Heavy gas signal verification method based on double-floating-ball gas relay baffle stress

Abstract

The invention discloses a heavy gas signal verification method based on double-floating-ball gas relay baffle stress. The heavy gas signal verification method comprises the following steps that a double-floating-ball gas relay heavy gas signal response platform is built; establishing a simulation model according to the structural parameters and material data of the gas relay in the step 2; compiling a stress analysis model of the double-floating-ball gas relay by using UDF, importing FLUENT software, and simulating the motion characteristics of the baffle by using a dynamic grid method; starting an energy equation and an SST k-omega turbulence model in sequence; setting numerical calculation parameters including physical parameters of the insulating oil, boundary conditions, a solving method and solving precision; simulating and calculating the stress corresponding to the baffle plate at the heavy gas action moment of the gas relay according to the action of different excitation pressure intensities, and judging whether the stress corresponding to the baffle plate at the heavy gas action moment measured by the test and simulation accords with each other or not; the invention provides a powerful tool for optimizing the design of the gas relay and improving the safe operation of the transformer.

Description

Technical Field

[0001] The invention belongs to the technical field of transformer relay protection in an electric power system, and particularly relates to a heavy gas signal verification method based on the stress of a double-float gas relay baffle. Background Art

[0002] Transformers are core equipment in power systems, and their safe and stable operation is crucial for power supply. Buchholz relays, a key device for detecting internal transformer faults, detect possible abnormal gas or oil flow in the transformer's oil tank, thereby promptly sounding an alarm or shutting off power to protect the transformer. However, limitations in the design, principles, and applications of Buchholz relays, such as complex structures and unclear mechanical operating characteristics, lead to frequent misoperation or failure to operate in actual operation, impacting the safe and stable operation of transformers.

[0003] Research on traditional gas relays has primarily focused on setting methods based on experience or simple experiments. These methods struggle to accurately simulate complex actual operating conditions, particularly the impact response to transient oil flow and the operating characteristics under different fault conditions. Furthermore, previous gas relays were complex in structure, large in size, and difficult to precisely control, all of which limited improvements in their performance. In recent years, with the continuous expansion of power systems, tripping faults caused by misoperation of transformer gas protection have occurred frequently, seriously impacting the safe and stable operation of the main transformer. As a key non-electrical protection measure for internal transformer faults, gas protection lacks effective verification of its setting value for the gas signal. Summary of the Invention

[0004] The present invention aims to overcome the above-mentioned shortcomings and provide a heavy gas signal verification method based on the force applied to the baffle of a double-float gas relay to solve the problems raised in the background technology.

[0005] To achieve the above object, the present invention adopts a technical solution: a heavy gas signal verification method based on the force applied to the baffle of a double-float gas relay, comprising the following steps:

[0006] Step 1: Build a double-float gas relay heavy gas signal response platform, which is used to monitor the oil flow rate at the time of heavy gas action;

[0007] Step 2, obtaining structural parameters and material data of the gas relay;

[0008] Step 3: Establish a simulation model based on the structural parameters and material data of the gas relay in step 2;

[0009] Step 4: Use UDF to compile the force analysis model of the double-float gas relay, import it into FLUENT software, and use the dynamic mesh method to simulate the motion characteristics of the baffle;

[0010] Step 5: Enable the energy equation and SST k-ω turbulence model in sequence.

[0011] Step 6: Set the numerical calculation parameters, including the physical properties of the insulating oil, boundary conditions, solution method, and solution accuracy;

[0012] Step 7: simulating and calculating the force on the baffle of the gas relay at the time of heavy gas operation under different excitation pressures, and determining whether the force on the baffle at the time of heavy gas operation obtained by the test and the simulation are consistent;

[0013] Step 8: If the test and simulation results are consistent, the baffle force value at that moment is used as the setting value of the heavy gas action signal of the gas relay; if the test and simulation results are inconsistent, the setting value needs to be corrected.

[0014] Preferably, in step 1, for the double-float gas relay heavy gas signal response platform, an air cannon is used as an excitation source to simulate the internal fault condition of the transformer; and an ultrasonic flow velocity sensor is used to measure the change in flow velocity in the pipe when the oil flow surges.

[0015] Preferably, in step 2, the structural parameters include: gas relay baffle, internal frame, magnet next to the float, upper float beam, upper float baffle, lower float beam, and gas relay outer body; the material data include: fluid material density and viscosity.

[0016] Preferably, in step 4, the specific process of constructing the double-float gas relay stress analysis model is as follows:

[0017] The total torque applied to the baffle during its movement is calculated as follows:

[0018] M=M3+M4-M1-M2

[0019] M1 is the attraction torque of the permanent magnet on the baffle:

[0020] M1=F1L1=F1l1cosα

[0021] Where: F1 represents the resistance of the magnet, L1 represents the force arm of the F1 application point, l1 represents the distance from the permanent magnet's equivalent suction point to the rotation center, and α represents the rotation angle of the baffle float device;

[0022] M2 is the buoyancy moment on the float:

[0023] M2=F2L2=4 / 3ρgπr 3 dsin(α+β)

[0024] Where: F2 represents the buoyancy of the float due to the fluid, L2 represents the force arm of the F2 point, ρ represents the density of the fluid, g represents the acceleration due to gravity, r represents the radius of the float, d represents the distance from the center of rotation to the center of the float, and β represents the angle between the baffle and the float connecting rod.

[0025] M3 is the oil flow impact torque on the baffle:

[0026] M3=M p +M v

[0027] Where: M p Indicates the pressure difference resistance torque, M v represents the viscous resistance torque;

[0028]

[0029] Where: p is the pressure, μ is the viscosity coefficient, (x, y, z) is the coordinate of any point on the baffle, (x0, y0, z0) is the coordinate of the baffle's rotation center, u, v, and w are the velocity components in the x, y, and z directions respectively;

[0030] M4 is the gravitational moment exerted on the baffle and the float:

[0031]

[0032] Where: F4 represents the equivalent gravity of the baffle and the lower float, L4 represents the arm of the F4 equivalent gravity point, P represents the equivalent center of gravity of the baffle and the lower float, m represents the mass of the baffle and the lower float, It represents the angle between the equivalent center of gravity and the initial position of the baffle, and l4 represents the distance from the equivalent gravity point P of the baffle and the float to the center of rotation.

[0033] Preferably, the baffle rotation angular velocity ω is obtained by calling the DEFINE_CG_MOTION(name, dt, vel, omega, time, dtime) macro using the UDF program. n The specific process is as follows:

[0034]

[0035] Where: ω n is the angular velocity at the current moment, I is the moment of inertia of the baffle along the axis of rotation, and Δt is the time step.

[0036] Preferably, in step 4, the dynamic mesh method selected is Smooth and Remesh, and the dynamic mesh area is the boundary between the baffle and the lower floating ball.

[0037] Preferably, in step 5, the turbulence model is the SST k-ω two-equation model, the fluid is insulating oil; the inlet boundary condition is velocity-inlet, the outlet boundary condition is pressure-outlet, and the remaining boundaries are no-slip walls.

[0038] Preferably, in step 7, when the force corresponding to the baffle at the time of heavy gas action is measured in the test, the oil flow rate at the initial stage of the baffle action is extracted and calculated as V0, and the oil flow rate when the baffle reaches its maximum rotation angle is V1, and the time from the start of the action to the maximum rotation angle of the baffle is t. The force corresponding to the baffle when the heavy gas signal action is calculated by the following formula:

[0039]

[0040] Where m is the mass of the lower float and baffle components of the gas relay.

[0041] Preferably, in step 7, when the force corresponding to the baffle at the time of heavy gas action is measured by simulation, the flow rate of the oil in the initial stage of the baffle action is extracted as V'0, and the flow rate of the oil when the baffle reaches its maximum rotation angle is V'1. The time from the start of the action to the maximum rotation angle of the baffle is t, and the force corresponding to the baffle during the heavy gas signal action of the numerical simulation is calculated by the following formula:

[0042]

[0043] Where m is the mass of the lower float and baffle components of the gas relay.

[0044] Preferably, in step 1, the constructed double-float gas relay heavy gas signal response platform includes: an air cannon, a pulsating flow generating chamber, a pipeline to be tested, a gas relay, a bellows, a butterfly valve, and a capsule oil pillow;

[0045] The air cannon provides the test platform with the external excitation source required for the test, and uses the instantaneous release of compressed air to simulate the internal fault source of the transformer box; the pulsating flow generating chamber provides a space for the compressed air to expand and do work, thereby stimulating the pulsating oil flow; the pipeline to be tested is used to arrange and install various test sensors, such as pressure sensors and speed sensors; the gas relay is used to detect the light and heavy gas signals generated by the impact of the pulsating flow in the pipeline, simulating the light and heavy gas actions during transformer faults; the bellows is used to connect the pipeline, perform pipeline correction and pipeline vibration suppression; the butterfly valve is used to control the on and off of the pipeline and simulate the change in the cross-sectional area of ​​the pipeline diameter by changing the opening and closing angle; the capsule oil pillow is used to store and replenish oil.

[0046] Compared with the existing technology, the present invention has the following beneficial effects:

[0047] The present invention uses a method combining experiments and simulations to determine whether a heavy gas action occurs based on the stress conditions of the double-float gas relay baffle, providing a new method for setting the heavy gas action of the transformer and a powerful tool for optimizing the design of gas relays and improving the safe operation of transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A model diagram of the double-float gas relay heavy gas signal response experimental platform provided by the present invention;

[0049] Figure 2 Design diagram of the heavy gas signal response experimental platform for the double-float gas relay provided by the present invention;

[0050] Figure 3 A diagram showing the geometrical model of the gas relay structure provided by the present invention;

[0051] Figure 4 A flow chart of the force simulation of the baffle of the double-float gas relay provided by the present invention;

[0052] Figure 5 A schematic diagram of the force acting on the baffle of the double-float gas relay provided by the present invention;

[0053] Figure 6 The present invention provides a double-float gas relay baffle force setting value verification flow chart. DETAILED DESCRIPTION

[0054] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

[0055] Example 1: Figure 1 As shown in the figure, a double-float gas relay heavy gas signal response experimental platform is built, which can simulate the pulsating oil flow excited by the heavy gas fault of the transformer;

[0056] like Figure 2 As shown in the figure, the construction of the double-float gas relay heavy gas signal response platform includes 7 parts: air cannon, pulsating flow generating chamber, pipeline to be tested, gas relay, bellows, butterfly valve, and capsule oil pillow.

[0057] The air cannon provides the test platform with the external excitation source required for the test, and uses the instantaneous release of compressed air to simulate the internal fault source of the transformer box; the pulsating flow generating chamber provides a space for the compressed air to expand and do work, thereby stimulating the pulsating oil flow; the pipeline to be tested is used to arrange and install various test sensors, such as pressure sensors and speed sensors; the gas relay is used to detect the light and heavy gas signals generated by the impact of the pulsating flow in the pipeline, simulating the light and heavy gas actions during transformer faults; the bellows is used to connect the pipeline, perform pipeline correction and pipeline vibration suppression; the butterfly valve is used to control the on and off of the pipeline and simulate the change in the cross-sectional area of ​​the pipeline diameter by changing the opening and closing angle; the capsule oil pillow is used to store and replenish oil.

[0058] like Figure 4 As shown in FIG. 1 , a heavy gas signal verification method based on the force applied to the baffle of a double-float gas relay according to this embodiment includes the following specific steps:

[0059] Step 1: Collect structural parameters including: gas relay baffle, internal frame, float magnet, upper float beam, upper float baffle, lower float beam, gas relay outer body; material data including: fluid material density, viscosity, and establish Figure 3 The geometric model shown.

[0060] Step 2: Use Meshing software to perform structured and unstructured mixed meshing on the relay fluid area in the double-float gas relay simulation model. The number of meshes in the fluid area model is large, and the overall mesh quality of the fluid area is high. Key parts such as the relay baffle are refined, and the number of nodes, number of units, and mesh quality of the fluid domain are counted. The mesh quality is then checked and adjusted.

[0061] Step 3: Establish the force analysis model of the double float gas relay as follows Figure 5 As shown, the specific process is as follows:

[0062] The total torque applied to the baffle during its movement is calculated as follows:

[0063] M=M3+M4-M1-M2

[0064] M1 is the attraction torque of the permanent magnet on the baffle:

[0065] M1=F1L1=F1l1cosα

[0066] Where: F1 represents the resistance of the magnet, L1 represents the force arm of the F1 application point, l1 represents the distance from the permanent magnet's equivalent suction point to the rotation center, and α represents the rotation angle of the baffle float device;

[0067] M2 is the buoyancy moment on the float:

[0068] M2=F2L2=4 / 3ρgπr 3 dsin(α+β)

[0069] Where: F2 represents the buoyancy of the float due to the fluid, L2 represents the force arm of the F2 point, ρ represents the density of the fluid, g represents the acceleration due to gravity, r represents the radius of the float, d represents the distance from the center of rotation to the center of the float, and β represents the angle between the baffle and the float connecting rod.

[0070] M3 is the oil flow impact torque on the baffle:

[0071] M3=M p +M v

[0072] Where: M p Indicates the pressure difference resistance torque, M v represents the viscous resistance torque;

[0073]

[0074] Where: p is the pressure, μ is the viscosity coefficient, (x, y, z) is the coordinate of any point on the baffle, (x0, y0, z0) is the coordinate of the baffle's rotation center, u, v, and w are the velocity components in the x, y, and z directions respectively;

[0075] M4 is the gravitational moment exerted on the baffle and the float:

[0076]

[0077] Where: F4 represents the equivalent gravity of the baffle and the lower float, L4 represents the arm of the F4 equivalent gravity point, P represents the equivalent center of gravity of the baffle and the lower float, m represents the mass of the baffle and the lower float, It represents the angle between the equivalent center of gravity and the initial position of the baffle, and l4 represents the distance from the equivalent gravity point P of the baffle and the float to the center of rotation.

[0078] Secondly, the UDF program is used to call the DEFINE_CG_MOTION(name,dt,vel,omega,time,dtime) macro to realize the angular velocity ω of the baffle. n The specific process is as follows:

[0079]

[0080] Where: ω n is the angular velocity at the current moment, I is the moment of inertia of the baffle along the axis of rotation, and Δt is the time step.

[0081] Step 4: Set the dynamic mesh, boundary conditions, and solution controller parameters for the meshed fluid domain. The baffle of the gas relay is driven by the total torque, so the force analysis model of the gas relay is compiled into FLUENT through a user-defined function (UDF). The SST k-ω two-equation model is selected as the turbulence model, and insulating oil is selected as the fluid. The inlet boundary condition is Velocity-inlet, the outlet boundary condition is Pressure-outlet, and the remaining boundaries are no-slip walls. The dynamic mesh method uses Smooth and Remesh, and the dynamic mesh area is the baffle and lower float boundary. In the solution settings, the coupling mode is SIMPLE, and the discretization format is second-order upwind to ensure calculation accuracy.

[0082] After setting the boundary conditions, the flow field distribution inside the double-float gas relay, particularly the oil flow velocity inside the gas relay, is calculated starting from t = 0 when a heavy gas signal is generated. The dynamic behavior of the insulating oil in the double-float gas relay when a heavy gas signal is generated satisfies the following control equation:

[0083] The continuity equation is as follows:

[0084]

[0085] Introducing vector symbols The continuity equation can be written as:

[0086]

[0087] Where: ρ is the transformer insulating oil density, t is time, and u, v, and w are the components of the velocity vector u in the x, y, and z directions.

[0088] The momentum conservation equation is as follows:

[0089]

[0090] Where: μ is the dynamic viscosity, Symbol S u 、S v and S w is the generalized source term of the momentum conservation equation.

[0091] The energy conservation equation is as follows:

[0092]

[0093] Where: E is the total energy of turbulence, including the sum of internal energy, kinetic energy and potential energy, h is enthalpy, h j Denote the enthalpy of component j and defined as Where T ref =298.15K,keff is the effective heat transfer coefficient, k eff =k+k t , k t is the turbulent heat transfer coefficient, S h It is the chemical reaction heat and its customized volume heat source term, J j is the diffusion flux of component j.

[0094] Step 5: Within the simulation step t, we calculated the oil flow velocity of the gas relay and analyzed the distribution of the internal flow field and the oil flow velocity when the relay triggered the heavy gas signal. When the residual in the iterative process drops below the preset threshold, we consider that the iteration step has converged. Then, the time step t is increased by Δt, and the calculation is continued in the next time step. Under the new oil flow velocity excitation, we calculate the baffle torque and the baffle rotation angular velocity again and repeat this calculation process. When the time step reaches t max , the calculation process ends and the engineering file and the calculation results of the oil flow velocity will be saved.

[0095] like Figure 6 As shown in the figure, in the extraction experiment, the oil flow rate at the initial stage of the baffle action is V0, and when the baffle reaches its maximum rotation angle, the oil flow rate is V1. The time from the start of the baffle action to the maximum rotation angle is t. The force corresponding to the baffle action when the heavy gas signal is activated is calculated using the following formula:

[0096]

[0097] Where m is the mass of the lower float and baffle components of the gas relay.

[0098] The oil flow rate at the initial stage of the baffle's movement is extracted from the simulation calculation as V'0. When the baffle reaches its maximum rotation angle, the oil flow rate is V'1. The time it takes for the baffle to move from the beginning to the maximum rotation angle is t. The force corresponding to the baffle's heavy gas signal movement in the numerical simulation is calculated using the following formula:

[0099]

[0100] Where m is the mass of the lower float and baffle components of the gas relay.

[0101] Analyze the damper force during the heavy gas operation of the gas relay and compare it with experimental data. If the calculated damper force matches the experimentally measured force, it can be used as the setting value for the heavy gas signal. If the two do not match, the setting value of the heavy gas signal needs to be adjusted.

[0102] This embodiment, through a combination of experiments and simulations, determines whether a heavy gas action has occurred based on the stress on the baffle of a double-float gas relay. This provides a new method for determining heavy gas action in transformers, offering a powerful tool for optimizing gas relay design and improving transformer safety. This approach not only ensures the high accuracy and reliability of gas relays in practical applications but also provides important technical support for intelligent monitoring and early warning systems for transformers, safeguarding their safe operation.

[0103] The above embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention shall be the technical solutions set forth in the claims, including equivalent alternatives to the technical features of the technical solutions set forth in the claims. In other words, equivalent alternatives and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A heavy gas signal verification method based on the force applied to the baffle of a double-float gas relay, characterized by: The following steps are involved: Step 1: Build a double-float gas relay heavy gas signal response platform, which is used to monitor the oil flow rate at the time of heavy gas action; Step 2, obtaining structural parameters and material data of the gas relay; Step 3: Establish a simulation model based on the structural parameters and material data of the gas relay in step 2; Step 4: Use UDF to compile the force analysis model of the double-float gas relay, import it into FLUENT software, and use the dynamic mesh method to simulate the motion characteristics of the baffle; Step 5: Enable the energy equation and SST k-ω turbulence model in sequence. Step 6: Set the numerical calculation parameters, including the physical properties of the insulating oil, boundary conditions, solution method, and solution accuracy; Step 7: simulating and calculating the force on the baffle of the gas relay at the time of heavy gas operation under different excitation pressures, and determining whether the force on the baffle at the time of heavy gas operation obtained by the test and the simulation are consistent; Step 8: If the test and simulation results are consistent, the baffle force value at that moment is used as the setting value of the heavy gas action signal of the gas relay; if the test and simulation results are inconsistent, the setting value needs to be corrected.

2. A heavy gas signal verification method based on the force applied to the baffle of a double-float gas relay according to claim 1, characterized in that: In step 1, for the double-float gas relay heavy gas signal response platform, an air cannon is used as an excitation source to simulate the internal fault of the transformer; and the change of the flow velocity in the pipe when the oil flow surges is measured based on the ultrasonic flow velocity sensor.

3. A heavy gas signal verification method based on the force applied to the baffle of a double-float gas relay according to claim 1, characterized in that: In step 2, the structural parameters include: gas relay baffle, internal frame, float magnet, upper float beam, upper float baffle, lower float beam, gas relay outer body; the material data include: fluid material density and viscosity.

4. A heavy gas signal verification method based on the force applied to the baffle of a double-float gas relay according to claim 1, characterized in that: In step 4, the specific process of constructing the double-float gas relay stress analysis model is as follows: The total torque applied to the baffle during its movement is calculated as follows: M=M3+M4-M1-M2 M1 is the attraction torque of the permanent magnet on the baffle: M1=F1L1=F1l1cosα Where: F1 represents the resistance of the magnet, L1 represents the force arm of the F1 application point, l1 represents the distance from the permanent magnet's equivalent suction point to the rotation center, and α represents the rotation angle of the baffle float device; M2 is the buoyancy moment on the float: M2=F2L2=4 / 3ρgπr 3 dsin(a+b) Where: F2 represents the buoyancy of the float due to the fluid, L2 represents the force arm of the F2 point, ρ represents the density of the fluid, g represents the acceleration due to gravity, r represents the radius of the float, d represents the distance from the center of rotation to the center of the float, and β represents the angle between the baffle and the float connecting rod. M3 is the oil flow impact torque on the baffle: M3=M p +M v Where: M p Indicates the pressure difference resistance torque, M v represents the viscous resistance torque; Where: p is the pressure, μ is the viscosity coefficient, (x, y, z) is the coordinate of any point on the baffle, (x0, y0, z0) is the coordinate of the baffle's rotation center, u, v, and w are the velocity components in the x, y, and z directions respectively; M4 is the gravitational moment exerted on the baffle and the float: Where: F4 represents the equivalent gravity of the baffle and the lower float, L4 represents the arm of the F4 equivalent gravity point, P represents the equivalent center of gravity of the baffle and the lower float, m represents the mass of the baffle and the lower float, It represents the angle between the equivalent center of gravity and the initial position of the baffle, and l4 represents the distance from the equivalent gravity point P of the baffle and the float to the center of rotation.

5. A heavy gas signal verification method based on the force applied to the baffle of a double-float gas relay according to claim 4, characterized in that: Use the UDF program to call the DEFINE_CG_MOTION(name,dt,vel,omega,time,dtime) macro to get the baffle rotation angular velocity ω n The specific process is as follows: Where: ω n is the angular velocity at the current moment, I is the moment of inertia of the baffle along the axis of rotation, and Δt is the time step.

6. The heavy gas signal verification method based on the double-float gas relay baffle stress according to claim 1, characterized in that: In step 4, the dynamic mesh method is selected as Smooth and Remesh, and the dynamic mesh area is the baffle and the lower floating ball boundary.

7. The heavy gas signal verification method based on the double-float gas relay baffle stress according to claim 1, characterized in that: In step 5, the SST k-ω two-equation model is selected as the turbulence model, and insulating oil is selected as the fluid; the inlet boundary condition is velocity-inlet, the outlet boundary condition is pressure-outlet, and the remaining boundaries are no-slip walls.

8. The heavy gas signal verification method based on the double-float gas relay baffle stress according to claim 1, characterized in that: In step 7, when the force on the baffle corresponding to the heavy gas action is measured, the oil flow rate at the initial stage of the baffle action is extracted and calculated as V0, and the oil flow rate when the baffle reaches its maximum rotation angle is V1. The time from the start of the baffle action to the maximum rotation angle is t. The force on the baffle corresponding to the heavy gas signal action in the experiment is calculated using the following formula: Where m is the mass of the lower float and baffle components of the gas relay.

9. The heavy gas signal verification method based on the double-float gas relay baffle stress according to claim 1, characterized in that: In step 7, when the force on the baffle corresponding to the heavy gas action is measured by simulation, the oil flow rate at the initial stage of the baffle action is extracted as V'0, and the oil flow rate when the baffle reaches its maximum rotation angle is V'1. The time from the start of the action to the maximum rotation angle of the baffle is t. The force on the baffle corresponding to the heavy gas signal action of the numerical simulation is calculated by the following formula: Where m is the mass of the lower float and baffle components of the gas relay.

10. The heavy gas signal verification method based on the double-float gas relay baffle stress according to claim 1, characterized in that: In step 1, the constructed double-float gas relay heavy gas signal response platform includes 7 major parts: air cannon, pulsating flow generating chamber, pipeline to be tested, gas relay, bellows, butterfly valve, and capsule oil pillow; The air cannon provides the test platform with the external excitation source required for the test, and uses the instantaneous release of compressed air to simulate the internal fault source of the transformer box; the pulsating flow generating chamber provides a space for the compressed air to expand and do work, thereby stimulating the pulsating oil flow; the pipeline to be tested is used to arrange and install various test sensors, such as pressure sensors and speed sensors; the gas relay is used to detect the light and heavy gas signals generated by the impact of the pulsating flow in the pipeline, simulating the light and heavy gas actions during transformer faults; the bellows is used to connect the pipeline, perform pipeline correction and pipeline vibration suppression; the butterfly valve is used to control the on and off of the pipeline and simulate the change in the cross-sectional area of ​​the pipeline diameter by changing the opening and closing angle; the capsule oil pillow is used to store and replenish oil.

Images