A hydro-generator single-phase grounding fault simulation system, method and application

Abstract

The invention discloses a single-phase grounding fault simulation system, method and application of a hydro-turbine generator, and relates to the technical field of fault simulation of hydro-turbine generators, including a test bench, a voltage regulator, a transformer, a circuit breaker, a current limiting resistor, a test system for collecting current and voltage characteristic values ​​before and after the simulated fault, and a test console for controlling the voltage regulator, the transformer and the circuit breaker; a stator bar and a stator core are installed in the test bench; one end of the test bench is grounded, and the other end is connected to the transformer through a circuit breaker; the transformer is a step-up transformer, the low-voltage side of the transformer is connected to the voltage regulator, and the high-voltage side of the transformer adopts a star connection structure, the neutral point of the star connection structure is connected to one end of the current limiting resistor, and the other end of the current limiting resistor is grounded. The invention realizes the simulation of the three-phase voltage, neutral point and grounded phase of the generator, can simulate the terminal voltage and fault current of the generator, and can accurately control the time when the core fault occurs.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic generator fault simulation, and more specifically to a hydraulic generator single-phase grounding fault simulation system, method and application. Background Art

[0002] Generators are an important part of the power system, and any failure will have a significant impact on the stability of the power system. Among all types of generator failures, operating experience and theoretical analysis have shown that internal faults in the stator winding are the most serious damage to the generator; in contrast, although the damage to the generator caused by a single-phase grounding fault in the stator winding is relatively minor, it is the most common fault that causes insulation damage to the generator stator winding.

[0003] Since it is an extremely difficult task to detect and eliminate the melting and welding phenomenon of the core laminations of generators, especially large generators, the study of single-phase grounding fault safety current is one of the major issues in the safe operation of large generators.

[0004] In the prior art, a Chinese patent document with publication number CN213149179U discloses a generator stator grounding protection and diagnostic device, which relates to the technical field of generator protection and solves the problem that the existing generator protection device cannot accurately distinguish whether the fault occurs inside or outside the zone, resulting in a large range of possible faults and a long time to eliminate the fault. The device includes a generator protection device and a negative-sequence power detection device. The negative-sequence power detection device includes a DSP processor, a single-chip microcomputer controller, a voltage / current transformer, an analog quantity acquisition circuit, and a liquid crystal display; the DSP processor is connected to the single-chip microcomputer controller; the voltage / current transformer is connected in series with the analog quantity acquisition circuit and then connected to the DSP processor; the switch liquid crystal display is connected to the single-chip microcomputer controller; the device has high sensitivity, and the negative-sequence power does not lock the single-phase grounding protection action, but only displays whether the fault point is inside or outside the zone, thereby greatly reducing the scope of fault elimination, reducing the difficulty and time of fault elimination, and improving the diagnostic efficiency.

[0005] The above patent discloses that a single-phase grounding fault of a generator can be simulated by using an analog quantity acquisition circuit, but does not disclose how to perform the simulation. Summary of the invention

[0006] In order to overcome the defects existing in the above-mentioned prior art, the purpose of the present invention is to provide a single-phase grounding fault simulation system, method and application of a hydro-turbine generator. By changing the voltage of the voltage regulator, the terminal-to-ground voltage of various generators of different capacity levels can be simulated, the discharge of the generator stator wire rod to the core can be simulated, and the stator core fault of the generator can be simulated; by controlling the circuit breaker and the current limiting resistor, the discharge time of the stator wire rod to the stator core and the degree of burning of the stator core sheets can be simulated, and the allowable value of the stator core fault grounding current of the generator can be obtained. According to the test results, relevant theoretical analysis and research can be carried out to master the physical laws of the influence of the fault current on the stator core.

[0007] In order to achieve the above objectives, the technical solution adopted by the present invention is:

[0008] A single-phase grounding fault simulation system for a hydro-turbine generator, comprising a test bench, a voltage regulator, a transformer, a circuit breaker, a current limiting resistor, a test system for collecting current and voltage characteristic values ​​before and after the simulated fault, and a test console for controlling the operation of the voltage regulator, the transformer, and the circuit breaker;

[0009] The test bench is equipped with stator bars and stator cores; one end of the test bench is grounded, and the other end is connected to a transformer through a circuit breaker; the transformer is a step-up transformer, the low-voltage side of the transformer is connected to a voltage regulator, and the high-voltage side of the transformer adopts a star connection structure, the neutral point of the star connection structure is connected to one end of a current limiting resistor, and the other end of the current limiting resistor is grounded;

[0010] The voltage regulator, transformer and circuit breaker are respectively connected to the test console;

[0011] The test system is respectively connected to the high voltage side of the transformer, the circuit breaker, the grounding end of the current limiting resistor and the grounding end of the test bench.

[0012] Furthermore, the three end wires of the star connection structure form three different simulation circuits with the test bench through the switching of the circuit breaker.

[0013] Furthermore, the test console is provided with a time relay for controlling the on and off of the circuit breaker.

[0014] Further, the test system includes a recorder for collecting current and voltage characteristic values ​​before and after the simulated fault, a three-phase high-voltage voltage transformer, a first high-voltage voltage transformer, a second high-voltage voltage transformer, a first current transformer and a second current transformer;

[0015] A first current transformer is arranged on the grounding line of the current limiting resistor, and is connected to the oscilloscope through the first current transformer;

[0016] A first high-voltage voltage transformer is arranged on the line of the star connection structure and the current-limiting resistor, and is connected to the wave recorder through the first high-voltage voltage transformer;

[0017] The three end wires of the star connection structure are respectively connected to a three-phase high-voltage voltage transformer, and connected to a wave recorder through the three-phase high-voltage voltage transformer;

[0018] A second high-voltage voltage transformer is provided on the line between the circuit breaker and the test bench, and is connected to the recorder via the second high-voltage voltage transformer;

[0019] A second current transformer is arranged on the grounding circuit of the test bench and is connected to the oscilloscope through the second current transformer.

[0020] Furthermore, the neutral points of the three-phase high-voltage voltage transformers are all grounded.

[0021] Furthermore, the circuit breaker is a high-voltage vacuum circuit breaker.

[0022] Furthermore, the current limiting resistor is a high-voltage current limiting resistor with different gears.

[0023] Furthermore, a plurality of stator bars and stator cores are installed in the test bench;

[0024] The stator core is provided with a plurality of stator slots, and the stator wire rods are placed on the stator slots; the stator core is formed by a plurality of stator silicon steel sheets, and the plurality of stator cores are arranged in sequence, and ventilation slot plates are provided at both upper and lower ends of the connection between two adjacent stator cores, and ventilation slot steel is provided between the two ventilation slot plates; a positioning slot is provided on the outer wall of the stator core, and the positioning ribs pass through the positioning slots of the plurality of stator cores in sequence; a pressure plate is provided on the outer side of the first and last stator cores, and a pull-in screw passes through the two pressure plates, and a nut is sleeved on the pull-in screw to lock the plurality of stator cores.

[0025] Furthermore, the stator slot is a U-shaped slot, including a stator core slot bottom at the bottom end, a stator slot opening for installing a slot wedge at the top end, and stator slot side surfaces at both sides.

[0026] Based on the above simulation system, the present invention also provides a method for simulating a single-phase grounding fault of a hydro-generator, including an installation inspection step, a fault simulation step and an information collection step;

[0027] The installation inspection step includes installing the stator bars and stator core on a test bench and inspecting the system circuits;

[0028] The fault simulation step is as follows: after the installation and inspection are completed, the three-phase power supply is connected to the voltage regulator, and the voltage value of the transformer is increased by the test console to make it equal to the terminal voltage of the generator; and the time of the time relay on the test console is set, and the circuit breaker is closed; after the fault time is reached, the power supply is disconnected;

[0029] In the information collection step, during fault simulation, the test system is used to collect and record characteristic values ​​of current and voltage before and after the simulated fault.

[0030] Finally, based on the above simulation system, the present invention also provides an application of a single-phase grounding fault simulation system for a hydro-generator, and the simulation system is applied to the following tests:

[0031] a. Simulate stator grounding faults of generators with different capacity levels;

[0032] b. Conduct ground fault simulation at different voltage levels and different levels of stator ground current;

[0033] c. Simulate stator ground fault with different protection tripping times;

[0034] d. Simulate the stator core grounding fault caused by different damage degrees of stator bars;

[0035] e. Simulate the stator core grounding fault of silicon steel sheets with different thicknesses;

[0036] f. Study the extent of stator core burning under various working conditions;

[0037] g. Study the simulation of grounding faults at various locations of the stator core;

[0038] h. Replace the core material with oriented or non-oriented one, and simulate the stator core failure;

[0039] i. Study the influence of magnetic field distribution, cooling conditions, etc. on stator grounding fault;

[0040] g. Determination of the safe current of single-phase ground fault of the generator stator winding;

[0041] k. Based on the test results, research and verify new analysis and calculation methods.

[0042] Beneficial effects of the present invention:

[0043] The single-phase grounding fault simulation system of the hydro-turbine generator provided by the present invention realizes the simulation of the three-phase voltage, neutral point and grounding phase of the generator on a simplified circuit through sophisticated design, can simulate the terminal voltage and fault current of the generator, can accurately control the time when the core fault occurs, can obtain the relationship between the degree of damage to the stator core caused by different current sizes to the generator stator and the fault current time, obtain the influence law on the safety of the core, and determine the safe current of the stator core grounding fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a schematic diagram of the present invention;

[0045] Figure 2 It is a schematic diagram of the test bench of the present invention;

[0046] Figure 3 It is a schematic diagram of the stator core of the present invention;

[0047] Reference numerals:

[0048] 1. Test bench; 2. Test control console; 3. Voltage regulator; 4. Transformer; 5. Circuit breaker; 6. Current limiting resistor; 7. Oscilloscope; 8. Three-phase high-voltage voltage transformer; 9. First high-voltage voltage transformer; 10. Second high-voltage voltage transformer; 11. First current transformer; 12. Second current transformer; 13. Stator wire rod; 14. Stator core; 15. Pressure plate; 16. Pull-in screw; 17. Nut; 18. Ventilation slot plate; 19. Positioning rib; 20. Stator silicon steel sheet; 21. Ventilation slot steel; 22. Stator core slot bottom; 23. Stator slot installation slot wedge; 24. Stator slot side. DETAILED DESCRIPTION

[0049] The concept, specific structure and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments and drawings to fully understand the purpose, characteristics and effects of the present invention.

[0050] Example 1

[0051] A single-phase grounding fault simulation system for a hydro-generator, such as Figure 1 As shown, it includes a test bench 1, a voltage regulator 3, a transformer 4, a circuit breaker 5, a current limiting resistor 6, a test system for collecting current and voltage characteristic values ​​before and after a simulated fault, and a test console 2 for controlling the operation of the voltage regulator 3, the transformer 4, and the circuit breaker 5.

[0052] The stator bar 13 and the stator core 14 are installed in the test bench 1; one end of the test bench 1 is grounded, and the other end is connected to the transformer 4 through the circuit breaker 5; the transformer 4 is a step-up transformer, the low-voltage side of the transformer 4 is connected to the voltage regulator 3, and the high-voltage side of the transformer 4 adopts a star connection structure, the neutral point of the star connection structure is connected to one end of the current limiting resistor 6, and the other end of the current limiting resistor 6 is grounded. The three end wires of the star connection structure are connected to the circuit breaker 5 to form three different simulation circuits with the test bench 1.

[0053] The voltage regulator 3 , the transformer 4 and the circuit breaker 5 are respectively connected to the test console 2 .

[0054] The test system is connected to the high voltage side of the transformer 4 , the circuit breaker 5 , the grounding terminal of the current limiting resistor 6 and the grounding terminal of the test bench 1 respectively.

[0055] In this embodiment, the voltage regulator 3, the transformer 4 and the circuit breaker 5 are controlled by the test console 2, and the prefabricated damaged stator bars are used to discharge the stator core, so as to achieve a simulated stator single-phase grounding fault test.

[0056] The test bench 1 is used to simulate the single-phase grounding fault of the hydro-generator. The test console 2 is used to control the operation of the voltage regulator 3, the transformer 4 and the circuit breaker 5. The test console 2 is provided with a time relay for controlling the on and off of the circuit breaker 5, and different times can be preset to perform simulation tests of different fault protection times.

[0057] The voltage regulator 3 and transformer 4 are mainly used as the source of stator core faults. The voltage regulator and transformer are used to adjust the voltage to the terminal voltage of the generator to be simulated. The voltage regulator is used to adjust the total line voltage, which can effectively expand the test voltage range. Transformer 4 uses a step-up transformer, and the high-voltage side of the transformer adopts a star connection method, which can completely simulate the generator terminal and neutral point; the step-up transformer can be used to perform simulation tests at 380V factory voltage.

[0058] Circuit breaker 5 is a high-voltage vacuum circuit breaker, which is used to simulate the loading of the generator terminal voltage. When the switch is closed, the time relay of the test console 2 starts timing. When the preset time of the time relay is reached, the circuit breaker is opened and disconnected, and the time is accurately controlled to simulate the generator stator grounding fault according to the generator protection tripping time.

[0059] The current limiting resistor 6 is a high-voltage current limiting resistor with different gears. The resistance values ​​of different gears are used to adjust the magnitude of the fault current and perform different fault current simulation tests.

[0060] The test system is used to collect the voltage value of each phase of the generator before and after the stator core fault, the core fault current value and the fault removal time, etc. The main purpose is to obtain the data in the simulation system of the core fault, which is used to analyze the generator fault current, fault time, fault voltage, fault power, etc.

[0061] Example 2

[0062] This embodiment is further improved on the basis of embodiment 1, such as Figure 1 As shown, the test system includes a recorder 7 for collecting current and voltage characteristic values ​​before and after a simulated fault, a three-phase high-voltage voltage transformer 8, a first high-voltage voltage transformer 9, a second high-voltage voltage transformer 10, a first current transformer 11 and a second current transformer 12.

[0063] A first current transformer 11 is arranged on the grounding line of the current limiting resistor 6 , and is connected to the oscilloscope 7 via the first current transformer 11 .

[0064] A first high-voltage voltage transformer 9 is provided on the line of the star connection structure and the current-limiting resistor 6 , and is connected to the recorder 7 via the first high-voltage voltage transformer 9 .

[0065] The three end wires of the star connection structure are respectively connected to the three-phase high-voltage voltage transformer 8, and connected to the recorder 7 through the three-phase high-voltage voltage transformer 8. The neutral points of the three-phase high-voltage voltage transformer 8 are all grounded.

[0066] A second high-voltage voltage transformer 10 is provided on the line between the circuit breaker 5 and the test bench 1 , and is connected to the wave recorder 7 via the second high-voltage voltage transformer 10 .

[0067] A second current transformer 12 is provided on the grounding line of the test bench 1 , and is connected to the oscilloscope recorder 7 via the second current transformer 12 .

[0068] In this embodiment, the test system is mainly composed of a recorder, a power transformer, a voltage transformer and a current transformer. The transformer accurately collects the voltage value of each phase of the generator before and after the stator core fault, the core fault current value and the fault removal time, etc., and transmits them to the recorder 7 for processing and display, and analyzes the generator fault current, fault time, fault voltage, fault power, etc. The recorder uses a high-precision waveform recorder, which can accurately capture the voltage and current waveforms before and after the fault, so as to accurately obtain the arcing power in the fault.

[0069] Example 3

[0070] This embodiment is further improved on the basis of embodiment 2, such as Figure 2 and 3 As shown, a plurality of stator bars 13 and a stator core 14 are installed in the test bench 1;

[0071] A plurality of stator slots are provided on the stator core 14, and the stator wire rods 13 are placed on the stator slots; the stator core 14 is formed by stacking a plurality of stator silicon steel sheets 20, and the plurality of stator cores 14 are arranged in sequence, and ventilation slot plates 18 are provided at both upper and lower ends of the connection between two adjacent stator cores 14, and ventilation slot steel 21 is provided between the two ventilation slot plates 18; positioning slots are provided on the outer wall of the stator core 14, and the positioning ribs 19 pass through the positioning slots of the plurality of stator cores 14 in sequence; pressure plates 15 are provided on the outer sides of the first and last stator cores 14, and a pull-in screw 16 passes through the two pressure plates 15, and a nut 17 is sleeved on the pull-in screw 16 to lock the plurality of stator cores 14.

[0072] In this embodiment, the test bench 1 is used to simulate a single-phase grounding fault of a hydro-turbine generator. Specifically, a stator wire rod 13 and a stator core 14 are installed on the test bench 1. The stator core is made of stator silicon steel sheets 20 stacked together. Several sections of the stator core 14 are taken, and the pressure plates 15 at both ends are used. The pressure plates 15 are pulled in and tightened by the screws 16 and nuts 17. The stator core 14, the ventilation slot plate 18, the ventilation slot steel 21, the positioning ribs 19, etc. are installed in a non-overlapping manner. The corresponding stator wire rods 13 can be placed in different positions to carry out the test.

[0073] The stator slot is a U-shaped slot, including a stator core slot bottom 22 at the bottom, a stator slot opening installation slot wedge 23 at the top, and stator slot side surfaces 24 at both sides, so as to facilitate the study of grounding position fault simulation at various locations of the stator core.

[0074] Example 4

[0075] Based on Example 3, this embodiment provides a method for simulating a single-phase grounding fault of a hydro-generator, including an installation inspection step, a fault simulation step, and an information collection step;

[0076] The installation inspection step includes installing the stator bars 13 and the stator core 14 on the inspection bench 1 and inspecting the system circuits;

[0077] In the fault simulation step, after the installation and inspection, the three-phase power supply is connected to the voltage regulator 3, and the voltage value of the transformer 4 is increased by the test console 2 to be equal to the terminal voltage of the generator; and the time of the time relay on the test console 2 is set, and then the circuit breaker 5 is closed to simulate the single-phase grounding fault of the hydro-generator; after the fault time is reached, the power supply is disconnected;

[0078] In the information collection step, during fault simulation, the test system is used to collect and record characteristic values ​​of current and voltage before and after the simulated fault.

[0079] Example 5

[0080] Based on Example 3, the simulation system can be applied to the following experimental studies:

[0081] 1. Simulate stator grounding faults of generators with different capacity levels

[0082] Generator capacity , where S is the generator capacity, U is the generator terminal line voltage, I is the stator current of the generator. When the generator capacity is different, its voltage level is different, that is, U is different. At the same time, due to the selection and calculation of the neutral point grounding equipment of the generator, its grounding current is also different. The grounding fault simulation parameters of generators of different capacities are different. This simulation system can study the grounding fault of generators of different capacity levels.

[0083] 2. Simulate ground faults at different voltage levels and different levels of stator ground current

[0084] The burning degree of ground fault is quantified by different voltage levels. The burning degree of ground fault is judged by different levels of ground current. The purpose is to fix one parameter and change another variable to simulate the ground fault.

[0085] 3. Simulate stator ground fault with different protection tripping times

[0086] Take a generator in a power station as an example. When the generator stator core is grounded, 95% of the grounding protection will be activated. The protection action time is 32 milliseconds, the delay is 0.5 seconds, and the switch opening time is 58 milliseconds. Therefore, the total fault removal time is 0.6 seconds. In addition, after the fault is removed, the no-load time constant of the generator is 9 seconds. Therefore, it is necessary to study the simulation of ground faults with different protection tripping times.

[0087] 4. Simulate stator core grounding faults caused by different degrees of damage to stator bars

[0088] The stator core grounding fault is caused by the stator bar insulation being damaged and then discharging with the core to ground. The degree of core burnout caused by the core grounding fault varies depending on the degree of damage to the stator bar. It is necessary to discharge the stator core on stator bars with different degrees of damage to simulate the stator core fault.

[0089] 5. Simulate the stator core grounding fault of silicon steel sheets with different thicknesses

[0090] According to the actual requirements of different power stations, the electromagnetic parameters in the generator design are different. The parameters of the stator core are different, and the stator core of the generator uses silicon steel sheets 20 of different thicknesses. To study different generators, it is necessary to simulate the grounding fault of the stator core of silicon steel sheets 20 of different thicknesses.

[0091] 6. Study the degree of stator core burning under various working conditions

[0092] The ground fault current flows to the ground through the stator core, which may cause damage to the core. The manufacturing and installation process of the stator core of modern large-scale generators is complex and difficult to repair. If a serious core failure occurs, it will cause huge economic losses. The degree of core damage is a relative concept and can be divided according to the on-site repair capability of the core damage. The core damage is divided into grades according to the core damage repair capability and the requirements of stator single-phase grounding protection, combined with the protection time requirements.

[0093] 7. Study the grounding position fault simulation at various parts of the stator core

[0094] There is uncertainty in the occurrence of ground faults, and the location of the fault may appear in certain positions of the stator core, such as the stator core slot bottom 22, the stator slot wedge installation position 23, the stator slot side 23, the stator ventilation slot plate 18, etc. When a fault occurs at one of the positions of the core, the degree of core damage and the difficulty of core repair are different. Therefore, it is necessary to study the fault simulation of each grounding position.

[0095] 8. Replace the core material with oriented or non-oriented one, and simulate the stator core failure

[0096] According to the actual requirements of different power stations, the electromagnetic parameters in the generator design are not the same. The parameters of the stator core are different, and the stator core of the generator uses silicon steel sheets of different materials. To study different generators, it is necessary to simulate the stator core grounding fault of silicon steel sheets with different core materials.

[0097] 9. Study the influence of magnetic field distribution, cooling conditions, etc. on stator grounding fault

[0098] When studying the magnetic field distribution, the calculation adopts the two-dimensional plane electromagnetic field time-step finite element plus field-path coupling method. This method can take into account the effects of mechanical movement, skin effect and proximity effect caused by induced eddy currents in the conductor area, and is simplified and reasonable, with high calculation accuracy and reasonable calculation time. The basic process of the solution is, according to t i The field quantities (vector magnetic potential and scalar potential on the finite element mesh nodes) and the total quantity (current in the circuit) at the time instant are calculated according to the discrete equation in the finite element segmentation area. i+1 The field quantity at the time is calculated in the middle and then synthesized into the circuit elements corresponding to the finite element area in the circuit. According to the circuit equation, t i+1 The total amount of circuit sets at time t i+1 The field quantity and the total amount at a certain moment are used to obtain the variables at the next moment, and so on, until the complete data that can describe the law of change of the regional electromagnetic field for the required total time is obtained, and finally the required results are obtained through post-processing.

[0099] The transient temperature field of the stator core during discharge burning is calculated using the assembler and ANSYS CFD software. Boundary conditions and assumptions:

[0100] The stator core is considered to be anisotropic material, that is, the thermal conductivity in the radial, tangential and axial directions in the cylindrical coordinate system takes different values ​​according to the actual operation. According to the actual operating environment of the motor, the inlet temperature of the cooling gas in the stator ventilation groove is 50℃, and the inlet wind speed is given as 25m / s.

[0101] The heat source term is loaded as follows:

[0102] According to the electromagnetic calculation of the generator, the iron loss is loaded on the stator core; according to the actual test data of the fault current, the arcing power is loaded in the temperature field calculation model; according to the eddy current calculation results, the eddy current loss is loaded near the burning point. The influence of magnetic field distribution, cooling conditions, etc. on stator grounding fault is studied.

[0103] 10. Determination of safe current for single-phase ground fault of generator stator winding

[0104] During the test, a series of fault currents were set according to the plan to study the impact on the stator core. During the test, the core burnout test was completed with the same fault duration and different fault currents, and the degree of core burnout was measured.

[0105] Taking into account the relationship between the fault current, the degree of core damage and the difficulty of core repair, the safe limit value of the stator grounding fault current of a large generator is determined under the condition of rapid tripping of the generator stator grounding protection (within 1s).

[0106] 11. Based on the test results, research and verify new analysis and calculation methods

[0107] The test data involves the calculation of arc power, and its theoretical formula is as follows:

[0108] (1)

[0109] Where t1 is the start time of power calculation, t2 is the end time of power calculation, and u arc is the arcing voltage, i arc is the arc current.

[0110] Since the data collected during the test is discrete, the arc power needs to be calculated in sections. The arc power calculation formula of formula (1) is improved as follows:

[0111] (2)

[0112] In the formula, m is the sampling start point of the recorder, n is the sampling end point of the recorder, Δt is the sampling point time interval, uarc1 is the arc voltage value recorded by the recorder at sampling point l, i arc1 is the arc current value recorded by the recorder at sampling point l.

[0113] The above calculation method is only one kind of test data analysis. There are many analysis methods based on a large amount of test data. Establish a dynamic model of the arc as the research object, combine the conclusions of the simulation test, improve the research efficiency and accuracy. Finally, build a simulation model of the arc in combination with the test, build a simulation circuit through the interactive graphical interface software, and form the test research results simulated by the physical model and the digital model.

[0114] The above is a specific description of the implementation mode of the present invention, but the present invention is not limited to the described embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention, and these equivalents or substitutions are all included in the scope defined by the claims of the present invention.

Claims

1. A hydro-generator single-phase grounding fault simulation system, characterized by: It comprises a test bench (1), a voltage regulator (3), a transformer (4), a circuit breaker (5), a current limiting resistor (6), a test system for collecting current and voltage characteristic values ​​before and after a simulated fault, and a test console (2) for controlling the operation of the voltage regulator (3), the transformer (4), and the circuit breaker (5); The test bench (1) is equipped with a stator bar (13) and a stator core (14); one end of the test bench (1) is grounded, and the other end is connected to a transformer (4) via a circuit breaker (5); the transformer (4) is a step-up transformer, the low-voltage side of the transformer (4) is connected to a voltage regulator (3), and the high-voltage side of the transformer (4) adopts a star connection structure, the neutral point of the star connection structure is connected to one end of a current limiting resistor (6), and the other end of the current limiting resistor (6) is grounded; The voltage regulator (3), transformer (4) and circuit breaker (5) are respectively connected to a test console (2), and a time relay for controlling the on and off of the circuit breaker (5) is provided on the test console (2); The test system is respectively connected to the high voltage side of the transformer (4), the circuit breaker (5), the grounding end of the current limiting resistor (6) and the grounding end of the test bench (1); The test system comprises a recorder (7) for collecting current and voltage characteristic values ​​before and after a simulated fault, a three-phase high-voltage voltage transformer (8), a first high-voltage voltage transformer (9), a second high-voltage voltage transformer (10), a first current transformer (11) and a second current transformer (12); A first current transformer (11) is arranged on the grounding line of the current limiting resistor (6), and is connected to the oscilloscope (7) via the first current transformer (11); A first high-voltage voltage transformer (9) is arranged on the line of the star connection structure and the current-limiting resistor (6), and is connected to the oscilloscope (7) via the first high-voltage voltage transformer (9); The three end wires of the star connection structure are respectively connected to a three-phase high-voltage voltage transformer (8), and connected to a recorder (7) via the three-phase high-voltage voltage transformer (8); A second high-voltage voltage transformer (10) is provided on the line between the circuit breaker (5) and the test bench (1), and is connected to the recorder (7) via the second high-voltage voltage transformer (10); A second current transformer (12) is provided on the grounding line of the test bench (1), and is connected to the oscilloscope (7) via the second current transformer (12).

2. The hydro-generator single-phase grounding fault simulation system according to claim 1, characterized in that: The three end wires of the star connection structure form three different simulation circuits with the test bench (1) through the switching on and off of the circuit breaker (5).

3. The hydro-generator single-phase grounding fault simulation system according to claim 1, characterized in that: The neutral points of the three-phase high-voltage voltage transformers (8) are all grounded.

4. The hydro-generator single-phase grounding fault simulation system according to claim 1, characterized in that: The circuit breaker (5) is a high-voltage vacuum circuit breaker; and the current-limiting resistor (6) is a high-voltage current-limiting resistor having different gears.

5. The hydro-generator single-phase grounding fault simulation system according to claim 1, characterized in that: A plurality of stator bars (13) and a stator core (14) are installed in the test bench (1); The stator core (14) is provided with a plurality of stator slots, and the stator wire rods (13) are placed on the stator slots; the stator core (14) is formed by laminating a plurality of stator silicon steel sheets (20), the plurality of stator cores (14) are arranged in sequence, and ventilation slot plates (18) are provided at both upper and lower ends of the connection between two adjacent stator cores (14), and ventilation slot steel (21) is provided between the two ventilation slot plates (18); positioning slots are provided on the outer wall of the stator core (14), and positioning ribs (19) pass through the positioning slots of the plurality of stator cores (14) in sequence; and pressure plates (15) are provided on the outer sides of the first and last stator cores (14), and a pull-in screw (16) passes through the two pressure plates (15), and a nut (17) is sleeved on the pull-in screw (16) to lock the plurality of stator cores (14).

6. The hydro-generator single-phase grounding fault simulation system according to claim 5, characterized in that: The stator slot is a U-shaped slot, comprising a stator core slot bottom (22) at the bottom end, a stator slot opening mounting slot wedge (23) at the top end, and stator slot side surfaces (24) at both sides.

7. A simulation method for a hydro-generator single-phase grounding fault simulation system according to any one of claims 1 to 6, characterized in that: It includes installation inspection steps, fault simulation steps and information collection steps; The installation inspection step comprises installing the stator wire rod (13) and the stator core (14) on the inspection bench (1) and inspecting the circuit of the system; The fault simulation step comprises the following steps: after the installation and inspection are completed, the three-phase power supply is connected to the voltage regulator (3), and the voltage value of the transformer (4) is increased by the test console (2) to be equal to the terminal voltage of the generator; and the time of the time relay on the test console (2) is set, and then the circuit breaker (5) is closed to simulate a single-phase grounding fault of the hydro-generator; after the fault time is reached, the power supply is disconnected; In the information collection step, during fault simulation, the test system is used to collect and record characteristic values ​​of current and voltage before and after the simulated fault.

8. The hydro-generator single-phase grounding fault simulation system according to any one of claims 1 to 6, characterized in that: The simulation system is used for: simulating stator grounding faults of generators with different capacity levels; simulating grounding faults at different voltage levels and different levels of stator grounding currents; simulating stator grounding faults with different protection tripping times; simulating stator core grounding faults caused by different degrees of damage to stator bars; simulating stator core grounding faults of silicon steel sheets with different thicknesses; studying the degree of stator core burning under various working conditions; studying the grounding position fault simulation at various parts of the stator core; replacing the core material with oriented or non-oriented, and simulating the stator core fault; studying the influence of magnetic field distribution, cooling conditions, etc. on stator grounding faults; determining the safe current of single-phase grounding fault of generator stator winding; and based on the test results, studying and verifying one or more experimental studies in new analysis and calculation methods.

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