and the diagnosis result is recorded in the patrol record.

[0115] Third, perform differential flow anomaly diagnosis according to preset rules to obtain and store diagnostic results, including:

[0116] In one phase, the waveform satisfies |ρ xy |>0.98, THD2<1%, and at least one phase waveform data meets |ρ xy |<0.98, THD2>1%, the diagnosis result of the target side protection device is determined to be a neutral line circuit abnormality or multiple neutral line grounding, and the diagnosis result is recorded in the patrol record;

[0117] Among them, |ρ xy | represents the absolute value of the similarity coefficient, and THD2 represents the second harmonic content.

[0118] In the above-mentioned specific embodiment, the method for handling differential current anomalies of high-voltage transmission lines provided by the present invention obtains analog data of the line protection devices provided on both sides of the line respectively, wherein the analog data includes at least the three-phase voltage, three-phase current, zero-sequence current and three-phase differential current of the line protection devices; when there is a load current in the line protection device, if it is determined that the maximum value of the three-phase current meets the preset conditions, the differential current warning threshold of the current differential protection is calculated; when the three-phase differential current is greater than the differential current warning threshold, the differential current anomaly warning is activated, and the analog data and the recorded waveform data are processed. In this line current differential protection differential current anomaly warning and diagnosis method, the three-phase current and waveform data of the local side and the opposite side are used to diagnose the differential current anomaly, which overcomes the error caused by the diagnosis of unilateral current data and improves the accuracy of the diagnosis. It is suitable for deployment of station control layer equipment or master station acquisition systems. It solves the problems of low diagnostic accuracy of differential current anomalies and untimely fault warnings in the current differential protection system in the prior art.

[0119] For ease of understanding, the implementation process of the method for handling abnormal differential current in high-voltage transmission lines provided by the present invention is briefly described below in conjunction with a usage scenario.

[0120] like Figure 3-Figure 5 As shown, Figure 3 This is an example diagram of analog data pushed by the line protection device in this usage scenario; Figure 4 This is an example diagram of the recorded waveform pushed by the line protection device in this usage scenario; Figure 5 This is a flow chart of the method for handling abnormal differential current in high-voltage transmission lines provided by the present invention in this usage scenario.

[0121] Step a: Using an online monitoring device for secondary equipment in the substation, analog data of the line protection device is collected according to the following rules. The analog data includes three-phase voltages and three-phase currents, zero-sequence current, and three-phase differential current of the protection devices on both sides. The line protection devices installed on both sides of the line include a line protection device on the local side and a line protection device on the opposite side.

[0122] Method 1: Call data regularly according to a manually set cycle.

[0123] Method 2: When receiving the fault recording pushed by the protection device, call the analog data of the protection device.

[0124] Step b, determine whether the system has load current: max(Ia, Ib, Ic)>0.05In (In is the rated secondary current of the device, 1A or 5A). If this condition is met, execute step c, otherwise execute step g.

[0125] Step c: Calculate the differential current warning threshold Icdyj of the current differential protection according to the following method:

[0126] Icdyj=K*max(Ia,Ib,Ic), K is the threshold coefficient, which can be 0.05~0.1.

[0127] Step d: Determine whether the three-phase differential current calculated within the device exceeds a preset differential current threshold value Icdyj:

[0128] max(Icda,Icdb,Icdb)>Icdyj

[0129] If the preset warning threshold is exceeded, the differential flow abnormality warning is activated and step e is executed; otherwise, the system records that the differential flow is normal and executes step g.

[0130] Step e: Process the analog data and the recorded waveform data as follows:

[0131] Processing 1: Calculate the three-phase current amplitude difference Icda ht 、Icdb ht 、Icdc ht and phase difference Anga ht Angb ht Angc ht :

[0132] Icda ht =Ia-Iar;Anga ht =AngIa-AngIar-180°

[0133] Icdb ht =Ib-Ibr;Angb ht =AngIb-AngIbr-180°

[0134] Icdc ht =Ic-Icr;Angc ht =AngIc-AngIcr-180°

[0135] Processing 2: Extract the three-phase current sequences on the local and opposite sides from the fault waveform corresponding to the current analog call or the most recent startup waveform. Based on the waveform startup time, calculate the similarity coefficient ρxy of the corresponding phase current sequences on the local and opposite sides (Xi (i = a, b, c)) and the opposite side current sequence (Yi (i = a, b, c)) for the cycle before and three cycles after the start time, as follows:

[0136]

[0137] Process 3: Use the Fourier analysis method to calculate the second harmonic content THD2i (i = a, b, c) of the three-phase current sequence on this side in the waveform;

[0138] Step f: diagnose the abnormal flow difference according to the following rules:

[0139] Criterion 1: Current amplitude difference Icda ht 、Icdb ht 、Icdc ht None of them exceed the threshold value (the current amplitude difference threshold value is 0.05In), the current phase difference Ang ht If the current phase difference exceeds the threshold (the current phase difference threshold is 15°), it is determined that the protection device time parameter or communication delay is abnormal. The diagnosis result is recorded in the inspection record and the process goes to step g;

[0140] Criterion 2: Current amplitude difference Icda ht 、Icdb ht 、Icdc ht Exceeding the threshold, the current phase difference Ang ht The threshold is not exceeded and the two consecutive call data are satisfied; or the waveform similarity coefficient of the abnormal phase of the differential current is: |ρ xy |>0.98, THD2<1%. Judgment: The amplitude parameters of the protection devices on both sides are abnormal or the secondary circuit is shunted. The diagnosis result is recorded in the inspection record and the process goes to step g;

[0141] Criterion 3: One phase waveform satisfies |ρ xy |>0.98, THD2<1%, at least one phase waveform data meets |ρ xy |<0.98, THD2>1%, judgment: The neutral line circuit of the protection device on this side is abnormal or the neutral line is grounded at multiple points. The diagnosis result is recorded in the inspection record and the process goes to step g;

[0142] Criterion 4: If none of the above criteria are met, the abnormal differential flow is determined to be caused by other reasons. The diagnosis result is recorded in the inspection record and the process goes to step g.

[0143] Step g: The secondary equipment online monitoring device pushes the diagnosis results to the centralized control station or the dispatching master station, and returns to step a.

[0144] Compared with the prior art, the present invention has the following beneficial effects:

[0145] 1. In the current differential protection differential current abnormal warning and diagnosis method and system of this line, the differential current abnormality diagnosis is performed using the sampling data and waveforms of the three-phase current on the local side and the opposite side, thereby improving the accuracy of the abnormality diagnosis.

[0146] 2. In the line current differential protection differential current abnormal warning and diagnosis method and system, diagnostic criteria for different differential current abnormalities are given, which improves the diagnostic accuracy.

[0147] 3. The protection device itself can provide three-phase current signals on the local and opposite sides, without adding additional equipment, and has high practical application value.

[0148] According to a second aspect of an embodiment of the present invention, a device for handling abnormal differential current in a high-voltage transmission line is provided.

[0149] In some embodiments, as Figure 6 As shown, the device includes:

[0150] A data acquisition unit 601 is configured to respectively acquire analog data from line protection devices disposed on both sides of a line, the analog data including at least three-phase voltage, three-phase current, zero-sequence current, and three-phase differential current of the line protection devices; the line protection devices disposed on both sides of the line include a line protection device on the local side and a line protection device on the opposite side;

[0151] a threshold calculation unit 602 for calculating a differential current warning threshold for current differential protection when a load current exists in the line protection device and if it is determined that the maximum value of the three-phase currents meets a preset condition;

[0152] The result generating unit 603 is configured to initiate a differential current abnormality warning when the three-phase differential current is greater than the differential current warning threshold, and to process the analog data and the recorded waveform data.

[0153] In some embodiments, obtaining analog data of a line protection device specifically includes:

[0154] The analog data is obtained by using an online monitoring device for secondary equipment in the substation through a preset calling strategy.

[0155] In some embodiments, the preset summoning strategy is any one of the following:

[0156] Regularly summon data based on a pre-set summon cycle;

[0157] In response to the fault recording pushed by the line protection device, the analog data is called.

[0158] In some embodiments, when it is determined that the maximum value among the three-phase currents meets a preset condition, the preset condition is: max(Ia, Ib, Ic)>0.05In;

[0159] Wherein, In is the rated secondary current of the line protection device, Ia, Ib, and Ic are the current amplitudes of phase a, phase b, and phase c respectively collected by the line protection device on this side.

[0160] In some embodiments, a first preset formula is used to calculate a differential current warning threshold value Icdyj of the current differential protection;

[0161] Among them, the first preset formula is:

[0162] Icdyj=K*max(Ia,Ib,Ic)

[0163] Where K is the threshold coefficient, Ia, Ib, and Ic are the current amplitudes of phase a, phase b, and phase c collected by the line protection device on this side, respectively.

[0164] In some embodiments, when the three-phase differential current is greater than the differential current warning threshold, a differential current abnormality warning is initiated, and the analog data and the recorded waveform data are processed, specifically including:

[0165] The three-phase current amplitude difference Icda is calculated according to the second preset formula ht 、Icdb ht 、Icdc ht and phase difference Anga ht Angb ht Angc ht ;

[0166] The second preset formula includes:

[0167] Icda ht =Ia-Iar

[0168] Anga ht =AngIa-AngIar-180°

[0169] Icdb ht =Ib-Ibr

[0170] Angb ht =AngIb-AngIbr-180°

[0171] Icdc ht =Ic-Icr

[0172] Angc ht =AngIc-AngIcr-180°

[0173] Wherein, Ia, Ib, and Ic are the current amplitudes of phase a, phase b, and phase c collected by the line protection device on this side, respectively; Iar, Ibr, and Icr represent the current amplitudes of phase a, phase b, and phase c collected by the line protection device on the opposite side; AngIa, AngIb, and AngIc represent the current phase angles of phase a, phase b, and phase c collected by the line protection device on this side; AngIar, AngIbr, and AngIcr represent the current phase angles of phase a, phase b, and phase c collected by the line protection device on the opposite side.

[0174] In some embodiments, when the three-phase differential current is greater than the differential current warning threshold, a differential current abnormality warning is initiated, and the analog data and the recorded waveform data are processed, specifically including:

[0175] Extract the three-phase current sequence on the local and opposite sides from the fault waveform or the most recent startup waveform. Taking the recording startup time as the benchmark, calculate the similarity coefficient ρ of the corresponding phase current sequence on the local and opposite sides (Xi (i = a, b, c) and the current sequence on the opposite side (Yi (i = a, b, c)) using the third preset formula, one cycle before the start time and three cycles after the start time. xy ;

[0176] Wherein, the third preset formula is:

[0177]

[0178] Where Cov(X,Y) represents the covariance of the phase current sequence on this side and the phase current sequence on the opposite side, represents the variance of the phase current sequence on this side, represents the variance of the contralateral phase current series.

[0179] In some embodiments, when the three-phase differential current is greater than the differential current warning threshold, a differential current abnormality warning is initiated, and the analog data and the recorded waveform data are processed, specifically including:

[0180] The Fourier analysis method is used to calculate the second harmonic content THD2i (i = a, b, c) of the three-phase current sequence on this side in the waveform.

[0181] In some embodiments, the process of initiating a differential flow abnormality warning further includes:

[0182] Perform differential flow abnormality diagnosis according to preset rules to obtain and store diagnostic results.

[0183] In some embodiments, differential flow anomaly diagnosis is performed according to preset rules to obtain and store diagnostic results, specifically including:

[0184] When the three-phase current amplitude differences do not exceed the threshold and the current phase difference exceeds the threshold, the diagnosis result of the line protection device is determined to be a time parameter or communication delay abnormality, and the diagnosis result is recorded in the patrol record.

[0185] In some embodiments, differential flow anomaly diagnosis is performed according to preset rules to obtain and store diagnostic results, specifically including:

[0186] In the analog data obtained twice in a row, if the three-phase current amplitude difference exceeds the threshold and the current phase difference does not exceed the threshold, the diagnosis result of the line protection device is determined to be an amplitude parameter abnormality or a secondary circuit shunt, and the diagnosis result is recorded in the patrol record.

[0187] In some embodiments, differential flow anomaly diagnosis is performed according to preset rules to obtain and store diagnostic results, specifically including:

[0188] In one phase, the waveform satisfies |ρ xy |>0.98, THD2<1%, and at least one phase waveform data meets |ρ xy |<0.98, THD2>1%, the diagnosis result of the target side protection device is determined to be a neutral line circuit abnormality or multiple neutral line grounding, and the diagnosis result is recorded in the patrol record;

[0189] Among them, |ρ xy | represents the absolute value of the similarity coefficient, and THD2 represents the second harmonic content.

[0190] In some embodiments, analog data of line protection devices disposed on both sides of the line are obtained respectively, and then the method further includes:

[0191] In the case where there is a load current in the line protection device, if it is determined that the maximum value of the three-phase current does not meet the preset conditions, the diagnosis result is pushed to the centralized control station or the dispatching master station.

[0192] In some embodiments, calculating the differential current warning threshold of the current differential protection further includes:

[0193] When the three-phase differential current is less than the differential current warning threshold, the diagnosis result is pushed to the centralized control station or the dispatching master station.

[0194] In the above-mentioned specific embodiment, the high-voltage transmission line differential current abnormality processing device provided by the present invention obtains analog data of the line protection devices arranged on both sides of the line respectively, and the analog data includes at least the three-phase voltage, three-phase current, zero-sequence current and three-phase differential current of the line protection device; when there is a load current in the line protection device, if it is determined that the maximum value of the three-phase current meets the preset conditions, the differential current warning threshold of the current differential protection is calculated; when the three-phase differential current is greater than the differential current warning threshold, the differential current abnormality warning is activated, and the analog data and recorded waveform data are processed. In this line current differential protection differential current abnormality warning and diagnosis method, the three-phase current and waveform data of the local side and the opposite side are used to diagnose the differential current abnormality, which overcomes the error caused by the diagnosis of unilateral current data and improves the accuracy of diagnosis. It is suitable for deployment of station control layer equipment or master station acquisition system. It solves the problem of low diagnostic accuracy of differential current abnormality and untimely fault warning in the current differential protection system in the prior art.

[0195] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Figure 7 As shown. The computer device includes a processor, a memory, and a network interface connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the computer device is used to store static information and dynamic information data. The network interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, the steps of the above-mentioned method embodiment are implemented.

[0196] Those skilled in the art will understand that Figure 7 The structure shown in the figure is merely a block diagram of a portion of the structure related to the solution of the present invention and does not constitute a limitation on the computer device to which the solution of the present invention is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0197] In one embodiment, a computer device is further provided, including a memory and a processor. The memory stores a computer program, and the processor implements the steps in the above method embodiment when executing the computer program.

[0198] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above method embodiment are implemented.

[0199] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0200] The present invention is not limited to the structures described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for handling abnormal differential current in a high-voltage transmission line, characterized in that: The method comprises: Acquire analog data of line protection devices disposed on both sides of the line, respectively, the analog data including at least three-phase voltage, three-phase current, zero-sequence current, and three-phase differential current of the line protection devices; the line protection devices disposed on both sides of the line include a line protection device on the local side and a line protection device on the opposite side; In the case where there is a load current in the line protection device, if it is determined that the maximum value of the three-phase current meets a preset condition, calculating a differential current warning threshold of the current differential protection; When the three-phase differential current is greater than the differential current warning threshold, the differential current abnormality warning is initiated, and the analog data and the recorded waveform data are processed, including: Calculate the three-phase current amplitude difference Icda ht 、Icdb ht 、Icdc ht and phase difference Anga ht Angb ht Angc ht ; Extract the three-phase current sequence on the local and opposite sides from the fault waveform or the most recent startup waveform. Based on the start time of the waveform recording, calculate the similarity coefficient ρ of the corresponding phase current sequence on the local and opposite sides for one cycle before the start time and three cycles after the start time. xy ; Using the Fourier analysis method, the second harmonic content THD2i of the three-phase current sequence on this side in the waveform is calculated, where i = a, b, c; Perform differential flow anomaly diagnosis according to preset rules to obtain and store diagnostic results, including: If the three-phase current amplitude differences do not exceed the threshold value and the current phase difference exceeds the threshold value, the diagnosis result of the line protection device is determined to be a time parameter or communication delay abnormality, and the diagnosis result is recorded in the patrol record; In two consecutive acquisitions of analog data, if the three-phase current amplitude differences all exceed the threshold value and the current phase difference does not exceed the threshold value, the line protection device diagnosis result is determined to be an amplitude parameter abnormality or a secondary circuit shunt, and the diagnosis result is recorded in the patrol record; In one phase, the waveform satisfies |ρ xy |>0.98, THD2<1%, and at least one phase waveform data meets |ρ xy |<0.98, THD2>1%, the diagnosis result of the target side protection device is determined to be a neutral line circuit abnormality or multiple neutral line grounding, and the diagnosis result is recorded in the patrol record; Among them, |ρ xy | represents the absolute value of the similarity coefficient, and THD2 represents the second harmonic content.

2. The method for handling abnormal differential current in high-voltage transmission lines according to claim 1, characterized in that: Obtain analog data from line protection devices, including: The analog data is obtained by using an online monitoring device for secondary equipment in the substation through a preset calling strategy.

3. The method for handling abnormal differential current in high-voltage transmission lines according to claim 2, characterized in that: The preset summoning strategy is any of the following: Regularly summon data based on a pre-set summon cycle; In response to the fault recording pushed by the line protection device, the analog data is called.

4. The method for handling abnormal differential current in high-voltage transmission lines according to claim 1, characterized in that: When it is determined that the maximum value among the three-phase currents meets a preset condition, the preset condition is: max(Ia,Ib,Ic)>0.05In; Wherein, In is the rated secondary current of the line protection device on this side, Ia, Ib, and Ic are the current amplitudes of phase a, phase b, and phase c respectively collected by the line protection device on this side.

5. The method for handling abnormal differential current in high-voltage transmission lines according to claim 1, characterized in that: Calculate the differential current warning threshold Icdyj of the current differential protection using the first preset formula; Among them, the first preset formula is: Icdyj=K*max(Ia,Ib,Ic) Where K is the threshold coefficient, Ia, Ib, and Ic are the current amplitudes of phase a, phase b, and phase c collected by the line protection device on this side, respectively.

6. The method for handling abnormal differential current in high-voltage transmission lines according to claim 1, characterized in that: When the three-phase differential current is greater than the differential current warning threshold, the differential current abnormality warning is initiated, and the analog data and the recorded waveform data are processed, specifically including: The three-phase current amplitude difference Icda is calculated according to the second preset formula ht 、Icdb ht 、Icdc ht and phase difference Anga ht Angb ht Angc ht ; The second preset formula includes: ICDA ht =Ia-Iar Shell ht =Anglia-Anglia-180° Icdb ht =Ib-Ibr The ht =AngIb-AngIbr-180° Icdc ht =Ic-Icr Eng ht =Angle-Angle-180° Wherein, Ia, Ib, and Ic are the current amplitudes of phase a, phase b, and phase c respectively collected by the line protection device on this side; Iar, Ibr, and Icr represent the current amplitudes of phase a, phase b, and phase c collected by the line protection device on the opposite side; AngIa, AngIb, and AngIc represent the current phase angles of phase a, phase b, and phase c collected by the line protection device on this side; AngIar, AngIbr, and AngIcr represent the current phase angles of phase a, phase b, and phase c collected by the line protection device on the opposite side.

7. The method for handling abnormal differential current in high-voltage transmission lines according to claim 1, characterized in that: When the three-phase differential current is greater than the differential current warning threshold, the differential current abnormality warning is initiated, and the analog data and the recorded waveform data are processed, specifically including: Extract the three-phase current sequence on the local side and the opposite side from the fault waveform or the most recent startup waveform. Based on the start time of the recording waveform, calculate the similarity coefficient ρ of the corresponding phase current sequence on the local side and the opposite side using the third preset formula for the first cycle before the start time and the three cycles after the start time. xy , the phase current sequence on this side is Xi, i = a, b, c, and the phase current sequence on the opposite side is Yi, i = a, b, c; Wherein, the third preset formula is: Where Cov(X,Y) represents the covariance of the phase current sequence on this side and the phase current sequence on the opposite side, represents the variance of the phase current sequence on this side, represents the variance of the contralateral phase current series.

8. The method for handling abnormal differential current in high-voltage transmission lines according to claim 1, characterized in that: The analog data of the line protection devices installed on both sides of the line are obtained respectively, and then the following is also included: In the case where there is a load current in the line protection device, if it is determined that the maximum value of the three-phase current does not meet the preset conditions, the diagnosis result is pushed to the centralized control station or the dispatching master station.

9. The method for handling abnormal differential current in high-voltage transmission lines according to claim 1, characterized in that: Calculate the differential current warning threshold of the current differential protection, followed by: When the three-phase differential current is less than the differential current warning threshold, the diagnosis result is pushed to the centralized control station or the dispatching master station.

10. A device for handling abnormal differential current in high-voltage transmission lines, characterized in that: The device comprises: a data acquisition unit, configured to respectively acquire analog data of line protection devices disposed on both sides of the line, the analog data including at least three-phase voltage, three-phase current, zero-sequence current, and three-phase differential current of the line protection devices; the line protection devices disposed on both sides of the line include a line protection device on the local side and a line protection device on the opposite side; a threshold calculation unit, configured to calculate a differential current warning threshold of a current differential protection when a load current exists in the line protection device and if it is determined that the maximum value of the three-phase current satisfies a preset condition; The result generating unit is used to start the abnormal differential current warning when the three-phase differential current is greater than the differential current warning threshold, and process the analog data and the recorded waveform data, including: calculating the three-phase current amplitude difference Icda ht 、Icdb ht 、Icdc ht and phase difference Anga ht Angb ht Angc ht ; Extract the three-phase current sequence on the local and opposite sides from the fault waveform or the most recent startup waveform. Based on the start time of the waveform recording, calculate the similarity coefficient ρ of the corresponding phase current sequence on the local and opposite sides for one cycle before the start time and three cycles after the start time. xy , the phase current sequence on this side is Xi, i = a, b, c, and the phase current sequence on the opposite side is Yi, i = a, b, c; Using the Fourier analysis method, the second harmonic content THD2i of the three-phase current sequence on this side in the waveform is calculated, where i = a, b, c; Perform differential flow anomaly diagnosis according to preset rules to obtain and store diagnostic results, including: If the three-phase current amplitude differences do not exceed the threshold value and the current phase difference exceeds the threshold value, the diagnosis result of the line protection device is determined to be a time parameter or communication delay abnormality, and the diagnosis result is recorded in the patrol record; In two consecutive acquisitions of analog data, if the three-phase current amplitude differences all exceed the threshold value and the current phase difference does not exceed the threshold value, the line protection device diagnosis result is determined to be an amplitude parameter abnormality or a secondary circuit shunt, and the diagnosis result is recorded in the patrol record; In one phase, the waveform satisfies |ρ xy |>0.98, THD2<1%, and at least one phase waveform data meets |ρ xy |<0.98, THD2>1%, the diagnosis result of the target side protection device is determined to be a neutral line circuit abnormality or multiple neutral line grounding, and the diagnosis result is recorded in the patrol record; Among them, |ρ xy | represents the absolute value of the similarity coefficient, and THD2 represents the second harmonic content.

11. The device for handling abnormal current difference in high-voltage transmission lines according to claim 10, characterized in that: The data acquisition unit acquires analog data of the line protection device, specifically including: The analog data is obtained by using an online monitoring device for secondary equipment in the substation through a preset calling strategy.

12. The device for handling abnormal current difference in high-voltage transmission lines according to claim 11, characterized in that: The preset summoning strategy is any of the following: Regularly summon data based on a pre-set summon cycle; In response to the fault recording pushed by the line protection device, the analog data is called.

13. The device for handling abnormal current difference in high-voltage transmission lines according to claim 10, characterized in that: When it is determined that the maximum value among the three-phase currents meets a preset condition, the preset condition is: max(Ia,Ib,Ic)>0.05In; Wherein, In is the rated secondary current of the line protection device on this side, Ia, Ib, and Ic are the current amplitudes of phase a, phase b, and phase c respectively collected by the line protection device on this side.

14. The device for handling abnormal current difference in high-voltage transmission lines according to claim 10, characterized in that: Calculate the differential current warning threshold Icdyj of the current differential protection using the first preset formula; Among them, the first preset formula is: Icdyj=K*max(Ia,Ib,Ic) Where K is the threshold coefficient, Ia, Ib, and Ic are the current amplitudes of phase a, phase b, and phase c collected by the line protection device on this side, respectively.

15. The device for handling abnormal current difference in high-voltage transmission lines according to claim 10, characterized in that: When the three-phase differential current is greater than the differential current warning threshold, the differential current abnormality warning is initiated, and the analog data and the recorded waveform data are processed, specifically including: The three-phase current amplitude difference Icda is calculated according to the second preset formula ht 、Icdb ht 、Icdc ht and phase difference Anga ht Angb ht Angc ht ; The second preset formula includes: ICDA ht =Ia-Iar Shell ht =Anglia-Anglia-180° Icdb ht =Ib-Ibr The ht =AngIb-AngIbr-180° Icdc ht =Ic-Icr Eng ht =Angle-Angle-180° Wherein, Ia, Ib, and Ic are the current amplitudes of phase a, phase b, and phase c respectively collected by the line protection device on this side; Iar, Ibr, and Icr represent the current amplitudes of phase a, phase b, and phase c collected by the line protection device on the opposite side; AngIa, AngIb, and AngIc represent the current phase angles of phase a, phase b, and phase c collected by the line protection device on this side; AngIar, AngIbr, and AngIcr represent the current phase angles of phase a, phase b, and phase c collected by the line protection device on the opposite side.

16. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 9 are implemented.

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