Transformer protection method and system based on positive sequence differential current energy abrupt change

Abstract

The invention discloses a transformer protection method and system based on positive sequence differential current energy abrupt change. The method comprises the steps of calculating a positive sequence differential current energy value in a single sampling interval of each phase based on positive sequence differential current of each phase on two sides of a transformer; calculating a positive sequence differential flow energy abrupt change value of each phase based on the positive sequence differential flow energy value; summing the sliding windows, and calculating the sum of the positive sequence differential current energy abrupt change values of each phase of the transformer corresponding to each sliding window based on the positive sequence differential current energy abrupt change values corresponding to the sampling points in each sliding window; and for any phase, if the sum of the positive sequence differential flow energy abrupt change values of any phase corresponding to a preset number of continuous sliding windows meets a preset criterion, protection action is performed. According to the method, the protection device does not operate mistakenly, the action speed of transformer protection after a serious fault occurs in the transformer is improved, meanwhile, the fault is isolated, and influence and serious damage to equipment and a system are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of relay protection, and more specifically, to a transformer protection method and system based on positive sequence differential current energy mutation. Background Art

[0002] As one of the key equipment in the UHV power grid, the converter transformer shoulders the important role of voltage and energy conversion in the entire power system. With the continuous increase in the capacity of a single transformer, the failure rate of large transformers has increased year by year. There have been many major accidents caused by internal short-circuit failures of large transformers (converter transformers) at home and abroad, which seriously affect the safe and stable operation of the power system.

[0003] Converter transformers are usually equipped with power protection and non-power protection. For steady-state winding inter-turn insulation damage, the main protections such as converter large difference ratio differential protection, Y / Y ratio differential protection, and Y / D ratio differential protection in power protection can quickly identify steady-state winding inter-turn short-circuit faults. Gas protection in non-power protection can also identify steady-state winding inter-turn short-circuit faults, forming effective protection for the equipment. However, as the voltage level of UHV converter stations connected to the AC power grid becomes higher and higher, the insulation damage between the turns of the converter transformer windings may quickly develop into a multi-turn short circuit after forming an internal short circuit, and the transient short-circuit current increases sharply, showing a rapidly developing fault form. According to the requirements of relevant technical standards, the action time of differential protection should not exceed 30ms, and the differential disconnection action time should not exceed 20ms. However, in recent years, serious faults have occurred, 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 explosion and combustion of the transformer.

[0004] Therefore, a transformer protection method based on positive sequence differential current energy mutation is needed. Summary of the invention

[0005] The present invention proposes a transformer protection method and system based on positive sequence differential current energy mutation to solve the problem of how to protect the transformer efficiently.

[0006] In order to solve the above problem, according to one aspect of the present invention, a transformer protection method based on positive sequence differential current energy mutation is provided, the method comprising:

[0007] Calculate the positive sequence differential current energy value of each phase within a single sampling interval based on the positive sequence differential current of each phase on both sides of the transformer;

[0008] Calculate the positive sequence difference current energy mutation value of each phase based on the positive sequence difference current energy value;

[0009] Perform sliding window summation, and calculate the sum of the positive sequence differential current energy mutation values ​​of each phase of the transformer corresponding to each sliding window based on the positive sequence differential current energy mutation values ​​corresponding to the sampling points in each sliding window;

[0010] For any phase, if there is a continuous preset number of sliding windows corresponding to the sum of the positive sequence differential current energy mutation values ​​of any phase that meets the preset criterion, the protection action is taken.

[0011] Preferably, the method calculates the positive sequence difference flow energy value in the following manner, including:

[0012]

[0013] Among them, W Δta , W Δtb and W Δtc are the positive sequence differential current energy values ​​of phase A, phase B and phase C at any two consecutive sampling points; i hA 、i hB 、i hC are respectively the positive sequence current sampling values ​​of phase A, phase B and phase C on the high voltage side of the transformer; i la 、i lb 、i lc are respectively the positive sequence current sampling values ​​of phase A, phase B and phase C on the low voltage side of the transformer; k is the transformer ratio; X d is the transformer impedance; Δt is the sampling time interval.

[0014] Preferably, the method calculates the positive sequence difference flow energy mutation value in the following manner, including:

[0015] ΔW Δtad =W Δta -W Δ(t-T)a ,

[0016] ΔW Δtbd =W Δtb -W Δ(t-T)b ,

[0017] ΔW Δtcd =W Δtc -W Δ(t-T)c ,

[0018] Where, ΔW Δtad , ΔW Δtbd and ΔW Δtcd are the positive sequence differential current energy mutation values ​​of phase A, phase B and phase C respectively; W Δta , W Δtb and W Δtc are the positive sequence differential current energy values ​​of phase A, phase B and phase C at any two consecutive sampling points; W Δ(t-T)a , W Δ(t-T)b and W Δ(t-T)cThey are the positive sequence differential current energy values ​​of phase A, phase B and phase C at the current sampling point and the sampling point of the previous cycle respectively.

[0019] Preferably, the method calculates the sum of the positive sequence difference flow energy mutation values ​​in the following manner, including:

[0020]

[0021] Among them, ∑ΔW Δtad ,∑ΔW Δtbd and ∑ΔW Δtbd are the sum of the positive sequence differential current energy mutation values ​​of phase A, phase B and phase C respectively; ΔW Δtadj , ΔW Δtbdj and ΔW Δtcdj are the j-th positive sequence differential current energy values ​​of phase A, phase B and phase C in any sliding window respectively; n is the number of sampling points in a sliding window.

[0022] Preferably, for any phase, if there is a continuous preset number of sliding windows corresponding to which the sum of the positive sequence differential current energy mutation values ​​of any phase meets a preset criterion, the protection action includes:

[0023] For any phase, if the sum of the positive sequence differential current energy mutation values ​​of any phase is greater than Then the protection action; where n is the number of sampling points in a sliding window; S is the rated power of the transformer; Δt is the sampling time interval; k1 is the reliability coefficient of the first energy calculation.

[0024] Preferably, the method further comprises:

[0025] Perform sliding window summation, and determine the total positive sequence differential current energy mutation value corresponding to each sliding window based on the sum of the positive sequence differential current energy mutation values ​​of the three phases;

[0026] If there is a total value of the positive sequence differential current energy mutation corresponding to a continuous preset number of sliding windows that is greater than k2nSΔt, the protection will be activated; where n is the number of sampling points in a sliding window; S is the rated power of the transformer; Δt is the sampling time interval; k2 is the second energy calculation reliability coefficient.

[0027] According to another aspect of the present invention, a transformer protection system based on positive sequence differential current energy mutation is provided, the system comprising:

[0028] A positive sequence differential current energy value calculation unit, used for calculating the positive sequence differential current energy value of each phase within a single sampling interval based on the positive sequence differential current of each phase on both sides of the transformer;

[0029] A positive-sequence differential current energy mutation value unit, used for calculating the positive-sequence differential current energy mutation value of each phase based on the positive-sequence differential current energy value;

[0030] A positive-sequence differential current energy mutation value sum calculation unit is used to perform sliding window summation, and calculate the sum of the positive-sequence differential current energy mutation values ​​of each phase of the transformer corresponding to each sliding window based on the positive-sequence differential current energy mutation values ​​corresponding to the sampling points in each sliding window;

[0031] The protection unit is used to take protection action for any phase if the sum of the positive sequence differential current energy mutation values ​​of any phase corresponding to a continuous preset number of sliding windows satisfies a preset criterion.

[0032] Preferably, the positive sequence difference flow energy value calculation unit calculates the positive sequence difference flow energy value in the following manner, including:

[0033]

[0034] Among them, W Δta , W Δtb and W Δtc are the positive sequence differential current energy values ​​of phase A, phase B and phase C at any two consecutive sampling points; i hA 、i hB 、i hC are respectively the positive sequence current sampling values ​​of phase A, phase B and phase C on the high voltage side of the transformer; i la 、i lb 、i lc are respectively the positive sequence current sampling values ​​of phase A, phase B and phase C on the low voltage side of the transformer; k is the transformer ratio; X d is the transformer impedance; Δt is the sampling time interval.

[0035] Preferably, the positive-sequence difference flow energy mutation value unit calculates the positive-sequence difference flow energy mutation value in the following manner, including:

[0036] ΔW Δtad =W Δta -W Δ(t-T)a ,

[0037] ΔW Δtbd =W Δtb -W Δ(t-T)b ,

[0038] ΔW Δtcd =W Δtc -W Δ(t-T)c ,

[0039] Where, ΔW Δtad , ΔW Δtbd and ΔW Δtcd are the positive sequence differential current energy mutation values ​​of phase A, phase B and phase C respectively; W Δta , W Δtb and W Δtcare the positive sequence differential current energy values ​​of phase A, phase B and phase C at any two consecutive sampling points; W Δ(t-T)a , W Δ(t-T)b and W Δ(t-T)c They are the positive sequence differential current energy values ​​of phase A, phase B and phase C at the current sampling point and the sampling point of the previous cycle respectively.

[0040] Preferably, the positive-sequence difference flow energy mutation value sum calculation unit calculates the positive-sequence difference flow energy mutation value sum in the following manner, including:

[0041]

[0042] Among them, ∑ΔW Δtad ,∑ΔW Δtbd and ∑ΔW Δtbd are the sum of the positive sequence differential current energy mutation values ​​of phase A, phase B and phase C respectively; ΔW Δtadj , ΔW Δtbdj and ΔW Δtcdj are the j-th positive sequence differential current energy values ​​of phase A, phase B and phase C in any sliding window respectively; n is the number of sampling points in a sliding window.

[0043] Preferably, the protection unit, for any phase, if there is a continuous preset number of sliding windows corresponding to the sum of the positive sequence differential current energy mutation values ​​of any phase that meets the preset criterion, the protection action includes:

[0044] For any phase, if the sum of the positive sequence differential current energy mutation values ​​of any phase is greater than Then the protection action; where n is the number of sampling points in a sliding window; S is the rated power of the transformer; Δt is the sampling time interval; k1 is the reliability coefficient of the first energy calculation.

[0045] Preferably, the system further comprises:

[0046] A positive-sequence differential current energy mutation total value calculation unit is used to perform sliding window summation, and determine the positive-sequence differential current energy mutation total value corresponding to each sliding window based on the sum of the positive-sequence differential current energy mutation values ​​of the three phases;

[0047] A protection unit is used to take protective action if the total value of the positive sequence differential current energy mutation corresponding to a continuous preset number of sliding windows is greater than k2nSΔt; wherein n is the number of sampling points in a sliding window; S is the rated power of the transformer; Δt is the sampling time interval; and k2 is the second energy calculation reliability coefficient.

[0048] Based on another aspect of the present invention, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any step of a transformer protection method based on positive-sequence differential current energy mutation.

[0049] According to another aspect of the present invention, the present invention provides an electronic device, including:

[0050] The computer-readable storage medium described above; and

[0051] One or more processors are used to execute the program in the computer-readable storage medium.

[0052] The present invention provides a transformer protection method and system based on positive sequence differential current energy mutation, including: calculating the positive sequence differential current energy value within a single sampling interval of each phase based on the positive sequence differential current of each phase on both sides of the transformer; calculating the positive sequence differential current energy mutation value of each phase based on the positive sequence differential current energy value; performing sliding window summation, calculating the sum of the positive sequence differential current energy mutation values ​​of each phase of the transformer corresponding to each sliding window based on the positive sequence differential current energy mutation value corresponding to the sampling point in each sliding window; for any phase, if there is a continuous preset number of sliding windows corresponding to the sum of the positive sequence differential current energy mutation values ​​of any phase that meet the preset criterion, then the protection action. The method of the present invention can prevent the protection device from malfunctioning, improve the action speed of the transformer protection after a serious fault occurs inside the transformer, and isolate the fault at the same time to avoid affecting and seriously damaging the equipment and system. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0054] Figure 1 Flow chart of a transformer protection method 100 based on positive sequence differential current energy mutation according to an embodiment of the present invention;

[0055] Figure 2 A schematic diagram of energy mutation waveform and action status when a fault occurs within a zone according to an embodiment of the present invention;

[0056] Figure 3 A schematic diagram of energy mutation waveform and action status during an out-of-zone fault according to an embodiment of the present invention;

[0057] Figure 4 A schematic diagram of energy mutation waveform and action status when a fault occurs within a zone according to an embodiment of the present invention;

[0058] Figure 5 Schematic diagram of the structure of a transformer protection system 500 based on positive sequence differential current energy mutation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0059] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0060] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0061] The present invention provides a transformer protection method based on positive sequence differential current energy mutation, aiming to utilize the mutation of positive sequence differential current energy after a serious fault occurs inside the transformer to form a rapid protection.

[0062] Figure 1 FIG. 1 is a flow chart of a transformer protection method 100 based on positive sequence differential current energy mutation according to an embodiment of the present invention. Figure 1 As shown, the transformer protection method based on positive sequence differential current energy mutation provided by the embodiment of the present invention can prevent the protection device from malfunctioning, improve the action speed of the transformer protection after a serious fault occurs inside the transformer, and isolate the fault at the same time to avoid affecting and causing serious damage to the equipment and system. The transformer protection method 100 based on positive sequence differential current energy mutation provided by the embodiment of the present invention starts from step 101. In step 101, the positive sequence differential current energy value within a single sampling interval of each phase is calculated based on the positive sequence differential current of each phase on both sides of the transformer.

[0063] Preferably, the method calculates the positive sequence difference flow energy value in the following manner, including:

[0064]

[0065] Among them, W Δta , W Δtb and W Δtc are the positive sequence differential current energy values ​​of phase A, phase B and phase C at any two consecutive sampling points; i hA 、i hB 、i hC are respectively the positive sequence current sampling values ​​of phase A, phase B and phase C on the high voltage side of the transformer; i la 、i lb 、i lc are respectively the positive sequence current sampling values ​​of phase A, phase B and phase C on the low voltage side of the transformer; k is the transformer ratio; Xd is the transformer impedance; Δt is the sampling time interval.

[0066] According to the law of energy conservation, the energy flowing into the high-voltage side of the transformer is equal to the energy output from the low-voltage side. Therefore, the present invention uses the product of the positive sequence differential current of each phase on both sides of the transformer and the inductive reactance (ignoring the resistance) and the time interval to obtain the electric energy of the positive sequence differential current of each phase. The positive sequence differential current energy value of the three-phase transformer in a single sampling interval can be expressed as:

[0067]

[0068] Among them, i hA 、i hB 、i hC are respectively the positive sequence current sampling values ​​of the transformer high voltage side, i la 、i lb 、i lc are respectively the positive sequence current sampling values ​​of the transformer low voltage side, k is the transformer ratio, X d is the transformer impedance, and Δt represents the sampling interval time.

[0069] At this time, the sum of the three-phase positive sequence differential current energy values ​​is:

[0070] W Δt =[(i hA +ki la ) 2 +(i hB +ki lb ) 2 +(i hC +ki lc ) 2 ]X d Δt(2)

[0071] Using the energy per unit sampling time, the above formula (2) can be rewritten as formula (3):

[0072]

[0073] In step 102, a positive sequence difference current energy mutation value of each phase is calculated based on the positive sequence difference current energy value.

[0074] Preferably, the method calculates the positive sequence difference flow energy mutation value in the following manner, including:

[0075] ΔW Δtad =W Δta -W Δ(t-T)a ,

[0076] ΔW Δtbd =W Δtb -W Δ(t-T)b ,

[0077] ΔW Δtcd =W Δtc -W Δ(t-T)c ,

[0078] Where, ΔW Δtad , ΔW Δtbd and ΔW Δtcd are the positive sequence differential current energy mutation values ​​of phase A, phase B and phase C respectively; W Δta , W Δtb and W Δtc are the positive sequence differential current energy values ​​of phase A, phase B and phase C at any two consecutive sampling points; W Δ(t-T)a , W Δ(t-T)b and W Δ(t-T)c They are the positive sequence differential current energy values ​​of phase A, phase B and phase C at the current sampling point and the sampling point of the previous cycle respectively.

[0079] In step 103, sliding window summation is performed, and the sum of the positive sequence differential current energy mutation values ​​of each phase of the transformer corresponding to each sliding window is calculated based on the positive sequence differential current energy mutation values ​​corresponding to the sampling points in each sliding window.

[0080] Preferably, the method calculates the sum of the positive sequence difference flow energy mutation values ​​in the following manner, including:

[0081]

[0082] Where ΣΔW Δtad ,∑ΔW Δtbd and ΣΔW Δtbd are the sum of the positive sequence differential current energy mutation values ​​of phase A, phase B and phase C respectively; ΔW Δtadj , ΔW Δtbdj and ΔW Δtcdj are the j-th positive sequence differential current energy values ​​of phase A, phase B and phase C in any sliding window respectively; n is the number of sampling points in a sliding window.

[0083] In step 104, for any phase, if there is a continuous preset number of sliding windows corresponding to the sum of the positive sequence differential current energy mutation values ​​of any phase that meet the preset criterion, the protection action is taken.

[0084] Preferably, for any phase, if there is a continuous preset number of sliding windows corresponding to which the sum of the positive sequence differential current energy mutation values ​​of any phase meets a preset criterion, the protection action includes:

[0085] For any phase, if the sum of the positive sequence differential current energy mutation values ​​of any phase is greater than Then the protection action; where n is the number of sampling points in a sliding window; S is the rated power of the transformer; Δt is the sampling time interval; k1 is the reliability coefficient of the first energy calculation.

[0086] In the present invention, the positive sequence differential current energy mutation value of each phase is calculated according to the positive sequence differential current energy value.

[0087] Specifically, the calculation method of the positive sequence difference flow energy mutation value within a single sampling interval can be expressed as:

[0088] ΔW Δtad =W Δta -W Δ(t-T)a (4)

[0089] ΔW Δtbd =W Δtb -W Δ(t-T)b (5)

[0090] ΔW Δtcd =W Δtc -W Δ(t-T)c (6)

[0091] Wherein, equations (4)-(6) represent the positive sequence differential current energy mutation value of phases A, B, and C in a single sampling interval respectively; ΔW Δtd represents the sudden change value of the total energy of the three-phase positive sequence differential current; where T represents one cycle. Similarly, using the energy per unit sampling time, (4)-(6) can be rewritten as:

[0092]

[0093] Finally, according to the characteristics of sudden energy changes after a fault, protection is performed according to the following protection action criteria. The protection criteria include:

[0094]

[0095] Where: n is the number of sampling points of the positive sequence differential current; S is the rated power of the transformer, Δt is the sampling time interval; k1 is the reliability coefficient of the first energy calculation, and k1 can be 2 to 3. When there are three consecutive points in any phase that satisfy formula (10), the protection will act quickly. Among them, the number of consecutive points can be 10 points.

[0096] Preferably, the method further comprises:

[0097] Perform sliding window summation, and determine the total positive sequence differential current energy mutation value corresponding to each sliding window based on the sum of the positive sequence differential current energy mutation values ​​of the three phases;

[0098] If there is a total value of the positive sequence differential current energy mutation corresponding to a continuous preset number of sliding windows that is greater than k2nSΔt, the protection will be activated; where n is the number of sampling points in a sliding window; S is the rated power of the transformer; Δt is the sampling time interval; k2 is the second energy calculation reliability coefficient.

[0099] In addition, in the present invention, a criterion can be constructed according to the total value of the sudden change of the positive sequence differential current energy of the three phases, and protection can be performed according to the criterion.

[0100] The total value of the positive sequence difference current energy mutation is calculated using the following method, including: ΔW Δtd =W Δt -W Δ(t-T) , and then determine whether there are 3 consecutive sliding windows that satisfy ∑ΔW Δtd >k2nSΔt, if satisfied, the protection will act quickly. Among them, ∑ΔW Δtd is the total value of the positive sequence differential flow energy mutation, and k2 is the reliability coefficient of the second energy calculation.

[0101] The method of the present invention can realize rapid protection action in the case of severe fault inside the transformer (differential current is greater than the differential speed setting value), and the action time is less than 5ms (excluding the action time of the device outlet relay). In the case of severe fault outside the zone causing CT saturation, the device will not malfunction. In any other fault or disturbance outside the zone, the protection device will not malfunction.

[0102] In the present invention, the staff used RTDS to carry out simulation verification of serious faults in the area, and a 94% turn-to-turn short-circuit fault occurred in the A phase of the star-delta connection transformer grid side. The 0.646s time is the start time of the fault. Figure 2 It is the sudden change value of the positive sequence differential current energy of each phase after the fault. It can be seen that the sudden change value of the positive sequence differential current energy of the fault phase changes rapidly after the fault. At the same time, the protection meets the action requirements within 3ms after the fault, and the action signal changes from low level to high level, and the protection acts correctly.

[0103] When an out-of-area fault occurs on the transformer grid side of the star-delta connection, Figure 3 It is the sudden change value of the positive sequence differential current energy of each phase after the fault. It can be seen that the sudden change value of the positive sequence differential current energy of the faulty phase has almost no change after the fault, and the protection does not operate.

[0104] Using RTDS to carry out simulation verification of severe faults in the area, a 5% turn-to-turn short circuit fault occurred on the A phase of the YY converter transformer valve side. The 0.648s time is the start time of the fault. Figure 4 It is the sudden change value of the positive sequence differential current energy of each phase after the fault. It can be seen that the sudden change value of the positive sequence differential current energy of the fault phase changes rapidly after the fault. It can be seen that the protection meets the action requirements within 3ms after the fault, the action signal changes from low level to high level, and the protection acts correctly.

[0105] Figure 5 FIG. 5 is a schematic diagram of a transformer protection system 500 based on positive sequence differential current energy mutation according to an embodiment of the present invention. Figure 5As shown, the transformer protection system 500 based on positive-sequence differential current energy mutation provided in an embodiment of the present invention includes: a positive-sequence differential current energy value calculation unit 501, a positive-sequence differential current energy mutation value unit 502, a positive-sequence differential current energy mutation value sum calculation unit 503 and a protection unit 504.

[0106] Preferably, the positive-sequence differential current energy value calculation unit 501 is used to calculate the positive-sequence differential current energy value of each phase within a single sampling interval based on the positive-sequence differential current of each phase on both sides of the transformer.

[0107] Preferably, the positive sequence difference flow energy value calculation unit 501 calculates the positive sequence difference flow energy value in the following manner, including:

[0108]

[0109] Among them, W Δta , W Δtb and W Δtc are the positive sequence differential current energy values ​​of phase A, phase B and phase C at any two consecutive sampling points; i hA 、i hB 、i hC are respectively the positive sequence current sampling values ​​of phase A, phase B and phase C on the high voltage side of the transformer; i la 、i lb 、i lc are respectively the positive sequence current sampling values ​​of phase A, phase B and phase C on the low voltage side of the transformer; k is the transformer ratio; X d is the transformer impedance; Δt is the sampling time interval.

[0110] Preferably, the positive-sequence differential current energy mutation value unit 502 is used to calculate the positive-sequence differential current energy mutation value of each phase based on the positive-sequence differential current energy value.

[0111] Preferably, the positive-sequence difference flow energy mutation value unit 502 calculates the positive-sequence difference flow energy mutation value in the following manner, including:

[0112] ΔW Δtad =W Δta -W Δ(t-T)a ,

[0113] ΔW Δtbd =W Δtb -W Δ(t-T)b ,

[0114] ΔW Δtcd =W Δtc -W Δ(t-T)c ,

[0115] Where, ΔW Δtad , ΔW Δtbd and ΔWΔtcd are the positive sequence differential current energy mutation values ​​of phase A, phase B and phase C respectively; W Δta , W Δtb and W Δtc are the positive sequence differential current energy values ​​of phase A, phase B and phase C at any two consecutive sampling points; W Δ(t-T)a , W Δ(t-T)b and W Δ(t-T)c They are the positive sequence differential current energy values ​​of phase A, phase B and phase C at the current sampling point and the sampling point of the previous cycle respectively.

[0116] Preferably, the positive-sequence differential current energy mutation value sum calculation unit 503 is used to perform sliding window summation, and calculate the sum of the positive-sequence differential current energy mutation values ​​of each phase of the transformer corresponding to each sliding window based on the positive-sequence differential current energy mutation values ​​corresponding to the sampling points in each sliding window.

[0117] Preferably, the positive-sequence difference flow energy mutation value sum calculation unit 503 calculates the positive-sequence difference flow energy mutation value sum in the following manner, including:

[0118]

[0119] Among them, ∑ΔW Δtad ,∑ΔW Δtbd and ∑ΔW Δtbd are the sum of the positive sequence differential current energy mutation values ​​of phase A, phase B and phase C respectively; ΔW Δtadj , ΔW Δtbdj and ΔW Δtcdj are the j-th positive sequence differential current energy values ​​of phase A, phase B and phase C in any sliding window respectively; n is the number of sampling points in a sliding window.

[0120] Preferably, the protection unit 504 is used for performing protection action for any phase if the sum of the positive sequence differential current energy mutation values ​​of any phase corresponding to a continuous preset number of sliding windows satisfies a preset criterion.

[0121] Preferably, the protection unit 504, for any phase, if there is a continuous preset number of sliding windows corresponding to the sum of the positive sequence differential current energy mutation values ​​of any phase that meets the preset criterion, the protection action includes:

[0122] For any phase, if the sum of the positive sequence differential current energy mutation values ​​of any phase is greater than Then the protection action; where n is the number of sampling points in a sliding window; S is the rated power of the transformer; Δt is the sampling time interval; k1 is the reliability coefficient of the first energy calculation.

[0123] Preferably, the system further comprises:

[0124] A positive-sequence differential current energy mutation total value calculation unit is used to perform sliding window summation, and determine the positive-sequence differential current energy mutation total value corresponding to each sliding window based on the sum of the positive-sequence differential current energy mutation values ​​of the three phases;

[0125] A protection unit is used to take protective action if the total value of the positive sequence differential current energy mutation corresponding to a continuous preset number of sliding windows is greater than k2nSΔt; wherein n is the number of sampling points in a sliding window; S is the rated power of the transformer; Δt is the sampling time interval; and k2 is the second energy calculation reliability coefficient.

[0126] The transformer protection system 500 based on positive-sequence differential current energy mutation of the embodiment of the present invention corresponds to the transformer protection method 100 based on positive-sequence differential current energy mutation of another embodiment of the present invention, which will not be described in detail here.

[0127] Based on another aspect of the present invention, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any step of a transformer protection method based on positive-sequence differential current energy mutation.

[0128] According to another aspect of the present invention, the present invention provides an electronic device, including:

[0129] The computer-readable storage medium described above; and

[0130] One or more processors are used to execute the program in the computer-readable storage medium.

[0131] The invention has been described above with reference to a few embodiments. However, it is readily apparent to a person skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

[0132] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise therein. All references to "a / said / the [means, components, etc.]" are to be openly interpreted as at least one instance of said means, components, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily have to be performed in the exact order disclosed, unless explicitly stated otherwise.

[0133] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0134] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0135] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0136] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A transformer protection method based on positive sequence differential current energy mutation, characterized in that: The method comprises: Calculate the positive sequence differential current energy value of each phase within a single sampling interval based on the positive sequence differential current of each phase on both sides of the transformer; Calculate the positive sequence difference current energy mutation value of each phase based on the positive sequence difference current energy value; Perform sliding window summation, and calculate the sum of the positive sequence differential current energy mutation values ​​of each phase of the transformer corresponding to each sliding window based on the positive sequence differential current energy mutation values ​​corresponding to the sampling points in each sliding window; For any phase, if there is a continuous preset number of sliding windows corresponding to the sum of the positive sequence differential current energy mutation values ​​of any phase that meets the preset criterion, the protection action is taken.

2. The method according to claim 1, characterized in that: The method calculates the positive sequence difference flow energy value in the following manner, including: W Δta =(i hA + key la ) 2 X d Δt W Δtb =(i hB + key lb ) 2 X d Δt, W Δtc =(i hC + key lc ) 2 X d Δt Among them, W Δta , W Δtb and W Δtc are the positive sequence differential current energy values ​​of phase A, phase B and phase C at any two consecutive sampling points; i hA 、i hB 、i hC are respectively the positive sequence current sampling values ​​of phase A, phase B and phase C on the high voltage side of the transformer; i la 、i lb 、i lc are respectively the positive sequence current sampling values ​​of phase A, phase B and phase C on the low voltage side of the transformer; k is the transformer ratio; X d is the transformer impedance; Δt is the sampling time interval.

3. The method according to claim 1, characterized in that The method calculates the positive sequence difference flow energy mutation value in the following manner, including: ΔW Δtad =In Δta -IN Δ(t-T)a , ΔW Δtbd =In Δtb -IN Δ(t-T)b , ΔW Δtcd =In Δtc -IN Δ(t-T)c , Where, ΔW Δtad , ΔW Δtbd and ΔW Δtcd are the positive sequence differential current energy mutation values ​​of phase A, phase B and phase C respectively; W Δta , W Δtb and W Δtc are the positive sequence differential current energy values ​​of phase A, phase B and phase C at any two consecutive sampling points; W Δ(t-T)a , W Δ(t-T)b and W Δ(t-T)c They are the positive sequence differential current energy values ​​of phase A, phase B and phase C at the current sampling point and the sampling point of the previous cycle respectively.

4. The method according to claim 1, characterized in that: The method calculates the sum of the positive sequence difference flow energy mutation values ​​in the following manner, including: Among them, ∑ΔW Δtad ,∑ΔW Δtbd and ∑ΔW Δtbd are the sum of the positive sequence differential current energy mutation values ​​of phase A, phase B and phase C respectively; ΔW Δtadj , ΔW Δtbdj and ΔW Δtcdj are the j-th positive sequence differential current energy values ​​of phase A, phase B and phase C in any sliding window respectively; n is the number of sampling points in a sliding window.

5. The method according to claim 1, characterized in that For any phase, if there is a continuous preset number of sliding windows corresponding to the sum of the positive sequence differential current energy mutation values ​​of any phase that meets the preset criterion, the protection action includes: For any phase, if the sum of the positive sequence differential current energy mutation values ​​of any phase is greater than Then the protection action; where n is the number of sampling points in a sliding window; S is the rated power of the transformer; Δt is the sampling time interval; k1 is the reliability coefficient of the first energy calculation.

6. The method according to claim 1, characterized in that The method further comprises: Perform sliding window summation, and determine the total positive sequence differential current energy mutation value corresponding to each sliding window based on the sum of the positive sequence differential current energy mutation values ​​of the three phases; If there is a total value of the positive sequence differential current energy mutation corresponding to a continuous preset number of sliding windows that is greater than k2nSΔt, the protection will be activated; where n is the number of sampling points in a sliding window; S is the rated power of the transformer; Δt is the sampling time interval; k2 is the second energy calculation reliability coefficient.

7. A transformer protection system based on positive sequence differential current energy mutation, characterized in that: The system comprises: A positive sequence differential current energy value calculation unit, used for calculating the positive sequence differential current energy value of each phase within a single sampling interval based on the positive sequence differential current of each phase on both sides of the transformer; A positive-sequence differential current energy mutation value unit, used for calculating the positive-sequence differential current energy mutation value of each phase based on the positive-sequence differential current energy value; A positive-sequence differential current energy mutation value sum calculation unit is used to perform sliding window summation, and calculate the sum of the positive-sequence differential current energy mutation values ​​of each phase of the transformer corresponding to each sliding window based on the positive-sequence differential current energy mutation values ​​corresponding to the sampling points in each sliding window; The protection unit is used to take protection action for any phase if the sum of the positive sequence differential current energy mutation values ​​of any phase corresponding to a continuous preset number of sliding windows satisfies a preset criterion.

8. The system according to claim 7, characterized in that The positive sequence difference flow energy value calculation unit calculates the positive sequence difference flow energy value in the following manner, including: W Δta =(i hA + key la ) 2 X d Δt W Δtb =(i hB + key lb ) 2 X d Δt, W Δtc =(i hC + key lc ) 2 X d Δt Among them, W Δta , W Δtb and W Δtc are the positive sequence differential current energy values ​​of phase A, phase B and phase C at any two consecutive sampling points; i hA 、i hB 、i hC are respectively the positive sequence current sampling values ​​of phase A, phase B and phase C on the high voltage side of the transformer; i la 、i lb 、i lc are respectively the positive sequence current sampling values ​​of phase A, phase B and phase C on the low voltage side of the transformer; k is the transformer ratio; X d is the transformer impedance; Δt is the sampling time interval.

9. The system according to claim 7, characterized in that The positive-sequence difference current energy mutation value unit calculates the positive-sequence difference current energy mutation value in the following manner, including: ΔW Δtad =In Δta -IN Δ(t-T)a , ΔW Δtbd =In Δtb -IN Δ(t-T)b , ΔW Δtcd =In Δtc -IN Δ(t-T)c , Where, ΔW Δtad , ΔW Δtbd and ΔW Δtcd are the positive sequence differential current energy mutation values ​​of phase A, phase B and phase C respectively; W Δta , W Δtb and W Δtc are the positive sequence differential current energy values ​​of phase A, phase B and phase C at any two consecutive sampling points; W Δ(t-T)a , W Δ(t-T)b and W Δ(t-T)c They are the positive sequence differential current energy values ​​of phase A, phase B and phase C at the current sampling point and the sampling point of the previous cycle respectively.

10. The system according to claim 7, characterized in that The positive sequence difference current energy mutation value sum calculation unit calculates the positive sequence difference current energy mutation value sum in the following manner, including: That Where ΣΔW Δtad ,ΣΔW Δtbd and ΣΔW Δtbd are the sum of the positive sequence differential current energy mutation values ​​of phase A, phase B and phase C respectively; ΔW Δtadj , ΔW Δtbdj and ΔW Δtcdj are the j-th positive sequence differential current energy values ​​of phase A, phase B and phase C in any sliding window respectively; n is the number of sampling points in a sliding window.

11. The system according to claim 7, characterized in that The protection unit, for any phase, if there is a continuous preset number of sliding windows corresponding to the sum of the positive sequence differential current energy mutation values ​​of any phase that meet the preset criterion, the protection action includes: For any phase, if the sum of the positive sequence differential current energy mutation values ​​of any phase is greater than Then the protection action; where n is the number of sampling points in a sliding window; S is the rated power of the transformer; Δt is the sampling time interval; k1 is the reliability coefficient of the first energy calculation.

12. The system according to claim 7, characterized in that The system further comprises: A positive-sequence difference current energy mutation total value calculation unit is used to perform sliding window summation, and determine the positive-sequence difference current energy mutation total value corresponding to each sliding window based on the sum of the positive-sequence difference current energy mutation values ​​of the three phases; A protection unit is used to take protective action if the total value of the positive sequence differential current energy mutation corresponding to a continuous preset number of sliding windows is greater than k2nSΔt; wherein n is the number of sampling points in a sliding window; S is the rated power of the transformer; Δt is the sampling time interval; and k2 is the second energy calculation reliability coefficient.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

14. An electronic device, characterized in that: include: The computer readable storage medium as claimed in claim 13; as well as One or more processors are used to execute the program in the computer-readable storage medium.

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