GIS built-in fiberscope electromagnetic force simulation model construction method

Abstract

The invention provides a GIS built-in fiberscope electromagnetic force simulation model construction method, which comprises the following steps: constructing a model by using acquired equipment and fiberscope parameters, then solving electromagnetic field distribution by using a finite element method, and calculating the electromagnetic force condition of a built-in fiberscope through the solved electromagnetic field distribution. And finally, carrying out optimization design on the built-in fiber mirror through the solved electromagnetic force condition of the fiber mirror. The method aims at solving the problem that a traditional external detection method is limited in high-voltage electrical equipment. The method comprises the following steps: S1, acquiring equipment parameters; s2, adding fiber mirror parameters; s3, electromagnetic field distribution simulation; s4, calculating the electromagnetic force on the fiberscope; and S5, designing and optimizing a fiber mirror. According to the method for constructing the simulation model of the electromagnetic force applied to the GIS built-in fiberscope, the model is constructed by utilizing acquired equipment and fiberscope parameters, then electromagnetic field distribution is solved by utilizing a finite element method, the electromagnetic force applied to the built-in fiberscope is calculated through the solved electromagnetic field distribution, and the simulation model of the electromagnetic force applied to the built-in fiberscope is obtained. And finally, performing built-in fiberscope optimization design according to the solved electromagnetic force condition of the fiberscope, so as to deal with the problem that a traditional external detection method is limited in the high-voltage electrical equipment, realize visual detection of the interior of the high-voltage electrical equipment, and provide powerful support for maintaining safe and stable operation of electrical equipment.

Description

Technical Field

[0001] The invention relates to the field of gas insulated switchgear (GIS) and electromagnetic force simulation technology, and in particular to a simulation model construction method for calculating the electromagnetic force exerted on a fiberscope inside a GIS device. Background Art

[0002] More and more high-voltage electrical equipment adopts closed structures. When an abnormality occurs inside the equipment, it is difficult to detect it directly through human senses, and the maintenance plan after the failure is complicated, long-term and expensive. Therefore, how to obtain the internal operating status of the equipment through reliable monitoring means and use reasonable methods to warn and diagnose equipment abnormalities has become an urgent problem to be solved in the power industry.

[0003] For the condition monitoring of high-voltage electrical equipment, scholars at home and abroad have proposed a variety of equipment condition monitoring methods, among which the five most widely used methods are:

[0004] (1) Pulse current method

[0005] The pulse current method is to install corresponding coupling capacitors Ca and detection impedance R at both ends of the GIS equipment. The loop formed by the coupling capacitor Ca and the detection impedance R is connected in parallel with the capacitor Cc formed by the metal shell and conductor of the equipment. Part of the pulse current generated by the partial discharge of the equipment passes through the capacitor Cc, and part of it passes through the loop formed by Ca and R. That is, the partial discharge signal inside the equipment is reflected in the voltage change V of the detection impedance. The discharge amount of the equipment is determined by measuring the change in voltage. The pulse current method is relatively easy to operate, highly sensitive, and can quantitatively measure the partial discharge amount of the equipment. At present, there are corresponding international testing standards. However, due to the presence of more electromagnetic pulse interference at the actual substation site, these pulse signals will affect the final measurement results, so the pulse current method is not suitable for use in practice.

[0006] (2) UHF method

[0007] When there is a discharge fault inside the equipment, electromagnetic waves of different frequencies will be generated. The detection pulse signal in the GHz frequency band can accurately realize the diagnosis of partial discharge fault of the equipment. The UHF method can not only identify the type of equipment discharge point fault but also locate the fault point. According to the installation position, UHF sensors are divided into built-in and external types. The signal measured by the built-in sensor is not attenuated by the outer shell and can better reflect the internal fault of the equipment. However, the built-in sensor can only be installed by the manufacturer before the equipment leaves the factory and cannot be placed as flexibly as the external sensor.

[0008] (3) Ultrasonic method

[0009] When partial discharge or other faults occur inside the equipment, causing the insulation inside the equipment to change, the internal electrons, particles, and gas molecules will collide violently, generating pressure pulse waves. This pulse will propagate to the metal shell through the gas and solid, causing the shell to vibrate. By measuring the vibration of the shell, partial discharge faults inside the equipment can be indirectly detected.

[0010] (4) Gas decomposition method

[0011] The chambers of high-voltage equipment are filled with SF6 gas at a certain pressure, and its main functions are insulation and arc extinguishing. SF6 gas has stable chemical properties and is extremely difficult to decompose under normal operating conditions. However, local discharge or local overheating caused by insulation failure inside the equipment will cause the decomposition of SF6 gas. Among the many decomposition products, CS2, CF4, SO2, and SO2F2 are generally selected as characteristic gases for equipment insulation failure. Some domestic scholars have made certain progress in using SF6 gas decomposition products to diagnose equipment insulation failures through experimental means. However, there are no systematic research results on the mechanism of SF6 gas decomposition under different faults.

[0012] (5) X-ray detection method

[0013] X-rays have strong penetrability, and X-ray detection technology can present the structural information of objects inside the GIS tank, and realize the defect determination of GIS internal components. At present, power companies in various provinces have used X-ray technology to carry out GIS live detection, and found problems such as loose bolts, inadequate opening and closing of disconnectors, and insufficient insertion depth of conductors. However, due to the complex internal structure of the equipment, there are problems of slow imaging and low resolution. At the same time, for abnormal images produced by impurities inside the tank wall, it is impossible to determine whether there are abnormal conditions inside the gas chamber, which is easy to cause misjudgment.

[0014] However, most of the existing high-voltage electrical equipment status detection technologies are indirect measurement methods, making it difficult to directly observe the internal conditions of the air chamber.

[0015] The industrial endoscope based on fiberscope technology is an innovative non-destructive testing device that integrates optics, precision mechanics, electronics and microphotography. It can operate safely and reliably under extreme conditions, such as high temperature, toxic and hazardous environments, and nuclear radiation areas. This device can accurately and clearly detect the internal conditions of gas-insulated power equipment and its components without disassembling the equipment or damaging the components, thereby significantly reducing maintenance costs and improving production efficiency.

[0016] Through the fiberscope built into high-voltage electrical equipment, it is possible to visually observe events inside the equipment. The internal working conditions of high-voltage electrical equipment are complex, requiring the fiberscope to have a good compatibility design. The fiberscope needs to work inside the equipment for a long time and is affected by the electromagnetic force of the GIS equipment during operation. Therefore, it is necessary to simulate the electromagnetic force of the fiberscope to ensure the sealing performance of the fiberscope, reduce the impact on the insulation of the equipment, and ensure that the fiberscope and the electrical equipment body can work reliably.

[0017] Embedding fiberscope equipment into GIS equipment is an innovative research that has rarely been carried out, and the relevant practical experience is relatively limited. When fiberscope equipment is introduced into GIS equipment, the fiberscope will inevitably be affected by the electromagnetic force of the GIS equipment itself during operation. This problem directly involves the security of the power grid and the safety protection of the staff. At the same time, this also provides a theoretical basis for subsequent experiments and work. Therefore, it is very important to conduct simulation calculation research on the electromagnetic force of the built-in fiberscope in GIS. Summary of the invention

[0018] The present invention provides a method for constructing a simulation model of electromagnetic force on a built-in fiberscope of GIS, which uses the acquired equipment and fiberscope parameters to construct a model, then uses the finite element method to solve the electromagnetic field distribution, calculates the electromagnetic force on the built-in fiberscope through the solved electromagnetic field distribution, and finally optimizes the design of the built-in fiberscope through the solved electromagnetic force on the fiberscope, aiming to address the limitation of traditional external detection methods inside high-voltage electrical equipment. The method comprises the following steps:

[0019] Step 1: Get device parameters

[0020] Obtain detailed parameters of high-voltage electrical equipment, including but not limited to electrical structure parameters, material parameters, working environment parameters, etc.

[0021] Step 2: Add fiberscope parameters

[0022] Add the relevant parameters of the fiberscope built into the GIS equipment, including the shape, material, mechanical structure, etc. of the fiberscope.

[0023] Step 3: Electromagnetic field distribution simulation

[0024] A GIS electromagnetic field model with a built-in fiberscope was constructed in COMSOL. A 220KV voltage was applied to the terminal busbar, and the steady-state electromagnetic field distribution was simulated and calculated, considering the electromagnetic field distribution under a high voltage environment.

[0025] Step 4: Calculation of electromagnetic force on fiberscope

[0026] Based on the obtained electromagnetic field distribution, the electromagnetic force acting on the fiberscope is calculated.

[0027] Step 5: Fiberscope Design and Optimization

[0028] The fiberscope parameters are changed to perform simulation, the simulation results are integrated, and the design of the fiberscope is adjusted according to the calculation results of the electromagnetic force on the fiberscope to ensure that the fiberscope is coordinated with the high-voltage electrical equipment and meets the requirements of reliable operation.

[0029] Through the method for constructing a simulation model of electromagnetic force on a GIS built-in fiberscope provided by the present invention, simulation calculation of the electromagnetic force on the GIS built-in fiberscope can be realized, providing scientific theoretical support for the feasibility of built-in fiberscopes in high-voltage electrical equipment and the design optimization of fiberscopes.

[0030] As a further solution of the present invention: the high-voltage power equipment involved in step 1 mainly refers to gas-insulated switchgear (GIS). GIS equipment usually adopts a closed structure, so a fiberscope needs to be embedded inside to achieve visual inspection of the inside of the equipment.

[0031] As a further solution of the present invention: the calculation of the electromagnetic field distribution in step 3 and the electromagnetic force on the fiberscope in step 4 are both completed by using COMSOL through the finite element method.

[0032] As a further solution of the present invention: the fiberscope parameters changed in step 5 include the fiberscope built-in depth and the fiberscope thickness. The fiberscope parameters are changed while other conditions remain unchanged, and the fiberscope design is evaluated by the electromagnetic force applied to the changed fiberscope. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the GIS built-in fiberscope structure model

[0034] Figure 2 Schematic diagram of the fiberscope structure model

[0035] Figure 3 Built-in fiberscope electric field distribution map for GIS

[0036] Figure 4 Magnetic field distribution and electromagnetic force diagram of fiber mirror

[0037] Figure 5 Flow chart of the method proposed for the invention DETAILED DESCRIPTION

[0038] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0039] The present invention provides a method for constructing a simulation model of electromagnetic force on a built-in fiberscope of GIS. The model is constructed using the acquired equipment and fiberscope parameters, and then the electromagnetic field distribution is solved using the finite element method. The electromagnetic force on the built-in fiberscope is calculated by the solved electromagnetic field distribution, and finally the built-in fiberscope is optimized and designed based on the solved electromagnetic force on the fiberscope, aiming to address the limitation of traditional external detection methods inside high-voltage electrical equipment. The method proposed by the present invention comprises the following steps:

[0040] Step 1: Get device parameters

[0041] Obtain detailed parameters of high-voltage electrical equipment, including but not limited to electrical structure parameters, material parameters, working environment parameters, etc.

[0042] Step 2: Add fiberscope parameters

[0043] Add the relevant parameters of the fiberscope built into the GIS equipment, including the shape, material, mechanical structure, etc. of the fiberscope.

[0044] Step 3: Electromagnetic field distribution simulation

[0045] A GIS electromagnetic field model with a built-in fiberscope was constructed in COMSOL. A 220KV voltage was applied to the terminal busbar, and the steady-state electromagnetic field distribution was simulated and calculated, considering the electromagnetic field distribution under a high voltage environment.

[0046] Step 4: Calculation of electromagnetic force on fiberscope

[0047] Based on the obtained electromagnetic field distribution, the electromagnetic force acting on the fiberscope is calculated.

[0048] Step 5: Fiberscope Design and Optimization

[0049] The fiberscope parameters are changed to perform simulation, the simulation results are integrated, and the design of the fiberscope is adjusted according to the calculation results of the electromagnetic force on the fiberscope to ensure that the fiberscope is coordinated with the high-voltage electrical equipment and meets the requirements of reliable operation.

[0050] Through the method for constructing a simulation model of electromagnetic force on a GIS built-in fiberscope provided by the present invention, simulation calculation of the electromagnetic force on the GIS built-in fiberscope can be realized, providing scientific theoretical support for the feasibility of built-in fiberscopes in high-voltage electrical equipment and the design optimization of fiberscopes.

[0051] The specific implementation process of the magnetic field distribution simulation used in step 3 of the present invention is as follows:

[0052] (1) Setting up GIS and fiberscope materials

[0053] The shell of the GIS equipment is made of aluminum alloy 6061 (solid, T6 state), filled with insulating gas SF6 gas, the solid insulation layer is made of silicone rubber, and the conductor part is made of copper material. An air domain is set around the GIS equipment to simulate the situation of GIS in the daily working environment.

[0054] The fiber core of a fiberscope is composed of multiple single-filament optical fibers, and the core is coated with a refractive layer, and the outer sides are respectively a primary coating layer and a secondary coating layer. The core and the refractive layer are both made of silica (SiO2) material, but they have different refractive indices. Normally, the refractive index of the fiber core is higher than that of the fiber cladding to achieve total reflection of light in the fiber core. Generally speaking, the dielectric constant and refractive index of a material are positively correlated, that is, the dielectric constant of a material with a higher refractive index should also be higher. Therefore, the relative dielectric constant of the core is higher than that of the refractive layer. The primary coating layer is made of silicone rubber (Silicone [solid]) material, and the secondary coating layer is made of polyimide (Polyimide, referred to as PI) material.

[0055] (2) Setting of electrostatic boundary conditions

[0056] 1) Set all domains to conserve charge. Under static conditions, the potential V is defined by the following relationship:

[0057]

[0058] The charge conservation node follows Gauss's law:

[0059]

[0060] The charge conservation equation is added to the electric displacement field to define the constitutive relation and its related properties. The relative permittivity uses the constitutive relation D = ε 0 ε r E.

[0061] 2) Set the outer boundary of the air domain to zero charge. The zero charge node adds the condition that the charge on the boundary is zero, so n·D=0.

[0062] 3) Set the bus terminal, V = 220KV. The terminal node provides boundary or domain conditions for connecting to external circuits, transmission lines, or carrying specified voltages or charges.

[0063] 4) Set grounding V=0 on the GIS housing, grounding switch and soil surface.

[0064] 5) Set the initial value V of all domains to 0.

[0065] (3) Setting of magnetic field boundary conditions

[0066] 1) Set all regions to Ampere's law

[0067] The integrated form of Ampere's law can be written as:

[0068] ∮B·dL=μ 0 ∫∫J·dS

[0069] B is the magnetic flux density,

[0070] ·dL is a tiny line element on the integration path,

[0071] The ∮ symbol represents the path integral (line integral),

[0072] μ0 is the magnetic permeability in vacuum (also called vacuum permeability, which is approximately 4π×10 -7 T m / A),

[0073] J is the current density, which is the amount of current flowing through a unit area.

[0074] ·The ∫∫ symbol represents an area integral.

[0075] The differential form of Ampere's law is part of Maxwell's equations:

[0076]

[0077] · represents the curl of the magnetic field B,

[0078] · The symbol represents the gradient operator (vector differential operator),

[0079] J is the current density,

[0080] μ0 is the magnetic permeability in vacuum,

[0081] ε0 is the dielectric constant in vacuum (vacuum permittivity, which is about 8.85×10^-12F / m),

[0082] E is the electric field,

[0083] · is the rate of change of the electric field with time, μ0ε0 is the displacement current term, which reflects the effect of the electric field changing with time.

[0084] 2) Set the air domain boundary to magnetic insulation

[0085] Magnetic insulation is a special case of the magnetic potential boundary condition, where the tangential component of the magnetic potential is zero on the boundary, i.e., n×A=0. This means that the normal component of the magnetic field (i.e., the component perpendicular to the boundary) is zero on this boundary. This is equivalent to assuming that there is no magnetic flux passing through the boundary. Mathematically, this boundary condition can be expressed as B·n=0, where B represents the magnetic field and n represents the unit normal vector pointing outside the boundary. Since the magnetic field mainly varies inside the simulation region and is independent of the boundary, it is reasonable to set a magnetic insulation boundary condition on the boundary.

[0086] 3) Coil

[0087] The copper conductor area is set as a single conductor coil, and the excitation voltage is 220KV. The coil section is used to simulate the conductor.

[0088] 4) Set the initial value of magnetic vector potential of all domains to 0Wb / m.

[0089] (3) Electric field distribution solution

[0090] COMSOL automatically solves the electric field partial differential equation using the finite element method.

[0091] (3) Magnetic field distribution solution and electromagnetic force calculation

[0092] COMSOL automatically solves the magnetic field partial differential equations using the finite element method.

[0093] The specific implementation process of calculating the electromagnetic force on the fiberscope used in step 4 of the present invention is as follows:

[0094] Based on the electromagnetic field distribution obtained in step 3, the force in the electric field interface is calculated by integrating (1) over the surface of the object on which the force acts.

[0095]

[0096] In a magnetic field interface, expression (2) is integrated over the surface to obtain the force.

[0097]

[0098] For the Maxwell stress tensor, the force is expressed as

[0099]

[0100] in Indicates domain boundaries.

[0101] Effects of the Invention

[0102] The present invention provides a method for constructing a simulation model of electromagnetic force of a built-in fiberscope of GIS. The model is constructed by using the acquired equipment and fiberscope parameters, and then the finite element method is used to solve the electromagnetic field distribution. The electromagnetic force of the built-in fiberscope is calculated according to the solved electromagnetic field distribution. Finally, the built-in fiberscope is optimized according to the solved electromagnetic force of the fiberscope. The method aims to cope with the limitation problems of traditional external detection methods inside high-voltage electrical equipment, so as to realize visual detection of the inside of high-voltage electrical equipment, thereby providing strong support for maintaining the safe and stable operation of power equipment.

[0103] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. The present invention provides a method for constructing a simulation model of electromagnetic force on a built-in fiberscope of GIS. The model is constructed using the acquired equipment and fiberscope parameters, and then the finite element method is used to solve the electromagnetic field distribution. The electromagnetic force on the built-in fiberscope is calculated by the solved electromagnetic field distribution. Finally, the built-in fiberscope is optimized and designed based on the solved electromagnetic force on the fiberscope, aiming to address the limitations of traditional external detection methods inside high-voltage electrical equipment. The method comprises the following steps: S1: Get device parameters; S2: Add fiberscope parameters; S3: electromagnetic field distribution simulation; S4: Calculation of electromagnetic force on fiberscope; S5: Fiberscope design and optimization.

2. The method for obtaining device parameters according to claim 1, characterized in that: High-voltage power equipment mainly refers to gas-insulated switchgear (GIS). GIS adopts a closed structure and requires a built-in fiberscope to achieve visual inspection inside the equipment.

3. The method for obtaining device parameters according to claim 2, characterized in that: The equipment parameters include but are not limited to electrical structure parameters, material parameters, working environment parameters, etc., which are used for electromagnetic field distribution simulation and electromagnetic force calculation in step S3 and step S4.

4. The fiberscope parameter addition according to claim 3, characterized in that: The fiberscope parameters include parameters such as the shape, material, and mechanical structure of the fiberscope, which are used for electromagnetic field distribution simulation and electromagnetic force calculation in step S3 and step S4.

5. The electromagnetic field distribution simulation according to claim 4, characterized in that: The method uses COMSOL software to apply finite element analysis to solve partial differential equations to obtain the electromagnetic field distribution before and after the built-in fiberscope, which is used in the calculation of the electromagnetic force on the fiberscope in step S4.

6. The electromagnetic force calculation according to claim 5, characterized in that: The method uses COMSOL software to calculate the electromagnetic force on the built-in fiberscope and performs further evaluation in step S5.

7. The design and optimization of the built-in fiberscope according to claim 6, characterized in that: The electromagnetic force on the fiberscope after insertion is obtained by step S4, and the influence of different fiberscope insertion depths and different fiberscope thicknesses on the electromagnetic force on the fiberscope is compared, so as to optimize the design of the built-in fiberscope.

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