Method and system for identifying magnetizing inrush current of transformer based on voltage plane partition

Abstract

The invention provides a method and a system for identifying magnetizing inrush current of a transformer based on voltage plane partition. The method comprises the following steps: acquiring three-phase voltage and phase voltage effective value of a high-voltage side of a to-be-identified transformer at a sampling moment; calculating a voltage difference quadratic sum at a sampling moment according to the three-phase voltage and a set sampling period; calculating a per unit value integral value of a difference absolute value of the voltage difference quadratic sum at the sampling moment to be identified according to the voltage difference quadratic sum at the sampling moment and the phase voltage effective value; and determining the property of the abnormal working condition of the to-be-identified transformer according to the distribution condition of the per unit value integral value in a fault identification partition of a pre-established coordinate plane, and outputting a corresponding control instruction. According to the method and the system, the magnetizing inrush current can be quickly identified within 5ms, the latching protection can be realized, and the protection action is allowed under the internal fault scene of the transformer, so that the transformer protection misoperation is avoided, and the transformer protection can quickly respond to the internal fault.

Description

Technical Field

[0001] The present invention relates to the technical field of relay protection, and more specifically, to a method and system for identifying transformer excitation inrush current based on voltage plane partitioning. Background Art

[0002] As the main equipment in the power transmission and transformation link of the power system, the safe and reliable operation of the power transformer is of vital importance. When an internal fault occurs in the transformer, the transformer differential protection usually detects the changes in the amplitude, direction, harmonics, etc. of the transformer's large and small differential currents to identify and eliminate the fault. However, when the transformer is switched on at no-load and other occasions where a sudden voltage change occurs, an excitation inrush current may occur. The excitation inrush current is very similar to the fault characteristics of the typical transformer area in a short period of time after it occurs, so it is easy to cause the transformer protection to malfunction.

[0003] Conventional differential protection is equipped with corresponding blocking elements to avoid false operation caused by abnormal conditions such as excitation inrush current and other non-internal faults. In order to solve the false operation problem caused by excitation inrush current, the inrush current identification criteria are generally constructed based on the harmonic content and time domain waveform characteristics brought by the discontinuity angle, such as the second harmonic restraint method, waveform similarity method, discontinuity angle identification method, etc. The action time of conventional differential protection is closely related to the performance of these blocking elements, so the action time of existing protection is generally above 20ms.

[0004] Large power transformers may experience serious faults during their life cycle. When a serious internal fault occurs, the transformer oil decomposes rapidly due to high temperature and produces a large amount of gas, which can cause the casing to rupture and explode in a very short time. In order to prevent such serious safety accidents, it is necessary to protect the output to achieve action within 5ms in such fault scenarios. However, the existing excitation inrush current identification scheme is difficult to identify the excitation inrush current condition within 5ms, which restricts the design of high-performance large power transformer differential disconnection protection. Therefore, it is urgent to propose an excitation inrush current identification and locking method that can quickly identify the inrush current characteristics within 5ms, so as to facilitate the transformer protection to quickly respond to internal faults. Summary of the invention

[0005] In order to solve the technical problem in the prior art that the transformer excitation inrush current recognition speed is slow, making it difficult to further improve the protection action speed in the transformer serious fault scenario, the present invention provides a method and device for identifying transformer excitation inrush current based on voltage plane partitioning.

[0006] According to one aspect of the present invention, the present invention provides a method for identifying transformer excitation inrush current based on voltage plane partitioning, the method comprising:

[0007] Based on the set sampling time interval, collect the three-phase voltage and phase voltage effective value of the high-voltage side of the transformer to be identified at the sampling time;

[0008] Calculate the square sum of voltage phase differences at the sampling moment according to the three-phase voltage and the set sampling period;

[0009] Calculate the per unit value of the absolute value of the difference of the square sum of the voltage phase difference at the sampling moment according to the square sum of the voltage phase difference at the sampling moment and the effective value of the phase voltage;

[0010] Calculate the per-unit integral value of the difference in the absolute value of the sum of squares of the voltage phase difference at the sampling moment to be identified according to the per-unit value of the difference in the absolute value of the sum of squares of the voltage phase difference at the sampling moment, wherein the sampling moment to be identified is a number of sampling moments before the start-up moment of the transformer main protection;

[0011] The nature of the abnormal operating condition of the transformer to be identified is determined and the corresponding control instruction is output according to the distribution of the per-unit integral value of the differential absolute value of the sum of squares of the voltage phase differences at the sampling moments to be identified in the fault identification partition of the pre-established coordinate plane, wherein the abscissa of the coordinate plane is time, and the ordinate is the per-unit multiple, and the coordinate plane is partitioned according to the straight lines obtained by setting the transformer to be identified under different fault conditions.

[0012] According to another aspect of the present invention, the present invention provides a system for identifying transformer excitation inrush current based on voltage plane partitioning, the system comprising:

[0013] A data acquisition module is used to collect the three-phase voltage and phase voltage effective value of the high-voltage side of the transformer to be identified at the sampling time based on the set sampling time interval;

[0014] A first calculation module, used for calculating the square sum of voltage phase differences at a sampling moment according to the three-phase voltages and a set sampling period;

[0015] A second calculation module, used for calculating the per unit value of the absolute value of the difference of the square sum of the voltage phase difference at the sampling moment according to the square sum of the voltage phase difference at the sampling moment and the effective value of the phase voltage;

[0016] A third calculation module is used to calculate the per-unit integral value of the difference absolute value of the sum of squares of the voltage phase difference at the sampling moment to be identified according to the per-unit value of the difference absolute value of the sum of squares of the voltage phase difference at the sampling moment, wherein the sampling moment to be identified is a number of sampling moments before the start-up moment of the transformer main protection;

[0017] The result output module is used to determine the nature of the abnormal operating condition of the transformer to be identified and output the corresponding control instruction according to the distribution of the per-unit value integral value of the differential absolute value of the sum of squares of the voltage phase differences at the sampling moments to be identified in the fault identification partition of the pre-established coordinate plane, wherein the abscissa of the coordinate plane is time, and the ordinate is the per-unit multiple, and the coordinate plane is partitioned according to the straight lines obtained by setting the transformer to be identified under different fault conditions.

[0018] According to another aspect of the present invention, the present invention provides a computer-readable storage medium, wherein the storage medium stores a computer program, and the computer program is used to execute the method described in any one of the above aspects of the present invention.

[0019] According to another aspect of the present invention, an electronic device is provided, comprising: a processor; a memory for storing instructions executable by the processor; the processor is configured to read the executable instructions from the memory and execute the instructions to implement the method described in any one of the above aspects of the present invention.

[0020] The method and system for identifying transformer excitation inrush current based on voltage plane partitioning of the present invention, wherein the method collects the three-phase voltage and phase voltage effective value of the high-voltage side of the transformer to be identified at the sampling moment based on the set sampling time interval; calculates the voltage phase difference square sum at the sampling moment according to the three-phase voltage and the set sampling period; calculates the per-unit value of the differential absolute value of the voltage phase difference square sum at the sampling moment according to the voltage phase difference square sum at the sampling moment and the phase voltage effective value; calculates the per-unit value integral value of the differential absolute value of the voltage phase difference square sum at the sampling moment to be identified according to the per-unit value of the differential absolute value of the voltage phase difference square sum at the sampling moment to be identified; determines the nature of the abnormal working condition of the transformer to be identified and outputs the corresponding control instruction according to the distribution of the per-unit value integral value of the differential absolute value of the voltage phase difference square sum at the sampling moment to be identified in the fault identification partition of the pre-established coordinate plane. The method and system can realize rapid identification of excitation inrush current and lock protection within 5ms, and allow protection action in the transformer internal fault scenario, thereby avoiding transformer protection malfunction, and transformer protection rapid response to internal fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0022] Figure 1 A flowchart of a method for identifying transformer excitation inrush current based on voltage plane partitioning according to a preferred embodiment of the present invention;

[0023] Figure 2 A schematic diagram of fault identification partitions of a coordinate plane according to a preferred embodiment of the present invention;

[0024] Figure 3 It is a schematic diagram of the result of identifying transformer excitation inrush current based on voltage plane partitioning according to a preferred embodiment of the present invention;

[0025] Figure 4 It is another schematic diagram of the result of identifying transformer excitation inrush current based on voltage plane partitioning according to a preferred embodiment of the present invention;

[0026] Figure 5 It is a schematic diagram of another result of identifying transformer excitation inrush current based on voltage plane partitioning according to a preferred embodiment of the present invention;

[0027] Figure 6 It is a structural schematic diagram of a system for identifying transformer excitation inrush current based on voltage plane partitioning according to a preferred embodiment of the present invention;

[0028] Figure 7 Schematic diagram of the structure of an electronic device according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0029] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0030] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0031] Exemplary Methods

[0032] Figure 1 Flow chart of a method for identifying transformer excitation inrush current based on voltage plane partitioning according to a preferred embodiment of the present invention. Figure 1 As shown, the flowchart of the method for identifying transformer excitation inrush current based on voltage plane partitioning described in this preferred embodiment starts from step 101.

[0033] In step 101, based on a set sampling time interval, the three-phase voltage and the effective value of the phase voltage at the high-voltage side of the transformer to be identified at the sampling moment are collected.

[0034] This preferred embodiment identifies transformer excitation inrush current and internal faults through the numerical and time characteristics of transient voltage. The excitation inrush current originates from the sudden change in the primary voltage of the transformer, but the excitation inrush current can only be observed when the core magnetic flux rises to the saturation magnetic flux. Therefore, the current change in the inrush current scenario must lag behind the voltage change. Therefore, in the excitation inrush current scenario, it should be observed that the voltage changes before the current, while in the fault scenario, the voltage and current should change simultaneously. This method can identify the excitation inrush current at a single sampling time point after the protection is started, which meets the actual demand of identifying the excitation inrush current within 5ms.

[0035] In step 102, the square sum of the voltage phase differences at the sampling moment is calculated according to the three-phase voltages and a set sampling period.

[0036] Preferably, the voltage phase difference square sum at the sampling moment is calculated according to the three-phase voltage and the set sampling period, and the calculation formula is:

[0037]

[0038] In the formula, is the sum of squares of the voltage differences at sampling time t, and are the changes of the three-phase voltages at the sampling time t, where:

[0039]

[0040] T=(N-1)*ΔT

[0041] In the formula, u A (t),u B (t) and u C (t) are the three-phase voltages at sampling time t, T is the set sampling period, N is the total number of sampling times in one sampling period, and ΔT is the sampling time interval. In this preferred embodiment, N is 24.

[0042] In step 103, the per unit value of the absolute value of the difference of the square sum of the voltage phase difference at the sampling moment is calculated according to the square sum of the voltage phase difference at the sampling moment and the effective value of the phase voltage.

[0043] Preferably, the per unit value of the absolute value of the difference of the square sum of the voltage phase difference at the sampling moment is calculated according to the square of the voltage phase difference at the sampling moment and the effective value of the phase voltage, and its calculation formula is:

[0044]

[0045] In the formula, is the per unit value of the absolute value of the difference of the sum of squares of the voltage differences at the sampling moment, U e is the effective value of the phase voltage, and They are the square sum of the voltage differences at sampling time t and sampling time t-ΔT, respectively, and ΔT is the sampling time interval.

[0046] In step 104, the per-unit integral value of the differential absolute value of the sum of squares of the voltage phase differences at the sampling moments to be identified is calculated according to the per-unit value of the differential absolute value of the sum of squares of the voltage phase differences at the sampling moments, wherein the sampling moments to be identified are several sampling moments before the start-up moment of the transformer main protection.

[0047] Preferably, the per-unit value integral value of the differential absolute value of the sum of squared voltage differences at the sampling moment is calculated based on the per-unit value of the differential absolute value of the sum of squared voltage differences at the sampling moment, and the calculation formula is:

[0048]

[0049] In the formula, is the per-unit value of the absolute value of the difference of the sum of squares of the voltage phase difference at the sampling time t to be identified, i, n are natural numbers, n is the number of sampling times, n<N, N is the total number of sampling times in a sampling cycle. In this preferred embodiment, n is 6, and the sampling time to be identified is the 12 sampling times before the transformer main protection start-up time to be identified.

[0050] The present invention takes effect after the transformer main protection is started, so it needs to act based on the start signal of the transformer differential protection start element. The transformer differential protection start element described in the present invention only needs to be based on the current principle and be sensitive enough in severe fault scenarios. Regarding the judgment of the start of the transformer differential protection start element, the start criterion in the prior art can be used, and the present invention does not limit this.

[0051] In step 105, the nature of the abnormal operating condition of the transformer to be identified is determined and the corresponding control instruction is output according to the distribution of the per-unit integral value of the differential absolute value of the sum of squares of the voltage differences at the sampling moments to be identified in the fault identification partition of the pre-established coordinate plane, wherein the abscissa of the coordinate plane is time, and the ordinate is per-unit multiples, and the coordinate plane is partitioned according to the straight lines obtained by setting the transformer to be identified under different fault conditions.

[0052] Preferably, the method further includes establishing fault identification partitions of a coordinate plane before collecting the three-phase voltage and phase voltage effective values ​​of the high-voltage side of the transformer to be identified at the sampling time instant based on the set sampling time interval, wherein:

[0053] Let the x-axis represent time, and the y-axis represent per unit multiples, and identify the start-up time of the transformer main protection as the coordinate origin to generate a coordinate plane;

[0054] The transformer to be identified is set under different fault conditions to obtain 4 straight lines, among which:

[0055] According to the principle of accurately determining the typical internal minor fault of the transformer to be identified, the setting is carried out to obtain the straight line l4, and the equation is:

[0056]

[0057] In the formula, k1 is a positive number;

[0058] The setting is carried out according to the principle of accurately determining the excitation inrush current caused by no-load closing at all closing angles and all operating modes, and the straight line l3 is obtained. The equation is:

[0059]

[0060] Where k2 and t0 are positive numbers, and k1<k2;

[0061] The straight line l1 is generated from the straight line l4, and the straight line l2 is generated from the straight line l3, wherein the equation of the straight line l1 is:

[0062]

[0063] The equation of the straight line l2 is:

[0064]

[0065] According to the straight line, the coordinate plane is divided into the inrush current blocking area, the fuzzy area and the fault tripping area, where:

[0066] The equation for the inrush current blocking region is:

[0067]

[0068] The equations in the fuzzy region include:

[0069] and

[0070] The equations for the fault trip zone include:

[0071] and

[0072] Figure 2 FIG. 1 is a schematic diagram of fault identification partitions of a coordinate plane according to a preferred embodiment of the present invention. Figure 2As shown, the transformer to be identified is first adjusted according to the principle that the per-unit integral value of the differential absolute value of the sum of squares of the voltage differences at the sampling moment cannot enter the fuzzy zone under the typical internal minor fault scenario - 5% inter-turn short circuit scenario within the zone, and the straight line l4 is obtained. Then, the adjustment is performed according to the principle that the excitation inrush current caused by no-load closing under all closing angles and all operating modes can enter the inrush current locking zone, and the straight line l3 is obtained. Then, the straight line l2 is set based on the condition of identifying fuzzy faults and ensuring that the protection is not falsely operated under the excitation inrush current scenario. Finally, the straight line l1 is set to define the fault tripping zone. According to the straight lines l1, l2, l3 and l4, the coordinate plane can be divided into a green locking inrush current zone, a purple fuzzy zone and a blue fault tripping zone.

[0073] Preferably, the method of determining the nature of the abnormal working condition of the transformer to be identified and outputting the corresponding control instruction according to the distribution of the per-unit value integral value of the differential absolute value of the sum of squares of the voltage phase differences at the sampling moment to be identified in the fault identification partition of the pre-established coordinate plane includes:

[0074] When the per-unit integral value of the absolute value of the difference of the sum of squares of the voltage phase differences at any sampling moment to be identified enters the inrush current blocking area, it is determined that the abnormal operating condition of the transformer to be identified is the excitation inrush current, and a main protection instruction for blocking the transformer to be identified is output;

[0075] When it is determined that the abnormal operating condition of the transformer to be identified is not the excitation inrush current, and the per-unit integral value of the absolute value of the difference of the square sum of the voltage phase difference at any sampling moment to be identified enters the fuzzy area, it is determined that the abnormal operating condition of the transformer to be identified is a minor fault, and a fault reference control word is output to the main protection of the transformer to be identified to assist the main protection in fault identification;

[0076] When the per-unit integral values ​​of the absolute values ​​of the difference sums of the squares of the voltage phase differences at all sampling moments to be identified do not enter the inrush current blocking area and the fuzzy area, the abnormal operating condition of the transformer to be identified is determined to be a fault, and an instruction for the main protection action of the transformer to be identified is output.

[0077] The method for identifying transformer excitation inrush current based on voltage plane partitioning described in this preferred embodiment collects the three-phase voltage and phase voltage effective value of the high-voltage side of the transformer to be identified at the sampling moment; calculates the voltage phase difference square sum at the sampling moment based on the three-phase voltage and the set sampling period; calculates the per-unit integral value of the differential absolute value of the voltage phase difference square sum at the sampling moment to be identified based on the voltage phase difference square at the sampling moment and the phase voltage effective value; determines the nature of the abnormal working condition of the transformer to be identified based on the distribution of the per-unit integral value in the fault identification partition of the pre-established coordinate plane and outputs the corresponding control instruction. The method and system can realize rapid identification of excitation inrush current and lock protection within 5ms, and allow protection action in the transformer internal fault scenario, thereby avoiding transformer protection malfunction and transformer protection rapid response to internal faults.

[0078] Figure 3 This is a schematic diagram of the result of identifying transformer excitation inrush current based on voltage plane partitioning according to a preferred embodiment of the present invention. Figure 3 As shown, RTDS is used to carry out no-load closing operation on the YY-connected transformer to form a simulation verification under the excitation inrush current scenario. By calculating the per-unit integral of the 12 proposed identification sampling moments (marked as -12 to -1 on the horizontal axis) before the protection start moment in this scenario, it can be seen that the per-unit integral of the -6 proposed identification sampling moments enters the inrush current locking area formed by the straight line l3 and the straight line l2. Therefore, the verification result of the method described in this preferred embodiment is consistent with the simulation verification scenario.

[0079] Figure 4 This is another schematic diagram of the results of identifying transformer excitation inrush current based on voltage plane partitioning according to a preferred embodiment of the present invention. Figure 4 As shown, Figure 3 For the YY-connected transformer, a metallic grounding fault occurs in the simulation area. Since the fault is a serious fault, the per-unit value integrals of the 12 intended identification sampling moments (marked as -12 to -1 on the horizontal axis) before the protection start-up moment in this scenario are known. The per-unit value integrals of the 12 intended identification sampling moments are all distributed below the straight line l4. Therefore, the verification result of the method described in this preferred embodiment is consistent with the simulation verification scenario.

[0080] Figure 5 FIG. 1 is another schematic diagram of the result of identifying transformer excitation inrush current based on voltage plane partitioning according to a preferred embodiment of the present invention. Figure 5 As shown, Figure 3For the YY-connected transformer, a 12% turn-to-turn short-circuit fault occurs in the simulation area, which is a minor fault. Then the switch is closed, and the integral of the per-unit values ​​of the 12 intended identification sampling moments before the protection start moment in this scenario is calculated. It can be seen that -3 to -1 intended identification sampling moments enter the fuzzy area, and no intended identification sampling moment enters the inrush current locking area. Therefore, the verification result of the method described in this preferred embodiment is consistent with the simulation verification scenario.

[0081] Exemplary Systems

[0082] Figure 6 FIG. 1 is a schematic diagram of a system for identifying transformer excitation inrush current based on voltage plane partitioning according to a preferred embodiment of the present invention. Figure 6 As shown, the system 600 for identifying transformer excitation inrush current based on voltage plane partitioning according to this preferred embodiment includes:

[0083] The data acquisition module 601 is used to collect the three-phase voltage and phase voltage effective value of the high-voltage side of the transformer to be identified at the sampling time based on the set sampling time interval;

[0084] A first calculation module 602, configured to calculate the square sum of voltage phase differences at a sampling moment according to the three-phase voltages and a set sampling period;

[0085] A second calculation module 603 is used to calculate the per unit value of the absolute value of the difference of the square sum of the voltage phase difference at the sampling moment according to the square sum of the voltage phase difference at the sampling moment and the effective value of the phase voltage;

[0086] The third calculation module 604 is used to calculate the per-unit integral value of the difference absolute value of the sum of squares of the voltage phase difference at the sampling moment to be identified according to the per-unit value of the difference absolute value of the sum of squares of the voltage phase difference at the sampling moment, wherein the sampling moment to be identified is a number of sampling moments before the start-up moment of the transformer main protection;

[0087] The result output module 605 is used to determine the nature of the abnormal operating condition of the transformer to be identified and output the corresponding control instruction according to the distribution of the per-unit integral value of the differential absolute value of the sum of squares of the voltage differences at the sampling moments to be identified in the fault identification partition of the pre-established coordinate plane, wherein the horizontal axis of the coordinate plane is time, and the vertical axis is the per-unit multiple, and the coordinate plane is partitioned according to the straight lines obtained by setting the transformer to be identified under different fault conditions.

[0088] Preferably, the system further comprises a plane partitioning module for establishing fault identification partitions of a coordinate plane, wherein:

[0089] Let the x-axis represent time, and the y-axis represent per unit multiples, and identify the start-up time of the transformer main protection as the coordinate origin to generate a coordinate plane;

[0090] The transformer to be identified is set under different fault conditions to obtain 4 straight lines, among which:

[0091] According to the principle of accurately determining the typical internal minor fault of the transformer to be identified, the setting is carried out to obtain the straight line l4, and the equation is:

[0092]

[0093] In the formula, k1 is a positive number;

[0094] The setting is carried out according to the principle of accurately determining the excitation inrush current caused by no-load closing at all closing angles and all operating modes, and the straight line l3 is obtained. The equation is:

[0095]

[0096] Where k2 and t0 are positive numbers, and k1<k2;

[0097] The straight line l1 is generated from the straight line l4, and the straight line l2 is generated from the straight line l3, wherein the equation of the straight line l1 is:

[0098]

[0099] The equation of the straight line l2 is:

[0100]

[0101] According to the straight lines l1, l2, l3 and l4, the coordinate plane is divided into the inrush current blocking area, the fuzzy area and the fault tripping area, where:

[0102] The equation for the inrush current blocking region is:

[0103]

[0104] The equations in the fuzzy region include:

[0105] and

[0106] The equations for the fault trip zone include:

[0107] and

[0108] Preferably, the first calculation module 302 calculates the square sum of the voltage phase differences at the sampling moment according to the three-phase voltages and the set sampling period, and the calculation formula is:

[0109]

[0110] In the formula, is the sum of squares of the voltage differences at sampling time t, and are the changes of the three-phase voltages at the sampling time t, where:

[0111]

[0112] T=(N-1)*ΔT

[0113] In the formula, u A (t),u B (t) and u C (t) are the three-phase voltages at sampling time t, T is the set sampling period, N is the total number of sampling times in one sampling period, and ΔT is the sampling time interval.

[0114] Preferably, the second calculation module 603 calculates the per unit value of the absolute value of the difference of the square sum of the voltage phase difference at the sampling moment according to the square of the voltage phase difference at the sampling moment and the effective value of the phase voltage, and the calculation formula is:

[0115]

[0116] In the formula, is the per unit value of the absolute value of the difference of the sum of squares of the voltage differences at the sampling moment, U e is the effective value of the phase voltage, and They are the square sum of the voltage differences at sampling time t and sampling time t-ΔT, respectively, and ΔT is the sampling time interval.

[0117] Preferably, the third calculation module 604 calculates the per-unit integral value of the difference absolute value of the sum of squares of the voltage phase difference at the sampling moment to be identified according to the per-unit value of the difference absolute value of the sum of squares of the voltage phase difference at the sampling moment, and the calculation formula is:

[0118]

[0119] In the formula, is the per-unit value of the absolute value of the difference of the sum of squares of the voltage phase differences at the sampling time t to be identified, i, n are natural numbers, n is the number of sampling times, n<N, N is the total number of sampling times in one sampling cycle.

[0120] Preferably, the result output module 605 determines the nature of the abnormal working condition of the transformer to be identified and outputs the corresponding control instruction according to the distribution of the per-unit value integral value of the differential absolute value of the sum of squares of the voltage phase difference at the sampling moment to be identified in the fault identification partition of the pre-established coordinate plane, including:

[0121] When the per-unit integral value of the absolute value of the difference of the sum of squares of the voltage phase differences at any sampling moment to be identified enters the inrush current blocking area, it is determined that the abnormal operating condition of the transformer to be identified is the excitation inrush current, and a main protection instruction for blocking the transformer to be identified is output;

[0122] When it is determined that the abnormal operating condition of the transformer to be identified is not the excitation inrush current, and the per-unit integral value of the absolute value of the difference of the square sum of the voltage phase difference at any sampling moment to be identified enters the fuzzy area, it is determined that the abnormal operating condition of the transformer to be identified is a minor fault, and a fault reference control word is output to the main protection of the transformer to be identified to assist the main protection in fault identification;

[0123] When the per-unit integral values ​​of the absolute values ​​of the difference sums of the squares of the voltage phase differences at all sampling moments to be identified do not enter the inrush current blocking area and the fuzzy area, the abnormal operating condition of the transformer to be identified is determined to be a fault, and an instruction for the main protection action of the transformer to be identified is output.

[0124] The system for identifying transformer excitation inrush current based on voltage plane partitioning described in this preferred embodiment collects the three-phase voltage on the high-voltage side of the transformer, calculates the per-unit integral of the differential absolute value of the sum of squares of the voltage phase differences at the sampling moment to be identified, and determines the nature of the abnormal operating condition of the transformer to be identified in combination with the fault identification partition of the established coordinate plane and outputs the corresponding control instructions. The steps are the same as those taken by the method for identifying transformer excitation inrush current based on voltage plane partitioning described in the present invention, and the technical effects achieved are also the same, which will not be repeated here.

[0125] Exemplary Electronic Devices

[0126] Figure 7 The electronic device may be any one or both of the first device and the second device, or a stand-alone device independent of them, and the stand-alone device may communicate with the first device and the second device to receive the collected input signals from them. Figure 7 FIG. 1 is a block diagram of an electronic device according to an embodiment of the present disclosure. Figure 7 As shown, the electronic device includes one or more processors 701 and a memory 702 .

[0127] The processor 701 may be a central processing unit (CPU) or other forms of processing units having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0128] The memory 702 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory (cache), etc. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 701 may run the program instructions to implement the energy consumption anomaly diagnosis method based on the enterprise energy consumption space of each disclosed embodiment described above and / or other desired functions. In one example, the electronic device may also include: an input device 703 and an output device 704, which are interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0129] In addition, the input device 703 may also include, for example, a keyboard, a mouse, and the like.

[0130] The output device 704 can output various information to the outside, and can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto.

[0131] Of course, to simplify, Figure 7 Only some of the components related to the present disclosure in the electronic device are shown, and components such as a bus, an input / output interface, etc. are omitted. In addition, according to specific application situations, the electronic device may further include any other appropriate components.

[0132] Exemplary computer program products and computer-readable storage media

[0133] In addition to the above-mentioned methods and devices, an embodiment of the present disclosure may also be a computer program product, which includes computer program instructions, which, when executed by a processor, enable the processor to execute the steps of the method for identifying transformer excitation inrush current based on voltage plane partitioning according to various embodiments of the present disclosure described in the above "Exemplary Method" section of this specification.

[0134] The computer program product may be written in any combination of one or more programming languages ​​to write program code for performing the operations of the disclosed embodiments, including object-oriented programming languages ​​such as Java, C++, etc., and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a separate software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0135] In addition, an embodiment of the present disclosure may also be a computer-readable storage medium having computer program instructions stored thereon, which, when executed by a processor, enables the processor to execute the steps of the method for identifying transformer excitation inrush current based on voltage plane partitioning according to various embodiments of the present disclosure described in the above “Exemplary Method” section of this specification.

[0136] The computer readable storage medium can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can include, for example, but is not limited to, a system, device or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0137] The basic principles of the present disclosure are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present disclosure are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present disclosure. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, and are not limitations. The above details do not limit the present disclosure to the necessity of adopting the above specific details to be implemented.

[0138] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system embodiment, since it basically corresponds to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0139] The block diagrams of the devices, apparatuses, equipment, and systems involved in this disclosure are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including," "comprising," "having," and the like are open words, referring to "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or," and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0140] The method and apparatus of the present disclosure may be implemented in many ways. For example, the method and apparatus of the present disclosure may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above order of steps for the method is for illustration only, and the steps of the method of the present disclosure are not limited to the order specifically described above, unless otherwise specifically stated. In addition, in some embodiments, the present disclosure may also be implemented as a program recorded in a recording medium, which includes machine-readable instructions for implementing the method according to the present disclosure. Therefore, the present disclosure also covers a recording medium storing a program for executing the method according to the present disclosure.

[0141] It should also be noted that in the apparatus, equipment and method of the present disclosure, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent schemes of the present disclosure. The above description of the disclosed aspects is provided to enable any technician in the field to make or use the present disclosure. Various modifications to these aspects are very obvious to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the aspects shown here, but to the widest range consistent with the principles and novel features disclosed herein.

[0142] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present disclosure to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A method for identifying transformer excitation inrush current based on voltage plane partitioning, characterized in that: The method comprises: Based on the set sampling time interval, collect the three-phase voltage and phase voltage effective value of the high-voltage side of the transformer to be identified at the sampling time; Calculate the square sum of voltage phase differences at the sampling moment according to the three-phase voltage and the set sampling period; Calculate the per unit value of the absolute value of the difference of the square sum of the voltage phase difference at the sampling moment according to the square sum of the voltage phase difference at the sampling moment and the effective value of the phase voltage; Calculate the per-unit integral value of the absolute value of the difference of the sum of squares of the voltage phase difference at the sampling moment to be identified according to the per-unit value of the absolute value of the difference of the sum of squares of the voltage phase difference at the sampling moment, wherein the sampling moment to be identified is a number of sampling moments before the start-up moment of the transformer main protection; The nature of the abnormal operating condition of the transformer to be identified is determined and the corresponding control instruction is output according to the distribution of the per-unit integral value of the differential absolute value of the sum of squares of the voltage phase differences at the sampling moments to be identified in the fault identification partition of the pre-established coordinate plane, wherein the abscissa of the coordinate plane is time, and the ordinate is the per-unit multiple, and the coordinate plane is partitioned according to the straight lines obtained by setting the transformer to be identified under different fault conditions.

2. The method according to claim 1, characterized in that The method further includes establishing a fault identification partition of a coordinate plane before collecting the three-phase voltage and phase voltage effective value of the high-voltage side of the transformer to be identified at the sampling time based on the set sampling time interval, wherein: Let the x-axis represent time, and the y-axis represent per unit multiples, and identify the start-up time of the transformer main protection as the coordinate origin to generate a coordinate plane; The transformer to be identified is set under different fault conditions to obtain 4 straight lines, among which: According to the principle of accurately determining the typical internal minor fault of the transformer to be identified, the setting is carried out to obtain the straight line l4, and the equation is: In the formula, k1 is a positive number; The setting is carried out according to the principle of accurately determining the excitation inrush current caused by no-load closing at all closing angles and all operating modes, and the straight line l3 is obtained. The equation is: Where k2 and t0 are positive numbers, and k1<k2; The straight line l1 is generated from the straight line l4, and the straight line l2 is generated from the straight line l3, wherein the equation of the straight line l1 is: The equation of the straight line l2 is: According to the straight lines l1, l2, l3 and l4, the coordinate plane is divided into the inrush current blocking area, the fuzzy area and the fault tripping area, where: The equation for the inrush current blocking region is: The equations in the fuzzy region include: and The equations for the fault trip zone include: and 3. The method according to claim 1, characterized in that The voltage phase difference square sum at the sampling moment is calculated according to the three-phase voltage and the set sampling period, and its calculation formula is: In the formula, is the sum of squares of the voltage differences at sampling time t, and are the changes of the three-phase voltages at the sampling time t, where: T=(N-1)*ΔT In the formula, u A (t),u B (t) and u C (t) are the three-phase voltages at sampling time t, T is the set sampling period, N is the total number of sampling times in one sampling period, and ΔT is the sampling time interval.

4. The method according to claim 1, characterized in that: The per unit value of the absolute value of the difference of the square sum of the voltage phase difference at the sampling moment is calculated according to the square sum of the voltage phase difference at the sampling moment and the effective value of the phase voltage, and the calculation formula is: In the formula, is the per unit value of the absolute value of the difference of the sum of squares of the voltage differences at the sampling moment, U e is the effective value of the phase voltage, and They are the square sum of the voltage differences at sampling time t and sampling time t-ΔT, respectively, and ΔT is the sampling time interval.

5. The method according to claim 4, characterized in that The per-unit value integral value of the difference absolute value of the sum of squared voltage differences at the sampling moment is calculated according to the per-unit value of the difference absolute value of the sum of squared voltage differences at the sampling moment, and the calculation formula is: In the formula, is the per-unit value of the absolute value of the difference of the sum of squares of the voltage phase differences at the sampling time t to be identified, i, n are natural numbers, n is the number of sampling times, n<N, N is the total number of sampling times in one sampling cycle.

6. The method according to claim 1, characterized in that The method of determining the nature of the abnormal working condition of the transformer to be identified and outputting the corresponding control instruction according to the distribution of the per-unit value integral value of the differential absolute value of the sum of squares of the voltage phase differences at the sampling moment to be identified in the fault identification partition of the pre-established coordinate plane includes: When the per-unit integral value of the absolute value of the difference of the sum of squares of the voltage phase differences at any sampling moment to be identified enters the inrush current blocking area, it is determined that the abnormal operating condition of the transformer to be identified is the excitation inrush current, and a main protection instruction for blocking the transformer to be identified is output; When it is determined that the abnormal operating condition of the transformer to be identified is not the excitation inrush current, and the per-unit integral value of the absolute value of the difference of the square sum of the voltage phase difference at any sampling moment to be identified enters the fuzzy area, it is determined that the abnormal operating condition of the transformer to be identified is a minor fault, and a fault reference control word is output to the main protection of the transformer to be identified to assist the main protection in fault identification; When the per-unit integral values ​​of the absolute values ​​of the difference sums of the squares of the voltage phase differences at all sampling moments to be identified do not enter the inrush current blocking area and the fuzzy area, the abnormal operating condition of the transformer to be identified is determined to be a fault, and an instruction for the main protection action of the transformer to be identified is output.

7. A system for identifying transformer excitation inrush current based on voltage plane partitioning, characterized in that: The system comprises: A data acquisition module is used to collect the three-phase voltage and phase voltage effective value of the high-voltage side of the transformer to be identified at the sampling time based on the set sampling time interval; A first calculation module, used for calculating the square sum of voltage phase differences at a sampling moment according to the three-phase voltages and a set sampling period; A second calculation module, used for calculating the per unit value of the absolute value of the difference of the square sum of the voltage phase difference at the sampling moment according to the square sum of the voltage phase difference at the sampling moment and the effective value of the phase voltage; A third calculation module is used to calculate the per-unit integral value of the difference absolute value of the sum of squares of the voltage phase difference at the sampling moment to be identified according to the per-unit value of the difference absolute value of the sum of squares of the voltage phase difference at the sampling moment, wherein the sampling moment to be identified is a number of sampling moments before the start-up moment of the transformer main protection; The result output module is used to determine the nature of the abnormal operating condition of the transformer to be identified and output the corresponding control instruction according to the distribution of the per-unit value integral value of the differential absolute value of the sum of squares of the voltage phase differences at the sampling moments to be identified in the fault identification partition of the pre-established coordinate plane, wherein the abscissa of the coordinate plane is time, and the ordinate is the per-unit multiple, and the coordinate plane is partitioned according to the straight lines obtained by setting the transformer to be identified under different fault conditions.

8. The system according to claim 7, characterized in that The system also includes a plane partitioning module for establishing fault identification partitions of a coordinate plane, wherein: Let the x-axis represent time, and the y-axis represent per unit multiples, and identify the start-up time of the transformer main protection as the coordinate origin to generate a coordinate plane; The transformer to be identified is set under different fault conditions to obtain 4 straight lines, among which: According to the principle of accurately determining the typical internal minor fault of the transformer to be identified, the setting is carried out to obtain the straight line l4, and the equation is: In the formula, k1 is a positive number; The setting is carried out according to the principle of accurately determining the excitation inrush current caused by no-load closing at all closing angles and all operating modes, and the straight line l3 is obtained. The equation is: Where k2 and t0 are positive numbers, and k1<k2; The straight line l1 is generated from the straight line l4, and the straight line l2 is generated from the straight line l3, wherein the equation of the straight line l1 is: The equation of the straight line l2 is: According to the straight lines l1, l2, l3 and l4, the coordinate plane is divided into the inrush current blocking area, the fuzzy area and the fault tripping area, where: The equation for the inrush current blocking region is: The equations in the fuzzy region include: The equations for the fault trip zone include: and 9. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 1 to 6.

10. An electronic device, characterized in that: The electronic device comprises: processor; a memory for storing instructions executable by the processor; The processor is used to read the executable instructions from the memory and execute the instructions to implement the method described in any one of claims 1 to 6.

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