A transformer protection method and system based on differential flow virtual sudden energy

Abstract

The application discloses a transformer protection method and system based on differential current virtual sudden change energy, and belongs to the technical field of transformer protection. The method comprises the following steps: constructing a first calculation model for calculating the sudden change energy of a certain phase of the target transformer based on the operation parameters and the law of conservation of energy; constructing a second calculation model for calculating the differential current virtual sudden change energy of a certain phase of the target transformer and the total differential current virtual sudden change energy based on the first calculation model; constructing a protection criterion of the target transformer based on the first calculation model and the second calculation model; determining the differential current virtual sudden change energy of a certain phase of the target transformer and the total differential current virtual sudden change energy; judging the differential current virtual sudden change energy of a certain phase of the target transformer and the total differential current virtual sudden change energy based on the protection criterion; and executing the protection action of the transformer based on the judgment result. The application can ensure that the protection device does not misoperate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transformer protection, and more particularly, to a transformer protection method and system based on differential current virtual sudden change energy. BACKGROUND

[0002] The safe and reliable operation of power transformers, as main equipment of power systems, is of great importance. After an internal fault occurs in a transformer, fault detection and fault removal are realized by a transformer relay protection device, thereby ensuring the safe operation of the transformer and the stable operation of the power system.

[0003] Current differential protection, as the main protection for transformers, is widely used due to its simple principle and good selectivity. In order to avoid misoperation caused by CT saturation and non-internal fault abnormal states such as magnetizing inrush, a corresponding blocking element is configured in conventional differential protection.

[0004] Therefore, the action time of conventional differential protection is closely related to the performance of these blocking elements. At the same time, in order to avoid the situation that the protection action speed cannot be quickly removed when a serious internal fault occurs in a transformer, a differential speed-break protection element without any blocking is usually configured in the transformer protection device. According to relevant technical standards, the action time of differential protection is not more than 30 ms, and the action time of differential speed-break protection is not more than 20 ms. However, in recent years, in the case of serious faults, the fault current rises very quickly, the energy accumulates rapidly in a short time, and the heat cannot be released in time, which eventually leads to the explosion and combustion of the transformer. SUMMARY

[0005] To solve the above problems, the present application provides a transformer protection method based on differential current virtual sudden change energy, comprising:

[0006] For a target transformer, the operating parameters of the target transformer in normal operation are obtained, and based on the operating parameters and the law of conservation of energy, a first calculation model for calculating the sudden change energy of a certain phase of the target transformer is constructed;

[0007] Based on the first calculation model, a second calculation model for calculating the differential current virtual sudden change energy of a certain phase of the target transformer and the total differential current virtual sudden change energy is constructed, and based on the first calculation model and the second calculation model, a protection criterion for the target transformer is constructed;

[0008] The operation parameter value of the target transformer is acquired, and the operation parameter value is brought into the first calculation model and the second calculation model to calculate a certain-phase differential current virtual sudden change energy and a differential current virtual sudden change energy sum of the target transformer, the certain-phase differential current virtual sudden change energy and the differential current virtual sudden change energy sum are judged based on the protection criterion, and a protection action of the transformer is executed based on a judgment result.

[0009] Optionally, the first calculation model is as follows:

[0010]

[0011] wherein, an energy value in a single sampling interval of a certain phase, is a current sampling value of a φ phase of the transformer in a single sampling interval, X d is a transformer impedance, and △t is a time of a sampling interval.

[0012] Optionally, the second calculation model is as follows:

[0013]

[0014]

[0015] wherein, is a differential current sudden change energy of a φ phase per unit sampling time, △t is a time of a sampling interval, X dd is a virtual differential impedance of the transformer, ∑ΔW dΔt is a three-phase differential current virtual energy sum of the transformer, n is a sampling point number of a current, j is a sampling starting point, Δi daj is a differential current sudden change value of an A phase, Δi dbj is a differential current sudden change value of a B phase, Δi dcj is a differential current sudden change value of a C phase, is a differential current sudden change value of a φ phase.

[0016] Optionally, the protection criterion is as follows:

[0017]

[0018] wherein, n is a sampling point number of a current, S is a rated power of the transformer, △t is a time of a sampling interval, k k3 and k k4 are single-phase and three-phase energy sudden change calculation reliability coefficients respectively, is a differential current sudden change energy of a φ phase per unit sampling time, ∑ΔW dΔt is a three-phase differential current virtual energy sum of the transformer.

[0019] Optionally, based on the judgment result, a protection action of the transformer is executed, including:

[0020] When any phase has continuous multiple points satisfying the protection criterion, the protection action is performed, and the continuous multiple points include at least 10.

[0021] Optionally, the transformer protection method further comprises:

[0022] The three-phase voltage criterion is adopted to calculate the instantaneous value of the three-phase voltage, if the calculated value is greater than a certain value, it is normal air drop, and the protection criterion is blocked, and if the calculated value is less than a certain value, it is inrush current fault, and the protection criterion is opened.

[0023] Optionally, the three-phase voltage criterion is as follows:

[0024]

[0025] Wherein, u a , u b , u c are three-phase voltage sampling values, and U e is the rated phase voltage.

[0026] In still another aspect, the present application further provides a transformer protection system based on differential current virtual sudden change energy, comprising:

[0027] The first model building unit is configured to obtain the operating parameters of the target transformer when the target transformer is normally operated, and construct a first calculation model for calculating the sudden change energy of a certain phase of the target transformer based on the operating parameters and the law of conservation of energy.

[0028] The second model building unit is configured to construct a second calculation model for calculating the differential current virtual sudden change energy of a certain phase of the target transformer and the total differential current virtual sudden change energy based on the first calculation model, and construct a protection criterion of the target transformer based on the first calculation model and the second calculation model.

[0029] The protection unit is configured to obtain the operating parameter values of the target transformer, and input the operating parameter values into the first calculation model and the second calculation model for calculation to determine the differential current virtual sudden change energy of a certain phase of the target transformer and the total differential current virtual sudden change energy, judge the differential current virtual sudden change energy of the certain phase and the total differential current virtual sudden change energy based on the protection criterion, and perform the protection action of the transformer based on the judgment result.

[0030] Optionally, the first calculation model is as follows:

[0031]

[0032] Wherein, The energy value in a single sampling interval of a certain phase, is the current sampling value of the transformer φ phase in a single sampling interval, and X dis the transformer impedance, and Δt is the time interval of sampling.

[0033] Optionally, the second calculation model is as follows:

[0034]

[0035]

[0036] wherein, is the differential current mutation energy of the φ phase per unit sampling time, ∑ΔW dd is the virtual differential impedance of the transformer, ∑ΔW dΔt is the total virtual differential energy of the three-phase differential current of the transformer, n is the sampling point number of the current, j is the sampling starting point, Δi daj is the A-phase differential current mutation, dbj is the B-phase differential current mutation, dcj is the C-phase differential current mutation, is the differential current mutation of the φ phase.

[0037] Optionally, the protection criterion is as follows:

[0038]

[0039] wherein, n is the sampling point number of the current, S is the rated power of the transformer, Δt is the time interval of sampling, k k3 and k k4 are the single-phase and three-phase energy mutation calculation reliability coefficients respectively, is the differential current mutation energy of the φ phase per unit sampling time, ∑ΔW dΔt is the total virtual differential energy of the three-phase differential current of the transformer.

[0040] Optionally, based on the determination result, a protection action of the transformer is performed, including:

[0041] When a plurality of continuous points of any phase satisfy the protection criterion, the protection action is performed, and the plurality of continuous points at least include 10 points.

[0042] Optionally, the protection unit is further used for:

[0043] A three-phase voltage criterion is adopted to calculate the three-phase voltage instantaneous values, if the calculated value is greater than a certain value, it is a normal air throw, and the criterion is blocked, and if the calculated value is less than a certain value, it is a inrush current fault, and the protection criterion is opened.

[0044] Optionally, the three-phase voltage criterion is as follows:

[0045]

[0046] wherein, u a , u b , and uc are three-phase voltage sampling values, U e is a rated phase voltage.

[0047] In still another aspect, the present application also provides a computing device, comprising: one or more processors;

[0048] a processor for executing one or more programs;

[0049] when the one or more programs are executed by the one or more processors, the method as described above is implemented.

[0050] In still another aspect, the present application also provides a computer readable storage medium, having stored thereon a computer program, which when executed, implements the method as described above.

[0051] Compared with the prior art, the present application has the following beneficial effects:

[0052] The present application provides a transformer protection method based on differential current virtual sudden change energy, comprising: for a target transformer, obtaining an operating parameter of the target transformer when the target transformer is normally operated, based on the operating parameter and the law of conservation of energy, constructing a first calculation model for calculating sudden change energy of a phase of the target transformer; based on the first calculation model, constructing a second calculation model for calculating differential current virtual sudden change energy of a phase of the target transformer and total differential current virtual sudden change energy, and based on the first calculation model and the second calculation model, constructing a protection criterion of the target transformer; obtaining an operating parameter value of the target transformer, bringing the operating parameter value into the first calculation model and the second calculation model for calculation, to determine the differential current virtual sudden change energy of a phase of the target transformer and the total differential current virtual sudden change energy, based on the protection criterion, judging the differential current virtual sudden change energy of a phase of the target transformer and the total differential current virtual sudden change energy, and based on the judgment result, performing a protection action of the transformer. The present application can ensure that the protection device does not misoperate. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 is a flowchart of the method of the present application;

[0054] Figure 2 is a schematic diagram of the principle of the method of the present application;

[0055] Figure 3 is a differential current sampling value schematic diagram of the method of the present application;

[0056] Figure 4 is a differential current virtual sudden change energy waveform schematic diagram of the method of the present application;

[0057] Figure 5 is an action situation schematic diagram of the method of the present application;

[0058] Figure 6 Fig. 2 is a schematic diagram of the action of the method of the present application in the case of an external fault;

[0059] Figure 7 Fig. 3 is a schematic diagram of the action of the method of the present application in the case of a full load with inrush;

[0060] Figure 8 Fig. 4 is a schematic diagram of the structure of the system of the present application. DETAILED DESCRIPTION

[0061] Reference will now be made to the exemplary embodiments of the present application with reference to the accompanying drawings, however, the present application can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the application to those skilled in the art. The terminology used in the description of the exemplary embodiments presented herein is not intended to be limiting of the present application. Identical elements are denoted using identical reference numerals throughout the various figures.

[0062] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0063] Example 1:

[0064] The present application proposes a transformer protection method based on differential flow virtual sudden change energy, as shown in Figure 1 , comprising:

[0065] Step 1, for a target transformer, obtaining the operating parameters of the target transformer when the target transformer is in normal operation, based on the operating parameters and the law of conservation of energy, a first calculation model for calculating the sudden change energy of a phase of the target transformer is constructed;

[0066] Step 2, based on the first calculation model, a second calculation model for calculating the differential flow virtual sudden change energy of a phase of the target transformer and the total differential flow virtual sudden change energy is constructed, and based on the first calculation model and the second calculation model, a protection criterion of the target transformer is constructed;

[0067] Step 3, obtaining the operating parameter value of the target transformer, bringing the operating parameter value into the first calculation model and the second calculation model for calculation, to determine the differential flow virtual sudden change energy of a phase of the target transformer and the total differential flow virtual sudden change energy, based on the protection criterion, the differential flow virtual sudden change energy of a phase of the target transformer and the total differential flow virtual sudden change energy are judged, and based on the judgment result, the protection action of the transformer is executed.

[0068] Wherein, the first calculation model is as follows:

[0069]

[0070] Wherein, the energy value in a single sampling interval of a certain phase, is the current sampling value of the transformer φ phase in a single sampling interval, X d is the transformer impedance, and △t is the time of the sampling interval.

[0071] Wherein, the second calculation model is as follows:

[0072]

[0073]

[0074] Wherein, is the differential flow sudden change energy of the φ phase in a unit sampling time, △t is the time of the sampling interval, X dd is the virtual differential impedance of the transformer, ∑ΔW dΔt is the total virtual energy of the three-phase differential flow of the transformer, n is the sampling point number of the current, j is the sampling starting point, Δi daj is the A-phase differential flow sudden change variable, Δi dbj is the B-phase differential flow sudden change variable, Δi dcj is the C-phase differential flow sudden change variable, is the differential flow sudden change variable of the φ phase.

[0075] Wherein, the protection criterion is as follows:

[0076]

[0077] Wherein, n is the sampling point number of the current, S is the rated power of the transformer, △t is the time of the sampling interval, k k3 and k k4 are the single-phase and three-phase energy sudden change calculation reliability coefficients, respectively, is the differential flow sudden change energy of the φ phase in a unit sampling time, ∑ΔW dΔt is the total virtual energy of the three-phase differential flow of the transformer.

[0078] Wherein, based on the determination result, the protection action of the transformer is executed, including:

[0079] When a continuous plurality of points of any phase satisfy the protection criterion, the protection action is executed, and the continuous plurality of points at least include 10.

[0080] Wherein, the transformer protection method further includes:

[0081] Adopt three-phase voltage criterion, calculate three-phase voltage instantaneous value, if the calculated value is greater than certain value, it is normal air throw, lock, less than certain value, it is inrush current fault, open protection criterion.

[0082] Among them, three-phase voltage criterion is as follows:

[0083]

[0084] Among them, u a , u b , u c Respectively, three-phase voltage sampling value, U e It is rated phase voltage.

[0085] The application will be further described below in combination with embodiments:

[0086] The implementation process is divided into four steps, and the principle is shown in Figure 2 , specifically including:

[0087] (1) Energy calculation method:

[0088] From the equivalent parameters of transformer, based on the law of conservation of energy, when normal operation, the energy flowing into the transformer should be equal to the energy flowing out (ignoring copper loss, iron loss, etc.). For double-winding transformer, the input energy is obtained according to the product of three-phase current and inductance (ignoring resistance), time interval; the output energy is obtained according to the product of three-phase current and inductance (ignoring resistance), time interval. Therefore, the current value flowing through the transformer winding is obtained from the sum of current instantaneous value, and then the instantaneous energy value on the transformer is calculated, that is, the energy calculation method can be defined. When the energy value of a single sampling interval of a phase (φ phase) can be expressed as:

[0089]

[0090] Among them, i is the current sampling value of transformer, X d Is the impedance of transformer, △t represents the time of sampling interval. Therefore, the total energy of three-phase is:

[0091] W Δt = W Δa + W Δb + W Δc = (i a 2 +i b 2 +i c 2 )X d Δt (2)

[0092] The energy of unit sampling time can be used to rewrite the above formula (1) as formula (3):

[0093]

[0094] Thus, equation (2) can be rewritten as:

[0095]

[0096] Therefore, according to equations (1) to (4), the fault post-mutation energy value can be further derived, i.e. the fault post-current sampling value is changed to the current mutation value, and thus the mutation energy of a certain phase (φ phase) can be expressed as:

[0097]

[0098] In the formula, Can be expressed as T represents one cycle.

[0099] (2) Difference flow virtual energy calculation method:

[0100] According to the energy calculation method in the first step, the transformer difference flow virtual energy can be expressed as:

[0101]

[0102] Where, i d is the differential current of the transformer, X dd is the virtual differential impedance of the transformer, and △t represents the sampling interval time. Thus, the total sum of the transformer difference flow virtual energy is:

[0103] W dΔt = W Δda + W Δdb + W Δdc = (i da 2 + i db 2 + i dc 2 ) X dd Δt (7)

[0104] Similarly, using the energy of the unit sampling time, the above equation (6) can be rewritten as equation (8):

[0105]

[0106] Thus, equation (7) can be rewritten as:

[0107]

[0108] Therefore, according to the formula (6) to (9), the virtual fault current mutation energy value after the fault can be further derived, that is, the fault current is changed into the fault current mutation value, and thus the virtual fault current mutation energy value of a phase (φ phase) can be expressed as:

[0109]

[0110] In the formula, is the change of the transformer differential current, which can be expressed as:

[0111]

[0112] In the formula, represents the current mutation value of a phase on the high-voltage side of the transformer, represents the current mutation value of a phase on the low-voltage side of the transformer. Thus, the total virtual fault current mutation energy of the transformer is:

[0113] ΔW dΔt = ΔW dΔta + ΔW dΔtb + ΔW dΔtc = (Δi da 2 + Δi db 2 + Δi dc 2 ) X dd Δt (12)

[0114] Similarly, the above formula (10) can be rewritten as formula (13) by using the energy of the unit sampling time:

[0115]

[0116] Thus, the formula (12) can be rewritten as:

[0117]

[0118] (3) Transformer fast protection method of virtual fault current mutation energy:

[0119] According to the law of conservation of energy, the transformer protection criterion is constructed:

[0120]

[0121] In the formula: n is the sampling point number of the current, and n = 10 can be taken; S is the rated power of the transformer, Δt is the interval time of sampling; k k3 ,k k4 are single-phase and three-phase energy mutation calculation reliability coefficients, and k k3 = 2, k k4 = 2.

[0122] When any phase has continuous multiple points satisfying condition (15), the protection will act quickly. The continuous multiple points can be 10 points.

[0123] (4) The excitation inrush blocking method based on three-phase voltage comprehensive judgment:

[0124] For the case of ground fault or serious inter-turn fault of the network side winding, the fault phase voltage will appear serious drop characteristics. When the inrush occurs, the three-phase voltage will not appear serious drop characteristics. Therefore, the three-phase voltage instantaneous value is calculated, and greater than a certain value is normal air drop and blocking, and less than the value is fault and opening protection criterion.

[0125]

[0126] u a 、u b 、u c respectively represent three-phase voltage sampling values, U e represents the rated phase voltage.

[0127] Since there is a certain magnetic flux accumulation time when the CT enters saturation, in order to prevent the CT saturation caused by serious out-of-area fault from causing the misoperation of the scheme, the protection method of the scheme can be put into operation only for 5 ms in actual application.

[0128] The transformer internal serious fault condition (the differential current is greater than the differential speed determination value) can be realized by the scheme, the protection acts quickly, and the action time is less than 5 ms (not including the device outlet relay action time). In the case of out-of-area serious fault leading to CT saturation, the device does not misoperate. In the case of any out-of-area fault or disturbance, the protection device does not misoperate.

[0129] The RTDS is used to carry out in-area serious fault simulation verification, the Y△ converter network side lead wire A-phase ground fault occurs, the differential current waveform is as shown in Figure 3 , the 0 time is the starting time of the fault, and the maximum instantaneous value of the differential current after the fault can reach 46.11 kA, Figure 4 is the virtual sudden change energy value of the differential current of each phase after the fault, and it can be seen that the virtual sudden change energy value of the differential current of the fault phase after the fault changes quickly.

[0130] As shown in Figure 5 , the 0 time here is the starting time of the protection, the differential current virtual sudden change energy protection meets the action requirement within 2 ms of the fault phase after the fault, the action signal changes from low level to high level, and the non-fault phases B and C do not act.

[0131] Figure 6 is the action condition of the principle under the out-of-area fault condition, and the protection reliably does not act.

[0132] Figure 7This is the protection action when there is inrush current during no-load closing. The closing time is 0. It can be seen that the proposed inrush current blocking method based on three-phase voltage comprehensive judgment has achieved the desired effect. After closing, the blocking criterion is greater than the set value, and the protection is blocked at this time. That is, the proposed protection does not malfunction, which verifies the reliability of the protection.

[0133] Example 2:

[0134] This invention also proposes a transformer protection system 200 based on differential current virtual transient energy, such as... Figure 8 As shown, it includes:

[0135] The first model building unit 201 is used to obtain the operating parameters of the target transformer when it is running normally, and to construct a first calculation model for calculating the sudden change energy of a certain phase of the target transformer based on the operating parameters and the law of conservation of energy.

[0136] The second model building unit 202 is used to construct a second calculation model based on the first calculation model for calculating the virtual transient energy of a certain phase differential current of the target transformer and the sum of the virtual transient energy of the differential current, and to construct the protection criteria of the target transformer based on the first calculation model and the second calculation model.

[0137] The protection unit 203 is used to acquire the operating parameter values ​​of the target transformer, input the operating parameter values ​​into the first calculation model and the second calculation model to calculate, so as to determine the virtual sudden change energy of a certain phase differential current and the sum of the virtual sudden change energy of differential current, and make a judgment on the virtual sudden change energy of a certain phase differential current and the sum of the virtual sudden change energy of differential current based on the protection criterion, and execute the protection action of the transformer based on the judgment result.

[0138] The first calculation model is as follows:

[0139]

[0140] in, The energy value within a single sampling interval of a certain phase. X represents the sampled current value of phase φ of the transformer within a single sampling interval. d Let t be the transformer impedance, and Δt be the sampling interval.

[0141] The second calculation model is as follows:

[0142]

[0143]

[0144] in, X represents the differential current mutation energy of phase φ per unit sampling time, where Δt is the sampling interval.dd is the virtual differential impedance of the transformer, ∑ΔW dΔt is the total virtual differential energy of the transformer three-phase differential current, n is the sampling point number of the current, j is the sampling starting point, Δi daj is the A-phase differential current sudden change variable, Δi dbj is the B-phase differential current sudden change variable, Δi dcj is the C-phase differential current sudden change variable, is the differential current sudden change variable of the φ phase.

[0145] Wherein, the protection criterion is as follows:

[0146]

[0147] Wherein, n is the sampling point number of the current, S is the rated power of the transformer, △t is the sampling interval time, k k3 and k k4 are the single-phase and three-phase energy sudden change calculation reliability coefficients, respectively, is the differential current sudden change energy of the φ phase in unit sampling time, ∑ΔW dΔt is the total virtual differential energy of the transformer three-phase differential current.

[0148] Wherein, based on the determination result, the protection action of the transformer is executed, including:

[0149] When any phase has continuous multiple points satisfying the protection criterion, the protection action is executed, and the continuous multiple points at least include 10.

[0150] Wherein, the protection unit 203 is further used for:

[0151] The three-phase voltage criterion is used to calculate the three-phase voltage instantaneous value, if the calculated value is greater than a certain value, it is normal air drop, is blocked, and if it is less than a certain value, it is inrush current fault, and the protection criterion is opened.

[0152] Wherein, the three-phase voltage criterion is as follows:

[0153]

[0154] Wherein, u a , u b , u c are three-phase voltage sampling values, U e is the rated phase voltage.

[0155] The application can ensure that the protection device does not misoperate.

[0156] Embodiment 3:

[0157] Based on the same inventive concept, the present application further provides a computer device, which comprises a processor and a memory, the memory is used to store a computer program, the computer program comprises program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc., which are the computing core and control core of the terminal, and are suitable for implementing one or more instructions, and are specifically suitable for loading and executing one or more instructions in the computer storage medium to implement a corresponding method flow or a corresponding function, so as to implement the steps of the method in the above embodiments.

[0158] Embodiment 4:

[0159] Based on the same inventive concept, the present application further provides a storage medium, specifically a computer readable storage medium (Memory), which is a memory device in the computer device, and is used to store programs and data. It can be understood that the computer readable storage medium herein can include the built-in storage medium in the computer device, and of course can also include the expansion storage medium supported by the computer device. The computer readable storage medium provides a storage space, and the storage space stores the operating system of the terminal. Moreover, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and the instructions can be one or more computer programs (including program codes). It should be noted that the computer readable storage medium herein can be a high-speed RAM memory, or a non-volatile memory such as at least one disk memory. One or more instructions stored in the computer readable storage medium can be loaded and executed by the processor to implement the steps of the method in the above embodiments.

[0160] Those skilled in the art will appreciate that embodiments of the present application can be readily used as software, hardware, or a combination of software and hardware. In a software embodiment, the methods can be tangibly embodied in a machine-readable storage medium having stored thereon instructions that can be used to program a computer to perform any of the methods. The software implementation can be initialized by loading and executing a set of instructions arranged to perform one of the methods into the computer's memory. Alternatively, hard-wired circuitry can be used in place of, or in combination with, software instructions. Thus, the

[0161] The present application is described in reference to the flowchart illustrations and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in one or more of the flowchart illustrations and / or block diagrams. Figure 1 means for performing the functions specified in one or more of the flowchart illustrations and / or block diagrams.

[0162] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in one or more of the flowchart illustrations and / or block diagrams. Figure 1 means for performing the functions specified in one or more of the flowchart illustrations and / or block diagrams.

[0163] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in one or more of the flowchart illustrations and / or block diagrams. Figure 1 means for performing the functions specified in one or more of the flowchart illustrations and / or block diagrams.

[0164] While preferred embodiments of the application have been described, additional variations and modifications can be made to these embodiments by those skilled in the art once they learn of the basic inventive concepts. Therefore, the appended claims are intended to cover all such modifications and variations as fall within the true scope of the present application.

[0165] It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

Claims

1. A transformer protection method based on differential flow virtual fault energy, characterized by, The transformer protection method comprises: For a target transformer, obtaining operation parameters of the target transformer in normal operation, and constructing a first calculation model for calculating a certain phase sudden energy of the target transformer based on the operation parameters and the law of conservation of energy; Based on the first calculation model, a second calculation model for calculating a certain phase differential flow virtual sudden energy and a total sum of differential flow virtual sudden energies of the target transformer is constructed, and a protection criterion of the target transformer is constructed based on the first calculation model and the second calculation model; Obtaining an operation parameter value of the target transformer, and bringing the operation parameter value into the first calculation model and the second calculation model for calculation to determine the certain phase differential flow virtual sudden energy and the total sum of differential flow virtual sudden energies of the target transformer, judging the certain phase differential flow virtual sudden energy and the total sum of differential flow virtual sudden energies based on the protection criterion, and performing a protection action of the transformer based on a judgment result.

2. The transformer protection method of claim 1, wherein, The first calculation model is as follows: wherein, the energy value within a single sampling interval of a phase, is the current sampling value of the transformer φ phase within a single sampling interval, X d is the transformer impedance, and Δt is the time of the sampling interval.

3. The transformer protection method of claim 1, wherein, The second calculation model is as follows: Where, is the energy of the phase φ difference flow sudden change, Δt is the sampling interval time, X dd is the virtual differential impedance of the transformer, ∑ΔW dΔt is the total energy of the transformer three-phase difference flow, n is the sampling point number of the current, j is the sampling starting point, Δi daj is the A-phase difference flow sudden change, Δi dbj is the B-phase difference flow sudden change, Δi dcj is the C-phase difference flow sudden change, is the difference flow sudden change of φ phase.

4. The transformer protection method of claim 1, wherein, The protection criterion is as follows: Where n is the sampling points of current, S is the rated power of transformer, △t is the time interval of sampling, k k3 and k k4 are the reliability coefficients of single-phase and three-phase energy sudden change calculation, respectively, is the sudden change energy of φ-phase in unit sampling time, ∑ΔW dΔt is the total of three-phase sudden change virtual energy of transformer.

5. The transformer protection method of claim 1, wherein, The protection action of the transformer based on the judgment result comprises: When a plurality of continuous points of any phase satisfy the protection criterion, the protection action is performed, and the plurality of continuous points at least include 10 points.

6. The transformer protection method of claim 1, wherein, The transformer protection method further comprises: A three-phase voltage criterion is used to calculate three-phase voltage instantaneous values, if a calculation value is greater than a certain value, it is a normal air drop, the protection criterion is blocked, and if the calculation value is less than a certain value, it is a inrush current fault, the protection criterion is opened.

7. The transformer protection method of claim 6, wherein, The three-phase voltage criterion is as follows: Wherein, u a , u b , u c are three-phase voltage sampling values, and U e is a rated phase voltage.

8. A transformer protection system based on differential flow virtual fault energy, characterized by, The transformer protection system comprises: A first model building unit is configured to obtain operation parameters of a target transformer in normal operation, and construct a first calculation model for calculating a certain phase sudden energy of the target transformer based on the operation parameters and the law of conservation of energy; A second model building unit is configured to construct a second calculation model for calculating a certain phase differential flow virtual sudden energy and a total sum of differential flow virtual sudden energies of the target transformer based on the first calculation model, and construct a protection criterion of the target transformer based on the first calculation model and the second calculation model; A protection unit is configured to obtain an operation parameter value of the target transformer, bring the operation parameter value into the first calculation model and the second calculation model for calculation to determine the certain phase differential flow virtual sudden energy and the total sum of differential flow virtual sudden energies of the target transformer, judge the certain phase differential flow virtual sudden energy and the total sum of differential flow virtual sudden energies based on the protection criterion, and perform a protection action of the transformer based on a judgment result.

9. The transformer protection system of claim 8, wherein, The first calculation model is as follows: wherein, the energy value within a single sampling interval of a phase, is the current sampling value of the transformer φ phase within a single sampling interval, X d is the transformer impedance, and Δt is the time of the sampling interval.

10. The transformer protection system of claim 8, wherein, The second calculation model is as follows: wherein, is the energy of the phase φ difference flow sudden change, Δt is the sampling interval time, X dd is the virtual differential impedance of the transformer, ∑ΔW dΔt is the total virtual energy of the three-phase difference flow of the transformer, n is the sampling point number of the current, j is the sampling starting point, Δi daj is the A-phase difference flow sudden change, Δi dbj is the B-phase difference flow sudden change, Δi dcj is the C-phase difference flow sudden change, is the difference flow sudden change of the φ phase.

11. The transformer protection system of claim 8, wherein, The protection criterion is as follows: Where n is the sampling points of current, S is the rated power of transformer, △t is the time interval of sampling, k k3 and k k4 are the reliability coefficients of single-phase and three-phase energy sudden change calculation, respectively, is the sudden change energy of φ-phase in unit sampling time, ∑ΔW dΔt is the total of three-phase sudden change virtual energy of transformer.

12. The transformer protection system of claim 8, wherein, The protection action of the transformer based on the judgment result comprises: When a plurality of continuous points of any phase satisfy the protection criterion, the protection action is performed, and the plurality of continuous points at least include 10 points.

13. The transformer protection system of claim 8, wherein, The protection unit is further configured to: A three-phase voltage criterion is used to calculate three-phase voltage instantaneous values, if a calculation value is greater than a certain value, it is a normal air drop, the protection criterion is blocked, and if the calculation value is less than a certain value, it is a inrush current fault, the protection criterion is opened.

14. The transformer protection system of claim 13, wherein, The three-phase voltage criterion is as follows: wherein u a , u b , u c are the three-phase voltage sample values, respectively, and U e is the rated phase voltage.

15. A computer device, comprising: Comprise: One or more processors; a processor to execute one or more programs; a computer program to implement the method of any of claims 1-7 when executed on the one or more processors.

16. A computer-readable storage medium, characterized in that, a computer program to implement the method of any of claims 1-7 when executed on the one or more processors.

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