An equivalent network-based three-phase transformer winding deformation fault simulation device

Abstract

The application provides a three-phase transformer winding deformation fault simulation device based on an equivalent network, which comprises a metal case, an equivalent circuit board arranged in the metal case, a grounding port, a wiring port and a double-control switch group arranged on the top of the metal case, wherein the grounding port, the wiring port and the double-control switch group are connected with the equivalent circuit board, the wiring port comprises a high-voltage winding wiring port and a low-voltage winding wiring port, and the high-voltage winding wiring port and the low-voltage winding wiring port are connected with the equivalent circuit board. The fault simulation device not only considers the inductance, the longitudinal capacitance, the ground capacitance and the coupling capacitance of the high-voltage winding and the low-voltage winding, but also increases the parallel resistance of the three kinds of capacitances to reflect the loss of the insulation medium between the windings, so that the simulated fault is closer to the real situation, and the accuracy of the experimental results is improved. The device has the advantages that various high-voltage winding deformation faults and low-voltage winding deformation faults and the simulation of different connection group transformers can be realized, and the horizontal / longitudinal comparative experiment can be carried out.

Description

Technical Field

[0001] This invention belongs to the field of power transformer winding deformation detection, and particularly relates to a three-phase transformer winding deformation fault simulation device based on an equivalent network. Background Technology

[0002] In recent years, my country's power industry has developed rapidly, and the grid capacity has been increasing day by day. People have put forward higher requirements for the operational safety and power supply reliability of the entire grid. Therefore, timely and accurate detection and repair of transformer winding deformation faults is one of the important measures to reduce transformer operation accidents and improve system safety. At present, the main methods used for detecting transformer winding deformation faults are frequency response analysis (FRA) and short circuit impedance (SCI). Among them, SCI determines whether there is deformation in the transformer winding by measuring the change of impedance or leakage reactance of the transformer winding at the power frequency (50Hz); FRA test, on the other hand, applies an excitation signal to the beginning of the transformer winding and tests the response signal at its end to obtain the frequency response characteristic curve characterizing the mechanical state of the transformer winding, and then judges the state of the transformer winding. However, when using the above two detection methods, the transformer on site needs to be shut down, which not only affects the normal operation of the grid, but also causes great economic losses. Figure 4 The scenario involves an inter-turn short circuit fault in the high-voltage winding of phase A of a transformer. In this case, the transformer should be shut down and repaired in a timely manner to avoid affecting the normal operation of the power grid. Moreover, once the transformer windings are deformed, they are irreversible and the fault type is singular. Therefore, data obtained from the faulty transformer on site is insufficient to meet the sample requirements for the research on winding deformation diagnosis methods based on FRA and SCI.

[0003] Therefore, there is an urgent need for an experimental platform that can conveniently simulate various types, degrees, and locations of mechanical faults in transformer windings (inter-turn short circuits, axial displacement, radial displacement, etc.). While existing patents CN 112992496A and CN 114035116A propose devices capable of simulating various transformer winding deformation faults, they cannot adjust the degree and location of the fault. Furthermore, these devices are based on physical transformers and use replaceable components to simulate winding deformation faults, which increases operational complexity and reduces portability. Patent CN112082467A improves the operability and portability of the simulation device by constructing an equivalent hardware circuit for the transformer winding to simulate winding faults, but it does not consider the adjustability of fault types and degrees, and its equivalent circuit only represents a single winding, which does not conform to the actual winding structure of a transformer. To solve these problems, this patent, based on an equivalent network and its hardware circuit, invents a three-phase transformer winding deformation fault simulation device with functions for simulating the type, degree, and location of winding deformation faults. Summary of the Invention

[0004] To address the high cost of existing transformer winding deformation fault simulation devices, this invention proposes a three-phase transformer winding deformation fault simulation device based on an equivalent network. This device is lightweight, small in size, simple to manufacture, and has a low cost.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A three-phase transformer winding deformation fault simulation device based on an equivalent network includes a metal chassis, an equivalent circuit board disposed inside the metal chassis, a grounding port, a wiring port and a double-control switch group disposed on the top of the metal chassis, the metal chassis being connected to the grounding port, the grounding port, the wiring port and the double-control switch group being connected to the equivalent circuit board, the wiring port including a high-voltage winding wiring port and a low-voltage winding wiring port, both of which are connected to the equivalent circuit board;

[0006] The high-voltage winding connection ports include a high-voltage winding input port group and a high-voltage winding output port group. The high-voltage winding input port group includes the A-phase high-voltage winding input port, the B-phase high-voltage winding input port, and the C-phase high-voltage winding input port. The high-voltage winding output port group includes the A-phase high-voltage winding output port, the B-phase high-voltage winding output port, and the C-phase high-voltage winding output port. All three high-voltage winding input ports (A-phase, B-phase, and C-phase) and output ports (A-phase, B-phase, and C-phase) are connected to the equivalent circuit board.

[0007] The low-voltage winding connection ports include a low-voltage winding input port group and a low-voltage winding output port group. The low-voltage winding input port group includes the A-phase low-voltage winding input port, the B-phase low-voltage winding input port, and the C-phase low-voltage winding output port group includes the A-phase low-voltage winding output port, the B-phase low-voltage winding output port, and the C-phase low-voltage winding output port. All three low-voltage winding input ports (A-phase, B-phase, and C-phase) and output ports (A-phase, B-phase, and C-phase) are connected to the equivalent circuit board.

[0008] The equivalent circuit board includes phase A winding circuit, phase B winding circuit, and phase C winding circuit. All three winding circuits are connected to grounding and wiring ports. The phase A winding circuit is connected to a double-control switch group. The double-control switch group includes a phase A high-voltage winding double-control switch group and a phase A low-voltage winding double-control switch group. Each switch group contains nine fault simulation double-control switches: upper inter-turn short-circuit double-control switch, middle inter-turn short-circuit double-control switch, lower inter-turn short-circuit double-control switch, upper axial displacement double-control switch, middle axial displacement double-control switch, lower axial displacement double-control switch, upper radial displacement double-control switch, middle radial displacement double-control switch, and lower radial displacement double-control switch. All switches in the double-control switch group are connected to the equivalent circuit board.

[0009] The A-phase winding circuit includes a high-voltage fault circuit, a low-voltage fault circuit, a high-voltage normal circuit, a low-voltage normal circuit, and a high-low voltage coupling circuit. The high-voltage fault circuit is connected to the low-voltage fault circuit through the high-low voltage coupling circuit. The high-voltage normal branch is connected to the low-voltage normal circuit through the high-low voltage coupling circuit. The high-voltage fault circuit includes a high-voltage upper fault circuit, a high-voltage middle fault circuit, and a high-voltage lower fault circuit. The low-voltage fault circuit includes a low-voltage upper fault circuit, a low-voltage middle fault circuit, and a low-voltage lower fault circuit. The high-voltage upper fault circuit, high-voltage middle fault circuit, and high-voltage lower fault circuit all include a high-voltage radial displacement fault branch, a high-voltage short-circuit fault branch, and a high-voltage axial displacement fault branch. The high-voltage short-circuit fault branch and the high-voltage axial displacement fault branch are connected in parallel. The low-voltage upper fault circuit, low-voltage middle fault circuit, and low-voltage lower fault circuit all include a low-voltage short-circuit fault branch, a low-voltage axial displacement fault branch, and a low-voltage radial displacement fault branch. The low-voltage short-circuit fault branch and the low-voltage axial displacement fault branch are connected in parallel. The high-voltage normal circuit includes a high-voltage normal radial branch and a high-voltage normal axial branch; the low-voltage normal circuit includes a low-voltage normal radial branch and a low-voltage normal axial branch; the high-low voltage coupling circuit includes five high-low voltage coupling branches.

[0010] One end of the high-voltage normal radial branch, the high-voltage normal axial branch, and the first high-low voltage coupling branch is connected to the input port of the A-phase high-voltage winding. The other end of the high-voltage normal radial branch is grounded through the grounding port. The other end of the first high-low voltage coupling branch, the low-voltage normal axial branch, and the low-voltage normal radial branch are connected to the input port of the A-phase low-voltage winding. The other end of the low-voltage normal radial branch is grounded through the grounding port.

[0011] The other end of the high-voltage normal axial branch is connected to one end of the high-voltage short-circuit fault branch, the high-voltage radial displacement fault branch, and the high-voltage axial displacement fault branch in the high-voltage upper fault circuit, and one end of the second high-low voltage coupling branch. The other end of the high-voltage radial displacement fault branch in the high-voltage upper fault circuit is grounded through a grounding port. The other end of the second high-low voltage coupling branch is connected to the other end of the low-voltage normal axial branch and one end of the low-voltage short-circuit fault branch, the low-voltage radial displacement fault branch, and the low-voltage axial displacement fault branch in the low-voltage upper fault circuit. The other end of the low-voltage radial displacement fault branch in the low-voltage upper fault circuit is grounded through a grounding port.

[0012] The other end of the high-voltage short-circuit fault branch and the high-voltage axial displacement fault branch in the high-voltage upper fault circuit are connected to one end of the high-voltage radial displacement fault branch, the high-voltage short-circuit fault branch, the high-voltage axial displacement fault branch in the high-voltage middle fault circuit, and one end of the third high-low voltage coupling branch. The other end of the high-voltage radial displacement fault branch in the high-voltage middle fault circuit is grounded through a grounding port. The other end of the third high-low voltage coupling branch is connected to the other end of the low-voltage short-circuit fault branch and the low-voltage axial displacement fault branch in the low-voltage upper fault circuit, and one end of the low-voltage radial displacement fault branch, the low-voltage short-circuit fault branch, and the low-voltage axial displacement fault branch in the low-voltage middle fault circuit. The other end of the low-voltage radial displacement fault branch in the low-voltage middle fault circuit is grounded through a grounding port.

[0013] The other end of the high-voltage short-circuit fault branch and the high-voltage axial displacement fault branch in the high-voltage middle fault circuit are connected to one end of the high-voltage radial displacement fault branch, the high-voltage short-circuit fault branch, the high-voltage axial displacement fault branch in the high-voltage lower fault circuit, and one end of the fourth high-low voltage coupling branch. The other end of the high-voltage radial displacement fault branch in the high-voltage lower fault circuit is grounded through a grounding port. The other end of the fourth high-low voltage coupling branch is connected to the other end of the low-voltage short-circuit fault branch and the low-voltage axial displacement fault branch in the low-voltage middle fault circuit, and one end of the low-voltage radial displacement fault branch, the low-voltage short-circuit fault branch, and the low-voltage axial displacement fault branch in the low-voltage lower fault circuit. The other end of the low-voltage radial displacement fault branch in the low-voltage lower fault circuit is grounded through a grounding port.

[0014] The other end of the high-voltage short-circuit fault branch and the high-voltage axial displacement fault branch in the high-voltage lower fault circuit are connected to the next set of high-voltage normal radial branches, one end of the fifth high-low voltage coupling branch, and the output port of the A-phase high-voltage winding. The other end of the next set of high-voltage normal radial branches is grounded through a grounding port. The other end of the fifth high-low voltage coupling branch is connected to the other end of the low-voltage short-circuit fault branch and the low-voltage axial displacement fault branch in the low-voltage lower fault circuit, one end of the next set of low-voltage normal radial branches, and the output port of the A-phase low-voltage winding. The other end of the next set of low-voltage normal radial branches is grounded through a grounding port.

[0015] Both the high-voltage radial displacement fault circuit and the low-voltage radial displacement fault circuit include a fault simulation capacitor I, a normal simulation capacitor I, and a double-control switch I. One end of the normal simulation capacitor I is connected to port I of the double-control switch I, and the other end of the normal simulation capacitor I is connected to the grounding port. Port II of the double-control switch I is connected to port II of the double-control switch II. One end of the fault simulation capacitor I is connected to port III of the double-control switch I, and the other end of the fault simulation capacitor I is connected to the grounding port. The upper radial displacement switch, the middle radial displacement switch, and the lower radial displacement switch of the double-control switch group are connected to the high-voltage radial displacement fault circuit and the low-voltage radial displacement fault circuit.

[0016] Both the high-voltage short-circuit fault circuit and the low-voltage short-circuit fault circuit include an axial inductor and a double-control switch II. The axial inductor includes normal inductor I, normal inductor II, and normal inductor III, which are connected in series. Port I of the double-control switch II is connected to one end of the axial inductor, port II of the double-control switch II is connected to the other end of the axial inductor of the previous unit, and port III of the double-control switch II is connected to the other end of the axial inductor.

[0017] The high-voltage axial displacement fault circuit and the low-voltage axial displacement fault circuit include a fault simulation capacitor II, a normal simulation capacitor II, and a double-control switch III. One end of the normal simulation capacitor II is connected to port I of the double-control switch III, and the other end of the normal simulation capacitor II is connected to the other end of the axial inductor. Port II of the double-control switch III is connected to port II of the double-control switch II. One end of the fault simulation capacitor II is connected to port III of the double-control switch III, and the other end of the fault simulation capacitor II is connected to the other end of the axial inductor. The upper axial displacement switch, the middle axial displacement switch, and the lower axial displacement switch of the double-control switch group are connected to the high-voltage axial displacement fault circuit and the low-voltage axial displacement fault circuit.

[0018] The high-low voltage coupling circuit includes five high-low voltage coupling branches, each including a coupling capacitor and a coupling resistor connected in parallel. One end of the first high-low voltage coupling branch is connected to one end of the high-voltage normal radial branch, one end of the high-voltage normal axial branch, and the input port of the A-phase high-voltage winding. The other end of the first high-low voltage coupling branch is connected to one end of the low-voltage normal axial branch, one end of the low-voltage normal radial branch, and the input port of the A-phase low-voltage winding. One end of the second high-low voltage coupling branch is connected to one end of the high-voltage radial displacement fault circuit, the high-voltage short-circuit fault branch, and the high-voltage axial displacement fault branch in the high-voltage upper fault circuit, and the other end of the high-voltage normal axial branch. The other end of the second high-low voltage coupling branch is connected to one end of the low-voltage short-circuit fault circuit, the low-voltage axial displacement fault branch, and the low-voltage radial displacement fault branch in the low-voltage upper fault circuit, and the other end of the low-voltage normal axial branch. The fifth... One end of the high-low voltage coupling branch is connected to the other end of the high-voltage short-circuit fault branch and the high-voltage axial displacement fault branch in the high-voltage lower fault circuit, one end of the high-voltage normal radial branch, and the output port of the A-phase high-voltage winding. The other end of the fifth high-low voltage coupling branch is connected to the other end of the low-voltage short-circuit fault circuit, the low-voltage axial displacement fault branch, the low-voltage normal radial branch, and the output port of the A-phase low-voltage winding in the low-voltage lower fault circuit. One end of the remaining two high-low voltage coupling branches is connected to the other end of the high-voltage short-circuit fault branch and the high-voltage axial displacement fault branch, and one end of the next set of high-voltage radial displacement fault circuit, high-voltage short-circuit fault branch, and high-voltage axial displacement fault branch. The other end of the remaining two high-low voltage coupling branches is connected to the one end of the low-voltage short-circuit fault circuit and the low-voltage axial displacement fault branch, and one end of the next set of low-voltage short-circuit fault circuit, low-voltage axial displacement fault branch, and low-voltage radial displacement fault branch.

[0019] The high-voltage normal radial branch and the low-voltage normal radial branch each include a radial capacitor and a radial resistor, which are connected in parallel. One end of the first high-voltage normal radial branch is connected to one end of the first high-low voltage coupling branch in the high-low voltage coupling circuit, one end of the high-voltage normal axial branch, and the input port of the A-phase high-voltage winding. The other end of the first high-voltage normal radial branch is grounded through a grounding port. One end of the second high-voltage normal radial branch is connected to one end of the fifth high-low voltage coupling branch in the high-low voltage coupling circuit, the other end of the high-voltage short-circuit fault branch and the high-voltage axial displacement fault branch in the high-voltage lower fault circuit, and the output port of the A-phase high-voltage winding. The other end of the high-voltage normal radial branch is grounded through a grounding port; one end of the first low-voltage normal radial branch is connected to the other end of the first high-low voltage coupling branch in the high-low voltage coupling circuit, one end of the low-voltage normal axial branch, and the input port of the A-phase low-voltage winding, and the other end of the first low-voltage normal radial branch is grounded through a grounding port; one end of the second low-voltage normal radial branch is connected to the other end of the fifth high-low voltage coupling branch in the high-low voltage coupling circuit, the other end of the low-voltage short-circuit fault branch and the low-voltage axial displacement fault branch in the high-voltage lower fault circuit, and the output port of the A-phase low-voltage winding, and the other end of the second low-voltage normal radial branch is grounded through a grounding port.

[0020] The high-voltage normal axial branch and the low-voltage normal axial branch include axial inductance, axial capacitance, and axial resistance. The axial inductance includes inductors IV, V, and VI, which are connected in series. The axial inductance, axial capacitance, and axial resistance are connected in parallel. One end of the high-voltage normal axial branch is connected to the input port of the A-phase high-voltage winding, one end of the high-voltage normal radial branch, and one end of the first high-low voltage coupling branch in the high-low voltage coupling circuit. The other end of the high-voltage normal axial branch is connected to the high-voltage radial displacement fault circuit and the high-voltage short circuit in the high-voltage upper fault circuit. One end of the fault branch and the high-voltage axial displacement fault branch is connected to one end of the second high-low voltage coupling branch in the high-low voltage coupling circuit; one end of the low-voltage normal axial branch is connected to the input port of the A-phase low-voltage winding, one end of the low-voltage normal radial branch and the other end of the first high-low voltage coupling branch in the high-low voltage coupling circuit; the other end of the low-voltage normal axial branch is connected to one end of the low-voltage short-circuit fault circuit, the low-voltage axial displacement fault branch, and the low-voltage radial displacement fault branch in the low-voltage upper fault circuit and the other end of the second high-low voltage coupling branch in the high-low voltage coupling circuit.

[0021] Both the B-phase winding circuit and the C-phase winding circuit include a high-voltage winding circuit, a high-low voltage coupling circuit, and a low-voltage winding circuit. The high-voltage winding and the low-voltage winding are connected through the high-low voltage coupling circuit. The high-voltage winding circuit includes four high-voltage normal winding circuits connected in series. Each high-voltage normal winding circuit includes resistor I, resistor II, capacitor I, capacitor II, inductor I, inductor II, and inductor III. Inductors I, II, and III are connected in series. Resistor I and capacitor I are connected in parallel. One end of resistor I is connected to one end of inductor I, and the other end of resistor I is connected to inductor III and one end of resistor I in the next high-voltage normal winding circuit. Resistor II and capacitor II are connected in parallel. One end of resistor II and capacitor II is connected to one end of resistor I, and the other end of resistor II and capacitor II is grounded through a grounding port.

[0022] The low-voltage winding circuit includes four low-voltage normal winding circuits connected in series. Each low-voltage normal winding circuit includes resistor III, resistor IV, capacitor III, capacitor IV, and inductor IV. Resistor III and capacitor III are connected in parallel. One end of resistor III is connected to one end of inductor IV. The other end of resistor III is connected to inductor IV and one end of resistor III in the next low-voltage normal winding circuit. Resistor IV and capacitor IV are connected in parallel. One end of resistor IV and capacitor IV is connected to one end of resistor III. The other ends of resistor IV and capacitor IV are connected to the grounding port.

[0023] The high-low voltage coupling circuit includes capacitor V and resistor V, which are connected in parallel. One end of resistor V is connected to one end of inductor IV, and the other end of resistor V is connected to one end of resistor I and inductor I.

[0024] The input port of the high-voltage winding circuit is connected to one end of inductor I, resistor I, resistor II, capacitor I, and capacitor II; the output port of the high-voltage winding circuit is connected to the other end of inductor III, resistor I, and capacitor I, and the other end of resistor II and capacitor II. The input port of the low-voltage winding circuit is connected to one end of resistor III, resistor IV, capacitor III, capacitor IV, and inductor IV; the output port of the low-voltage winding circuit is connected to the other end of resistor III, capacitor III, and inductor IV, and one end of resistor IV and capacitor IV.

[0025] The beneficial effects of this invention are as follows:

[0026] (1) The device not only considers the inductance, axial capacitance and radial capacitance of each phase high and low voltage winding, but also adds the coupling capacitance between the high and low voltage windings to reflect the coupling relationship between the windings. This makes the simulated fault closer to the real situation and improves the accuracy of the experimental results.

[0027] (2) By using a double-controlled switch to change the inductance and capacitance values ​​of a certain unit in the ladder network, the mechanical faults of the winding, such as inter-turn short circuit, axial displacement, and radial displacement, can be simulated. Compared with existing devices that simulate winding deformation faults by replacing mechanical parts, the double-controlled switch in this invention greatly improves the efficiency of fault simulation and reduces labor costs.

[0028] (3) The device chassis is mainly made of aluminum alloy with insulating material coated on the surface. The metal shell can effectively shield external interference. On this basis, the device chassis is further grounded to reduce the stray capacitance caused by the change of chassis potential and improve the test repeatability.

[0029] (4) The frequency response and short-circuit impedance data of the transformer under normal and different winding fault conditions simulated by the device are significantly different, which proves the feasibility of the device for simulating different winding fault types, locations and degrees.

[0030] (5) The equivalent circuits of the high-voltage and low-voltage windings of phase A of this device are equipped with fault simulation units, while phases B and C are equivalent circuits of normal windings. Therefore, both longitudinal and lateral comparisons of winding deformation diagnosis can be conducted using this device for practical training, reducing the training costs for enterprises. At the same time, by changing the wiring method of the winding start and end ports leading out from the top cover of the chassis, simulation of different connection groups of three-phase transformers can also be achieved, demonstrating the flexibility and comprehensiveness of this device.

[0031] (6) Since the device is built using small nonlinear components such as inductors and capacitors, it has advantages such as light weight, small size, simple manufacturing and low cost compared with the winding fault simulation device formed by modifying a physical transformer. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of a transformer winding deformation fault simulation device.

[0034] Figure 2 The schematic diagram of the equivalent circuit for simulating deformation fault in phase A winding of a transformer.

[0035] Figure 3 This is the schematic diagram of the equivalent circuit of the B and C phase windings of the transformer.

[0036] Figure 4Diagram of inter-turn short circuit fault in the high-voltage winding of phase A of transformer.

[0037] Figure 5 Wiring diagram for frequency response testing of phase A high-voltage winding of Yd11 connection winding deformation fault simulation device.

[0038] Figure 6 The frequency response curves of the A-phase high-voltage winding of the simulation device under Yd11 connection are shown under normal conditions and under conditions of short circuit, axial and radial displacement.

[0039] Figure 7 The frequency response diagrams are shown for the A-phase high-voltage winding of the simulation device under Yd11 connection when it is normal and when there are short-circuit faults of different degrees.

[0040] Figure 8 Wiring diagram for the A, B, and C phases of the short-circuit impedance test of the Yd11 wiring winding deformation fault simulation device.

[0041] Figure 9 A comparison of the normal frequency response curves of phase A of the simulated winding deformation fault device and the actual transformer for the Yd11 connection.

[0042] In the diagram, 1 is the chassis, 2 is the high-voltage winding interface, 3 is the low-voltage winding interface, 4 is the dual-control switch group, 5 is the grounding port, 6 is the high-voltage radial displacement fault circuit, 7 is the high-voltage short-circuit fault circuit, 8 is the high-voltage axial displacement fault circuit, 9 is the high-low voltage coupling circuit, 10 is the low-voltage short-circuit fault circuit, 11 is the low-voltage axial displacement fault circuit, 12 is the low-voltage radial displacement fault circuit, 13 is the high-voltage normal radial branch, 14 is the high-voltage normal axial branch, 15 is the low-voltage normal axial branch, 16 is the low-voltage normal radial branch, 17 is the computer, 18 is the wire, 19 is the frequency response analyzer, and 20 is the short-circuit impedance meter. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] When the frequency of the applied voltage of a transformer exceeds 1kHz, the transformer core becomes essentially ineffective, and the transformer windings can be represented as a passive linear two-port network composed of distributed parameters such as resistance, capacitance, and inductance. Each unit consists of inter-turn inductance, inter-turn capacitance, capacitance to ground, conductance to ground, and capacitance and conductance between high and low voltage levels. When deformation phenomena such as inter-turn short circuits, radial and axial dimensional changes occur in the windings, the parameters such as inter-turn capacitance, capacitance to ground, and inductance in the network will change, leading to changes in the zero-point and pole distribution of its transfer function. Therefore, components such as capacitors, inductors, and resistors can be used to simulate the normal and faulty circuits of the transformer, and by changing the parameters of the components in the network, it is possible to further simulate the different types, locations, and degrees of faults in the transformer windings.

[0045] like Figure 1 As shown, a three-phase transformer winding deformation simulation device based on an equivalent network includes a metal chassis 1, an equivalent circuit board inside the metal chassis 1, a grounding port 5, a wiring port, and a double-control switch group 4 on the top of the metal chassis 1. The grounding port 5, the wiring port, and the double-control switch group 4 are all connected to the equivalent circuit board. The wiring port includes a high-voltage winding wiring port 2 and a low-voltage winding wiring port 3, both of which are connected to the equivalent circuit board.

[0046] Specifically, the high-voltage winding connection port 2 includes a high-voltage winding input port group and a high-voltage winding output port group. The high-voltage winding input port group includes the A-phase high-voltage winding input port, the B-phase high-voltage winding input port, and the C-phase high-voltage winding input port. The high-voltage winding output port group includes the A-phase high-voltage winding output port, the B-phase high-voltage winding output port, and the C-phase high-voltage winding output port. All the A-phase high-voltage winding input ports, B-phase high-voltage winding input ports, C-phase high-voltage winding input ports, A-phase high-voltage winding output ports, B-phase high-voltage winding output ports, and C-phase high-voltage winding output ports are connected to the equivalent circuit board's IN_A0 port, IN_B0 terminal, IN_C0 port, OUT_A0 port, OUT_B0 port, and OUT_C0 port.

[0047] The low-voltage winding connection port 3 includes a low-voltage winding input port group and a low-voltage winding output port group. The low-voltage winding input port group includes an A-phase low-voltage winding input port, a B-phase low-voltage winding input port, and a C-phase low-voltage winding input port. The low-voltage winding output port group includes an A-phase low-voltage winding output port, a B-phase low-voltage winding output port, and a C-phase low-voltage winding output port. All of the A-phase low-voltage winding input ports, B-phase low-voltage winding input ports, C-phase low-voltage winding input ports, A-phase low-voltage winding output ports, B-phase low-voltage winding output ports, and C-phase low-voltage winding output ports are connected to the equivalent circuit board's IN_a port, IN_b terminal, IN_c port, OUT_a port, OUT_b port, and OUT_c port.

[0048] In use, the testing instrument can be connected to the circuit through the high-voltage winding connection port 2 and the low-voltage winding connection port 3 to detect and analyze the fault simulated by the circuit.

[0049] The equivalent circuit board includes phase A winding circuit, phase B winding circuit, and phase C winding circuit. All three circuits are connected to grounding port 5 and connection ports 2 and 3. Phase A winding circuit is connected to the double-control switch group 4. In use, the phase A winding circuit is used to simulate high-voltage and low-voltage short-circuit faults, axial displacement faults, and radial displacement faults. The phase B and phase C winding circuits are both set as normal windings and used for lateral comparison in winding deformation diagnosis. By changing the wiring method of the first and last ports of the high and low voltage sides of the phase A, B, and C windings leading out from the top cover of the chassis, simulation of different connection groups of the three-phase transformer can also be achieved.

[0050] Among them, such as Figure 2As shown, the A-phase winding circuit includes a high-voltage fault circuit, a low-voltage fault circuit, a high-voltage normal branch, a high-low voltage coupling circuit, and a low-voltage normal branch. The high-voltage fault circuit and the low-voltage fault circuit are connected in parallel. The high-voltage fault circuit includes a high-voltage upper fault circuit, a high-voltage middle fault circuit, and a high-voltage lower fault circuit. The low-voltage fault circuit includes a low-voltage upper fault circuit, a low-voltage middle fault circuit, and a low-voltage lower fault circuit. The high-voltage upper fault circuit, the high-voltage middle fault circuit, and the high-voltage lower fault circuit all include a high-voltage short-circuit fault circuit 7, a high-voltage radial displacement fault circuit 6, and a high-voltage axial displacement fault circuit 8. The high-voltage short-circuit fault circuit 7, the high-voltage radial displacement fault circuit 6, and the high-voltage axial displacement fault circuit 8 are connected in parallel. The low-voltage upper fault circuit, the low-voltage middle fault circuit, and the low-voltage lower fault circuit all include a low-voltage short-circuit fault circuit 10, a low-voltage radial displacement fault circuit 12, and a low-voltage axial displacement fault circuit 11. The low-voltage short-circuit fault circuit 10, the low-voltage radial displacement fault circuit 12, and the low-voltage axial displacement fault circuit 11 are connected in parallel. The high-voltage normal branch includes a high-voltage normal radial branch 13 and a high-voltage normal axial branch 14, which are connected in parallel. The low-voltage normal branch includes a low-voltage normal radial branch 16 and a low-voltage normal axial branch 15, which are connected in parallel. The high-low voltage coupling circuit 9 is connected in parallel with the high-voltage normal radial branch 13, the high-voltage normal axial branch 14, the low-voltage normal axial branch 15, and the low-voltage normal radial branch 16.

[0051] Both the high-voltage radial displacement fault circuit 6 and the low-voltage radial displacement fault circuit 12 include a fault simulation capacitor I, a normal simulation capacitor I, and a double-control switch I. One end of the normal simulation capacitor I is connected to port I of the double-control switch I, and the other end of the normal simulation capacitor I is grounded. Port II of the double-control switch I is connected to port II of the double-control switch II. One end of the fault simulation capacitor I is connected to port III of the double-control switch I, and the other end of the fault simulation capacitor I is connected to the grounding port 5. The high-voltage radial displacement fault circuit 6 is used to simulate the radial displacement fault of the high-voltage winding of the transformer, and the low-voltage radial displacement fault circuit 12 is used to simulate the radial displacement fault of the low-voltage winding of the transformer. The fault simulation capacitor I of the high-voltage radial displacement fault circuit 6 is 330pF, and the normal simulation capacitor I is 56pF. The fault simulation capacitor I of the low-voltage radial displacement fault circuit 10 is 390pF, and the normal simulation capacitor I is 220pF. When simulating a normal circuit, port I of double-control switch I is connected to port II of double-control switch I. When simulating a radial displacement fault of the transformer, port III of double-control switch I is connected to port II of double-control switch I.

[0052] Both the high-voltage short-circuit fault circuit 7 and the low-voltage short-circuit fault circuit 10 include an axial inductor and a double-control switch II. Port I of the double-control switch II is connected to one end of the axial inductor, and port II of the double-control switch II is connected to the other end of the axial inductor of the previous unit. Port III of the double-control switch II is also connected to the other end of the axial inductor. The high-voltage short-circuit fault circuit 7 is mainly used to simulate a short-circuit fault in the high-voltage winding of the transformer, while the low-voltage short-circuit fault circuit 10 is mainly used to simulate a short-circuit fault in the low-voltage winding of the transformer. The axial inductance of the high-voltage short-circuit fault circuit 7 is 45mH, and the axial inductance of the low-voltage short-circuit fault circuit 10 is 220mH. When the simulated circuit is normal, port I of the double-control switch II is connected to port II; when the simulated circuit is short-circuited, port II of the double-control switch II is connected to port III.

[0053] The high-voltage axial displacement fault circuit 8 and the low-voltage axial displacement fault circuit 11 include a fault simulation capacitor II, a normal simulation capacitor II, and a double-control switch III. One end of the normal simulation capacitor II is connected to port I of the double-control switch III, and the other end is connected to the other end of the axial inductor. Port II of the double-control switch III is connected to port II of the double-control switch II. One end of the fault simulation capacitor II is connected to port III of the double-control switch III, and the other end is connected to the other end of the axial inductor. The high-voltage axial displacement fault circuit 8 is mainly used to simulate axial displacement faults in the high-voltage winding of the transformer, while the low-voltage axial displacement fault circuit 11 is mainly used to simulate axial displacement faults in the low-voltage winding of the transformer. The fault simulation capacitor II in the high-voltage axial displacement fault circuit 8 is 762pF, and the normal simulation capacitor II in the high-voltage axial displacement fault circuit 8 is 78pF. The fault simulation capacitor II in the low-voltage axial displacement fault circuit 11 is 390pF, and the normal simulation capacitor II in the low-voltage axial displacement fault circuit 11 is 39pF. When simulating a normal circuit, port I of double-control switch III is connected to port II of double-control switch III. When simulating an axial displacement fault of the transformer, port III of double-control switch III is connected to port II of double-control switch III.

[0054] like Figure 3 As shown, both the B-phase winding circuit and the C-phase winding circuit include a high-voltage winding circuit, a high-low voltage coupling circuit, and a low-voltage winding circuit. The high-voltage winding and the low-voltage winding are connected through the high-low voltage coupling circuit. The input port of the high-voltage winding circuit is connected to the input port of either the B-phase high-voltage winding or the C-phase high-voltage winding, and the output port of the high-voltage winding circuit is connected to the output port of either the B-phase high-voltage winding or the C-phase high-voltage winding. Similarly, the input port of the low-voltage winding circuit is connected to the input port of either the B-phase low-voltage winding or the C-phase low-voltage winding, and the output port of the low-voltage winding circuit is connected to the output port of either the B-phase low-voltage winding or the C-phase low-voltage winding.

[0055] The high-voltage winding circuit includes four high-voltage normal winding circuits connected in series. Each high-voltage normal winding circuit includes resistor I, resistor II, capacitor I, capacitor II, inductor I, inductor II, and inductor III. Inductors I, II, and III are connected in series. Resistor I and capacitor I are connected in parallel. One end of resistor I is connected to one end of inductor I, and the other end of resistor I is connected to inductor III and one end of resistor I in the next high-voltage normal winding circuit. Resistor II and capacitor II are connected in parallel. One end of resistor II and capacitor II is connected to one end of resistor I, and the other end of resistor II and capacitor II is connected to grounding port 5. The low-voltage winding circuit includes four series-connected low-voltage normal winding circuits, each consisting of resistor III, resistor IV, capacitor III, capacitor IV, and inductor IV. Resistor III and capacitor III are connected in parallel. One end of resistor III is connected to one end of inductor IV, and the other end of resistor III is connected to inductor IV and one end of resistor III in the next low-voltage winding circuit. Resistor IV and capacitor IV are connected in parallel, with one end of resistor IV and capacitor IV connected to one end of resistor III. The other ends of resistor IV and capacitor IV are connected to grounding port 5. The high-low voltage coupling circuit includes five parallel-connected normal high-low voltage coupling circuits, each consisting of capacitor V and resistor V. Capacitor V and resistor V are connected in parallel, with one end of capacitor V and resistor V connected to one end of inductor IV, and the other end of capacitor V and resistor V connected to one end of inductor I. Using high-voltage normal winding circuit, high-low voltage coupling circuit, and low-voltage normal winding circuit to represent the B and C phases of a three-phase transformer can be used for lateral comparison in winding deformation diagnosis. It can also be used to simulate different connection groups of a three-phase transformer by changing the wiring method of the first and last ports of the high and low voltage sides of the A, B, and C phase windings leading out of the top cover of the chassis.

[0056] like Figure 4 As shown, when performing frequency response testing, the experimental power supply and computer 17 are connected to the frequency response analyzer 19, and the signal terminal and input terminal of the frequency response analyzer 19 are connected to the X port of the fault simulation device through the wire 18. The A port of the fault simulation device is connected to the frequency response analyzer 19, and the grounding ports of the frequency response analyzer 19 and the fault simulation device are both grounded.

[0057] The method of using this fault simulation device with a frequency response tester is as follows:

[0058] S1: First, adjust the A-phase winding circuit in the simulation device to a normal circuit, and connect the frequency response analyzer 19 through the software of computer 17.

[0059] S2: Select the connection group for this simulation device. Common connection groups for two-winding transformers include Yyn0, Dyn11, and Yd11. The winding connection methods differ under different connection groups; please refer to the standard GB / T 6451-2015 "Technical Parameters and Requirements for Oil-Immersed Power Transformers" for details. This embodiment uses the Yd11 connection group as an example to perform frequency response testing on the A-phase high-voltage winding. The test wiring is as follows... Figure 5 As shown.

[0060] S3: Use the frequency response analyzer 19 to test the frequency response data of the simulation device when it is in normal condition, and transmit it to the computer 17. Use the software in the computer 17 to use the frequency response curve in the normal state as the reference data.

[0061] S4: Subsequently, by controlling the dual-control switch group 4, transformer winding short circuit, axial displacement and radial displacement faults at different positions and degrees are simulated, and the above-mentioned fault frequency response data are collected by computer 17 and frequency response analyzer 19, and compared with the normal frequency response curve. Figure 6 This is a frequency response curve of the A-phase high-voltage winding under Yd11 connection under normal conditions, short-circuit fault, axial displacement fault, and radial displacement fault.

[0062] S5: After completing the test, remove wire 18 and restore the double-control switch to normal status.

[0063] The specific steps for simulating the short-circuit fault on the high-voltage side of phase A are as follows:

[0064] S41: Adjust the double-control switch in the double-control switch group 4 corresponding to the inter-turn short circuit of the upper high-voltage winding of phase A, so that the high-voltage short-circuit fault circuit 7 in the high-voltage upper fault circuit is connected to the circuit.

[0065] S42: The computer 17 and frequency response analyzer 19 are used to collect experimental data and obtain the frequency response curve under the short circuit fault at the top of phase A.

[0066] To simulate a short-circuit fault on the high-voltage side of phase A at different locations, the specific steps are as follows:

[0067] S41: Adjust the double-control switch in the double-control switch group 4 corresponding to the inter-turn short circuit of the upper part of the high voltage winding of phase A, and use computer 17 and frequency response analyzer 19 to collect experimental data.

[0068] S42: Adjust the double-control switch corresponding to the inter-turn short circuit in the middle of the high-voltage winding of phase A, and at the same time adjust the double-control switch of the inter-turn short circuit in the upper part of the high-voltage winding of phase A to connect to the normal circuit, so that only the fault circuit in the middle of the high-voltage winding of phase A is in a simulated short circuit state, and use computer 17 and frequency response analyzer 19 to collect experimental data.

[0069] S43: Adjust the double-control switch corresponding to the inter-turn short circuit at the lower part of the high-voltage winding of phase A, and at the same time adjust the double-control switch of the inter-turn short circuit in the middle part of the high-voltage winding of phase A to connect to the normal circuit, so that only the fault circuit at the lower part of the high-voltage winding of phase A is in a simulated short circuit state, and use computer 17 and frequency response analyzer 19 to collect experimental data.

[0070] The specific steps for simulating short-circuit faults on the high-voltage side of phase A at different degrees are as follows:

[0071] S41: Adjust the double-control switch in the double-control switch group 4 corresponding to the inter-turn short circuit of the upper part of the high voltage winding of phase A, and use computer 17 and frequency response analyzer 19 to collect experimental data.

[0072] S42: Adjust the double-control switch corresponding to the inter-turn short circuit in the middle of the high-voltage winding of phase A, so that the upper fault circuit and the middle fault circuit of the high-voltage winding of phase A are both in a simulated short circuit state, and use computer 17 and frequency response analyzer 19 to collect experimental data.

[0073] S43: Adjust the double-control switch corresponding to the inter-turn short circuit of the lower part of the high-voltage winding of phase A, so that the upper fault circuit, middle fault circuit and lower fault circuit of the high-voltage winding of phase A are all in a simulated short circuit state, and use computer 17 and frequency response analyzer 19 to collect experimental data. Figure 7 This is a comparison of frequency response curves for different degrees of short-circuit faults in the A-phase high-voltage winding under the Yd11 connection configuration. Based on... Figure 7 It can be seen that when a short-circuit fault occurs, the frequency response curve differs significantly from the normal frequency response curve. Furthermore, the degree of agreement decreases with increasing fault severity. In addition, during a short-circuit fault, the resonant point of the frequency response curve shifts to higher frequencies due to the reduction in the equivalent inductance of the winding. This trend becomes more pronounced as the fault severity increases.

[0074] The same principle applies to simulating axial or radial displacement faults of different degrees and locations.

[0075] The method of using this fault simulation device with the short-circuit impedance meter 20 is as follows:

[0076] S1: Select the high and low voltage connection groups of the fault simulation device. Common connection groups include Yyn0, Dyn11, Yd11, etc. This embodiment adopts the Yd11 connection group mode.

[0077] S2: Adjust the A-phase winding circuit in the fault simulation device to a normal circuit, and connect the short-circuit impedance meter 20 to the fault simulation device. Since the short-circuit impedance test wiring method differs under different connection groups (refer to "DL / T1093-2018 Guidelines for Reactance Method Detection and Judgment of Winding Deformation of Power Transformers" for details), considering that this embodiment uses the Yd11 connection group, the following method is adopted. Figure 8 The method for measuring the short-circuit impedance of a three-phase transformer under Y-connection is as follows: The short-circuit impedance meter 20 is connected to the experimental power supply. The A port of the fault simulation device is connected to the U port of the short-circuit impedance meter 20 via wire 18. a Ports and I a The ports are connected, with port B of the fault simulation device connected to port U of the short-circuit impedance meter 20. b Ports and I b The C port of the fault simulation device is connected to the U port of the short-circuit impedance meter 20. c Ports and I c The ports are connected, and ports a, b, and c of the fault simulation device are connected. The short-circuit impedance meter 20 and the grounding port N of the fault simulation device are both grounded.

[0078] S3: The short-circuit impedance value of the fault simulation device under normal conditions is measured by the short-circuit impedance meter 20.

[0079] S4: Simulate faults such as short circuits, axial displacement, and radial displacement at different locations and degrees on the device. Use the short-circuit impedance meter 20 to obtain short-circuit impedance data under the above fault conditions and compare it with normal data to observe the difference between normal and faulty short-circuit impedance data. Since axial displacement and radial displacement faults have little impact on the equivalent parameters of the transformer, it is difficult to distinguish between the two. Therefore, this embodiment only shows the impedance test data of the A-phase winding when it is normal and when there is a short circuit fault. Table 1 shows the impedance, reactance, and resistance data of the A-phase winding under the three-phase three-wire short-circuit impedance test method of the Y-connected transformer when it is normal and when there is a slight short circuit fault, obvious short circuit fault, and severe short circuit fault. As can be seen from Table 1, since the short-circuit impedance test obtains data between two phases, if a short circuit fault occurs in the A-phase winding, it will simultaneously cause the short-circuit impedance data of both AB and CA, which contain the A-phase, to show a decreasing trend.

[0080] Table 1 Comparison of three-phase short-circuit impedance data of the fault simulation device under different conditions

[0081]

[0082]

[0083] S5: After completing the test wiring, remove wire 18.

[0084] The simulation of the above fault, taking a short circuit on the high-voltage side of phase A as an example, involves the following specific steps:

[0085] S41: Adjust the double-control switch in the double-control switch group 4 corresponding to the inter-turn short circuit of the upper high-voltage winding of phase A, so that the high-voltage short-circuit fault circuit 7 in the high-voltage upper fault circuit is connected to the circuit.

[0086] S42: Use short-circuit impedance meter 20 to collect experimental data and obtain short-circuit impedance data when there is a short-circuit fault in the upper part of phase A.

[0087] To simulate a short-circuit fault on the high-voltage side of phase A at different locations, the specific steps are as follows:

[0088] S41: Adjust the double-control switch in the double-control switch group 4 corresponding to the inter-turn short circuit of the upper part of the high voltage winding of phase A, and use the short-circuit impedance meter 20 to collect experimental data.

[0089] S42: Adjust the double-control switch corresponding to the inter-turn short circuit in the middle of the high-voltage winding of phase A, and at the same time adjust the double-control switch of the inter-turn short circuit in the upper part of the high-voltage winding of phase A to connect to the normal circuit, so that only the fault circuit in the middle part of the high-voltage winding of phase A is in a simulated short circuit state, and use the short-circuit impedance meter 20 to collect experimental data.

[0090] S43: Adjust the double-control switch corresponding to the inter-turn short circuit at the lower part of the high-voltage winding of phase A, and at the same time adjust the double-control switch of the inter-turn short circuit in the middle part of the high-voltage winding of phase A to connect to the normal circuit, so that only the lower fault circuit in the high-voltage winding of phase A is in a simulated short circuit state, and use the short-circuit impedance meter 20 to collect experimental data.

[0091] The specific steps for simulating short-circuit faults on the high-voltage side of phase A at different degrees are as follows:

[0092] S41: Adjust the double-control switch in the double-control switch group 4 corresponding to the inter-turn short circuit of the upper part of the high voltage winding of phase A, and use the short-circuit impedance meter 20 to collect experimental data.

[0093] S42: Adjust the double-control switch corresponding to the inter-turn short circuit in the middle of the high-voltage winding of phase A, so that the upper fault circuit and the middle fault circuit of the high-voltage winding of phase A are both in a simulated short circuit state, and use the short-circuit impedance meter 20 to collect experimental data.

[0094] S43: Adjust the double-control switch corresponding to the inter-turn short circuit of the lower part of the high-voltage winding of phase A, so that the upper fault circuit, middle fault circuit and lower fault circuit of the high-voltage winding of phase A are all in a simulated short circuit state, and use the short-circuit impedance meter 20 to collect experimental data.

[0095] This principle can be applied to simulate axial or radial displacement faults of different locations and degrees.

[0096] Figure 9 By comparing the fault simulation device under Yd11 connection with the normal frequency response curve of phase A of a real three-phase transformer, the feasibility of using the device of the present invention to simulate the winding deformation fault of a real transformer is further demonstrated.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A three-phase transformer winding deformation fault simulation device based on an equivalent network, characterized in that, The device includes a metal chassis (1), an equivalent circuit board is installed inside the metal chassis (1), and a grounding port (5), a wiring port and a double-control switch group (4) are installed on the top of the metal chassis (1). The metal chassis (1) is connected to the grounding port (5), and the grounding port (5), the wiring port and the double-control switch group (4) are all connected to the equivalent circuit board. The wiring port includes a high-voltage winding wiring port (2) and a low-voltage winding wiring port (3). Both the high-voltage winding wiring port (2) and the low-voltage winding wiring port (3) are connected to the equivalent circuit board. The high-voltage winding connection port (2) includes a high-voltage winding input port group and a high-voltage winding output port group. The high-voltage winding input port group includes the A-phase high-voltage winding input port, the B-phase high-voltage winding input port and the C-phase high-voltage winding input port. The high-voltage winding output port group includes the A-phase high-voltage winding output port, the B-phase high-voltage winding output port and the C-phase high-voltage winding output port. The A-phase high-voltage winding input port, the B-phase high-voltage winding input port, the C-phase high-voltage winding input port, the A-phase high-voltage winding output port, the B-phase high-voltage winding output port and the C-phase high-voltage winding output port are all connected to the equivalent circuit board. The low-voltage winding connection port (3) includes a low-voltage winding input port group and a low-voltage winding output port group. The low-voltage winding input port group includes the A-phase low-voltage winding input port, the B-phase low-voltage winding input port and the C-phase low-voltage winding input port. The low-voltage winding output port group includes the A-phase low-voltage winding output port, the B-phase low-voltage winding output port and the C-phase low-voltage winding output port. The A-phase low-voltage winding input port, the B-phase low-voltage winding input port, the C-phase low-voltage winding input port, the A-phase low-voltage winding output port, the B-phase low-voltage winding output port and the C-phase low-voltage winding output port are all connected to the equivalent circuit board. The equivalent circuit board includes an A-phase winding circuit, a B-phase winding circuit and a C-phase winding circuit. The A-phase winding circuit, the B-phase winding circuit and the C-phase winding circuit are all connected to the grounding port (5) and the wiring port. The A-phase winding circuit is connected to the double-control switch group (4). The double-control switch group (4) includes the A-phase high voltage winding double-control switch group and the A-phase low voltage winding double-control switch group. Each switch group contains 9 types of fault simulation double-control switches, namely the upper inter-turn short circuit double-control switch, the middle inter-turn short circuit double-control switch, the lower inter-turn short circuit double-control switch, the upper axial displacement double-control switch, the middle axial displacement double-control switch, the lower axial displacement double-control switch, the upper radial displacement double-control switch, the middle radial displacement double-control switch and the lower radial displacement double-control switch. The switches of the double-control switch group (4) are all connected to the equivalent circuit board. The A-phase winding circuit includes a high-voltage fault circuit, a low-voltage fault circuit, a high-voltage normal circuit, a low-voltage normal circuit, and a high-low voltage coupling circuit (9). The high-voltage fault circuit is connected to the low-voltage fault circuit through the high-low voltage coupling circuit (9), and the high-voltage normal branch is connected to the low-voltage normal circuit through the high-low voltage coupling circuit (9). The high-voltage fault circuit includes a high-voltage upper fault circuit, a high-voltage middle fault circuit, and a high-voltage lower fault circuit. The low-voltage fault circuit includes a low-voltage upper fault circuit, a low-voltage middle fault circuit, and a low-voltage lower fault circuit. The high-voltage upper fault circuit, high-voltage middle ... Both the high-voltage upper fault circuit and the high-voltage middle fault circuit include a high-voltage radial displacement fault branch (6), a high-voltage short-circuit fault branch (7), and a high-voltage axial displacement fault branch (8). The high-voltage short-circuit fault branch (7) and the high-voltage axial displacement fault branch (8) are connected in parallel. Both the low-voltage upper fault circuit, the low-voltage middle fault circuit, and the low-voltage lower fault circuit include a low-voltage short-circuit fault branch (10), a low-voltage axial displacement fault branch (11), and a low-voltage radial displacement fault branch (12). The low-voltage short-circuit fault branch (10) and the low-voltage axial displacement fault branch (11) are connected in parallel. The high-voltage normal circuit includes a high-voltage normal radial branch (13) and a high-voltage normal axial branch (14), and the low-voltage normal circuit includes a low-voltage normal radial branch (16) and a low-voltage normal axial branch (15); the high-low voltage coupling circuit (9) includes five high-low voltage coupling branches. The B-phase winding circuit and the C-phase winding circuit both include a high-voltage winding circuit, a high-low voltage coupling circuit and a low-voltage winding circuit. The high-voltage winding and the low-voltage winding are connected through the high-low voltage coupling circuit. The high-voltage winding circuit includes four high-voltage normal winding circuits connected in series. The high-voltage normal winding circuit includes resistor I, resistor II, capacitor I, capacitor II, inductor I, inductor II and inductor III. Inductor I, inductor II and inductor III are connected in series. Resistor I and capacitor I are connected in parallel. One end of resistor I is connected to one end of inductor I. The other end of resistor I is connected to inductor III and one end of resistor I of the next high-voltage normal winding circuit. Resistor II and capacitor II are connected in parallel. One end of resistor II and capacitor II is connected to one end of resistor I. The other end of resistor II and capacitor II is grounded through the grounding port (5). The low-voltage winding circuit includes four series-connected low-voltage normal winding circuits. The low-voltage normal winding circuit includes resistor III, resistor IV, capacitor III, capacitor IV, and inductor IV. Resistor III and capacitor III are connected in parallel. One end of resistor III is connected to one end of inductor IV. The other end of resistor III is connected to inductor IV and one end of resistor III of the next low-voltage normal winding circuit. Resistor IV and capacitor IV are connected in parallel. One end of resistor IV and capacitor IV is connected to one end of resistor III. The other end of resistor IV and capacitor IV is connected to the grounding port (5). The high-low voltage coupling circuit includes capacitor V and resistor V, which are connected in parallel. One end of resistor V is connected to one end of inductor IV, and the other end of resistor V is connected to one end of resistor I and inductor I. The input port of the high-voltage winding circuit is connected to one end of inductor I, resistor I, resistor II, capacitor I, and capacitor II; the output port of the high-voltage winding circuit is connected to the other end of inductor III, resistor I, and capacitor I, and the other end of resistor II and capacitor II. The input port of the low-voltage winding circuit is connected to one end of resistor III, resistor IV, capacitor III, capacitor IV, and inductor IV; the output port of the low-voltage winding circuit is connected to the other end of resistor III, capacitor III, and inductor IV, and one end of resistor IV and capacitor IV.

2. The three-phase transformer winding deformation fault simulation device based on equivalent network according to claim 1, characterized in that, One end of the high voltage normal radial branch (13), the high voltage normal axial branch (14), and the first high-low voltage coupling branch is connected to the input port of the high voltage winding of phase A. The other end of the high voltage normal radial branch (13) is grounded through the grounding port (5). The other end of the first high-low voltage coupling branch, the low voltage normal axial branch (15), and the low voltage normal radial branch (16) are connected to the input port of the low voltage winding of phase A. The other end of the low voltage normal radial branch (16) is grounded through the grounding port (5). The other end of the high-voltage normal axial branch (14) is connected to one end of the high-voltage short-circuit fault branch (7), high-voltage radial displacement fault branch (6), and high-voltage axial displacement fault branch (8) in the high-voltage upper fault circuit and one end of the second high-low voltage coupling branch. The other end of the high-voltage radial displacement fault branch (6) in the high-voltage upper fault circuit is grounded through the grounding port (5). The other end of the second high-low voltage coupling branch is connected to the other end of the low-voltage normal axial branch (15) and one end of the low-voltage short-circuit fault branch (10), low-voltage radial displacement fault branch (12), and low-voltage axial displacement fault branch (11) in the low-voltage upper fault circuit. The other end of the low-voltage radial displacement fault branch (12) in the low-voltage upper fault circuit is grounded through the grounding port (5). The other end of the high voltage short circuit fault branch (7) and the high voltage axial displacement fault branch (8) in the high voltage upper fault circuit are connected to one end of the high voltage radial displacement fault branch (6), the high voltage short circuit fault branch (7), the high voltage axial displacement fault branch (8) in the high voltage middle fault circuit and one end of the third high-low voltage coupling branch. The other end of the high voltage radial displacement fault branch (6) in the high voltage middle fault circuit is grounded through the grounding port (5). The other end of the third high-low voltage coupling branch is connected to the other end of the low voltage short circuit fault branch (10) and the low voltage axial displacement fault branch (11) in the low voltage upper fault circuit and one end of the low voltage radial displacement fault branch (12), the low voltage short circuit fault branch (10), and the low voltage axial displacement fault branch (11) in the low voltage middle fault circuit. The other end of the low voltage radial displacement fault branch (12) in the low voltage middle fault circuit is grounded through the grounding port (5). The other end of the high voltage short circuit fault branch (7) and the high voltage axial displacement fault branch (8) in the high voltage middle fault circuit are connected to one end of the high voltage radial displacement fault branch (6), the high voltage short circuit fault branch (7), the high voltage axial displacement fault branch (8) in the high voltage lower fault circuit and one end of the fourth high-low voltage coupling branch. The other end of the high voltage radial displacement fault branch (6) in the high voltage lower fault circuit is grounded through the grounding port (5). The other end of the fourth high-low voltage coupling branch is connected to the other end of the low voltage short circuit fault branch (10) and the low voltage axial displacement fault branch (11) in the low voltage middle fault circuit and one end of the low voltage radial displacement fault branch (12), the low voltage short circuit fault branch (10), and the low voltage axial displacement fault branch (11) in the low voltage lower fault circuit. The other end of the low voltage radial displacement fault branch (12) in the low voltage lower fault circuit is grounded through the grounding port (5). The other end of the high voltage short circuit fault branch (7) and the high voltage axial displacement fault branch (8) in the high voltage lower fault circuit are connected to the next high voltage normal radial branch (13), one end of the fifth high-low voltage coupling branch and the output port of the A phase high voltage winding. The other end of the next high voltage normal radial branch (13) is grounded through the grounding port (5). The other end of the fifth high-low voltage coupling branch is connected to the other end of the low voltage short circuit fault branch (10) and the low voltage axial displacement fault branch (11) in the low voltage lower fault circuit circuit, one end of the next low voltage normal radial branch (16) and the output port of the A phase low voltage winding. The other end of the next low voltage normal radial branch (16) is grounded through the grounding port (5).

3. The three-phase transformer winding deformation fault simulation device based on equivalent network according to claim 2, characterized in that, The high-voltage radial displacement fault branch (6) and the low-voltage radial displacement fault branch (12) both include a fault simulation capacitor I, a normal simulation capacitor I, and a double-control switch I. One end of the normal simulation capacitor I is connected to port I of the double-control switch I, and the other end of the normal simulation capacitor I is connected to the grounding port (5). Port II of the double-control switch I is connected to port II of the double-control switch II. One end of the fault simulation capacitor I is connected to port III of the double-control switch I, and the other end of the fault simulation capacitor I is connected to the grounding port (5). The upper radial displacement switch, the middle radial displacement switch, and the lower radial displacement switch of the double-control switch group (4) are connected to the high-voltage radial displacement fault branch (6) and the low-voltage radial displacement fault branch (12).

4. The three-phase transformer winding deformation fault simulation device based on equivalent network according to claim 3, characterized in that, Both the high-voltage short-circuit fault branch (7) and the low-voltage short-circuit fault branch (10) include an axial inductor and a double-control switch II. The axial inductor includes normal inductor I, normal inductor II, and normal inductor III, which are connected in series. Port I of the double-control switch II is connected to one end of the axial inductor, and port II of the double-control switch II is connected to the other end of the axial inductor of the previous unit. Port III of the double-control switch II is connected to the other end of the axial inductor.

5. The three-phase transformer winding deformation fault simulation device based on an equivalent network according to claim 3 or 4, characterized in that, The high-voltage axial displacement fault branch (8) and the low-voltage axial displacement fault branch (11) include a fault simulation capacitor II, a normal simulation capacitor II and a double-control switch III. One end of the normal simulation capacitor II is connected to port I of the double-control switch III, and the other end of the normal simulation capacitor II is connected to the other end of the axial inductor. Port II of the double-control switch III is connected to port II of the double-control switch II. One end of the fault simulation capacitor II is connected to port III of the double-control switch III, and the other end of the fault simulation capacitor II is connected to the other end of the axial inductor. The upper axial displacement switch, the middle axial displacement switch and the lower axial displacement switch of the double-control switch group (4) are connected to the high-voltage axial displacement fault branch (8) and the low-voltage axial displacement fault branch (11).

6. The three-phase transformer winding deformation fault simulation device based on equivalent network according to claim 5, characterized in that, The high-low voltage coupling circuit (9) includes five high-low voltage coupling branches. Each high-low voltage coupling branch includes a coupling capacitor and a coupling resistor connected in parallel. One end of the first high-low voltage coupling branch is connected to one end of the high-voltage normal radial branch (13) and the high-voltage normal axial branch (14) and the input port of the A-phase high-voltage winding. The other end of the first high-low voltage coupling branch is connected to one end of the low-voltage normal axial branch (15) and the low-voltage normal radial branch (16) and the input port of the A-phase low-voltage winding. The second high-low voltage coupling... One end of the high-voltage coupling branch is connected to one end of the high-voltage radial displacement fault branch (6), high-voltage short-circuit fault branch (7), and high-voltage axial displacement fault branch (8) in the high-voltage upper fault circuit, and the other end of the high-voltage normal axial branch (14). The other end of the second high-low voltage coupling branch is connected to one end of the low-voltage short-circuit fault branch (10), low-voltage axial displacement fault branch (11), and low-voltage radial displacement fault branch (12) in the low-voltage upper fault circuit, and the other end of the low-voltage normal axial branch (15). The fifth high-low voltage coupling branch... One end of the combined branch is connected to the other end of the high-voltage short-circuit fault branch (7) and the high-voltage axial displacement fault branch (8) in the high-voltage lower fault circuit, one end of the high-voltage normal radial branch (13) and the output port of the A-phase high-voltage winding; the other end of the fifth high-low voltage coupling branch is connected to the other end of the low-voltage short-circuit fault branch (10) and the low-voltage axial displacement fault branch (11) in the low-voltage lower fault circuit, one end of the low-voltage normal radial branch (16) and the output port of the A-phase low-voltage winding; one end of the other two high-low voltage coupling branches The other end of the high-voltage short-circuit fault branch (7) and the high-voltage axial displacement fault branch (8) is connected to one end of the next set of high-voltage radial displacement fault branches (6), high-voltage short-circuit fault branches (7) and high-voltage axial displacement fault branches (8). The other ends of the other two high- and low-voltage coupling branches are connected to one end of the low-voltage short-circuit fault branch (10) and the low-voltage axial displacement fault branch (11) and one end of the next set of low-voltage short-circuit fault branches (10), low-voltage axial displacement fault branches (11) and low-voltage radial displacement fault branches (12).

7. The three-phase transformer winding deformation fault simulation device based on equivalent network according to claim 6, characterized in that, The high-voltage normal radial branch (13) and the low-voltage normal radial branch (16) include radial capacitors and radial resistors, which are connected in parallel. One end of the first high-voltage normal radial branch (13) is connected to one end of the first high-voltage coupling branch in the high-low voltage coupling circuit (9), one end of the high-voltage normal axial branch (14), and the input port of the A-phase high-voltage winding. The other end of the first high-voltage normal radial branch (13) is grounded through the grounding port (5). One end of the second high-voltage normal radial branch (13) is connected to one end of the fifth high-voltage coupling branch in the high-low voltage coupling circuit (9), the other end of the high-voltage short-circuit fault branch (7) and the high-voltage axial displacement fault branch (8) in the high-voltage lower fault circuit, and the output port of the A-phase high-voltage winding. The other end of the radial branch (13) is grounded through the grounding port (5); one end of the first low-voltage normal radial branch (16) is connected to the other end of the first high-low voltage coupling branch in the high-low voltage coupling circuit (9), one end of the low-voltage normal axial branch (15) and the input port of the A-phase low-voltage winding, and the other end of the first low-voltage normal radial branch (16) is grounded through the grounding port (5); one end of the second low-voltage normal radial branch (16) is connected to the other end of the fifth high-low voltage coupling branch in the high-low voltage coupling circuit (9), the other end of the low-voltage short-circuit fault branch (10) and the low-voltage axial displacement fault branch (11) in the high-voltage lower fault circuit and the output port of the A-phase low-voltage winding, and the other end of the second low-voltage normal radial branch (16) is grounded through the grounding port (5).

8. The three-phase transformer winding deformation fault simulation device based on equivalent network according to claim 7, characterized in that, The high-voltage normal axial branch (14) and the low-voltage normal axial branch (15) include axial inductance, axial capacitance and axial resistance. The axial inductance includes inductor IV, inductor V and inductor VI. Inductor IV, inductor V and inductor VI are connected in series. The axial inductance, axial capacitance and axial resistance are connected in parallel. One end of the high-voltage normal axial branch (14) is connected to the input port of the A-phase high-voltage winding, one end of the high-voltage normal radial branch (13), and one end of the first high-low voltage coupling branch in the high-low voltage coupling circuit (9). The other end of the high-voltage normal axial branch (14) is connected to one end of the high-voltage radial displacement fault branch (6), the high-voltage short-circuit fault branch (7), and the high-voltage axial displacement fault branch (8) in the high-voltage upper fault circuit, and one end of the second high-low voltage coupling branch in the high-low voltage coupling circuit (9); low voltage One end of the normal axial branch (15) is connected to the input port of the low-voltage winding of phase A, one end of the low-voltage normal radial branch (16) and the other end of the first high-low voltage coupling branch in the high-low voltage coupling circuit (9). The other end of the low-voltage normal axial branch (15) is connected to one end of the low-voltage short-circuit fault branch (10), the low-voltage axial displacement fault branch (11), the low-voltage radial displacement fault branch (12) in the low-voltage upper fault circuit and the other end of the second high-low voltage coupling branch in the high-low voltage coupling circuit (9).

Images