Three-phase transformer winding turn-to-turn short circuit simulation device and fault identification method

Abstract

The invention discloses a three-phase transformer winding turn-to-turn short circuit simulation device adopting a fault detection index and a fault identification method, a gear transmission device is driven by a motor, turn-to-turn short circuit fault simulation of a three-phase transformer winding at different positions is realized, real-time current flowing through the winding is further acquired by a current transformer, and the real-time current of the three-phase transformer winding is calculated. A measurement matrix and a coefficient matrix are constructed to solve unknown number vectors, fault detection indexes are further calculated, finally, whether the turn-to-turn short circuit fault occurs or not is judged through the fault detection indexes, the method has the advantages of being high in sensitivity, good in accuracy and high in field applicability, and the transformer winding turn-to-turn short circuit fault can be found in time.

Description

Technical Field

[0001] This application relates to the technical field of power equipment fault diagnosis, and specifically relates to a three-phase transformer winding turn-to-turn short circuit simulation device and a fault identification method. Background Art

[0002] As a key device in the power system, the three-phase transformer, the turn-to-turn short circuit fault of its winding is one of the common fault types. This kind of fault may cause local overheating of the transformer, trigger more serious accidents, and pose a threat to the safe and stable operation of the power system. Therefore, timely detection of the turn-to-turn short circuit fault of the transformer winding is of great significance for ensuring the safe operation and timely maintenance of the transformer. At present, in the diagnosis of turn-to-turn short circuits of transformers, most traditional fault diagnoses rely on the operating state of the transformer before the fault occurs, are not sensitive enough in fault detection, have a large amount of calculation, and poor on-site applicability. Therefore, the present invention proposes a mechanical device to simulate the turn-to-turn short circuit fault of a three-phase transformer winding and judge whether the winding has a turn-to-turn short circuit by calculating the fault detection index. Summary of the Invention

[0003] The purpose of the present invention is to provide a three-phase transformer winding turn-to-turn short circuit simulation device and a fault identification method, which simulate the turn-to-turn short circuit fault of the three-phase transformer winding, collect the winding current samples at different times during the operation of the transformer, and calculate the fault detection index to achieve the identification of the turn-to-turn short circuit fault.

[0004] To achieve the above technical purpose, the present invention provides a three-phase transformer winding turn-to-turn short circuit fault simulation device, which uses a non-contact mechanical device to simulate the turn-to-turn short circuit fault, including: a three-phase winding iron core, a mechanical device support platform, an A-phase primary winding wound around the iron core, an A-phase secondary winding, a B-phase primary winding, a B-phase secondary winding, a C-phase primary winding, a C-phase secondary winding, a driving gear connected to the first stepping motor through an output shaft, a first-stage reduction gear meshing with the driving gear, a transmission gear connected to the first-stage reduction gear through a transmission shaft, a second-stage reduction gear meshing with the transmission gear, a fixed shaft, an external gear meshing with the second-stage reduction gear, an internal gear tightly connected to the external gear and maintaining the same rotational angular velocity, a cylindrical hollow structure working platform, a first spur gear located above the working platform and meshing with the internal gear, a bearing a connecting the first spur gear and a first-stage rotating gear a, a second-stage rotating gear a meshing with the first-stage rotating gear a, a bearing b connecting the second-stage rotating gear a and a first lifting gear, a first fixed column, a first lifting device, a second spur gear located at the axisymmetric position of the first lifting spur gear and meshing with the internal gear, a bearing c connecting the second spur gear and a first-stage rotating gear b, a second-stage rotating gear b meshing with the first-stage rotating gear a, a bearing d connecting the second-stage rotating gear b and a second lifting gear, a second fixed column, and a second lifting device.

[0005] The second elevator device includes: an elevator housing, a hollow cylinder capable of freely sliding in the vertical direction, a rack guide rail tightly connected to the hollow cylinder, a rotary motor a, a support platform, a second stepping motor, an electric push rod, a hydraulic device, a metal jaw a, and a metal wire a.

[0006] The difference between the first elevator device and the second elevator device is that the first elevator device further includes: a short-range micro-lifting platform driven by a rotary motor b.

[0007] The present invention also provides a method for identifying inter-turn short-circuit faults in a three-phase transformer winding, including the following steps:

[0008] Step 1: Simulate an inter-turn short-circuit fault in the three-phase transformer winding;

[0009] Step 2: Conduct the identification of the inter-turn short-circuit fault in the three-phase transformer winding.

[0010] Further, the said Step 1 includes:

[0011] 1) Install the three-phase windings of the transformer and the gear transmission mechanical device and complete the fixation. Place the upper surfaces of the first elevator device and the second elevator device on the same plane as the initial position;

[0012] 2) Control the first stepping motor to drive the driving gear to rotate, further drive the first-stage reduction gear and the transmission gear to rotate, further drive the second-stage reduction gear to rotate, realize the process of reducing the speed and increasing the torque, further drive the external gear and the internal gear to transmit, further drive the second straight gear and the first-stage rotary gear b, further drive the second-stage rotary gear b and the second lifting gear, and further drive the second elevator device to rise to the specified position;

[0013] 3) Control the rotary motor a to rotate, and drive the support platform to rotate until the metal jaw a is directly opposite to the primary winding of the transformer;

[0014] 4) Control the second stepping motor to drive the electric push rod to move horizontally until the metal jaw a is located between two turns of the coil of the primary winding of the transformer;

[0015] 5) Control the hydraulic device to open the metal jaw a until the metal jaw a contacts the two turns of the coil of the winding, forming a short-circuit loop of the coil contact point, the metal jaw a, and the metal wire a;

[0016] 6) Control the rotary motor b to rotate, drive the short-range micro-lifting platform to rise vertically until the metal jaw b is level with the gap between the other two adjacent turns of the coil in 4), and control the first elevator device according to the process in 3) to 5) to form another short-circuit loop of the coil contact point, the metal jaw b, and the metal wire b;

[0017] 7) Repeat the operation steps in 2) to 6) to complete the simulation of inter-turn short circuit faults at multiple positions of the primary winding of the transformer.

[0018] Further, the second step includes:

[0019] 1) Determine the number of turns of the primary winding, the number of turns of the secondary winding, and the magnetic reluctance of the cross-section of the three-phase iron core for the simulation of inter-turn short circuit faults;

[0020] 2) Set the sampling frequency of the host computer to 1 KHz, collect the winding currents through 6 current transformers connected in series on the primary winding and the secondary winding of the three-phase transformer, and input them into the host computer through an analog-to-digital converter (A / D) to achieve the collection of n groups of currents of the primary winding and the secondary winding of the three-phase transformer;

[0021] 3) Calculate and solve the coefficient matrix M of the fault detection index and the measurement matrix N composed of the sampled current signals:

[0022]

[0023] Where: R a 、R b 、R c are the magnetic reluctances of the cross-sections of the iron cores of the windings of phases A, B, and C of the transformer respectively, N p is the number of turns of the primary winding of the transformer winding, N s is the number of turns of the secondary winding of the transformer winding, n is the number of sampling samples, i pa 、i pb 、i pc are the currents flowing through the primary windings of phases A, B, and C of the three-phase transformer respectively, i sa 、i sb 、i sc are the currents flowing through the secondary windings of phases A, B, and C of the three-phase transformer respectively;

[0024] 4) Calculate the unknown vector X that can reflect the fault detection index:

[0025] X = (M T M) -1 N

[0026]

[0027] Where N f is the number of shorted turns, and I f is the effective value of the induced current at the position where the inter-turn short circuit occurs;

[0028] 5) Select a suitable fault detection threshold (Δ), calculate the fault detection index a according to the value of the unknown vector X in 4), and determine whether there is an inter-turn short circuit fault in the transformer winding:

[0029]

[0030] If |a| > Δ, then an inter-turn short circuit fault occurs in the transformer winding.

[0031] The beneficial effects of the present invention are as follows: A non-contact mechanical device is used to simulate the inter-turn short circuit fault of the three-phase transformer winding. The current transformer is used to collect the current information of the transformer winding, and whether an inter-turn short circuit fault of the winding occurs is judged through the fault detection index, which can more sensitively and accurately identify the inter-turn short circuit fault of the winding. Description of the Drawings

[0032] Figure 1 It is a diagram of the inter-turn short circuit simulation device for the three-phase transformer winding of the present invention;

[0033] Figure 2 It is a diagram of the mechanical gear transmission device of the present invention;

[0034] Figure 3 It is a schematic diagram of the elevator device;

[0035] Figure 4 It is a flowchart of a method for identifying the inter-turn short circuit fault of the three-phase transformer winding of the present invention. Detailed Embodiment

[0036] The present invention will be further described in detail below with reference to the drawings:

[0037] Such as Figure 1 、 Figure 2 、 Figure 3As shown in the figure, a simulation device for inter-turn short circuit faults in the windings of a three-phase transformer according to the present invention includes, in the figure, a three-phase winding iron core 1, a mechanical device support platform 2, an A-phase primary winding 3 wound around the iron core, an A-phase secondary winding 4, a B-phase primary winding 5, a B-phase secondary winding 6, a C-phase primary winding 7, a C-phase secondary winding 8, a driving gear 11 connected to a first stepping motor 9 through an output shaft 10, a first-stage reduction gear 12 meshing with the driving gear, a transmission gear 14 connected to the first-stage reduction gear through a transmission shaft 13, a second-stage reduction gear 15 meshing with the transmission gear, a fixed shaft 16, an external gear 17 meshing with the second-stage reduction gear, an internal gear 18 tightly connected to the external gear and maintaining the same rotational angular velocity, a cylindrical hollow-structured working platform 19, a first straight gear 20 located above the working platform and meshing with the internal gear, a bearing a22 connecting the first straight gear and a first-stage rotating gear a21, a second-stage rotating gear a23 meshing with the first-stage rotating gear a, a bearing b25 connecting the second-stage rotating gear a and a first lifting gear 24, a first fixing column 26, a first lifting device 27, a second straight gear 28 located at the axisymmetric position of the first lifting straight gear and meshing with the internal gear, a bearing c30 connecting the second straight gear and a first-stage rotating gear b29, a second-stage rotating gear b31 meshing with the first-stage rotating gear a, a bearing d33 connecting the second-stage rotating gear b and a second lifting gear 32, a second fixing column 34, a second lifting device 35, a lifting device housing 36, a hollow cylinder 37 capable of freely sliding in the vertical direction, a rack guide 38 tightly connected to the hollow cylinder, a rotating motor a39, a support platform 40, a second stepping motor 41, an electric push rod 42, a hydraulic device 43, a metal jaw a44, a metal wire a45, a short-range micro-lifting platform 47 driven by a rotating motor b46, a metal jaw b48, and a metal wire b49.

[0038] As Figure 4 shown, a method for identifying inter-turn short circuit faults in the windings of a three-phase transformer according to the present invention uses a non-contact mechanical device to simulate inter-turn short circuit faults in the windings of a three-phase transformer, collects current information of the transformer windings by using current transformers, and determines whether an inter-turn short circuit fault has occurred through fault detection indicators, specifically including the following steps:

[0039] Step 1: Simulate inter-turn short circuit faults in the windings of a three-phase transformer, including:

[0040] 1) Install the three-phase windings of the transformer and the gear transmission mechanical device and complete the fixation, and place the upper surfaces of the first lifting device 27 and the second lifting device 35 on the same plane as the initial position;

[0041] 2) Control the first stepping motor 9 to drive the driving gear 11 to rotate, further drive the first-stage reduction gear 12 and the transmission gear 13 to rotate, further drive the second-stage reduction gear 15 to rotate, realizing the process of reducing the rotational speed and increasing the torque, further drive the external gear 17 and the internal gear 18 to transmit power, further drive the second spur gear 28 and the first-stage rotating gear b 29, further drive the second-stage rotating gear b 31 and the second lifting gear 32, and further drive the second elevator device 35 to rise to the designated position;

[0042] 3) Control the rotation of the rotating motor a 39 to drive the support platform 40 to rotate until the metal jaw a 44 is directly opposite to the primary winding of the transformer;

[0043] 4) Control the second stepping motor 41 to drive the electric push rod 42 to move horizontally until the metal jaw a is located between two turns of the primary winding of the transformer;

[0044] 5) Control the hydraulic device 43 to open the metal jaw a until the metal jaw a contacts two turns of the winding, forming a short-circuit loop of the coil contact point, the metal jaw a, and the metal wire b 45;

[0045] 6) Control the rotation of the rotating motor b 46 to drive the short-range micro-lifting platform 47 to rise vertically until the metal jaw b 48 is level with the gap between the other two adjacent turns of the two turns of the coil in 4), and control the first elevator device according to the process in 3) to 5) to form another short-circuit loop of the coil contact point, the metal jaw b, and the metal wire b 49;

[0046] 7) Repeat the operation steps from 2) to 6) to complete the simulation of the turn-to-turn short-circuit fault at multiple positions of the primary winding of the transformer.

[0047] Step 2: Conduct the identification of the turn-to-turn short-circuit fault of the three-phase transformer winding, including:

[0048] 1) Determine the number of turns of the primary winding, the number of turns of the secondary winding, and the magnetic reluctance of the cross-section of the three-phase iron core of the three-phase transformer used for the turn-to-turn short-circuit fault simulation;

[0049] 2) Set the sampling frequency of the upper computer to 1KHz, collect the winding current through 6 current transformers connected in series on the primary winding and the secondary winding of the three-phase transformer, and input it to the upper computer through an analog-to-digital converter (A / D) to realize the collection of n groups of currents of the primary winding and the secondary winding of the three-phase transformer;

[0050] 3) Calculate and solve the coefficient matrix M of the fault detection index and the measurement matrix N composed of the sampled current signals:

[0051]

[0052] Where: R a 、R b 、Rc are respectively the magnetic reluctances of the iron core cross-sections of the three-phase windings A, B, and C of the transformer, N p is the number of turns of the primary winding of the transformer winding, N s is the number of turns of the secondary winding of the transformer winding, n is the number of sampling samples, i pa , i pb , i pc are respectively the currents flowing through the primary windings of the three-phase transformer A, B, and C, i sa , i sb , i sc are respectively the currents flowing through the secondary windings of the three-phase transformer A, B, and C;

[0053] 4) Calculate the unknown vector X that can reflect the fault detection index:

[0054] X = (M T M) -1 N

[0055]

[0056] where N f is the number of shorted turns, I f is the effective value of the induced current at the position of the inter-turn short circuit;

[0057] 5) Select a suitable fault detection threshold (Δ), calculate the fault detection index a according to the value of the unknown vector X in 4) and judge whether there is an inter-turn short circuit fault in the transformer winding:

[0058]

[0059] If |a| > Δ, then there is an inter-turn short circuit fault in the transformer winding.

Claims

1. A simulation device for inter-turn short circuit faults in a three-phase transformer winding, characterized in that: Using a mechanical device to simulate the inter-turn short circuit of a three-phase transformer winding, including a three-phase winding iron core (1), a mechanical device support platform (2), an A-phase primary winding (3) wound around the iron core, an A-phase secondary winding (4), a B-phase primary winding (5), a B-phase secondary winding (6), a C-phase primary winding (7), a C-phase secondary winding (8), a driving gear (11) connected to a first stepping motor (9) through an output shaft (10), a first-stage reduction gear (12) meshing with the driving gear, a transmission gear (14) connected to the first-stage reduction gear through a transmission shaft (13), a second-stage reduction gear (15) meshing with the transmission gear, a fixed shaft (16), an external gear (17) meshing with the second-stage reduction gear, an internal gear (18) tightly connected to the external gear and maintaining the same rotational angular velocity, a working platform (19) with a cylindrical hollow structure, a first spur gear (20) located above the working platform and meshing with the internal gear, a bearing a (22) connecting the first spur gear and a first-stage rotating gear a (21), a second-stage rotating gear a (23) meshing with the first-stage rotating gear a, a bearing b (25) connecting the second-stage rotating gear a and a first lifting gear (24), a first fixed column (26), a first lifting device (27), a second spur gear (28) located at the axisymmetric position of the first lifting spur gear and meshing with the internal gear, a bearing c (30) connecting the second spur gear and a first-stage rotating gear b (29), a second-stage rotating gear b (31) meshing with the first-stage rotating gear a, a bearing d (33) connecting the second-stage rotating gear b and a second lifting gear (32), a second fixed column (34), and a second lifting device (35).

2. The first lift device and the second lift device according to claim 1, characterized in that: The second lifting device includes: a lifting device housing (36), a hollow cylinder (37) capable of freely sliding in the vertical direction, a rack guide (38) tightly connected to the hollow cylinder, a rotating motor a (39), a support platform (40), a second stepping motor (41), an electric push rod (42), a hydraulic device (43), a metal jaw a (44), and a metal wire a (45); Among them, the difference between the first lifting device and the second lifting device is that the first lifting device further includes: a short-range micro-lifting platform (47) driven by a rotating motor b (46).

3. The inter-turn short circuit fault simulation device for the three-phase transformer winding according to claim 1, wherein The output shaft, the transmission shaft, and the fixed shaft are connected to the mechanical device support platform, and the bearing a, the first fixed column, the bearing c, and the second fixed column are connected to the working platform to keep the relative spatial positions of the mechanical gears fixed.

4. A method for identifying inter-turn short-circuit faults in a three-phase transformer winding according to claim 1, characterized in that, It includes the following steps: Step 1: Simulate the inter-turn short circuit fault of the three-phase transformer winding; Step 2: Conduct the identification of the inter-turn short circuit fault of the three-phase transformer winding.

5. A method for identifying inter-turn short circuit faults in a three-phase transformer winding according to claim 4, characterized in that, The said Step 1 includes: 1) Install the three-phase windings of the transformer and the gear transmission mechanical device and complete the fixation, and place the upper surfaces of the first lifting device (27) and the second lifting device (35) on the same plane as the initial position; 2) Control the first stepping motor (9) to drive the driving gear (11) to rotate, further drive the first-stage reduction gear (12) and the transmission gear (13) to rotate, further drive the second-stage reduction gear (15) to rotate, realizing the process of reducing the rotational speed and increasing the torque, further drive the external gear (17) and the internal gear (18) to transmit power, further drive the second spur gear (28) and the first-stage rotating gear b (29), further drive the second-stage rotating gear b (31) and the second lifting gear (32), and further drive the second lifting device (35) to rise to the specified position; 3) Control the rotating motor a (39) to rotate, driving the support platform (40) to rotate until the metal jaw a (44) is directly opposite to the primary winding of the transformer; 4) Control the second stepping motor (41) to drive the electric push rod (42) to move horizontally until the metal jaw a is located between two turns of the coil of the primary winding of the transformer; 5) Control the hydraulic device (43) to open the metal jaw a until the metal jaw a touches the two turns of the coil of the winding, forming a short-circuit loop of the coil contact point, the metal jaw a, and the metal wire a (45); 6) Control the rotating motor b (46) to rotate, driving the short-range micro-lifting platform (47) to rise vertically until the metal jaw b (48) is level with the gap between the other two adjacent turns of the coil in 4), and control the first lifting device according to the process in 3) to 5) to form another short-circuit loop of the coil contact point, the metal jaw b, and the metal wire b (49); 7) Repeat the operation steps in 2) to 6) to complete the simulation of the turn-to-turn short-circuit fault at multiple positions of the primary winding of the transformer.

6. A method for identifying inter-turn short circuit faults in a three-phase transformer winding according to claim 4, characterized in that, The second step includes: 1) Determine the number of turns of the primary winding, the number of turns of the secondary winding, and the magnetic reluctance of the three-phase iron core cross-section for the simulation of the turn-to-turn short-circuit fault; 2) Set the sampling frequency of the upper computer to 1KHz, collect the winding current through 6 current transformers connected in series on the primary winding and the secondary winding of the three-phase transformer, and input it to the upper computer through an analog-to-digital converter (A / D) to collect n groups of currents of the primary winding and the secondary winding of the three-phase transformer; 3) Calculate and solve the coefficient matrix M of the fault detection index and the measurement matrix N composed of the sampled current signals; Where: R a , R b , R c are respectively the magnetic reluctances of the iron core cross-sections of the windings of phases A, B, and C of transformer, N p is the number of turns of the primary winding of the transformer winding, N s is the number of turns of the secondary winding of the transformer winding, n is the number of sampling samples, i pa , i pb , i pc are respectively the currents flowing through the primary windings of phases A, B, and C of the three-phase transformer, i sa , i sb , i sc are respectively the currents flowing through the secondary windings of phases A, B, and C of the three-phase transformer; 4) Calculate the unknown vector X that can reflect the fault detection index; X = (M T M) -1 N Where N f is the number of short - circuited turns, I f is the effective value of the induced current at the position where the turn - to - turn short - circuit occurs; 5) Select a suitable fault detection threshold (Δ), calculate the fault detection index a according to the value of the unknown vector X in 4), and judge whether there is a turn-to-turn short-circuit fault in the transformer winding: If |a| > Δ, then there is a turn-to-turn short-circuit fault in the transformer winding.

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