CN117712997A

CN117712997A - Differential protection method, differential protection device, electronic equipment and storage medium

Info

Publication number: CN117712997A
Application number: CN202311603404.5A
Authority: CN
Inventors: 林撒迦; 刘宏君; 马文斌; 陈远生; 俞伟国; 高小全; 凌昊; 周浩
Original assignee: CYG Sunri Co Ltd
Current assignee: CYG Sunri Co Ltd
Priority date: 2023-11-27
Filing date: 2023-11-27
Publication date: 2024-03-15

Abstract

The application is applicable to the technical field of relay protection, and provides a differential protection method, a differential protection device, electronic equipment and a storage medium, wherein the differential protection method comprises the following steps: acquiring a first current sequence corresponding to a transformer to be tested, wherein the first current sequence comprises a plurality of differential currents of the transformer to be tested; determining a first sum from all of the differential currents in the first current sequence; determining a first part corresponding to each first current sub-sequence according to all the differential currents in each first current sub-sequence, wherein any one of the first current sub-sequences comprises a plurality of continuous differential currents in the first current sequence, and different differential currents exist in any two of the first current sub-sequences; determining a first reference value from the first portion having the smallest value and the first sum; and under the condition that the first reference value is larger than a first threshold value, performing differential protection on the transformer to be tested. The method and the device can improve the accuracy of differential protection of the transformer.

Description

Differential protection method, differential protection device, electronic equipment and storage medium

Technical Field

The application belongs to the technical field of relay protection, and particularly relates to a differential protection method, a differential protection device, electronic equipment and a computer readable storage medium.

Background

The current differential protection is a protection method in relay protection, and when the current difference between two ends of an input Current Transformer (CT) reaches a set action value, an action element is started to protect electrical equipment such as a line, a transformer and the like between the two ends of the input CT. Differential protection is currently commonly employed as the primary protection for internal faults of transformers.

At present, whether the differential protection of a transformer is opened is generally judged by taking the second harmonic in the current as a basis, the differential protection is locked when the second harmonic content of the current is large, so that the misoperation of the differential protection caused by exciting inrush current of the transformer is prevented, the differential protection is opened when the second harmonic content is small, but the second harmonic content judgment threshold value is usually set by staff according to experience, and under the condition that the second harmonic content of fault current is large, misjudgment of exciting inrush current is possibly caused, and the protection is delayed and not opened, so that the safe operation of the transformer is influenced.

Disclosure of Invention

The embodiment of the application provides a differential protection method, a differential protection device, electronic equipment and a storage medium, which can improve the accuracy of differential protection of a transformer.

In a first aspect, an embodiment of the present application provides a differential protection method, including:

acquiring a first current sequence corresponding to a transformer to be tested, wherein the first current sequence comprises a plurality of differential currents of the transformer to be tested;

determining a first sum from all of the differential currents in the first current sequence;

determining a first part corresponding to each first current sub-sequence according to all the differential currents in each first current sub-sequence, wherein any one of the first current sub-sequences comprises a plurality of continuous differential currents in the first current sequence, and different differential currents exist in any two of the first current sub-sequences;

determining a first reference value from the first portion having the smallest value and the first sum;

and under the condition that the first reference value is larger than a first threshold value, performing differential protection on the transformer to be tested.

In a second aspect, an embodiment of the present application provides a differential protection device, including:

the first current sequence acquisition module is used for acquiring a first current sequence corresponding to a transformer to be tested, wherein the first current sequence comprises a plurality of differential currents of the transformer to be tested;

A first sum acquisition module configured to determine a first sum according to all of the differential currents in the first current sequence;

the first part and acquisition module is used for respectively determining a first part sum corresponding to each first current sub-sequence according to all the differential currents in each first current sub-sequence, wherein any one of the first current sub-sequences comprises a plurality of continuous differential currents in the first current sequences, and different differential currents exist in any two of the first current sub-sequences;

a first reference value determining module, configured to determine a first reference value according to the first portion with the smallest value and the first sum;

and the differential protection judging module is used for carrying out differential protection on the transformer to be tested under the condition that the first reference value is larger than a first threshold value.

In a third aspect, an embodiment of the present application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor implements the steps of the differential protection method described in the first aspect when the processor executes the computer program.

In a fourth aspect, embodiments of the present application provide a computer-readable storage medium storing a computer program which, when executed by a processor, implements the steps of the differential protection method described in the first aspect.

In a fifth aspect, embodiments of the present application provide a computer program product, which, when run on an electronic device, causes the electronic device to perform the differential protection method of any one of the first aspects described above.

Compared with the prior art, the embodiment of the application has the beneficial effects that:

in the embodiment of the application, a first current sequence corresponding to a transformer to be tested is obtained, then a first sum is determined according to all differential currents contained in the first current sequence, and a first partial sum corresponding to each first current sub-sequence is determined according to all differential currents in the first current sub-sequence. When the transformer to be tested breaks down, the change rule of the differential current generally accords with a sine waveform, and when excitation surge current is generated, the waveform of the differential current generates larger distortion, namely the change rule of the differential current, the first current sequence comprises a plurality of differential currents of the transformer to be tested in a certain time period, the corresponding first sum can reflect the integral change characteristic of the differential current in the corresponding whole time period, the first current sub-sequence comprises a plurality of continuous differential currents in the first current sequence, and different differential currents exist in each first current sub-sequence, namely, the first part corresponding to each first current sub-sequence and the first part corresponding to the differential current can reflect the change characteristic of the differential current in different time periods in the whole time period, and the first part and the first sum corresponding to the minimum value reflect the change characteristic of the differential current under extreme conditions. And judging whether the differential current is caused by the fault current or not based on the change characteristics of the differential current in the time period corresponding to the first current sequence, namely judging whether the transformer to be tested has the fault current or not so as to determine whether the differential protection is opened or not, and judging whether the current of the transformer to be tested is the fault current or not without calculating the content of the second harmonic in the current so as to determine whether the differential protection is opened or not, so that the situation that the differential protection is refused when the content of the second harmonic of the fault current is higher can be avoided, and the stable operation of the transformer to be tested is ensured.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings used in the description of the embodiments or the prior art will be briefly described below.

FIG. 1 is a flow chart of a differential protection method according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a variation waveform of a fault current of a transformer provided in an embodiment of the present application;

fig. 3 is a schematic diagram of a variation waveform of a magnetizing inrush current of a transformer provided in an embodiment of the present application;

fig. 4 is a schematic structural diagram of a differential protection device according to an embodiment of the present application;

fig. 5 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system configurations, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

It should be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It should also be understood that the term "and/or" as used in this specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.

Furthermore, the terms first, second and the like in the description and in the claims, are used for distinguishing between the descriptions and not necessarily for indicating or implying relative importance.

Reference in the specification to "one embodiment" or "some embodiments" or the like means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," and the like in the specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments" unless expressly specified otherwise.

Embodiment one:

fig. 1 shows a flow chart of a differential protection method according to an embodiment of the present invention, which is described in detail below:

Step S101, a first current sequence corresponding to a transformer to be tested is obtained, wherein the first current sequence comprises a plurality of differential currents of the transformer to be tested.

The differential current refers to the current used to protect the device between the two ends of the input current transformer (Current Transformer, CT), typically the difference in current between the two ends of the input CT.

Specifically, the differential protection regards the transformer to be tested as a node, when the transformer to be tested has no fault, the current flowing into the transformer to be tested is equal to the current flowing out, namely the differential current is zero, and when the transformer to be tested has fault, the differential current is not zero, so that the differential current of the transformer to be tested can be obtained, and whether the transformer to be tested has fault or not can be judged according to the differential current.

When the transformer fails, the fault current generally conforms to the periodic regular change of the sine waveform, so that the differential current also presents the periodic regular change, but the differential current caused by the reasons of no-load closing and the like of the transformer is generally distorted current, namely, the change is irregular, so that in order to accurately judge whether the transformer to be tested has faults or not, so as to accurately perform differential protection, a plurality of differential currents of the transformer to be tested in a time period can be obtained, and a first current sequence is obtained. It is understood that each differential current in the first current sequence is a temporally continuous differential current.

In some embodiments, the respective differential current in the obtained first current sequence is determined from the instantaneous value of the current of the transformer under test, i.e. the respective differential current obtained is also an instantaneous value. The instantaneous value of the current refers to a value of the current at a certain instant.

In some embodiments, the current waveform of the transformer to be tested may be continuously sampled based on a preset sampling frequency (for example, sampling once every 0.5 ms), so as to obtain a plurality of differential currents which are continuous in time, and then a first current sequence is determined according to a preset number (for example, 30) of differential currents, so as to realize fault monitoring of the transformer to be tested based on each first current sequence, thereby performing differential protection on the transformer to be tested in time when the transformer to be tested has faults.

For example, since the current of the transformer to be tested completes one period of change within one cycle (usually 20 milliseconds (ms)), the current waveform of the transformer to be tested can be continuously obtained, the current waveform corresponding to each cycle is sampled, the first current sequence corresponding to each cycle is determined according to a plurality of differential currents which are obtained by sampling and are continuous in time, and the differential currents in each first current sequence just reflect the change of the current of the transformer within one cycle, so that whether the current of the transformer to be tested is regularly changed or not, that is, whether the current of the transformer to be tested is fault current or not can be well judged, and the accuracy of differential protection can be improved while the real-time monitoring of the transformer to be tested is realized.

In other embodiments, since the differential current of the transformer to be tested is usually zero under normal conditions, and the differential current is usually not zero when an abnormality such as a fault or no-load closing occurs, in order to reduce the calculation amount and save resources, a differential current at the current moment can also be obtained, and in the case that the differential current at the current moment is greater than or equal to a threshold value (e.g. 0.1), that is, in the case that the transformer to be tested may generate a larger differential current due to the fault or no-load closing, the first current sequence is obtained to perform the judgment of differential protection.

In the embodiment of the present application, under the condition that a transformer to be tested has a fault, the differential current caused by the fault current generally shows a periodic regular change according with a sinusoidal waveform along with the fault current, so that a first current sequence including a plurality of differential currents of the transformer to be tested is obtained, and the obtained plurality of differential currents are continuous in time, so that whether the transformer to be tested has a fault can be determined according to the change characteristics of the plurality of differential currents in the first current sequence, thereby determining whether the transformer to be tested needs to be subjected to differential protection, and improving the accuracy of the differential protection.

Step S102, determining a first sum according to all the differential currents in the first current sequence.

Specifically, in order to further improve the accuracy of differential protection, the sum of the differential currents in the first current sequence may be calculated according to all the differential currents in the first current sequence to obtain a first sum, where the differential currents in the first current sequence are a plurality of differential currents of the transformer to be tested in a certain period of time, so that the first sum obtained according to all the differential currents in the first current sequence can be used to determine whether the transformer to be tested has an abnormality according to the integral change of the differential currents of the transformer to be tested in the corresponding whole period of time, and further, misjudgment caused by situations such as occasional distortion of the differential currents is avoided.

Step S103, determining a first partial sum corresponding to the first current sub-sequence according to all the differential currents in each first current sub-sequence, wherein any one of the first current sub-sequences includes a plurality of continuous differential currents in the first current sequence, and any two of the first current sub-sequences have different differential currents.

Specifically, to further improve the accuracy of the differential protection, a plurality of first current sub-sequences may be determined from the first current sequences, where any one first current sub-sequence includes a plurality of continuous differential currents in the first current sequence, and where different differential currents exist in any two first current sub-sequences.

After each first current sub-sequence is determined from the first current sequences, for each first current sub-sequence, a sum of the first current sub-sequences is calculated according to all differential currents contained in the first current sub-sequences, so as to obtain a first partial sum corresponding to the first current sub-sequences.

It will be appreciated that the differential currents in the first current sub-sequence comprise a plurality of consecutive differential currents in the first current sequence, and that each differential current comprised in the first current sequence is consecutive in time, so are each differential current comprised in each first current sub-sequence.

In some embodiments, the number of differential currents in the first current sub-sequence may be determined according to a preset time period (e.g., a fifth cycle time period, i.e., 0.2 x cycle time period) or a preset number (e.g., 3).

In this embodiment of the present invention, the first portion sums corresponding to each first current sub-sequence are determined according to all the differential currents in each first current sub-sequence, and each differential current in the first current sub-sequence is continuous in time, so that the first portion sums can reflect the change characteristics of the differential current of the transformer to be tested in the time period corresponding to the first current sub-sequence, and then, whether the transformer to be tested has a fault is determined based on the first portion sums corresponding to each first current sub-sequence, and whether the differential current of the transformer to be tested has a regular change can be determined better based on the change characteristics of the differential current of the transformer to be tested in each smaller time period, i.e. whether the transformer to be tested has a fault current is determined.

Step S104, determining a first reference value according to the first part with the minimum value and the first sum.

Specifically, since the first portion corresponding to each first current sub-sequence and the first portion with the smallest value are capable of reflecting the change characteristics of the differential current in different time periods within the whole time period, and the first portion with the smallest value and the first portion corresponding to the smallest value are capable of reflecting the change characteristics of the differential current under extreme conditions, in order to further improve the accuracy of differential protection, the ratio of the first portion with the smallest value and the first sum can be used as a first reference value, and the obtained first reference value can intuitively and accurately reflect whether the change of the differential current in the first portion with the smallest value and the corresponding time period accords with a certain change rule relative to the whole change of the differential current within the whole time period, so that whether the fault current exists in the transformer to be detected can be accurately judged according to the first reference value later, and the accuracy of differential protection of the transformer is improved.

Step S105, performing differential protection on the transformer under test when the first reference value is greater than a first threshold value.

Specifically, when the transformer to be tested has a fault, the fault current of the transformer to be tested is usually periodically changed, and the change rule of the transformer to be tested accords with the sine waveform, so that the differential current of the transformer to be tested also shows periodic change according with the sine waveform, and the first reference value of the differential current is usually larger than a certain value when the differential current periodically changes, so that whether the current of the transformer to be tested is the fault current or not can be judged according to the magnitude relation between the first reference value and the first threshold value (such as 0.1), and whether the transformer to be tested needs differential protection or not is determined.

It can be understood that whether the transformer to be tested is subjected to differential protection is determined, that is, whether the differential protection is opened is determined, and the opening differential protection enables the protection action element of the transformer to be tested to be started so as to isolate the failed transformer to be tested from other devices, thereby ensuring the normal operation of the power system.

Under the condition that the first reference value is larger than the first threshold value, the distortion of the differential current is considered smaller, and the change rule of the periodic change of the sine waveform is met, namely, the differential current of the transformer to be tested is caused by the fault current of the transformer to be tested, and the transformer to be tested has faults and needs to be subjected to differential protection. When the first reference value is smaller than or equal to the first threshold value, the distortion of the differential current is considered to be larger, and the change rule of the periodic change is not met, namely, the differential current of the transformer to be tested is caused by excitation surge current caused by abnormal conditions such as no-load closing of the transformer to be tested, and differential protection is not needed.

When the first reference value is smaller than or equal to the first threshold value, the distortion of the differential current is considered to be larger, and the periodic change rule of the sine waveform is not met, namely, the differential current of the transformer to be tested is possibly caused by excitation current generated by abnormal conditions such as no-load closing or unbalanced current caused by reasons such as a transformer winding wiring mode, and the transformer to be tested does not have faults, and at the moment, differential protection is not needed to be carried out on the transformer to be tested, namely, the differential protection of the transformer to be tested is locked, and a protection action element of the transformer to be tested is not started, so that the transformer to be tested can normally operate, and the situation of differential protection misoperation is reduced.

For example, assume that the current waveforms in the time periods t1-t7 correspond to the current waveform of one cycle of the transformer to be tested, and the current waveforms are sampled at a plurality of times (i.e., t1, t2, t3...t7) in the time periods t1-t7, so as to obtain differential currents corresponding to the respective times. The differential currents included in the obtained first current sequence are assumed to include the following differential currents in chronological order: (A1, A2, A3, A4, A5, A6, A7) and assuming that the first current sub-sequence comprises 3 consecutive differential currents in the first current sequence, i.e. the first current sub-sequence comprises: b1 (A1, A2, A3), B2 (A2, A3, A4), B3 (A3, A4, A5), B4 (A4, A5, A6), B5 (A5, A6, A7), assuming that the first sum corresponding to the first current sequence is a, the first portion corresponding to each of the first current sub-sequences (B1-B5) and (B1, B2, B3, B4, B5) are sequentially arranged, wherein B1 reflects the characteristic of the change in differential current in the time period t1-t3, B2 reflects the characteristic of the change in differential current in the time period t2-t4, B3 reflects the characteristic of the change in differential current in the time period t3-t5, B4 reflects the characteristic of the change in differential current in the time period t4-t6, and B5 reflects the characteristic of the change in differential current in the time period t5-t 7.

As shown in fig. 2 and 3, since the differential current of the transformer to be tested is caused by the fault current, the change rule thereof conforms to the periodic change of the sine waveform, when the differential current is caused by the magnetizing inrush current, the waveform of the differential current is greatly distorted, the change is irregular, the first sum a reflects the integral change characteristics of the differential current in the time period t1-t7, each of the first parts and (b 1-b 5) can reflect the change characteristics of different time periods in the time period t1-t7, when the differential current is caused by the fault current, the smallest first part and larger, when the ratio of the differential current to the first sum (i.e., the first reference value) is generally greater than a certain value and the differential current is caused by the magnetizing inrush current, the ratio of the smallest first part of the differential current to the first sum (i.e., the first reference value) is smaller, it can be considered that the greater the first reference value is, the greater the possibility that the differential current is caused by the fault current is, the smaller the first reference value is, the greater the possibility that the differential current is caused by the magnetizing inrush current is, and therefore, whether the differential current is caused by the fault current can be judged according to whether the first reference value is greater than the first threshold value, so as to determine whether the differential protection of the transformer to be tested is required.

In some embodiments, the first threshold may be dynamically determined in combination with a duty ratio of a duration of a time period corresponding to the differential current in the first current sub-sequence to a duration corresponding to one cycle, and a change rule of a sinusoidal waveform, and accuracy of differential protection is further improved through the dynamic first threshold associated with the first portion.

In this embodiment of the present invention, when a transformer has a fault, its fault current generally conforms to the periodic variation of a sinusoidal waveform, that is, its differential current conforms to the periodic variation of a sinusoidal waveform, and when excitation surge current is generated due to an abnormality such as no load, the excitation surge current is greatly distorted, so that the differential current is also greatly distorted, and the variation of the differential current is irregular, therefore, a plurality of differential currents of the transformer to be tested in a certain period of time can be obtained, a first current sequence is obtained, and whether the transformer to be tested has a fault current is determined based on the variation rule of the differential current in the first current sequence, that is, whether the transformer to be tested needs to be differentially protected. Meanwhile, when judging whether fault current exists based on the first current sequence, calculating to obtain a first sum according to all differential currents in the first current sequence, and calculating to obtain a first partial sum according to each first current subsequence, since the first current sub-sequence contains a plurality of continuous differential currents in the first current sequence, and any two first current sub-sequences have different differential currents, that is, the first portion corresponding to each first current sub-sequence and the variable characteristic capable of reflecting the differential current in different time periods throughout the time period, the first sum can reflect the integral change characteristics of the differential current of the transformer to be tested in the corresponding whole time period, and the first part with the smallest value corresponds to the minimum value and reflects the change characteristics of the differential current under the extreme condition, therefore, the ratio of the first part with the smallest value and the first sum can be used as a first reference value, the obtained first reference value can intuitively and accurately reflect whether the change of the differential current in the first part with the smallest value and the corresponding time period accords with a certain rule or not relative to the integral change of the differential current in the whole time period, so as to better judge whether the transformer to be tested has fault current according to the first reference value, and judging whether the current of the transformer to be tested is fault current or not based on the change characteristics of the differential current in the time period corresponding to the first current sequence, therefore, whether differential protection is opened is determined, whether differential protection is performed or not is judged without calculating the content of the second harmonic in the current, the situation that differential protection refuses due to the fact that the content of the second harmonic of the fault current is high can be avoided, differential protection is performed in time, and stable operation of the transformer to be tested is guaranteed.

In some embodiments, the step S101 includes:

a1, obtaining differential currents of all phase lines of the transformer to be tested at the current moment, and obtaining reference currents corresponding to the phase lines.

A2, under the condition that any one of the reference currents is larger than or equal to a second threshold value, acquiring the first current sequences corresponding to the phase lines of the transformer to be tested.

It should be noted that the values of the first threshold and the second threshold may be the same value or different values, but the values are different, the first threshold is a pure value, and the second threshold is a current value, and the values are amperes.

Specifically, since the differential current of the transformer to be tested is usually zero under normal conditions, and the differential current is not zero when an abnormality such as a fault or no-load closing occurs, in order to reduce unnecessary judgment, the differential current of the transformer to be tested at the current moment can be obtained first, and taken as a reference current, and whether the first current sequence needs to be obtained for differential protection is judged according to whether the reference current is greater than or equal to a preset second threshold value.

In practical application, the transformers are usually transformers with a plurality of phases, such as a three-phase transformer or a multi-phase transformer, and when the transformers fail, one or more phases may fail, so that the corresponding phase lines generate fault currents.

When determining whether the first current sequence needs to be acquired according to the reference current, if the reference current corresponding to any one phase line is greater than or greater than a second threshold (e.g., 0.05A, i.e., 0.05 ampere), the phase corresponding to the phase line in the transformer to be tested is indicated to possibly fail, i.e., the transformer to be tested may possibly fail, at this time, the first current sequences corresponding to the phase lines of the transformer to be tested may be acquired respectively, and whether the fault current exists in the transformer to be tested is determined based on the phase lines respectively, thereby improving the accuracy of differential protection of the transformer to be tested.

In some embodiments, when the first current sequence corresponding to the phase line of the transformer to be tested is obtained, only the differential current of the phase line (target phase line) with the reference current greater than or equal to the second threshold value may be obtained, so as to obtain the first current sequence corresponding to the target phase line, and then, based on the first current sequence, whether the current of the target phase line is a fault current is judged, so as to determine whether the transformer to be tested has a fault, that is, only the target phase line with the abnormal reference current (that is, the reference current greater than or equal to the second threshold value) is obtained, and the differential protection judgment is performed by obtaining the first current sequence, instead of the differential protection judgment based on the phase line with the normal reference current, so that the differential protection judgment efficiency is improved.

For example, assuming that the transformer to be tested includes a phase a, a phase B and a phase C, the second threshold is 0.08A, the reference current corresponding to a is 0.06a, the reference current corresponding to B is 0.08A, and the reference current corresponding to C is 0A, where the reference current corresponding to B is 0.08A equal to the second threshold 0.08A, the phase line corresponding to B is taken as the target phase line, the current waveform of the target phase line is sampled to obtain multiple differential currents of the target phase line, that is, a first current sequence B corresponding to the target phase line is obtained, and then, based on the first current sequence B, whether the current of the target phase line is a fault current is determined, so as to determine whether the phase B of the transformer to be tested has a fault, so as to perform differential protection on the phase B of the transformer to be tested, that is determined whether the transformer to be tested needs to perform differential protection.

In this embodiment of the present application, since the differential current of the transformer to be tested is usually zero under normal conditions, and when an abnormality such as a fault or no-load closing occurs, the differential current is abnormal and is usually not zero, so that the differential current of each phase line of the transformer to be tested at the current moment can be obtained first, and taken as the reference current corresponding to the phase line, and under the condition that any reference current corresponding to one phase line has an abnormality, the first current sequence corresponding to each phase line is obtained again to perform differential protection judgment, and the first current sequence corresponding to each phase line does not need to be continuously obtained to perform differential protection judgment, thereby improving the differential protection judgment efficiency, reducing unnecessary judgment, and saving calculation resources.

In some embodiments, the step A1 includes:

and performing full-cycle Fourier transform processing on each reference current to obtain the amplitude corresponding to each reference current.

Correspondingly, the step A2 includes:

and under the condition that the amplitude of any one of the reference currents is larger than or equal to a second threshold value, acquiring the first current sequence corresponding to each phase line of the transformer to be tested.

Specifically, in order to further improve accuracy of reference current judgment and further reduce unnecessary judgment of differential protection, full-cycle fourier transform processing may be performed on the obtained reference currents corresponding to the phase lines to obtain magnitudes corresponding to the reference currents, and when the judgment is performed, it is judged whether the magnitudes of the reference currents are greater than or equal to a second threshold.

The full-cycle fourier transform processing refers to filtering processing based on a full-cycle fourier algorithm. Because the magnetizing inrush current of the transformer is usually a distorted nonlinear current and contains more harmonic components, the judgment of the reference current is interfered, therefore, the differential current can be subjected to filtering treatment through a full-cycle Fourier algorithm to inhibit constant direct current in the differential current and eliminate each positive harmonic component, the fundamental component in the differential current is accurately calculated, the amplitude of the reference current is obtained, the judgment is carried out based on the amplitude of the reference current, and the interference of the harmonic components in the reference current is reduced, so that the accuracy of the judgment of the reference current is improved.

In the embodiment of the application, the interference quantity such as the direct current component and the harmonic component contained in the reference current is filtered through the full-cycle Fourier transform processing, so that the amplitude corresponding to the reference current is obtained, whether the reference current is normal or not is judged according to the amplitude of the reference current, namely whether the transformer to be tested is likely to have faults or abnormal conditions such as no-load closing or the like is judged according to the amplitude of the reference current, and the accuracy of the judgment result of the reference current is improved.

In some embodiments, the obtaining the first current sequence corresponding to each phase line of the transformer to be tested in the step A2 includes:

and determining the first current sequence corresponding to each phase line based on a preset sampling frequency and a current waveform of a cycle of the phase line before the current moment.

Specifically, in order to improve the efficiency of differential protection judgment, to improve the efficiency of differential protection of the transformer to be tested, when it is judged that the first current sequence corresponding to each phase line of the transformer to be tested needs to be obtained, a current waveform of the phase line before the current moment is obtained for each phase line, then the current waveform before the current moment is sampled based on a preset sampling frequency (such as sampling every 0.5 ms), and a corresponding differential current is determined according to the sampled current, so as to obtain the first current sequence corresponding to the phase line for differential protection, and the current waveform of the phase line before the current moment is a known current waveform and is related to the current at the current moment.

The fault current of the transformer to be tested is usually changed periodically and is changed in one cycle, so that in order to accurately judge whether the fault current exists in the transformer to be tested according to the obtained differential current and improve the judging efficiency, the current waveform of the previous cycle of each phase line at the current moment can be sampled, namely, only the current waveform of the known one cycle before the current moment is sampled, the required first current sequence is obtained, the number of differential currents in the first current sequence is reduced while the accuracy is ensured, and the calculation amount of subsequent judgment is reduced.

It can be understood that when the differential current corresponding to the transformer to be measured is obtained, the transformer to be measured is generally regarded as a node, the currents of the input transformer and the output transformer to be measured are sampled, the differential current corresponding to the transformer to be measured is determined according to the difference value between the currents of the input transformer and the currents of the output transformer, when the differential current corresponding to the phase line of the transformer to be measured is obtained, the phase of the transformer to be measured is generally regarded as a node, the phase currents of the input phase and the output phase are sampled based on the phase line of each phase of the transformer to be measured, and the differential current corresponding to the phase (i.e. the phase line) is determined according to the difference value between the input phase current and the output phase current.

In the embodiment of the application, when it is determined that the first current sequence corresponding to the phase line of the transformer to be tested needs to be obtained, the current waveform of one cycle of the phase line before the current moment is sampled according to the preset sampling frequency to obtain a plurality of differential currents which are continuous in time and can reflect the complete periodic variation of the differential currents, namely, the first current sequence corresponding to the phase line is obtained, and the efficiency of differential protection determination is improved while the accuracy of differential protection determination based on the first current sequence is ensured.

In some embodiments, the step S102 includes:

the first sum is determined based on the absolute value of each of the differential currents in the first sequence of currents.

The determining a first partial sum corresponding to the first current sub-sequence according to all the differential currents in each first current sub-sequence includes:

for each of the first current sub-sequences, determining the first partial sum corresponding to the first current sub-sequence according to the absolute value of each of the differential currents in the first current sub-sequence.

Specifically, since the differential current is the difference between the currents at the two ends of the input CT, when the current at the output end is greater than the current at the input end, the obtained differential current may have a negative value, so in order to further improve the accuracy of differential protection, in this embodiment of the present application, when calculating the first sum according to all the differential currents in the first current sequence, the absolute value of each differential current may be calculated first, and then the first sum corresponding to the first current sequence may be determined according to the absolute value of each differential current.

Correspondingly, when determining the corresponding first partial sums according to all the differential currents in each first current sub-sequence, the absolute value of each differential current contained in each first current sub-sequence can be calculated, and then the sum of the absolute values of each differential current can be calculated to obtain the first partial sums corresponding to the first current sub-sequence.

In the embodiment of the application, when the first sum and each first partial sum are obtained by calculation, the absolute value of each differential current contained in the first current sequence and each first current subsequence is determined, and the sum of the absolute values of the differential currents is calculated to obtain the corresponding first sum and each first partial sum, so that the accuracy of the obtained first sum and each first partial sum is improved, and the accuracy of differential protection of the transformer to be tested is further improved.

In some embodiments, the first current sequence includes N differential currents, the first current sub-sequence includes M differential currents, M is greater than or equal to 2, and N is greater than M, and the method further includes, before the step S103:

and determining each first current sub-sequence according to M continuous differential currents in the first current sequences which are connected end to end by taking the first current sequences as a circular queue which is connected end to end, so as to obtain N first current sub-sequences, wherein the first differential current in the N first current sub-sequences is the N differential current in the first current sequences.

Optionally, the value of N is determined based on a sampling frequency adopted when the first current sequence is acquired and a duration corresponding to the sampled current waveform, and the value of M may be a preset fixed value (for example, 5 values) or a value determined based on a preset duration. For example, assuming that when the first current sequence is acquired, the current waveform of one cycle (assuming 20 milliseconds (ms)) is sampled at intervals of 0.4ms, so as to calculate corresponding 50 differential currents, and assuming that the preset duration is 3ms, M may be expressed as follows:

wherein X is the preset time length, T is the time length corresponding to a cycle wave, N is the number of differential currents in the first current sequence,is pointing down and rounding up->Namely, the operation result of X/T is rounded downwards to obtain M. According to the above formula, the number M of differential currents in the first current sub-sequence may be calculated to be 7 (3/20×50=7.5, rounded down to 7.5).

It should be noted that M is greater than or equal to 2, that is, the first current sub-sequence at least includes two continuous differential currents in the first current sequence, and N is greater than M, that is, at least two first current sub-sequences are determined, so as to ensure that the differential currents included in the obtained first current sub-sequence can reflect the change characteristics of the differential currents in different time periods within the whole time period corresponding to the first current sequence, thereby ensuring the accuracy of differential protection judgment.

Specifically, since the M differential currents included in the first current sequence reflect the complete change of one period of the differential current of the transformer to be tested, and when the current of the transformer to be tested is a fault current, the differential currents of the transformer to be tested are periodically changed, so that in order to accurately determine the change of different time periods of the transformer to be tested in the time period of one period, when determining the first current subsequence containing continuous M differential currents, the first current sequence may be used as an end-to-end cyclic queue, and each first current subsequence is determined according to M continuous differential current sequences in the end-to-end first current sequence, so as to obtain N first current subsequences, and in the obtained N first current subsequences, the first differential current is the nth differential current in the first current sequence.

It can be understood that, since the first current sequences are used as the end-to-end circulation queues, the first current subsequences with the same number as the number N of the differential currents in the first current sequences are determined according to the continuous multiple differential currents in the first current sequences, and the obtained N first current subsequences can more accurately reflect the change characteristics of the differential currents in different time periods in one change period of the differential currents, so that each first part obtained based on each first current subsequence can more accurately reflect the change characteristics of the differential currents in different time periods, thereby improving the accuracy of the subsequent differential protection.

For example, as shown in fig. 2, assuming that t7 in fig. 2 is the current time, and assuming that sampling and calculation are performed based on the current waveform of the previous cycle of t7 (the waveform corresponding to t1-t 7), the first current sequence a obtained sequentially includes the following differential currents: (A1, A2, A3, A4, A5, A6, A7), the change of the differential current in the time period of t7-t9 is basically the same as the change in the time period of t1-t2 based on the fact that the fault current conforms to the periodical change law of the sine waveform, so the first differential current A1 can be regarded as the differential current continuous with the last differential current A7 when the first current sequence A is used as a circular queue connected end to end, namely, the first differential current A1 can be regarded as the differential current A8 corresponding to t8, and the second differential current A2 can be regarded as the differential current A9 corresponding to t 9.

Assuming that the first current sub-sequence includes 3 differential currents (i.e., M is 3), when the first current sub-sequence is determined according to the first current sequence a, the following 7 first current sub-sequences (i.e., the following B1-B7) are obtained according to the 3 continuous differential currents in the first current sequence a: b1 (A1, A2, A3), B2 (A2, A3, A4), B3 (A3, A4, A5), B4 (A4, A5, A6), B5 (A5, A6, A7), B6 (A6, A7, A1), (A7, A1, A2).

Since t7 is the current time, and the differential currents A8 and A9 corresponding to t8 and t9 after t7 are not known, in order to improve the judging efficiency of the differential protection, the differential current continuous with the 7 th differential current in the first current sequence is obtained by taking the current A1 corresponding to t1 as the current A8 corresponding to t8 and the current A2 corresponding to t2 as the current A9 corresponding to t9, instead of waiting for the acquisition of the differential currents corresponding to t8 and t9 after the current time t7, based on the periodic variation rule of the sine waveform of the fault current. When the first partial sums are calculated according to the first current subsequences, the first partial sums corresponding to the first current subsequence B6 can reflect the change characteristics of the differential current in the time period t6-t8, and the first partial sums corresponding to the first current subsequence B7 can reflect the change characteristics of the differential current in the time period t7-t9, namely, a plurality of first partial sums which accurately and comprehensively reflect the change characteristics of different time periods in one change period of the differential current are obtained, so that the accuracy of a final judging result can be improved when whether the differential protection of the transformer to be tested is needed or not is judged based on the first partial sums and the first sums, namely, the accuracy of the differential protection is improved.

In the embodiment of the present application, in order to reduce the calculation amount and the waiting time, so as to improve the differential protection efficiency, the differential current in the first current sequence is the differential current obtained based on the previous cycle at the current moment, and meanwhile, in order to improve the accuracy of the differential protection, when determining each first current subsequence to determine the corresponding part sum of the first current subsequences, since the fault current accords with the periodic variation of the sine waveform, the first current sequence can be used as an end-to-end connected circular queue, i.e. the first differential current in the first current sequence is used as the differential current continuous with the nth differential current, so that when determining the first current subsequence according to the continuous differential currents in the first current sequence, for example, the nth differential current and other differential currents, the corresponding first current subsequence can be accurately obtained, thereby obtaining the first current subsequence identical to the number of the differential currents in the first current sequence, more comprehensively reflecting the variation of the differential current in a variation period (i.e. a cycle), and further improving the accuracy of the differential protector to be tested.

In some embodiments, before the step S105, the method further includes:

and determining a second current sequence according to the first current sequence, wherein the second current sequence comprises a plurality of differential currents, and the differential currents are obtained by differential filtering processing on the differential currents in the first current sequence.

And determining a second sum according to all the differential currents in the second current sequence.

And determining a second partial sum corresponding to each second current sub-sequence according to all the differential currents in each second current sub-sequence, wherein any one of the second current sub-sequences comprises a plurality of continuous differential currents in the second current sequence, and different differential currents exist in any two of the second current sub-sequences.

And determining a second reference value, wherein the second reference value is the ratio of the second part with the smallest value to the second sum.

Correspondingly, the step S105 includes:

and under the condition that the first reference value is larger than the first threshold value and the second reference value is larger than a third threshold value, performing differential protection on the transformer to be tested.

Specifically, when the transformer generates the magnetizing inrush current, the differential current caused by the magnetizing inrush current contains a large amount of direct current components, so in order to reduce the interference of the direct current components and further improve the accuracy of differential protection, differential filtering processing can be performed on each differential current in the first current sequence, and the direct current components in the differential current are filtered through the differential filtering processing, so that differential current with higher accuracy corresponding to each differential current is obtained, namely, the second current sequence is obtained.

After obtaining the second current sequence consisting of the respective differential currents, the second current sequence may be subjected to the same processing as the first current sequence, i.e. the sum thereof is calculated from all differential currents in the second current sequence, resulting in a second sum.

And simultaneously, determining a plurality of second current subsequences based on the second current sequences, wherein any one of the obtained second current subsequences comprises a plurality of continuous differential currents in the second current sequences, and different differential currents exist in any two of the second current subsequences. After obtaining each second current sub-sequence, calculating the sum of all differential currents contained in each second current sub-sequence to obtain a second partial sum corresponding to the second current sub-sequence.

After determining the second sum and the respective second partial sums based on the second current sequence, the ratio of the second partial sum with the smallest value to the second sum is calculated to obtain a second reference value. Correspondingly, when judging whether the transformer to be tested needs to be subjected to differential protection, judging whether the differential current of the transformer to be tested is caused by fault current according to the first reference value and the second reference value, thereby determining whether the transformer to be tested is subjected to differential protection. Under the condition that the first reference value is larger than the first threshold value and the second reference value is larger than the third threshold value (such as 0.08), the differential current of the transformer to be tested can be considered to be caused by the fault current, the transformer to be tested has the fault current, and differential protection needs to be carried out on the transformer to be tested so as to realize fault removal of the transformer to be tested and ensure the safety of the transformer to be tested.

It can be understood that, in order to ensure the accuracy of the differential protection, the method for determining each second current sub-sequence based on the second current sequence is the same as the method for determining each first current sub-sequence based on the first current sequence, which is not described in detail in the embodiment of the present application.

In the embodiment of the application, differential filtering is performed on each differential current in the first current sequence, direct current components possibly contained in the differential current are filtered, so that corresponding differential currents, namely, a second current sequence is obtained, then the same processing as that of the first current sequence is performed on the basis of the second current sequence, a second reference value is obtained, and the second reference value calculated on the basis of each differential current in the second current sequence reduces the interference of the direct current components, namely, improves the accuracy of the second reference value, therefore, whether a fault exists in the transformer to be tested is judged together according to the first reference value corresponding to the first current sequence and the second reference value corresponding to the second current sequence, and accordingly whether differential protection is performed on the transformer to be tested is determined, and the accuracy of the differential protection of the transformer can be improved.

It should be understood that the sequence number of each step in the foregoing embodiment does not mean that the execution sequence of each process should be determined by the function and the internal logic of each process, and should not limit the implementation process of the embodiment of the present application in any way.

Embodiment two:

corresponding to the differential protection method described in the above embodiments, fig. 4 shows a block diagram of the differential protection device provided in the embodiment of the present application, and for convenience of explanation, only the portion related to the embodiment of the present application is shown.

Referring to fig. 4, the apparatus includes: a first current sequence acquisition module 41, a first sum acquisition module 42, a first partial sum acquisition module 43, a first reference value determination module 44, a differential protection judgment module 45. Wherein,

the first current sequence obtaining module 41 is configured to obtain a first current sequence corresponding to a transformer to be tested, where the first current sequence includes a plurality of differential currents of the transformer to be tested.

A first sum acquisition module 42 for determining a first sum from all of the differential currents in the first current sequence.

The first portion and obtaining module 43 is configured to determine a first portion sum corresponding to each first current sub-sequence according to all the differential currents in each first current sub-sequence, where any one of the first current sub-sequences includes a plurality of continuous differential currents in the first current sequence, and any two of the first current sub-sequences have different differential currents.

A first reference value determining module 44, configured to determine a first reference value according to the first portion with the smallest value and the first sum.

The differential protection judging module 45 is configured to perform differential protection on the transformer under test when the first reference value is greater than a first threshold value.

In some embodiments, the first current sequence obtaining module 41 includes:

and the reference current acquisition unit is used for acquiring the differential current of each phase line of the transformer to be tested at the current moment to obtain the reference current corresponding to the phase line.

And the first current sequence acquisition unit is used for acquiring the first current sequence corresponding to each phase line of the transformer to be tested under the condition that any one of the reference currents is larger than or equal to a second threshold value.

In some embodiments, the first current sequence obtaining module 41 further includes:

and the transformation unit is used for carrying out full-cycle Fourier transformation processing on each reference current to obtain the amplitude corresponding to each reference current.

Correspondingly, the first current obtaining unit is configured to obtain the first current sequence corresponding to each phase line of the transformer to be tested when the amplitude of any one of the reference currents is greater than or equal to a second threshold value.

In some embodiments, the first current sequence obtaining module 41 includes:

and the phase line first current sequence acquisition unit is used for determining the first current sequence corresponding to each phase line based on a preset sampling frequency and a current waveform of a cycle of the phase line before the current moment.

In some embodiments, the first sum acquisition module 42 includes:

a first sum calculating unit for determining the first sum based on the absolute value of each of the differential currents in the first current sequence.

The first portion and acquisition module 43 includes:

and a first partial sum calculation unit configured to determine, for each of the first current sub-sequences, the first partial sum corresponding to the first current sub-sequence based on an absolute value of each of the differential currents in the first current sub-sequence.

In some embodiments, the first current sequence includes N differential currents, the first current sub-sequence includes M differential currents, M is greater than or equal to 2, and N is greater than M, and the differential protection device further includes:

the first current sub-sequence obtaining module is configured to determine each of the first current sub-sequences according to M consecutive differential currents in the first current sequences connected end to end, to obtain N first current sub-sequences, where a first differential current in an nth first current sub-sequence is an nth differential current in the first current sequence.

In some embodiments, the differential protection device further includes:

and the second current sequence acquisition module is used for determining a second current sequence according to the first current sequence, wherein the second current sequence comprises a plurality of differential currents, and the differential currents are obtained by carrying out differential filtering processing on the differential currents in the first current sequence.

And the second sum acquisition module is used for determining a second sum according to all the differential currents in the second current sequence.

And the second part and acquisition module is used for respectively determining second part sums corresponding to the second current sub-sequences according to all the differential currents in each second current sub-sequence, wherein any one of the second current sub-sequences comprises a plurality of continuous differential currents in the second current sequence, and different differential currents exist in any two of the second current sub-sequences.

And the second reference value determining module is used for determining a second reference value, wherein the second reference value is the ratio of the second part with the minimum value to the second sum.

Correspondingly, the differential protection judging module is configured to perform differential protection on the transformer to be tested when the first reference value is greater than the first threshold value and the second reference value is greater than a third threshold value.

It should be noted that, because the content of information interaction and execution process between the above devices/units is based on the same concept as the method embodiment of the present application, specific functions and technical effects thereof may be referred to in the method embodiment section, and will not be described herein again.

Embodiment III:

fig. 5 is a schematic structural diagram of an electronic device according to an embodiment of the present application. As shown in fig. 5, the electronic apparatus 5 of this embodiment includes: at least one processor 50 (only one processor is shown in fig. 5), a memory 51 and a computer program 52 stored in the memory 51 and executable on the at least one processor 50, the processor 50 implementing the steps in any of the various method embodiments described above when executing the computer program 52.

The electronic device 5 may be a computing device such as a desktop computer, a notebook computer, a palm computer, a cloud server, etc. The electronic device may include, but is not limited to, a processor 50, a memory 51. It will be appreciated by those skilled in the art that fig. 5 is merely an example of the electronic device 5 and is not meant to be limiting of the electronic device 5, and may include more or fewer components than shown, or may combine certain components, or different components, such as may also include input-output devices, network access devices, etc.

The processor 50 may be a central processing unit (Central Processing Unit, CPU), the processor 50 may also be other general purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), field-programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

The memory 51 may in some embodiments be an internal storage unit of the electronic device 5, such as a hard disk or a memory of the electronic device 5. The memory 51 may in other embodiments also be an external storage device of the electronic device 5, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card) or the like, which are provided on the electronic device 5. Further, the memory 51 may also include both an internal storage unit and an external storage device of the electronic device 5. The memory 51 is used for storing an operating system, application programs, boot loader (BootLoader), data, other programs, etc., such as program codes of the computer program. The memory 51 may also be used to temporarily store data that has been output or is to be output.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional units and modules is illustrated, and in practical application, the above-described functional distribution may be performed by different functional units and modules according to needs, i.e. the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-described functions. The functional units and modules in the embodiment may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit, where the integrated units may be implemented in a form of hardware or a form of a software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working process of the units and modules in the above system may refer to the corresponding process in the foregoing method embodiment, which is not described herein again.

The embodiment of the application also provides a network device, which comprises: at least one processor, a memory, and a computer program stored in the memory and executable on the at least one processor, which when executed by the processor performs the steps of any of the various method embodiments described above.

Embodiments of the present application also provide a computer readable storage medium storing a computer program which, when executed by a processor, implements steps that may implement the various method embodiments described above.

Embodiments of the present application provide a computer program product which, when run on an electronic device, causes the electronic device to perform steps that may be performed in the various method embodiments described above.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the present application implements all or part of the flow of the method of the above embodiments, and may be implemented by a computer program to instruct related hardware, where the computer program may be stored in a computer readable storage medium, where the computer program, when executed by a processor, may implement the steps of each of the method embodiments described above. Wherein the computer program comprises computer program code which may be in source code form, object code form, executable file or some intermediate form etc. The computer readable medium may include at least: any entity or device capable of carrying computer program code to a camera device/electronic apparatus, a recording medium, a computer Memory, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), an electrical carrier signal, a telecommunications signal, and a software distribution medium. Such as a U-disk, removable hard disk, magnetic or optical disk, etc. In some jurisdictions, computer readable media may not be electrical carrier signals and telecommunications signals in accordance with legislation and patent practice.

In the foregoing embodiments, the descriptions of the embodiments are emphasized, and in part, not described or illustrated in any particular embodiment, reference is made to the related descriptions of other embodiments.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

In the embodiments provided in the present application, it should be understood that the disclosed apparatus/network device and method may be implemented in other manners. For example, the apparatus/network device embodiments described above are merely illustrative, e.g., the division of the modules or units is merely a logical functional division, and there may be additional divisions in actual implementation, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection via interfaces, devices or units, which may be in electrical, mechanical or other forms.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

The above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.

Claims

1. A differential protection method, comprising:

2. The differential protection method as set forth in claim 1, wherein the obtaining a first current sequence corresponding to the transformer to be tested includes:

obtaining differential currents of all phase lines of the transformer to be tested at the current moment to obtain reference currents corresponding to the phase lines;

and under the condition that any one of the reference currents is larger than or equal to a second threshold value, acquiring the first current sequence corresponding to each phase line of the transformer to be tested.

3. The differential protection method according to claim 2, wherein after obtaining the differential current of each phase line of the transformer to be tested at the present moment, obtaining the reference current corresponding to the phase line, the method comprises:

Performing full-cycle Fourier transform processing on each reference current to obtain amplitude values corresponding to each reference current;

correspondingly, the obtaining the first current sequence corresponding to each phase line of the transformer to be tested when any one of the reference currents is greater than or equal to a second threshold value includes:

4. The differential protection method according to claim 2, wherein said obtaining the first current sequence corresponding to each phase line of the transformer to be tested comprises:

and for each phase line, determining the first current sequence corresponding to the phase line based on a preset sampling frequency and a current waveform of a cycle of the phase line before the current moment.

5. The differential protection method of claim 1, wherein said determining a first sum from all of said differential currents in said first sequence of currents comprises:

determining said first sum from the absolute value of each of said differential currents in said first sequence of currents;

The determining the first partial sum corresponding to the first current sub-sequence according to all the differential currents in each first current sub-sequence includes:

and for each first current sub-sequence, determining the first partial sum corresponding to the first current sub-sequence according to the absolute value of each differential current in the first current sub-sequence.

6. The differential protection method according to claim 5, wherein the first current sequence includes N differential currents, the first current sub-sequence includes M differential currents, M is greater than or equal to 2, and N is greater than M, and before determining the first partial sums corresponding to the first current sub-sequence according to all the differential currents in each first current sub-sequence, the method further includes:

and taking the first current sequences as end-to-end circulation queues, determining each first current subsequence according to M continuous differential currents in the first current sequences which are end-to-end, and obtaining N first current subsequences, wherein the first differential current in the N first current subsequences is the N differential current in the first current sequences.

7. The differential protection method according to any one of claims 1 to 6, characterized by further comprising, before said differential protection of said transformer under test, in the case where said first reference value is greater than a first threshold value:

determining a second current sequence according to the first current sequence, wherein the second current sequence comprises a plurality of differential currents, and the differential currents are obtained by performing differential filtering processing on each differential current in the first current sequence;

determining a second sum from all of the differential currents in the second current sequence;

determining second partial sums corresponding to the second current sub-sequences according to all the differential currents in each second current sub-sequence, wherein any one of the second current sub-sequences comprises a plurality of continuous differential currents in the second current sequence, and different differential currents exist in any two of the second current sub-sequences;

determining a second reference value, the second reference value being the ratio of the second portion having the smallest value and the second sum;

correspondingly, the performing differential protection on the transformer to be tested when the first reference value is greater than a first threshold value includes:

8. A differential protection device, comprising:

9. An electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the method of any one of claims 1 to 7 when the computer program is executed.

10. A computer readable storage medium storing a computer program, characterized in that the computer program when executed by a processor implements the method according to any one of claims 1 to 7.