Heavy gas maloperation prevention method for double-floating-ball gas relay

Abstract

The invention discloses a double-floating-ball gas relay heavy gas maloperation prevention method, which comprises the steps of building a simulation transformer fault test experiment platform, and simulating different faults; gas relay operating characteristics caused by surging oil flow under different fault excitation are measured, and the rotation angle of a baffle is actually measured; collecting the pipeline oil flow speed under different fault excitation in the experiment process, the pipeline vibration acceleration of the surging oil flow flowing through the to-be-measured pipeline where the gas relay is located, and a heavy gas action signal measured and simulated through the double-floating-ball gas relay; establishing an analytical model among the rotation angle of the baffle of the double-floating-ball gas relay, the pipeline oil flow speed and the pipeline vibration acceleration, and calculating a theoretical value of the rotation angle of the baffle of the double-floating-ball gas relay; judging the working state of the baffle of the double-floating-ball gas relay; and on the basis of confirming that the baffle plate of the double-floating-ball gas relay works normally, identifying the heavy gas action output of the gas relay based on the pipeline vibration acceleration, the pipeline oil flow velocity and the heavy gas action signal.

Description

Technical Field

[0001] The present invention relates to the technical field of gas relay protection for oil-immersed transformers, and more specifically, to a method for preventing misoperation of the heavy gas of a double-float gas relay. Background Art

[0002] Oil-immersed power transformers are high-voltage equipment widely used in the current power system. Due to their high cost and complex structure, once a failure occurs and they are damaged, the repair is difficult and time-consuming, and it will also cause serious economic losses to enterprises.

[0003] Transformer-related protection devices include electrical quantity protection and non-electrical quantity protection. The electrical quantity protection is not sensitive enough to internal faults of the transformer body. This is mainly because internal faults start from inter-turn short circuits. Although the fault current inside the short-circuited turns is very large, the reflected line current is not large. Only when the fault develops into multi-turn short circuit or ground short circuit can the power supply be cut off. Therefore, most of the protection related to the transformer body adopts non-electrical quantity protection. Gas relay protection, also known as heavy gas protection, is an important protection measure when an internal fault occurs in an oil-immersed power transformer. The main protection for internal faults in an oil-immersed power transformer is heavy gas protection, which can immediately cut off the faulty equipment.

[0004] At present, there is no corresponding experimental device that can simulate the surging oil flow during internal faults of the transformer; the flow rate of the surging oil flow excited by inter-turn faults generated by faults at different positions and of different degrees in the transformer cannot be determined; and the faults outside the gas protection area of the transformer, the abnormal vibration of the transformer box body, the transmission and attenuation of the surging oil flow between the transformer box body and the pipeline cannot be predicted. For example, the invention with the patent application number 202411144249.X discloses a method for preventing misoperation of the heavy gas of a double-float gas relay, constructs an analytical model of the rotation angle of the baffle of the double-float gas relay and the flow rate, analyzes the relationship between the operating parameters of the transformer and the rotation angle of the baffle, and calculates the theoretical rotation angle of the baffle. The abnormality of the gas relay is judged by the relative error between the measured value and the theoretical value. In addition, a transformer fault test platform is built, the pressure change is measured by a pressure sensor, the variance is calculated to distinguish internal and external faults, and combined with the operating parameters, the authenticity of the heavy gas signal is effectively identified. This method only considers the misoperation of the heavy gas of the gas relay caused by external faults in the transformer area, and does not involve the influence of the vibration of the pipeline where the gas relay is located on the rotation angle of the baffle. However, according to the actual operation situation and theoretical analysis, the pipeline vibration will indeed affect the rotation of the baffle.

[0005] Therefore, how to provide a method to prevent the misoperation of the heavy gas caused by the vibration of the pipeline where the gas relay is located is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a method for preventing misoperation of the heavy gas of a double-floating-ball gas relay, which can effectively distinguish the authenticity of the heavy gas action of the gas relay, and in particular can avoid the misoperation of the heavy gas of the gas relay caused by pipeline vibration.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preventing misoperation of the heavy gas of a double-floating-ball gas relay includes:

[0009] Step 1: Build a simulation test platform for transformer faults to simulate different faults;

[0010] Step 2: Based on the simulation test platform for transformer faults, measure the action characteristics of the gas relay caused by the surging oil flow under different fault excitations, measure the actual rotation angle of the baffle, synchronously collect the pipeline oil flow velocity, the pipeline vibration acceleration of the surging oil flow passing through the pipeline where the gas relay is located under different fault excitations during the experiment, and the heavy gas action signal measured by the double-floating-ball gas relay;

[0011] Step 3: Establish an analytical model between the rotation angle of the baffle of the double-floating-ball gas relay, the pipeline oil flow velocity, and the pipeline vibration acceleration, and calculate the theoretical value of the rotation angle of the baffle of the double-floating-ball gas relay according to the pipeline oil flow velocity and the pipeline vibration acceleration collected in Step 2;

[0012] Step 4: Compare and analyze the theoretical value with the measured rotation angle of the baffle to judge the working state of the baffle of the double-floating-ball gas relay;

[0013] Step 5: On the basis of confirming that the baffle of the double-floating-ball gas relay works normally, identify the heavy gas action output of the gas relay based on the pipeline vibration acceleration, the pipeline oil flow velocity, and the heavy gas action signal collected in Step 2.

[0014] Preferably, establishing an analytical model between the rotation angle of the baffle of the double-floating-ball gas relay, the pipeline oil flow velocity, and the pipeline vibration acceleration, and calculating the theoretical value of the rotation angle of the baffle of the double-floating-ball gas relay according to the pipeline oil flow velocity and the pipeline vibration acceleration includes:

[0015] The total torque M received by the baffle is:

[0016] M = M3 + M4 - M1 - M2 + M5

[0017] The pipeline vibration causes an additional vibration torque M5 on the baffle:

[0018]

[0019] Wherein, F5 represents the vibration force, with the opening direction of the baffle defined as the positive direction, L5 represents the lever arm of the equivalent vibration force acting point, m represents the mass of the baffle and the mass of the lower floating ball, represents the pipeline vibration acceleration, represents the angle between the equivalent center of gravity and the initial position of the baffle, α represents the theoretical value of the rotation angle of the baffle of the double-floating-ball gas relay, and l5 represents the distance from the equivalent vibration force acting point of the baffle and the floating ball to the rotation center;

[0020] The suction torque M1 between the permanent magnet inside the gas relay and the baffle:

[0021] M1 = F1L1 = F1l1 cosa

[0022] Wherein, F1 represents the suction force of the permanent magnet, L1 represents the lever arm of the acting point of F1, and l1 represents the distance from the equivalent suction point of the permanent magnet to the rotation center;

[0023] The buoyancy torque M2 received by the floating ball;

[0024] M2 = F2L2 = 4 / 3ρgπr 3 l2 sin(α + β)

[0025] Wherein, F2 represents the buoyancy of the floating ball in the fluid, L2 represents the lever arm of the acting point of F2, ρ represents the density of the fluid, g represents the acceleration due to gravity, r represents the radius of the floating ball, l2 represents the distance from the rotation center to the center of the floating ball, and β represents the angle between the baffle and the connecting rod of the floating ball;

[0026] The impact torque M3 received by the baffle:

[0027] M3 = M p +M v

[0028] Wherein, M p represents the differential pressure resistance torque, and M v represents the viscous resistance torque;

[0029]

[0030] Wherein, p is the pressure, μ is the viscosity coefficient, (x, y, z) are the coordinates of any point on the baffle, (x0, y0, z0) are the coordinates of the rotation center of the baffle, and u, v, and w are the pipeline oil flow velocity components in the x, y, and z directions respectively;

[0031] The gravity torque M4 of the baffle around the rotation center:

[0032]

[0033] Wherein, F4 represents the equivalent gravity of the baffle and the floating ball, and L4 represents the lever arm of the equivalent gravity acting point, 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 points of the baffle and the floating ball to the rotation center;

[0034] Calculate the rotational angular velocity ω of the baffle:

[0035] ω = M / I

[0036] In the formula, I represents the moment of inertia of the baffle. The theoretical value of the rotation angle of the baffle can be obtained by integrating the rotational angular velocity of the baffle with respect to time.

[0037] Preferably, identifying the heavy gas operation output of the gas relay based on the pipeline vibration acceleration, the pipeline oil flow velocity, and the heavy gas operation signal includes:

[0038] (1) The pipeline vibration acceleration is greater than or equal to the acceleration threshold The pipeline oil flow velocity v is greater than or equal to the flow velocity threshold v s , then judge the heavy gas signal. If the heavy gas operation signal S is high level, that is v ≥ v s and S = 1, output the heavy gas signal; if the heavy gas operation signal S is low level, that is v ≥ v s and S = 0, it is necessary to judge again at the next Δt. If the result is consistent, output the heavy gas refusal signal;

[0039] (2) The pipeline vibration acceleration is greater than or equal to the acceleration threshold The pipeline oil flow velocity v is less than the flow velocity threshold v s , then judge the heavy gas signal. If the heavy gas operation signal S is high level, that is v < v s and S = 1, it is necessary to judge again at the next Δt. If the result is consistent, output the heavy gas misoperation signal; if the heavy gas operation signal S is low level, that is v < v s and S = 0, only output the reminder information;

[0040] (3) The pipeline vibration acceleration is less than the acceleration threshold The pipeline oil flow velocity v is greater than or equal to the flow velocity threshold v s , then judge the heavy gas signal. If the heavy gas operation signal S is high level, that is v ≥ v s and S = 1, output the heavy gas signal; if the heavy gas operation signal S is low level, that is v ≥ v s and S = 0, it is necessary to judge again at the next Δt. If the result is consistent, output the heavy gas refusal signal;

[0041] (4) Pipeline vibration acceleration Less than the acceleration threshold The pipeline oil flow velocity v is less than the flow velocity threshold v s , then judge the heavy gas signal. If the heavy gas action signal S is high level, that is v < v s And S = 1, it is necessary to make a re - judgment at the next Δt. If the result is consistent, output the heavy gas misoperation signal, reminding that the misoperation may be caused by the contact being damp; If the heavy gas action signal S is low level, that is v < v s And S = 0, it indicates normal operation.

[0042] Preferably, obtain the data of voltage and time collected from the pipeline to be measured by an ultrasonic flowmeter, and inversely deduce the relationship between the pipeline oil flow velocity and time;

[0043] Obtain the data of acceleration and time collected from the pipeline to be measured by an acceleration sensor, and use it as the relationship between the wall acceleration at the pipeline inlet and time calculated by ANSYS Mechanical numerical simulation, as the pipeline vibration acceleration.

[0044] Preferably, compare and analyze the theoretical value with the measured baffle rotation angle to judge the working state of the double - floating - ball gas relay baffle, including:

[0045] If the relative error between the theoretical value and the measured baffle rotation angle is less than or equal to 10%, then judge that the gas relay baffle is working normally; If the relative error is greater than 10%, then judge that the gas relay baffle is abnormal and the gas relay baffle needs to be recalibrated.

[0046] Preferably, the simulated transformer fault test platform includes a transformer oil tank. There is an iron core arranged in the transformer oil tank. 3 air cannons are installed at different positions between the iron cores, and 9 jet ports are designed at the 9 positions of the iron cores with the air cannons as the power source. The oil filling port of the transformer oil tank is connected to the oil conservator through the pipeline to be measured, and a double - floating - ball gas relay, an ultrasonic flowmeter and an acceleration sensor are installed on the pipeline to be measured.

[0047] Preferably, the air cannon includes an air inlet, a gas storage box body, solenoid valve Ⅰ, three jet ports and solenoid valve Ⅱ at the jet ports. The gas storage box body is connected to the external compressed air supply system through the air inlet. The solenoid valve Ⅰ is arranged on the bottom side of the gas storage box body. According to the jet direction, the solenoid valve Ⅰ is connected to the three jet ports through a jet pipeline, and the solenoid valve Ⅱ is installed on the jet ports.

[0048] Preferably, it further includes a PLC controller, which is used to control the solenoid valve I and the solenoid valve II to fire individually or in groups, so as to simulate the phase - transformer faults with different coils, different positions and different heights.

[0049] Preferably, it further includes a data acquisition instrument, which is used to acquire the data collected by the gas relay, the ultrasonic flowmeter and the acceleration sensor.

[0050] Through the above - mentioned technical solutions, compared with the prior art, the present invention discloses a method for preventing misoperation of the heavy gas of a double - float gas relay. Based on the transformer fault test experimental platform, it can simulate the different energies generated during transformer short - circuit and the surging oil flow at different speeds to the greatest extent and with higher precision. Based on the method for identifying the heavy - gas action of the gas relay according to the pipeline vibration acceleration and the oil - flow velocity, it can effectively identify the abnormal heavy - gas action, solve the accident of abnormal - action tripping of the gas relay, improve the accuracy and reliability of the gas relay, and ensure the stable operation of the gas monitoring system. Description of the Drawings

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following - described drawings are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0052] Figure 1 It is a flowchart of a method for preventing misoperation of the heavy gas of a double - float gas relay provided by the present invention.

[0053] Figure 2 It is an overall structure diagram of a simulation transformer - fault test experimental platform provided by the present invention.

[0054] Figure 3 It is a structure diagram of an air cannon provided by the present invention.

[0055] Figure 4 It is a partial structure diagram of a simulation transformer - fault test experimental platform provided by the present invention.

[0056] Figure 5 It is a flowchart of the oil - flow transfer experiment on the experimental bench provided by the present invention.

[0057] Figure 6 It is a flowchart of the heavy - gas action simulation of a double - float gas relay provided by the present invention.

[0058] Figure 7 It is a force - analysis diagram of a double - float gas relay provided by the present invention.

[0059] Figure 8 Flow chart for identifying the operation of the heavy gas of the gas relay provided by the present invention.

[0060] Among them, 1. Transformer oil tank, 2. Iron core, 3. Air cannon, 301. Air inlet, 302. Gas storage box, 303. Jet port, 304. Solenoid valve II, 4. Conservator, 5. Double-float gas relay, 6. Ultrasonic flowmeter, 7. Acceleration sensor, 8. Solenoid valve I, 9. Bellows, 10. Shut-off valve, 11. Data acquisition instrument. Specific implementation mode

[0061] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0062] The embodiment of the present invention discloses a method for preventing misoperation of the heavy gas of a double-float gas relay, as Figure 1 shown, including:

[0063] Step 1: Build a simulation test platform for transformer faults to simulate different faults;

[0064] Step 2: Measure the action characteristics of the gas relay caused by the surging oil flow under different fault excitations based on the simulation test platform for transformer faults, and measure the actual rotation angle of the baffle; synchronously collect the pipeline oil flow velocity, the pipeline vibration acceleration of the surging oil flow passing through the pipeline where the gas relay is located under different fault excitations during the experiment, and the simulated heavy gas action signal measured by the double-float gas relay;

[0065] Step 3: Establish an analytical model between the rotation angle of the baffle of the double-float gas relay and the pipeline oil flow velocity and pipeline vibration acceleration, and calculate the theoretical value of the rotation angle of the baffle of the double-float gas relay according to the pipeline oil flow velocity and pipeline vibration acceleration collected in Step 2;

[0066] Step 4: Compare and analyze the theoretical value with the actual measured baffle rotation angle to judge the working state of the baffle of the double-float gas relay;

[0067] Step 5: On the basis of confirming that the baffle of the double-float gas relay works normally, identify the heavy gas action output of the gas relay based on the pipeline vibration acceleration, pipeline oil flow velocity and heavy gas action signal collected in Step 2.

[0068] In this embodiment, as Figure 2As shown in the figure, the simulation transformer fault test experimental platform includes a transformer oil tank 1, in which an iron core 2 is arranged. Three air cannons 3 are installed at different positions between the iron cores 2, and jet nozzles are designed at 9 positions of the iron core with the air cannons 3 as the power source. The oil filling port of the transformer oil tank 1 is connected to an oil conservator 4 through a pipeline to be tested. A double-floating ball gas relay 5, an ultrasonic flowmeter 6 and an acceleration sensor 7 are installed on the pipeline to be tested.

[0069] The present invention adopts a three-phase five-column transformer. The iron core 2 of the transformer has five columns and four windows. Coils are installed on the middle three columns, and the two side columns are used as magnetic circuits. The air cannon 3 uses compressed air as the power, which solves the generation of the oil body velocity in the pipeline during flow velocity measurement, and uses the same medium as the compressed air required for generating pressure in the closed test and the air required for pressing into the gas relay in the volume experiment, simplifying the power composition required by the system. The selected air cannon 3 is a pulse air cannon.

[0070] As Figure 3 shown in the figure, the air cannon 3 includes an air inlet 301, a gas storage box body 302, a solenoid valve I 8 on the side of the bottom of the gas storage box body and three jet nozzles 303 and a solenoid valve II 304 at the jet nozzle. The gas storage box body is connected to an external compressed air supply system through the air inlet 301. The solenoid valve I 8 is arranged on the side of the bottom of the gas storage box body 302. According to the jet direction, the solenoid valve I 8 is connected to the three jet nozzles 303 through a jet pipeline, and a solenoid valve II 304 is installed on the jet nozzle 303.

[0071] During operation, compressed air is injected into the gas storage box body 302 through the air inlet 301. When a certain pressure is reached, the solenoid valve I 8 on the side is opened, so that the compressed air in the gas storage box body 302 is instantaneously ejected through the nozzle, impacting the oil in the transformer box body, causing the oil in the pipeline to be tested to surge. The solenoid valve II 304 on the jet nozzle is used to control the opening of the jet nozzle, thereby simulating interphase transformer faults at different coils, different positions and different heights.

[0072] In the above process, the PLC controller plays a role in controlling the solenoid valve I 8 and the solenoid valve II 304 to perform single or group firing (release of high-pressure gas) to simulate interphase transformer faults at different coils, different positions and different heights. For example: the jet nozzles A-phase A1, A2, A3 jet separately or the jet nozzles A1, B1, C1 jet simultaneously, causing the oil flow in the box body to surge into the pipeline to be tested, simulating different faults.

[0073] In this embodiment, as Figure 4 shown in the figure, the double-floating ball gas relay 5 is a BF-type double-floating ball gas relay; a corrugated pipe 9 and a shut-off valve 10 are also arranged on the pipeline to be tested. Figure 4The middle bellows 9 is on the right side of the double-float gas relay 5, and the shut-off valve 10 is on the right side of the bellows 9. The bellows 9 is a bellows with a diameter of Φ80; the shut-off valve 10 is a normally open electromagnetic valve with a diameter of Φ80; the transformer oil pillow 4 is scaled proportionally according to the actual size. The oil pillow 4 is an oil storage device for the transformer. When the volume of the transformer oil expands or shrinks with the change of the oil temperature, the oil pillow 4 plays the role of storing and replenishing oil, which can ensure that the oil tank is full of oil. At the same time, due to the equipment of the oil pillow 4, the contact surface between the transformer oil and the air is reduced, and the moisture, dust and oxidized oil stains absorbed from the air are deposited in the sedimentation device at the bottom of the oil pillow, thereby greatly slowing down the deterioration rate of the transformer oil; the acceleration sensor 7 is firmly installed on the pipeline to be tested by bolt connection method, which provides guarantee for accurately measuring the vibration acceleration of the pipeline, and the data acquisition instrument 11 is used to complete the collection of experimental data. The signal output end of the ultrasonic flowmeter 6 and the acceleration sensor 7 is connected to the signal input end of the data acquisition instrument 11 through a wire. The ultrasonic flowmeter 6 is directly clamped outside the pipeline to be tested. It is easy to install and disassemble, and does not affect the characteristics of the oil flow in the pipeline. It can measure the oil flow velocity change curve in the pipeline under different faults inside the system.

[0074] like Figure 5 As shown, the specific steps of oil flow transmission in the experimental platform of the present invention are as follows:

[0075] First, determine the fault point simulated by the test bench and clarify the goal and object of the experiment. Then, set the on-off state of the electromagnetic valve Ⅰ8 on the side of the air cannon 3 and the electromagnetic valve Ⅱ304 at the air cannon jet port through the PLC controller to prepare for subsequent operations. Then set the pressure of the air cannon 3 and pressurize it so that the air cannon 3 reaches the required working state. After that, the PLC controller controls the corresponding electromagnetic valve Ⅰ8 and electromagnetic valve Ⅱ304 to trigger the corresponding experimental process. In this process, the pipeline vibration acceleration and pipeline oil flow velocity are collected to obtain key experimental data. Finally, the acceleration and velocity change curves are obtained based on the collected data to complete the entire process, providing data support and basis for subsequent analysis and research.

[0076] In this embodiment, an analytical model between the rotation angle of the double-float gas relay baffle and the pipeline oil flow velocity and pipeline vibration acceleration is established, and the theoretical value of the rotation angle of the double-float gas relay baffle is calculated according to the pipeline oil flow velocity and pipeline vibration acceleration. The specific steps of the simulation calculation are as follows: Figure 6 As shown:

[0077] 1. Structural topology

[0078] The double-floating-ball gas relay 5 was modeled using SolidWorks. On the premise of ensuring the accuracy of experimental results, the model was simplified to reduce the computational complexity. The geometric model of the fluid domain of the double-floating-ball gas relay model was extracted through Ansys SpaceClaim. Further, the fluid domain was divided using tetrahedral meshes, and local mesh encryption was performed on the internal structure of the double-floating-ball gas relay to accurately simulate its dynamic response under the influence of fluid excitation forces. To avoid excessive time consumption caused by interpolation operations and possible non-convergence errors during the coupled calculation process, it is recommended to ensure that the sizes of the structural meshes and fluid meshes at the fluid-structure interface are consistent during mesh division.

[0079] 2. Fluid-structure interaction dynamics analysis:

[0080] Structural dynamics analysis:

[0081] Loading of prestressed boundary conditions: An acceleration sensor 7 was used to monitor the vibration response of the pipeline to be measured; a data acquisition instrument 11 was used to output the acceleration and time data collected by the acceleration sensor 7, which was used as the relationship between the wall acceleration at the inlet and time in the ANSYS Mechanical numerical simulation calculation.

[0082] Pipeline constraints: For the connection between pipelines, a bonded connection constraint was selected; Pipeline support: The support method between the pipeline and the ground was selected.

[0083] Structural analysis calculation: The motion differential equation of the pipeline and the double-floating-ball gas relay structure under the action of external excitation forces is:

[0084] [M]u″ + [C]u′ + [K]u = {F}

[0085] Where: [M] is the mass matrix, [C] is the damping matrix, [K] is the stiffness matrix, u″ is the nodal acceleration vector, u′ is the nodal velocity vector, u is the nodal displacement vector, and {F} is the fluid excitation force. During fluid-structure interaction calculation, {F} is the pressure pulsation excitation of the fluid on the fluid-structure interface.

[0086] Fluid dynamics analysis:

[0087] For the selection of the fluid domain model: When calculating the vibration caused by pipeline flow, the pipeline vibration is closely related to the instantaneous pressure fluctuations of the turbulent flow. Large eddy simulation (LES) can accurately simulate this instantaneous pressure change, thereby more accurately reflecting the force exerted by the fluid on the structure during the fluid-structure interaction process.

[0088] The large eddy simulation control equation processed by the filtering function is:

[0089]

[0090] In the formula, ρ is the fluid density, t is the time, u is the fluid velocity, x is the rectangular coordinate component, p is the pressure, and τ i ′ j is the sub-grid stress.

[0091] Boundary conditions: Use the data acquisition instrument 11 to output the data of the voltage and time of the ultrasonic flowmeter 6, inversely deduce the relationship between the flow velocity and time based on Matlab, and fit the functional relationship between the inlet flow velocity and time; set the relationship between the flow velocity and time at the inlet in the ANSYS Fluent numerical simulation calculation through the DEFINE_PROFILE(name,t,i) macro.

[0092] Dynamic mesh: Establish the baffle motion equation according to the force analysis model of the gas relay, and realize the baffle motion control through the DEFINE_CG_MOTION(name,dt,vel,omega,time,dtime) macro, including the suction torque M1 between the permanent magnet inside the gas relay and the baffle:

[0093] M1 = F1L1 = F1l1 cosa

[0094] In the formula, F1 represents the suction force of the permanent magnet, L1 represents the force arm of the acting point of F1, l1 represents the distance from the equivalent suction point of the permanent magnet to the rotation center, and α represents the theoretical value of the rotation angle of the baffle of the double-float gas relay;

[0095] The buoyancy torque M2 on the float;

[0096] M2 = F2L2 = 4 / 3ρgπr 3 l2 sin(α + β)

[0097] In the formula, L2 represents the force arm of the acting point of F2, ρ represents the fluid density, g represents the acceleration due to gravity, r represents the radius of the float, l2 represents the distance from the rotation center to the center of the float, and β represents the angle between the baffle and the connecting rod of the float;

[0098] The impact torque M3 is generated by the oil flow fluctuation caused by the transformer fault and the fluid pressure pulsation caused by the pipeline vibration. Through the Compute_Force_And_Moment internal function, the oil flow impact torque M3 can be extracted:

[0099] M3 = M p +M v

[0100] In the formula, M p represents the pressure difference resistance torque, and M v represents the viscous resistance torque;

[0101]

[0102] In the formula, p is the pressure, μ is the viscosity coefficient, (x, y, z) are the coordinates of any point on the baffle, (x0, y0, z0) are the coordinates of the rotation center of the baffle, and u, v, and w are the pipeline oil flow velocity components in the x, y, and z directions respectively;

[0103] The gravitational moment M4 of the baffle around the rotation center:

[0104]

[0105] In the formula, L4 represents the arm of the equivalent gravitational force application point, point P represents the equivalent center of gravity of the baffle and the lower floating ball, m represents the mass of the baffle and the mass of the lower floating ball, g represents the acceleration due to gravity, represents the angle between the equivalent center of gravity and the initial position of the baffle, and l4 represents the distance from the equivalent gravitational point P of the baffle and the floating ball to the rotation center O;

[0106] The additional vibration moment M5 acting on the baffle due to pipeline vibration:

[0107]

[0108] In the formula, F5 represents the vibration force, with the positive direction defined as the baffle opening direction, L5 represents the arm of the equivalent vibration force application point, point P represents the equivalent center of gravity of the baffle and the lower floating ball, m represents the mass of the baffle and the mass of the lower floating ball, represents the pipeline vibration acceleration, represents the angle between the equivalent center of gravity and the initial position of the baffle, and l5 represents the distance from the equivalent vibration force application point P of the baffle and the floating ball to the rotation center O.

[0109] Calculate the total moment M acting on the baffle, M = M3 + M4 - M1 - M2 + M5, as Figure 7 shown.

[0110] Calculate the rotational angular velocity ω of the baffle, ω = M / I, where I represents the moment of inertia of the baffle. Integrating the rotational angular velocity with respect to time gives the theoretical value of the rotation angle of the baffle, α = ∫ωdt. In the formula, dt is the time step.

[0111] Select the SIMPLE model analysis method, which is simple to implement, has a small computational amount, and is applicable to a wide range of fluid problems.

[0112] 3. Two-way coupling

[0113] Using the finite element analysis software ANSYS Workbench as the calculation platform, the fluid mechanics analysis module (Fluent) calculates the oil flow, and the solid mechanics analysis module (Transient Structural) calculates the structural vibration. The system coupling module (System Coupling) is used to realize the data interaction between the vibration displacement of the solid domain and the pressure wave force of the fluid domain. Given that the analysis frequency of this experiment is 50 Hz, the time step is set to 0.001 seconds. The simulation time is set to 1 second to ensure that sufficient vibration cycles can be captured. At the same time, a fixed constraint is applied to the connection part between the gas relay and the pipeline to be measured to simulate the installation state under actual working conditions. Through this configuration, the structural dynamic response characteristics under the fluid-structure interaction effect can be analyzed more accurately.

[0114] In this embodiment, the theoretical value is compared with the measured baffle rotation angle for analysis to judge the working state of the double-float gas relay baffle, including:

[0115] If the relative error between the theoretical value and the measured baffle rotation angle is less than or equal to 10%, it is judged that the gas relay baffle is working normally; if the relative error is greater than 10%, it is judged that the gas relay baffle is abnormal and the gas relay baffle needs to be recalibrated.

[0116] In this embodiment, based on the pipeline vibration acceleration, the pipeline oil flow velocity, and the heavy gas operation signal, the heavy gas operation output of the gas relay is identified, as Figure 8 shown, including:

[0117] (1) If the pipeline vibration acceleration is greater than or equal to the acceleration threshold and the pipeline oil flow velocity is greater than or equal to the flow velocity threshold, then the heavy gas signal is judged. If the heavy gas signal is high level, that is v≥v s and S = 1, the heavy gas signal is output; if the heavy gas signal is low level, that is v≥v s and S = 0, then it needs to be judged again at the next Δt. If the result is the same (still v≥v s and S = 0), then the heavy gas rejection signal is output;

[0118] (2) If the pipeline vibration acceleration is greater than or equal to the acceleration threshold and the pipeline oil flow velocity is less than the flow velocity threshold, then the heavy gas signal is judged. If the heavy gas signal is high level, that is v<v s and S = 1, it is judged that the action is caused by excessive pipeline vibration rather than excessive oil flow caused by an internal fault, and it needs to be judged again at the next Δt. If the result is the same (still v<v sIf S = 1, then output a false operation signal for the heavy gas; if the heavy gas signal is at a low level, that is v < v s and S = 0, only output a reminder message;

[0119] (3) If the pipeline vibration acceleration is less than the acceleration threshold and the pipeline oil flow velocity is greater than or equal to the flow velocity threshold, then judge the heavy gas signal. If the heavy gas signal is at a high level, that is v ≥ v s and S = 1, output the heavy gas signal; if the heavy gas signal is at a low level, that is v ≥ v s and S = 0, it is necessary to make a re - judgment at the next Δt. If the result is consistent (still that is v ≥ v s and S = 0), then output a refusal - to - operate signal for the heavy gas;

[0120] (4) If the pipeline vibration acceleration is less than the acceleration threshold and the pipeline oil flow velocity is less than the flow velocity threshold, then judge the heavy gas signal. If the heavy gas signal is at a high level, that is v < v s and S = 1, it is necessary to make a re - judgment at the next Δt. If the result is consistent (still v < v s and S = 1), then output a false operation signal for the heavy gas, reminding that the false operation may be caused by the contact getting damp; if the heavy gas signal is at a low level, that is v < v s and S = 0, indicating normal operation.

[0121] Among them, the threshold pipeline wall acceleration and the oil flow velocity v s are the average values of the pipeline vibration acceleration and the oil flow velocity when the baffle of the gas relay operates measured through multiple experiments.

[0122] The time interval Δt refers to the duration from the start of the operation of the baffle of the gas relay to the end of the operation.

[0123] In this specification, each embodiment is described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0124] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preventing malfunction of a double-float gas relay, characterized in that: include: Step 1: Build a simulated transformer fault test experimental platform to simulate different faults; Step 2: Based on the simulated transformer fault test experimental platform, the gas relay action characteristics caused by surging oil flow under different fault excitations are measured, the baffle rotation angle is measured, and the pipeline oil flow velocity under different fault excitations during the experiment, the pipeline vibration acceleration of the surging oil flow through the pipeline to be tested where the gas relay is located, and the heavy gas action signal simulated by the double float gas relay are synchronously collected; Step 3: Establish an analytical model between the rotation angle of the double-float gas relay baffle and the pipeline oil flow velocity and pipeline vibration acceleration, and calculate the theoretical value of the rotation angle of the double-float gas relay baffle according to the pipeline oil flow velocity and pipeline vibration acceleration collected in step 2; Step 4: Compare and analyze the theoretical value with the measured baffle rotation angle to determine the working state of the double-float gas relay baffle; Step 5: After confirming that the double-float gas relay baffle is working normally, identify the heavy gas action output of the gas relay based on the pipeline vibration acceleration, pipeline oil flow velocity and heavy gas action signal collected in step 2.

2. A method for preventing malfunction of a double-float gas relay according to claim 1, characterized in that: The theoretical value of the double-float gas relay baffle rotation angle is calculated based on the pipeline oil flow velocity and pipeline vibration acceleration, including: The total moment M on the baffle is: M=M3+M4-M1-M2+M5 The vibration of the pipeline causes the baffle to be subjected to an additional vibration moment M5: In the formula, F5 represents the vibration force, which is defined as the positive direction in the direction of the baffle opening, L5 represents the equivalent vibration force application point arm, m represents the mass of the baffle and the mass of the lower floating ball, represents the pipeline vibration acceleration, represents the angle between the equivalent center of gravity and the initial position of the baffle, α represents the theoretical value of the rotation angle of the baffle of the double-float gas relay, and l5 represents the distance from the equivalent vibration force point of the baffle and the float to the rotation center; The suction torque M1 between the permanent magnet and the baffle inside the Buchholz relay: M1=F1L1=F1l1 cosa In the formula, F1 represents the suction force of the permanent magnet, L1 represents the force arm of the F1 application point, and l1 represents the distance from the permanent magnet's equivalent suction point to the rotation center; The buoyancy moment M2 on the float; M2=F2L2=4 / 3ρgπr 3 l2 sin(α+β) In the formula, F2 represents the buoyancy of the float ball under the influence of the fluid, L2 represents the force arm of the F2 point of application, ρ represents the density of the fluid, g represents the acceleration of gravity, r represents the radius of the float ball, l2 represents the distance from the center of rotation to the center of the float ball, and β represents the angle between the baffle plate and the float ball connecting rod; Impact moment M3 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 pipeline oil flow velocity components in the x, y, and z directions respectively; The gravitational moment M4 of the baffle around the center of rotation: In the formula, F4 represents the equivalent gravity of the baffle and the float, L4 represents the equivalent gravity force arm, represents the angle between the equivalent center of gravity and the initial position of the baffle, l4 represents the distance from the equivalent gravity point of the baffle and the float to the rotation center; Calculate the baffle rotation angular velocity ω: ω=M / I Where I represents the moment of inertia of the baffle, and the theoretical value of the baffle rotation angle can be obtained by integrating the baffle rotation angular velocity over time.

3. A method for preventing malfunction of a double-float gas relay according to claim 1, characterized in that: Based on pipeline vibration acceleration, pipeline oil flow velocity and heavy gas action signal, the heavy gas action output of the gas relay is identified, including: (1) Pipeline vibration acceleration Greater than or equal to the acceleration threshold The pipeline oil flow velocity v is greater than or equal to the flow velocity threshold v s , then judge the heavy gas signal, if the heavy gas action signal S is high level, that is v≥v s And S = 1, output heavy gas signal; if the heavy gas action signal S is low level, that is, v≥v s If S=0, it is necessary to make another judgment at the next Δt. If the result is consistent, a heavy gas refusal signal is output; (2) Pipeline vibration acceleration Greater than or equal to the acceleration threshold The oil flow velocity v in the pipeline is less than the velocity threshold v s , then judge the heavy gas signal, if the heavy gas action signal S is high level, that is v <v s And S = 1, it is necessary to judge again in the next Δt. If the result is consistent, the heavy gas malfunction signal is output. The output may be caused by excessive pipeline vibration acceleration. If the heavy gas action signal S is low level, that is, v <v s And S=0, only the reminder information is output; (3) Pipeline vibration acceleration Less than the acceleration threshold The pipeline oil flow velocity v is greater than or equal to the flow velocity threshold v s , then judge the heavy gas signal, if the heavy gas action signal S is high level, that is v≥v s And S = 1, output heavy gas signal; if the heavy gas action signal S is low level, that is, v≥v s And S=0, it is necessary to make another judgment at the next Δt. If the result matches, the heavy gas refusal signal is output; (4) Pipeline vibration acceleration Less than the acceleration threshold The oil flow velocity v in the pipeline is less than the velocity threshold v s , then judge the heavy gas signal, if the heavy gas action signal S is high level, that is v <v s And S = 1, it is necessary to judge again in the next Δt. If the result matches, the heavy gas misoperation signal is output. The output may be caused by the misoperation of the contact due to moisture; if the heavy gas action signal S is low level, that is, v <v s And S=0, indicating normal operation.

4. A method for preventing malfunction of a double-float gas relay according to claim 1, characterized in that: Obtain the voltage and time data collected by the ultrasonic flowmeter on the pipeline to be tested, and infer the relationship between the oil flow velocity in the pipeline and time; The acceleration and time data collected by the acceleration sensor on the pipeline to be tested are obtained, and the relationship between the wall acceleration at the pipeline inlet and time is calculated by ANSYS Mechanical numerical simulation as the pipeline vibration acceleration.

5. A method for preventing malfunction of a double-float gas relay according to claim 1, characterized in that: Compare and analyze the theoretical value with the measured baffle rotation angle to determine the working status of the double-float gas relay baffle, including: If the relative error between the theoretical value and the measured baffle rotation angle is less than or equal to 10%, it is judged that the gas relay baffle is working normally; if the relative error is greater than 10%, it is judged that the gas relay baffle is abnormal and needs to be recalibrated.

6. A method for preventing malfunction of a double-float gas relay according to claim 1, characterized in that: The simulated transformer fault test experimental platform includes a transformer oil tank, an iron core is arranged in the transformer oil tank, three air cannons are installed at different positions between the iron cores, and jet nozzles are designed at 9 positions of the iron core with the air cannons as the power source. The oil filling port of the transformer oil tank is connected to the oil pillow through the pipeline to be tested, and a double float gas relay, an ultrasonic flowmeter and an acceleration sensor are installed on the pipeline to be tested.

7. A method for preventing malfunction of a double-float gas relay according to claim 6, characterized in that: The air cannon includes an air inlet, an air storage box, a solenoid valve I, three air jets and a solenoid valve II at the air jet. The air storage box is connected to an external compressed air supply system through the air inlet. The solenoid valve I is arranged on the bottom side of the air storage box. According to the jet direction, the solenoid valve I is connected to the three air jets through an air jet pipe, and the solenoid valve II is installed on the air jet.

8. A method for preventing malfunction of a double-float gas relay according to claim 7, characterized in that: It also includes a PLC controller, which is used to control the solenoid valve I and the solenoid valve II to perform single and group blasting, thereby simulating interphase transformer faults with different coils, different positions and different heights.

9. A method for preventing malfunction of a double-float gas relay according to claim 6, characterized in that: It also includes a data acquisition device for acquiring data collected by the gas relay, the ultrasonic flow meter and the acceleration sensor.

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