Intelligent diagnosis method and system for transformer fault

Abstract

The invention discloses a transformer fault intelligent diagnosis method and system, and the method comprises the steps: reading a longitudinal differential protection action switching value from transformer fault recording, according to the fault recording information, calculating rated current of each side of the transformer, longitudinal three-phase differential current amplitude, voltage and current amplitude of each side and zero-sequence voltage and zero-sequence current amplitude of each side; and combining different criteria to intelligently identify fault types such as a non-internal fault, a three-phase symmetric fault, a single-phase earth fault, a two-phase earth fault, a two-phase interphase short circuit and an interturn fault of the transformer, and fault sides and fault phases. According to the invention, the fault type and the fault position of the transformer can be rapidly and automatically positioned, manual fault analysis is assisted or replaced, and an intelligent automatic solution is provided for accident handling of the transformer fault in an engineering field.

Description

Technical Field

[0001] The invention belongs to the technical field of transformer equipment fault diagnosis, and in particular relates to an intelligent transformer fault diagnosis method and system. Background Art

[0002] At present, the accident analysis after the transformer failure in the power system, including the fault type and fault location, is mainly completed through manual offline analysis, which is far from the current development theme of power system automation and intelligence. Moreover, manual analysis of transformer failures completely relies on the professional skills and psychological quality of relay protection professionals, which is labor-intensive, inefficient, and prone to errors, making it impossible to carry out transformer maintenance in a timely manner, affecting power production and power supply reliability.

[0003] It is clear that most of the research on intelligent diagnosis of power system transformers requires fault location based on non-electrical quantity information such as oil, gas, vibration, etc. from the transformer itself, which cannot meet the requirements of power system relay protection professionals at the project site to quickly locate faults based on electrical quantities. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present invention provides an intelligent diagnosis method and system for transformer faults, which can intelligently identify the type and location of transformer faults by automatically acquiring fault recording information.

[0005] The present invention adopts the following technical solution.

[0006] A first aspect of the present invention provides an intelligent diagnosis method for transformer faults, comprising:

[0007] S1: Read the longitudinal differential protection action switch quantity from the transformer fault recording, and calculate the rated current of each side of the transformer, the longitudinal three-phase differential current amplitude, the voltage and current amplitude of each side, and the zero-sequence voltage and zero-sequence current amplitude of each side according to the fault recording information;

[0008] S2: Determine whether the longitudinal differential protection of the transformer is actuated according to the longitudinal differential protection action switch value. If so, enter S3; otherwise, diagnose the transformer out-of-zone fault;

[0009] S3: Compare the amplitudes of the three-phase differential currents. If the amplitude of the differential current of a certain phase is greater than twice the amplitude of the maximum differential current of the other two phases, proceed to S4; otherwise, proceed to S7;

[0010] S4: Determine whether the zero-sequence voltage and zero-sequence current amplitudes on the Y side of the transformer are both greater than their respective set values ​​set1 and set2, where set1 and set2 are set according to the rated values ​​on the Y side. If so, enter S5; otherwise, enter S6;

[0011] S5: Determine whether the current amplitudes on the Y side and the common winding side of the transformer meet the single-phase grounding fault criterion on the Y side. If so, diagnose a single-phase grounding fault on the Y side, and the fault phase is the phase with the largest differential current. Otherwise, diagnose a turn-to-turn short circuit fault on the Y side, and the fault phase is the phase with the largest differential current.

[0012] S6: Determine whether the voltage amplitude on the △ side of the transformer meets the criterion for the △ side phase-to-phase short circuit fault. If so, diagnose the △ side phase-to-phase short circuit fault and its faulty phase; otherwise, diagnose the △ side turn-to-turn short circuit fault and its faulty phase;

[0013] S7: Determine whether the amplitude of the longitudinal three-phase differential current meets the three-phase symmetric fault criterion. If so, diagnose a three-phase symmetric fault, otherwise enter S8;

[0014] S8: Determine whether the voltage amplitude on the Y side of the transformer meets the two-phase grounding fault criterion on the Y side. If so, diagnose the two-phase grounding fault on the Y side and its faulty phase; otherwise, diagnose the two-phase interphase short circuit fault on the Y side and its faulty phase.

[0015] Preferably, in S4, if the following equation is satisfied, then proceed to S5; otherwise, proceed to S6:

[0016]

[0017] Where: is the zero-sequence voltage amplitude on the Y side of the transformer;

[0018] is the zero-sequence current amplitude on the Y side of the transformer;

[0019] The Y side is divided into high-voltage side and medium-voltage side;

[0020] They are the voltage vectors of phases A, B and C on the Y side of the transformer respectively;

[0021] They are the A, B, and C phase current vectors on the Y side of the transformer respectively;

[0022] U YN is the PT rating of the transformer Y side;

[0023] I YN is the CT rating of the Y-side winding of the transformer;

[0024] I Ye is the rated current of the transformer Y side;

[0025] k1 is the zero-sequence overvoltage coefficient;

[0026] k2 is the zero-sequence overcurrent coefficient.

[0027] Preferably, in S5, the single-phase grounding fault criterion on the Y side is:

[0028]

[0029] In the formula, is the current amplitude on the Y side and the common winding side of the transformer;

[0030] Take A, B or C, which means A, B or C respectively;

[0031] Respectively represent the high voltage side, medium voltage side and common winding side of the transformer Phase current vector;

[0032] Set g Indicates the set deviation allowable value, which is set to 0.1Ie, where Ie is the rated current of the transformer;

[0033] If any phase satisfies the above formula, it means that the input and output currents of all Y sides and common winding sides of the phase are not equal, and it is judged that a ground fault occurs in the phase.

[0034] Preferably, in S6, the criterion for the phase-to-phase short circuit fault on the △ side is:

[0035] There are two-phase voltage amplitude drops on the △ side of the transformer and they are in the same phase.

[0036] Preferably, in S6, the faulty phases of the △-side phase-to-phase short circuit fault are two phases whose voltage amplitude drops;

[0037] The fault phase of the △ side turn-to-turn short-circuit fault is the phase with the largest voltage amplitude drop.

[0038] Preferably, in S7, the three-phase symmetry fault criterion is:

[0039] The longitudinal three-phase differential current amplitude deviation is less than 30%.

[0040] Preferably, in S8, the Y-side two-phase grounding fault criterion is:

[0041] The two-phase voltage amplitude on the Y side of the transformer is less than 0.04Un or the zero-sequence current amplitude is greater than the set value set2, where Un is the rated voltage on the Y side of the transformer.

[0042] Preferably, in S8, the faulty phases of the two-phase grounding fault on the Y side are two phases whose voltage is less than 0.04Un;

[0043] The faulty phases of the two-phase short-circuit fault on the Y side are the two phases with the largest differential current.

[0044] A second aspect of the present invention provides an intelligent diagnosis system for transformer faults, comprising:

[0045] A calculation module is used to read the longitudinal differential protection action switch quantity from the transformer fault recording, and calculate the rated current of each side of the transformer, the longitudinal differential three-phase differential current amplitude, the voltage and current amplitude of each side, and the zero-sequence voltage and zero-sequence current amplitude of each side according to the fault recording information;

[0046] The action discrimination module is used to judge whether the longitudinal differential protection of the transformer is actuated according to the action switch quantity of the longitudinal differential protection. If it is actuated, it enters the three-phase differential current comparison module, otherwise it diagnoses the transformer out-of-zone fault;

[0047] The three-phase differential current comparison module is used to compare the magnitude of the longitudinal differential current amplitudes of the three-phase differential currents. If the differential current amplitude of a phase is greater than twice the maximum differential current amplitude of the other two phases, the zero-sequence component comparison module is performed; otherwise, the three-phase symmetric fault judgment module is entered;

[0048] The zero-sequence component comparison module is used to determine whether the zero-sequence voltage and zero-sequence current amplitudes on the Y side of the transformer are both greater than their respective set values. If so, it enters the Y-side fault judgment module; otherwise, it enters the △-side fault judgment module;

[0049] The Y-side fault determination module determines whether the current amplitudes on the Y-side and common winding side of the transformer meet the Y-side single-phase grounding fault determination criteria. If so, a Y-side single-phase grounding fault is diagnosed, and the fault phase is the phase with the largest differential current. Otherwise, a Y-side turn-to-turn short circuit fault is diagnosed, and the fault phase is the phase with the largest differential current.

[0050] The △ side fault identification module is used to determine whether the voltage amplitude on the △ side of the transformer meets the △ side phase-to-phase short circuit fault criterion. If so, the △ side phase-to-phase short circuit fault and its faulty phase are diagnosed; otherwise, the △ side turn-to-turn short circuit fault and its faulty phase are diagnosed;

[0051] The three-phase symmetry fault judgment module is used to judge whether the amplitude of the longitudinal three-phase differential current meets the three-phase symmetry fault judgment criterion. If so, a three-phase symmetry fault is diagnosed, otherwise it enters the Y-side two-phase fault judgment module;

[0052] The Y-side two-phase fault discrimination module is used to determine whether the voltage amplitude on the Y-side of the transformer meets the Y-side two-phase grounding fault judgment criterion. If so, the Y-side two-phase grounding fault and its faulty phase are diagnosed; otherwise, the Y-side two-phase interphase short circuit fault and its faulty phase are diagnosed.

[0053] A third aspect of the present invention provides a terminal, comprising a processor and a storage medium; the storage medium is used to store instructions; the processor is used to operate according to the instructions to execute the steps of the method.

[0054] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the method when executed by a processor.

[0055] Compared with the prior art, the beneficial effects of the present invention include at least:

[0056] The present invention automatically obtains the fault recording information recorded after the transformer protection device is actuated, and intelligently identifies the fault type and fault location of the transformer according to the electrical quantity information such as voltage and current on each side of the transformer in the fault recording information and in combination with different criteria; the transformer fault type includes non-zone fault, three-phase symmetric fault, single-phase grounding fault, two-phase grounding fault, two-phase phase-to-phase short circuit, turn-to-turn fault, etc.; the transformer fault location includes the side where the fault is located and the fault phase.

[0057] The fault diagnosis criterion system of the present invention can quickly and accurately diagnose the transformer fault type and fault location, assist or replace manual fault analysis, solve the many disadvantages of manual analysis of transformer faults, and provide an intelligent automatic solution for accident handling of transformer faults at the engineering site, which is of great significance for quickly restoring power supply and quickly completing the repair of faulty transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 The present invention provides a flow chart of an intelligent diagnosis method for transformer faults. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0060] Embodiment 1 of the present invention provides an intelligent diagnosis method for transformer faults, which specifically includes the following steps:

[0061] S1: Read the longitudinal differential protection action switch quantity from the transformer fault recording, and calculate the rated current of each side of the transformer, the longitudinal three-phase differential current amplitude, the voltage and current amplitude of each side, and the zero-sequence voltage and zero-sequence current amplitude of each side according to the fault recording information, including:

[0062] (1) Automatically obtain the corresponding fault recording after the transformer fault occurs;

[0063] (2) Automatically obtain the fixed values ​​of the transformer equipment parameters from the fault recording and calculate the rated current on each side of the transformer;

[0064] (3) Automatically obtain the transformer's longitudinal differential protection action switch quantity, longitudinal differential three-phase differential current, voltage and current on each side from the fault recording, calculate the amplitude of the three-phase differential current, and calculate the amplitude of the voltage and current on each side and their zero-sequence components;

[0065] S2: Determine whether the longitudinal differential protection of the transformer is actuated according to the longitudinal differential protection action switch value. If so, it is a transformer fault and the process goes to S3. Otherwise, it is a transformer fault outside the transformer area and the diagnosis ends.

[0066] S3: Compare the amplitudes of the three-phase differential currents. If the amplitude of the differential current of a certain phase is greater than twice the amplitude of the maximum differential current of the other two phases, proceed to S4; otherwise, proceed to S7;

[0067] S4: Determine whether the self-generated zero-sequence voltage 3U0 and self-generated zero-sequence current 3I0 on the Y side of the transformer are both greater than their respective set values. If so, enter S5; otherwise, enter S6; the specific expression can be expressed as follows:

[0068]

[0069] Where: They represent the A, B, and C phase voltage vectors on the Y side of the transformer respectively, and the sum of the three is the zero-sequence voltage on the Y side;

[0070] They represent the A, B, and C phase current vectors on the Y side of the transformer respectively, and the sum of the three is the zero-sequence current on the Y side;

[0071] Y indicates the side of the transformer, which refers to the high voltage side or the medium voltage side;

[0072] For the high voltage side, Refers to the voltage vector of phase B on the high voltage side; Refers to the current vector of phase A on the high voltage side; U YN Refers to the PT rating on the high-voltage side; I YN Refers to the CT rating of the high-voltage side winding; I Ye Refers to the rated current on the high voltage side.

[0073] For the medium voltage side, Refers to the voltage vector of phase B on the medium voltage side; Refers to the current vector of phase A on the medium voltage side; U YN Refers to the PT rating on the medium voltage side; I YN Refers to the rated value of the CT on the medium voltage side winding; I Ye Refers to the rated current on the medium voltage side.

[0074] k1 is the zero-sequence overvoltage coefficient, which can be taken as 0.2; k2 is the zero-sequence overcurrent coefficient, which can be taken as 0.5.

[0075] S5: Determine whether the current amplitudes on the Y side and the common winding side of the transformer meet the single-phase grounding fault criterion on the Y side. If so, diagnose a single-phase grounding fault on the Y side, and the fault phase is the phase with the largest differential current. Otherwise, diagnose a turn-to-turn short circuit fault on the Y side, and the fault phase is the phase with the largest differential current.

[0076] Further preferably, the Y-side single-phase grounding fault judgment criterion is: the current amplitudes of all Y-sides and common windings of the transformer are not equal.

[0077] This step determines whether the currents of all Y-side and common windings of the transformer are unequal; if they are equal, it is a Y-side turn-to-turn short circuit fault, the fault phase is the phase with the largest differential current, and the diagnosis is completed; otherwise, it is a Y-side ground fault, the fault phase is the phase with the largest differential current, and the diagnosis is completed;

[0078] Specifically, the current on the high-voltage side and the medium-voltage side is the input quantity, and the current on the common winding side is the output quantity. In theory, it is sufficient to judge whether they are unequal. However, in engineering, the following formula is greater than a certain set value to be considered unequal. If they are unequal, it means that there is grounding, so it is a short circuit to the ground. Therefore, by judging whether the current vectors on the high-voltage side, the medium-voltage side and the common winding side of the transformer satisfy the following formula by phase, it is determined whether the current amplitudes on all Y sides and the common winding of the transformer are unequal in and out. If any phase satisfies the following formula, it means that the currents on all Y sides and the common winding side of the phase are unequal in and out, and it is judged that a ground fault has occurred in the phase:

[0079]

[0080] In the formula, Indicates differences, A, B, C;

[0081] Respectively represent the high voltage side, medium voltage side and common winding side of the transformer Phase current vector;

[0082] Set g It indicates that the set deviation is an allowable constant value and can be adjusted. In engineering, it is generally set to 0.1Ie (Ie is the rated current of the transformer).

[0083] S6: Determine whether the voltage amplitude on the △ side of the transformer meets the criterion for the △ side phase-to-phase short circuit fault. If so, diagnose the △ side phase-to-phase short circuit fault and its faulty phase; otherwise, diagnose the △ side turn-to-turn short circuit fault and its faulty phase;

[0084] Further preferably, the △ side phase-to-phase short circuit fault judgment criterion is: there is a two-phase voltage amplitude drop on the △ side of the transformer and the two phases are in the same phase.

[0085] The fault phases of the △ side phase-to-phase short circuit fault are the two phases with voltage amplitude drop; the fault phase of the △ side turn-to-turn short circuit fault is the phase with the largest voltage amplitude drop.

[0086] This step determines whether there are two-phase voltage drops on the △ side of the transformer and they are in the same phase. If so, it is a phase-to-phase short circuit on the △ side, and the two phases with voltage drops are the fault phases, and the diagnosis is completed; otherwise, it is a turn-to-turn short circuit on the △ side, and the phase with the largest voltage drop is the fault phase, and the diagnosis is completed;

[0087] S7: Determine whether the amplitude of the longitudinal three-phase differential current meets the three-phase symmetric fault criterion. If so, diagnose a three-phase symmetric fault, otherwise enter S8;

[0088] Further preferably, the three-phase symmetry fault judgment criterion is: the longitudinal three-phase differential current amplitude deviation is less than 30%.

[0089] This step compares whether the amplitude deviation of the longitudinal three-phase differential current is less than 30%. If so, it is a three-phase symmetrical fault and the diagnosis ends; otherwise, go to S8;

[0090] S8: Determine whether the voltage amplitude on the Y side of the transformer meets the two-phase grounding fault criterion on the Y side. If so, diagnose the two-phase grounding fault on the Y side and its faulty phase; otherwise, diagnose the two-phase interphase short circuit fault on the Y side and its faulty phase.

[0091] Further preferably, the Y side two-phase grounding fault criterion is: the two-phase voltage amplitude on the Y side of the transformer is less than 0.04Un or the zero-sequence current amplitude is greater than the set value set2=max(0.06I YN ,k2*I Ye ).

[0092] The fault phases of the two-phase grounding fault on the Y side are the two phases with a voltage less than 0.04Un; the fault phases of the two-phase interphase short-circuit fault on the Y side are the two phases with the largest differential current.

[0093] This step determines whether the two-phase voltage on the Y side of the transformer meets the condition that it is less than 0.04Un or the self-generated zero-sequence current 3I0 is greater than the set value. If so, it is a two-phase grounding fault on the Y side, and the faulty phases are the two phases with a voltage less than 0.04Un, and the diagnosis is completed. Otherwise, it is a two-phase interphase short-circuit fault on the Y side, and the faulty phases are the two phases with the largest differential current, and the diagnosis is completed.

[0094] Embodiment 2 of the present invention provides an intelligent diagnosis system for transformer faults, using the method described in any one of claims 1 to 7, including:

[0095] A calculation module is used to read the longitudinal differential protection action switch quantity from the transformer fault recording, and calculate the rated current of each side of the transformer, the longitudinal differential three-phase differential current amplitude, the voltage and current amplitude of each side, and the zero-sequence voltage and zero-sequence current amplitude of each side according to the fault recording information;

[0096] The action discrimination module is used to judge whether the longitudinal differential protection of the transformer is actuated according to the action switch quantity of the longitudinal differential protection. If it is actuated, it enters the three-phase differential current comparison module, otherwise it diagnoses the transformer out-of-zone fault;

[0097] The three-phase differential current comparison module is used to compare the magnitude of the longitudinal differential current amplitudes of the three-phase differential currents. If the differential current amplitude of a phase is greater than twice the maximum differential current amplitude of the other two phases, the zero-sequence component comparison module is performed; otherwise, the three-phase symmetric fault judgment module is entered;

[0098] The zero-sequence component comparison module is used to determine whether the zero-sequence voltage and zero-sequence current amplitudes on the Y side of the transformer are both greater than their respective set values. If so, it enters the Y-side fault judgment module; otherwise, it enters the △-side fault judgment module;

[0099] The Y-side fault determination module determines whether the current amplitudes on the Y-side and common winding side of the transformer meet the Y-side single-phase grounding fault determination criteria. If so, a Y-side single-phase grounding fault is diagnosed, and the fault phase is the phase with the largest differential current. Otherwise, a Y-side turn-to-turn short circuit fault is diagnosed, and the fault phase is the phase with the largest differential current.

[0100] The △ side fault identification module is used to determine whether the voltage amplitude on the △ side of the transformer meets the △ side phase-to-phase short circuit fault criterion. If so, the △ side phase-to-phase short circuit fault and its faulty phase are diagnosed; otherwise, the △ side turn-to-turn short circuit fault and its faulty phase are diagnosed;

[0101] The three-phase symmetry fault judgment module is used to judge whether the amplitude of the longitudinal three-phase differential current meets the three-phase symmetry fault judgment criterion. If so, a three-phase symmetry fault is diagnosed, otherwise it enters the Y-side two-phase fault judgment module;

[0102] The Y-side two-phase fault discrimination module is used to determine whether the voltage amplitude on the Y-side of the transformer meets the Y-side two-phase grounding fault judgment criterion. If so, the Y-side two-phase grounding fault and its faulty phase are diagnosed; otherwise, the Y-side two-phase interphase short circuit fault and its faulty phase are diagnosed.

[0103] Embodiment 3 of the present invention provides a terminal, including a processor and a storage medium; the storage medium is used to store instructions; the processor is used to operate according to the instructions to execute the steps according to the method.

[0104] Embodiment 4 of the present invention provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the method when executed by a processor.

[0105] Compared with the prior art, the beneficial effects of the present invention include at least:

[0106] The present invention automatically obtains the fault recording information recorded after the transformer protection device is actuated, and intelligently identifies the fault type and fault location of the transformer according to the voltage and current information on each side of the transformer in the fault recording information and in combination with different criteria; the transformer fault type includes non-zone fault, three-phase symmetric fault, single-phase grounding fault, two-phase grounding fault, two-phase phase-to-phase short circuit, turn-to-turn fault, etc.; the transformer fault location includes the side where the fault is located and the fault phase.

[0107] The fault diagnosis criterion system provided by the present invention can quickly and accurately diagnose the transformer fault type and fault location, assist or replace manual fault analysis, solve the many drawbacks of manual analysis of transformer faults, and provide an intelligent automatic solution for accident handling of transformer faults at the engineering site, which is of great significance for quickly restoring power supply and quickly completing the repair of faulty transformers.

[0108] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0109] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0110] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0111] The computer program instructions for performing the operation of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0112] 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, and any modifications or equivalent replacements that do 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. An intelligent diagnosis method for transformer faults, characterized in that: The method comprises: S1: Read the longitudinal differential protection action switch quantity from the transformer fault recording, and calculate the rated current of each side of the transformer, the longitudinal three-phase differential current amplitude, the voltage and current amplitude of each side, and the zero-sequence voltage and zero-sequence current amplitude of each side according to the fault recording information; S2: Determine whether the longitudinal differential protection of the transformer is actuated according to the longitudinal differential protection action switch value. If so, enter S3; otherwise, diagnose the transformer out-of-zone fault; S3: Compare the amplitudes of the three-phase differential currents. If the amplitude of the differential current of a certain phase is greater than twice the amplitude of the maximum differential current of the other two phases, proceed to S4; otherwise, proceed to S7; S4: Determine whether the zero-sequence voltage and zero-sequence current amplitudes on the Y side of the transformer are both greater than their respective set values ​​set1 and set2, where set1 and set2 are set according to the rated values ​​on the Y side. If so, enter S5; otherwise, enter S6; S5: Determine whether the current amplitudes on the Y side and the common winding side of the transformer meet the single-phase grounding fault criterion on the Y side. If so, diagnose a single-phase grounding fault on the Y side, and the fault phase is the phase with the largest differential current. Otherwise, diagnose a turn-to-turn short circuit fault on the Y side, and the fault phase is the phase with the largest differential current. S6: Determine whether the voltage amplitude on the △ side of the transformer meets the criterion for the △ side phase-to-phase short circuit fault. If so, diagnose the △ side phase-to-phase short circuit fault and its faulty phase; otherwise, diagnose the △ side turn-to-turn short circuit fault and its faulty phase; S7: Determine whether the amplitude of the longitudinal three-phase differential current meets the three-phase symmetric fault criterion. If so, diagnose a three-phase symmetric fault, otherwise enter S8; S8: Determine whether the voltage amplitude on the Y side of the transformer meets the two-phase grounding fault criterion on the Y side. If so, diagnose the two-phase grounding fault on the Y side and its faulty phase; otherwise, diagnose the two-phase interphase short circuit fault on the Y side and its faulty phase.

2. The intelligent diagnosis method for transformer fault according to claim 1 is characterized in that: In S4, if the following equation is satisfied, then go to S5; otherwise go to S6: Where: is the zero-sequence voltage amplitude on the Y side of the transformer; is the zero-sequence current amplitude on the Y side of the transformer; The Y side is divided into high-voltage side and medium-voltage side; They are the voltage vectors of phases A, B and C on the Y side of the transformer respectively; They are the A, B, and C phase current vectors on the Y side of the transformer respectively; U YN is the PT rating of the transformer Y side; I YN is the CT rating of the Y-side winding of the transformer; I Ye is the rated current of the transformer Y side; k1 is the zero-sequence overvoltage coefficient; k2 is the zero-sequence overcurrent coefficient.

3. The intelligent diagnosis method for transformer fault according to claim 1 is characterized in that: In S5, the single-phase grounding fault criterion on the Y side is: In the formula, is the current amplitude on the Y side and the common winding side of the transformer; Take A, B or C, which means A, B or C respectively; Respectively represent the high voltage side, medium voltage side and common winding side of the transformer Phase current vector; Set g Indicates the set deviation allowable value, which is set to 0.1Ie, where Ie is the rated current of the transformer; If any phase satisfies the above formula, it means that the input and output currents of all Y sides and common winding sides of the phase are not equal, and it is judged that a ground fault occurs in the phase.

4. The intelligent diagnosis method for transformer fault according to claim 1 is characterized in that: In S6, the criterion for the phase-to-phase short-circuit fault on the △ side is: There are two-phase voltage amplitude drops on the △ side of the transformer and they are in the same phase.

5. The intelligent diagnosis method for transformer fault according to claim 4 is characterized in that: In S6, the fault phases of the phase-to-phase short-circuit fault on the △ side are the two phases with voltage amplitude drops; The fault phase of the △ side turn-to-turn short-circuit fault is the phase with the largest voltage amplitude drop.

6. The intelligent diagnosis method for transformer fault according to claim 1 is characterized in that: In S7, the three-phase symmetric fault criterion is: The longitudinal three-phase differential current amplitude deviation is less than 30%.

7. The intelligent diagnosis method for transformer fault according to claim 1 is characterized in that: In S8, the criterion for the two-phase grounding fault on the Y side is: The two-phase voltage amplitude on the Y side of the transformer is less than 0.04Un or the zero-sequence current amplitude is greater than the set value set2, where Un is the rated voltage on the Y side of the transformer.

8. The intelligent diagnosis method for transformer fault according to claim 7 is characterized in that: In S8, the fault phases of the two-phase grounding fault on the Y side are two phases with a voltage less than 0.04Un; The faulty phases of the two-phase short-circuit fault on the Y side are the two phases with the largest differential current.

9. An intelligent diagnosis system for transformer faults, using the method according to any one of claims 1 to 8, characterized in that: The system comprises: A calculation module is used to read the longitudinal differential protection action switch quantity from the transformer fault recording, and calculate the rated current of each side of the transformer, the longitudinal differential three-phase differential current amplitude, the voltage and current amplitude of each side, and the zero-sequence voltage and zero-sequence current amplitude of each side according to the fault recording information; The action discrimination module is used to judge whether the longitudinal differential protection of the transformer is actuated according to the action switch quantity of the longitudinal differential protection. If it is actuated, it enters the three-phase differential current comparison module, otherwise it diagnoses the transformer out-of-zone fault; The three-phase differential current comparison module is used to compare the magnitude of the longitudinal differential current amplitudes of the three-phase differential currents. If the differential current amplitude of a phase is greater than twice the maximum differential current amplitude of the other two phases, the zero-sequence component comparison module is performed; otherwise, the three-phase symmetric fault judgment module is entered; The zero-sequence component comparison module is used to determine whether the zero-sequence voltage and zero-sequence current amplitudes on the Y side of the transformer are both greater than their respective set values. If so, it enters the Y-side fault judgment module; otherwise, it enters the △-side fault judgment module; The Y-side fault determination module determines whether the current amplitudes on the Y-side and common winding side of the transformer meet the Y-side single-phase grounding fault determination criteria. If so, a Y-side single-phase grounding fault is diagnosed, and the fault phase is the phase with the largest differential current. Otherwise, a Y-side turn-to-turn short circuit fault is diagnosed, and the fault phase is the phase with the largest differential current. The △ side fault identification module is used to determine whether the voltage amplitude on the △ side of the transformer meets the △ side phase-to-phase short circuit fault criterion. If so, the △ side phase-to-phase short circuit fault and its faulty phase are diagnosed; otherwise, the △ side turn-to-turn short circuit fault and its faulty phase are diagnosed; The three-phase symmetry fault judgment module is used to judge whether the amplitude of the longitudinal three-phase differential current meets the three-phase symmetry fault judgment criterion. If so, a three-phase symmetry fault is diagnosed, otherwise it enters the Y-side two-phase fault judgment module; The Y-side two-phase fault discrimination module is used to determine whether the voltage amplitude on the Y-side of the transformer meets the Y-side two-phase grounding fault judgment criterion. If so, the Y-side two-phase grounding fault and its faulty phase are diagnosed; otherwise, the Y-side two-phase interphase short circuit fault and its faulty phase are diagnosed.

10. A terminal comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1-8.

11. 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 8 are implemented.

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