GIL electromagnetic property detection method and system based on field circuit-mechanical coupling

Abstract

The invention discloses a GIL electromagnetic property detection method and system based on field circuit-mechanical coupling, and the method comprises the steps: building an electromagnetic field-circuit-mechanical coupling mathematical model based on a circuit mathematical model through employing a stiffness matrix of a magnetic vector position, a stiffness matrix of a conductor eddy current, and a load matrix of a conductor conduction current; engineering sections are divided, a finite element two-dimensional simulation model is built, an equivalent external circuit is built, coupling connection is conducted through an external circuit port voltage matrix, and an electromagnetic property detection model of the GIL is obtained; performing iterative solution to obtain transient electromagnetic response of each engineering section, wherein the transient electromagnetic response comprises magnetic flux density, current density and node transient electromagnetic force; detecting whether electromagnetic response abnormity exists in the actual operation process of the GIL or not; and simulating the electromagnetic stress of the GIL component in the abnormal engineering section in the three-dimensional structure field by adopting harmonic response analysis, and checking the electromagnetic and mechanical characteristics of the GIL. According to the method, the electromagnetic characteristics of the GIL can be simulated more accurately, the applicability is wide, the operation speed is high, and guarantee is provided for GIL short-circuit fault monitoring and safe and stable operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of power transmission and transformation, and more specifically, relates to a GIL electromagnetic characteristic detection method and system based on field-circuit-mechanical coupling. Background Art

[0002] With the development of power systems, more and more GILs (Gas-Insulated Transmission Lines) are being used in power transmission and distribution. During normal operation, the GIL's casing and conductors are exposed to the alternating electromagnetic field generated by the load current and eddy currents. These alternating electromagnetic forces generate electromotive force. If the GIL experiences a short-circuit condition, the electromotive force surges under the influence of the short-circuit current, potentially leading to serious mechanical failure.

[0003] There are full three-dimensional electromagnetic response analysis methods in the existing technology. However, their shortcomings are that they only implement physical analysis of specific structures and cannot solve the electromagnetic response of GIL equipment in different engineering sections. They are limited, time-consuming, and require finite element analysis equipment with extremely high computing power.

[0004] Furthermore, research on the electromagnetic characteristics of GILs often relies primarily on direct current excitation, which fails to accurately represent the transient changes in the electromagnetic characteristics of gas-insulated transmission lines under field-circuit coupling. Prior art CN117272895A discloses a method, dielectric, and electronic device for calculating transient electrodynamic forces in gas-insulated transmission lines. While this method studies the electromagnetic characteristics of GILs through direct current excitation, its shortcomings include neglecting the combined effects of field-circuit coupling and mechanical response of gas-insulated transmission lines under different operating conditions and lacking a solution for electromagnetic stress.

[0005] Therefore, a GIL electromagnetic property detection method based on field-circuit-mechanical coupling multi-physics field is needed. Summary of the Invention

[0006] To address the deficiencies in the prior art, the present invention provides a GIL electromagnetic characteristics detection method and system based on field-circuit-mechanical coupling, which simulates actual operating conditions, couples an external circuit, solves the electromagnetic force, detects the electromagnetic characteristics of gas-insulated transmission lines under different operating conditions, and introduces harmonic response analysis to obtain the electromagnetic stress of key components.

[0007] The present invention adopts the following technical solutions.

[0008] A first aspect of the present invention provides a method for detecting electromagnetic characteristics of a GIL based on field-circuit-mechanical coupling, comprising the following steps:

[0009] Step 1: Based on the electromagnetic field mathematical model, obtain the magnetic vector potential and conductor eddy current of the gas-insulated transmission line; based on the mechanical mathematical model, obtain the stiffness matrix of the magnetic vector potential and the stiffness matrix of the conductor eddy current, and the load matrix of the conductor conduction current in the gas-insulated transmission line; using the stiffness matrix of the magnetic vector potential, the stiffness matrix of the conductor eddy current, and the load matrix of the conductor conduction current, establish an electromagnetic field-circuit-mechanical coupling mathematical model based on the circuit mathematical model;

[0010] Step 2: Divide the actually operated gas-insulated transmission line into multiple engineering sections to establish a finite element two-dimensional simulation model of the gas-insulated transmission line; build an equivalent external circuit of the gas-insulated transmission line, connect the finite element two-dimensional simulation model with the equivalent external circuit, and obtain the external circuit port voltage matrix through simulation; the electromagnetic field-circuit-mechanical coupling mathematical model and the finite element two-dimensional simulation model are coupled through the external circuit port voltage matrix to obtain an electromagnetic characteristic detection model of the gas-insulated transmission line;

[0011] Step 3: Iteratively solve the electromagnetic characteristic detection model to obtain the transient electromagnetic response of each engineering section, including magnetic flux density, current density and node transient electromagnetic force;

[0012] Step 4: Use the calculated node transient electromagnetic force to detect whether there is any electromagnetic response anomaly in the gas-insulated transmission line during actual operation; use the harmonic response analysis method to simulate the electromagnetic stress of the gas-insulated transmission line components in the engineering section with electromagnetic response anomaly in the three-dimensional structural field, and verify the electromagnetic and mechanical characteristics of the gas-insulated transmission line.

[0013] Preferably, in step 1, the electromagnetic field mathematical model of the gas-insulated transmission line includes an electromagnetic field control equation, an electromagnetic field Poisson equation, and electromagnetic field energy storage;

[0014] The electromagnetic field control equation is expressed as follows:

[0015]

[0016] Where:

[0017] A is the magnetic vector potential;

[0018] H is the magnetic field strength;

[0019] J represents the current density flowing through the conductor of the gas-insulated transmission line, and J includes the conduction current J s and the eddy current J flowing through the shell e ;

[0020] E is the induced electromotive force of the magnetic field;

[0021] B is the magnetic induction intensity;

[0022] is the gradient operator;

[0023] The Poisson equation for the electromagnetic field is expressed as follows:

[0024]

[0025] Where:

[0026] μ is the magnetic permeability;

[0027] is the Laplace operator;

[0028] The electromagnetic field energy storage is expressed as follows:

[0029]

[0030] Where:

[0031] W is the electromagnetic field energy storage;

[0032] Ω e is the integration domain at the e-th iteration;

[0033] n is the number of iterations;

[0034] x and y are the coordinates in the integration domain.

[0035] Preferably, in step 1, a circuit mathematical model of the gas-insulated transmission line is constructed according to the current constraint equation and the loop voltage control equation of the gas-insulated transmission line;

[0036] The current constraint equation is expressed as follows:

[0037]

[0038] Where:

[0039] I a (t), I b (t), I c (t) are the cross-sectional currents of phase a, phase b, and phase c conductors at time t respectively;

[0040] S a 、S b 、S c are the conductor cross sections of phase a, phase b, and phase c respectively;

[0041] σ is the conductivity of the conductor;

[0042] A is the magnetic vector potential;

[0043] is the conductor potential;

[0044] Using a three-phase power supply with a steady-state symmetrical power frequency for voltage control, the loop voltage control equation is expressed as follows:

[0045]

[0046] Where:

[0047] u a (t),u b (t),u c (t) are the voltage drops across the conductors of phase a, phase b, and phase c at time t respectively;

[0048] R a 、R b 、R c are the line resistances of phase a, phase b, and phase c of the external circuit respectively;

[0049] L a 、L b 、L c are the line inductances of phase a, phase b, and phase c of the external circuit respectively;

[0050] U is the voltage of the independent voltage source of the external circuit;

[0051] are the conductor potentials of phase a, phase b, and phase c at time t respectively;

[0052] ω is the three-phase power frequency;

[0053] θ is the phase angle of the three-phase power supply voltage.

[0054] Preferably, in step 1, based on the dynamic equations and the interaction between the deformation and movement of various components of the gas-insulated transmission line, a mechanical mathematical model of the gas-insulated transmission line is constructed and expressed as the following formula:

[0055]

[0056] Where:

[0057] [M] is the mass matrix of the mechanical mathematical model;

[0058] [C] is the damping matrix of the mechanical mathematical model;

[0059] [K] is the stiffness matrix of the mechanical mathematical model;

[0060] {F(t)} is the function of the load vector of the mechanical mathematical model with respect to time;

[0061] u are the acceleration vector, velocity vector and displacement vector of the mechanical mathematical model respectively.

[0062] Preferably, in step 1, constructing an electromagnetic field-circuit-mechanical coupling mathematical model includes:

[0063] Taking the magnetic vector potential A and the loop current I as unknown variables, the spatial discrete coupling equation of the transient electromagnetic field-circuit of the gas-insulated transmission line is obtained as the electromagnetic field-circuit-mechanical coupling mathematical model, which is expressed as the following formula:

[0064]

[0065] Where:

[0066] K A and D represent the magnetic vector potential and the stiffness matrix of the eddy current in the conductor, respectively;

[0067] F s The load matrix for the conductors conducting current;

[0068] R and L are the resistance and inductance parameter matrices of the external circuit respectively;

[0069] U s is the voltage matrix of the external circuit ports.

[0070] Preferably, step 2 includes:

[0071] Step 2.1, dividing the gas-insulated transmission line in actual operation into multiple engineering sections, and determining the size parameters and layout parameters of the gas-insulated transmission line;

[0072] Step 2.2, based on the electromagnetic field mathematical model, a finite element two-dimensional simulation model of the gas-insulated transmission line is established using size parameters and layout parameters in finite element software;

[0073] Step 2.3: Build an external circuit based on the electrical parameters of the gas-insulated transmission line, and simulate normal operating conditions, single-phase short-circuit conditions, and three-phase short-circuit conditions by opening and closing different switches;

[0074] In step 2.4, the finite element two-dimensional simulation model is connected to the equivalent external circuit. The external circuit port voltage matrix under different working conditions is obtained through simulation, and the electromagnetic field-circuit-mechanical coupling mathematical model is connected through the port voltage matrix coupling.

[0075] Preferably, step 3 includes:

[0076] Step 3.1, using finite element simulation software, based on the finite element two-dimensional simulation model of the gas-insulated transmission line and the equivalent external circuit, simulate the electromagnetic characteristics of the gas-insulated transmission line under different operating conditions, including magnetic flux density and current density;

[0077] In step 3.2, in each different engineering section, the node transient electromagnetic force is calculated using the real-time simulation data of current and magnetic field.

[0078] Preferably, the virtual work method is used to calculate the transient electromagnetic force on the conductor node, which is used as the load vector of the mechanical mathematical model and is expressed as follows:

[0079]

[0080] Where:

[0081] s is the cross-sectional area of ​​the gas-insulated transmission line;

[0082] V is the volume of the integration domain;

[0083] B is the magnetic induction intensity;

[0084] H is the magnetic field strength;

[0085] h is the upper limit of magnetic field strength.

[0086] Preferably, in step 4, the frequency of the transient electromagnetic force of the node is detected by using a spectrum analysis method. If the frequency of the transient electromagnetic force of the node is greater than 100 Hz, it is determined that there is an abnormal electromagnetic response.

[0087] A second aspect of the present invention provides a GIL electromagnetic property detection system based on field-circuit-mechanical coupling, and the method for detecting the electromagnetic property of a GIL based on field-circuit-mechanical coupling is executed, comprising:

[0088] Model building module, used to build electromagnetic field-circuit-mechanical coupling mathematical model;

[0089] The simulation analysis module is used to divide the gas-insulated transmission line into engineering sections, establish a finite element two-dimensional simulation model, build an equivalent external circuit, obtain the external circuit port voltage matrix, and generate an electromagnetic characteristic detection model;

[0090] The electromagnetic response module is used to iteratively solve the electromagnetic characteristic detection model to obtain the transient electromagnetic response of each project section;

[0091] The abnormality verification module is used to detect whether there are abnormal electromagnetic responses in the gas-insulated transmission line during actual operation, simulate the electromagnetic stress of gas-insulated transmission line components, and verify the electromagnetic and mechanical properties of the gas-insulated transmission line.

[0092] Compared with the prior art, the beneficial effects of the present invention include at least:

[0093] (1) The present invention can more accurately simulate the electromagnetic characteristics of GIL by constructing an electromagnetic field-circuit-mechanical coupling mathematical model.

[0094] (2) The present invention takes into account the interaction between electrical parameters and geometric structures. By sequentially coupling multi-physics field models and adopting harmonic response analysis, it can comprehensively consider the influence of electromagnetic forces on the GIL structure. It is applicable to GILs of different structures and lengths and has the advantages of wide applicability, fast calculation speed, and high precision.

[0095] (3) The present invention provides a guarantee for GIL short-circuit fault monitoring and safe and stable operation. It uses transient electromagnetic response and node transient electromagnetic force as the abnormality judgment criterion of GIL operation status to achieve real-time monitoring and fault diagnosis, which helps to timely discover potential problems, reduce the probability of faults, and improve the reliability and safety of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0096] Figure 1 The following is a flow chart of a GIL electromagnetic characteristics detection method based on field-circuit-mechanical multi-physics field coupling:

[0097] Figure 2 Schematic diagram of the electromagnetic force and electromagnetic stress solution process;

[0098] Figure 3 Schematic diagram of the GIL finite element 2D simulation model;

[0099] Figure 4 is the equivalent external circuit under different working conditions;

[0100] Figure 5 is a schematic diagram of electromagnetic characteristics of a GIL under normal operating conditions in an exemplary embodiment;

[0101] Figure 6 A schematic diagram of the electromagnetic characteristics of a GIL single-phase short circuit in an exemplary embodiment;

[0102] Figure 7 A schematic diagram of the electromagnetic characteristics of a three-phase short circuit of a GIL in an exemplary embodiment;

[0103] Figure 8 Schematic diagram of electromagnetic stress distribution of GIL in an exemplary embodiment. DETAILED DESCRIPTION

[0104] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without making creative efforts are all within the scope of protection of the present invention.

[0105] like Figure 1As shown, embodiment 1 of the present invention provides a GIL electromagnetic characteristic detection method based on field-circuit-mechanical multi-physics field coupling, comprising the following steps:

[0106] Step 1: Construct a 2D-3D multi-physics field coupling mathematical model. Specifically, according to the relevant theories of electromagnetic field, circuit and mechanical vibration, establish the GIL electromagnetic field mathematical model, GIL circuit mathematical model and GIL mechanical mathematical model; obtain the magnetic vector potential and conductor eddy current of GIL based on the electromagnetic field mathematical model; obtain the stiffness matrix of the magnetic vector potential and the stiffness matrix of the conductor eddy current, and the load matrix of the conductor conduction current in GIL based on the mechanical mathematical model; and use the stiffness matrix of the magnetic vector potential, the stiffness matrix of the conductor eddy current, and the load matrix of the conductor conduction current, based on the circuit mathematical model, adopt a sequential coupling method to obtain the electromagnetic field-circuit-mechanical multi-physics field coupling mathematical model.

[0107] In a preferred but non-limiting embodiment of the present invention, step 1 specifically comprises:

[0108] Step 1.1, establish the GIL electromagnetic field mathematical model, including the electromagnetic field control equation, the GIL electromagnetic field Poisson equation and the GIL electromagnetic field energy storage.

[0109] In a further preferred but non-limiting embodiment of the present invention, step 1.1 specifically comprises:

[0110] Step 1.1.1: Apply electromagnetic field theory and Maxwell's equations, introduce the magnetic vector potential A as an auxiliary variable, and obtain the following electromagnetic field control equation:

[0111]

[0112] Where:

[0113] A is the magnetic vector potential;

[0114] H is the magnetic field strength;

[0115] J represents the current density flowing through the GIL conductor, J includes the conduction current J s and the eddy current J flowing through the shell e ;

[0116] E is the induced electromotive force of the magnetic field;

[0117] B is the magnetic induction intensity;

[0118] is the gradient operator.

[0119] Step 1.1.2: Substitute the expression of the magnetic vector potential A into the Ampere loop equation. At the same time, according to the Coulomb specification, assume that ▽·A=0 in the electromagnetic control equation as the solution of equation (2), and the GIL electromagnetic field Poisson equation is obtained:

[0120]

[0121] Where:

[0122] μ is the magnetic permeability;

[0123] is the Laplace operator;

[0124] Step 1.1.3, use the magnetic field potential function to calculate the GIL electromagnetic field energy storage, which is expressed as the following formula:

[0125]

[0126] Where:

[0127] W is the electromagnetic field energy storage;

[0128] Ω e is the integration domain at the e-th iteration;

[0129] n is the number of iterations, e = 1, 2, 3…n;

[0130] x and y are the coordinates in the integration domain.

[0131] Step 1.2: Construct a GIL circuit mathematical model based on the GIL current constraint equation and the loop voltage control equation (Kirchhoff's voltage law).

[0132] In actual operation, the current inside the GIL conductor is mainly constrained by the external voltage. Therefore, when performing transient electromagnetic field calculations, the field-circuit coupling method must be used to solve the current constraint problem.

[0133] Further preferably, the current constraint equation of the GIL conductor cross section is expressed as follows:

[0134]

[0135] Where:

[0136] I a (t), I b (t), I c (t) are the cross-sectional currents of phase a, phase b, and phase c conductors at time t respectively;

[0137] S a 、S b 、S c are the conductor cross sections of phase a, phase b, and phase c respectively;

[0138] σ is the conductivity of the conductor;

[0139] A is the magnetic vector potential;

[0140] is the conductor potential;

[0141] Using a three-phase power supply with a steady-state symmetrical power frequency for voltage control, the loop voltage control equation is expressed as follows:

[0142]

[0143] Where:

[0144] u a (t),u b (t),u c (t) are the voltage drops across the conductors of phase a, phase b, and phase c at time t respectively;

[0145] R a 、R b 、R c are the line resistances of phase a, phase b, and phase c of the external circuit respectively;

[0146] L a , L b , L c are the line inductances of phase a, phase b, and phase c of the external circuit respectively;

[0147] U is the voltage of the independent voltage source of the external circuit.

[0148] are the conductor potentials of phase a, phase b, and phase c at time t respectively;

[0149] ω is the three-phase power frequency;

[0150] θ is the phase angle of the three-phase power supply voltage.

[0151] In step 1.3, the mechanical coupling effect is taken into account, and the mutual influence of the deformation and motion of each GIL component is measured through the dynamic equation to construct the GIL mechanical mathematical model.

[0152] Further preferably, the GIL is a typical complex multi-degree-of-freedom mechanical vibration system. Under the excitation of the electromotive force, the GIL satisfies the following dynamic equation:

[0153]

[0154] Where:

[0155] M is the mass matrix of the GIL model;

[0156] C is the damping matrix of the GIL model;

[0157] K is the stiffness matrix of the GIL model;

[0158] F(t) is the function of the GIL model load vector with respect to time. For the GIL in actual operation, the model load vector F(t) is the transient electromagnetic force on the conductor node;

[0159] u are the acceleration vector, velocity vector and displacement vector of the model respectively.

[0160] In step 1.4, the electromagnetic field mathematical model of step 1.1, the circuit mathematical model of step 1.2, and the mechanical mathematical model of step 1.3 are coupled in a sequential coupling manner to obtain the GIL electromagnetic field-circuit-mechanical multi-physics field coupling mathematical model.

[0161] In a further preferred but non-limiting embodiment of the present invention, the magnetic vector potential A in step 1.1 and the loop current I in step 1.2 are used as unknown variables, and the electromagnetic field control equation, the current constraint equation, and the dynamic equation are combined to obtain the spatial discrete coupling equation of the GIL transient electromagnetic field-circuit as follows:

[0162]

[0163] Where:

[0164] K A and D represent the magnetic vector potential A and the eddy current J in the conductor, respectively e The stiffness matrix of

[0165] F s The conductor conducts current J s The load matrix;

[0166] R and L are the resistance and inductance parameter matrices of the external circuit respectively;

[0167] U s is the voltage matrix of the external circuit ports.

[0168] Further preferably, in order to accurately analyze the time transient characteristics of the electromagnetic field and electrodynamic force of the GIL, the time variables in the spatial discrete coupling equation are discretely changed in the time domain and expressed as the following formula:

[0169]

[0170] Where:

[0171] Δt is the time substep. More preferably, in order to accurately reflect the electromagnetic characteristics of the GIL, the total solution time is set to 80 ms, the time substep is set to 400, and the time substep interval is 0.02 ms.

[0172] It can be understood that the sequential coupling method is used to perform spatial discrete coupling of multiple physical fields of electromagnetic field, circuit and mechanical multi-physics field, and the electromagnetic analysis results are passed to the mechanical analysis as known conditions, avoiding the frequent interactive calculations of direct coupling, and further saving computing resources while meeting the accuracy.

[0173] Step 2: Divide the actually operating GIL into multiple engineering sections to establish a GIL finite element 2D simulation model and build an equivalent external circuit that simulates different working conditions of the GIL. According to the 2D-3D multi-physics field coupling mathematical model in step 1, the finite element 2D simulation model is connected with the equivalent external circuit to obtain the external circuit port voltage matrix through simulation. The electromagnetic field-circuit-mechanical coupling mathematical model is coupled with the finite element 2D simulation model through the external circuit port voltage matrix to obtain the electromagnetic characteristics detection model of the GIL.

[0174] In a preferred but non-limiting embodiment of the present invention, step 2 specifically comprises:

[0175] Step 2.1: Divide the actual GIL into multiple engineering sections and determine the size and layout parameters of the GIL finite element 2D simulation model;

[0176] Step 2.2, based on the electromagnetic field mathematical model, a GIL finite element 2D simulation model is established using size parameters and layout parameters in finite element software;

[0177] In step 2.3, an external circuit is built based on the actual electrical parameters of the GIL. Different operating conditions are simulated by opening and closing different switches, including normal operating conditions, single-phase short-circuit conditions, and three-phase short-circuit conditions.

[0178] Further preferably, an external circuit is constructed based on actual GIL electrical parameters, and different operating conditions are simulated by opening and closing different switches. The actual GIL electrical parameters include equivalent voltage source, line resistance, line inductance, load resistance, and load inductance.

[0179] In step 2.4, the finite element 2D simulation model is connected to the equivalent external circuit. The external circuit port voltage matrix under different working conditions is obtained through simulation, and the electromagnetic field-circuit-mechanical coupling mathematical model is connected through the port voltage matrix coupling.

[0180] Step 3: Iteratively solve the electromagnetic characteristic detection model to obtain the transient electromagnetic response of each engineering section, including magnetic flux density, current density and node transient electromagnetic force.

[0181] In a preferred but non-limiting embodiment of the present invention, step 3 specifically comprises:

[0182] In step 3.1, finite element simulation software is used to simulate the magnetic flux density and current density of the GIL under different working conditions based on the GIL finite element 2D simulation model and the equivalent external circuit built in step 2.

[0183] In step 3.2, in each different engineering section, the node transient electromagnetic force is calculated using the real-time simulation data of current and magnetic field.

[0184] Further preferably, the virtual work method is used in combination with formula (4) to obtain the transient electromotive force on the GIL conductor, that is, the node transient electromagnetic force, which is used as the load vector of the mechanical mathematical model in step 1.3 and is expressed as the following formula:

[0185]

[0186] Where:

[0187] W(s,i) is the electromagnetic field energy storage of the GIL with a cross-sectional area of ​​s and an electromagnetic field current of i;

[0188] B is the magnetic induction intensity;

[0189] H is the magnetic field strength, h is the upper limit of the magnetic field strength;

[0190] V is the volume of the integration domain.

[0191] It can be understood that the virtual work method fully considers the complex interaction between the electromagnetic force and the mechanical structure of each GIL component, and the virtual work method is insensitive to the finite element mesh division and has good accuracy even in the case of uneven electromagnetic field distribution under asymmetric short-circuit conditions.

[0192] Step 4: Use the node transient electromagnetic force calculated in Step 3 to evaluate and monitor whether there are any electromagnetic response anomalies in the actual operation of the GIL. Based on the transient electromagnetic response analysis results in Step 3, use the harmonic response analysis method to simulate the electromagnetic stress of the key components of the GIL in the engineering section with electromagnetic response anomalies in the three-dimensional structural field, and verify the electromagnetic and mechanical characteristics of the GIL.

[0193] In a preferred but non-limiting embodiment of the present invention, based on the obtained calculation results of the node transient electromagnetic force, the frequency component of the node transient electromagnetic force is detected using spectrum analysis technology. If the monitored electromagnetic response frequency exceeds the electromagnetic resonance range of 100 Hz, it indicates that there may be an electromagnetic resonance anomaly, and immediate measures must be taken to avoid huge harm.

[0194] In a preferred but non-limiting embodiment of the present invention, Figure 2As shown in the figure, the GIL geometry, static structure analysis, modal analysis, and transient structure analysis modules are set up in the finite element software. The transfer function model of the material under the alternating electromagnetic force is established. The implicit integration is used to assume the law of acceleration change within the time step. The modal superposition method is used to simulate and solve the dynamic equations of step 1.3, thereby obtaining the dynamic response of the GIL under the time-varying electromagnetic force load, that is, the change of displacement, stress, and strain with time.

[0195] Embodiment 2 of the present invention provides a GIL electromagnetic property detection system based on field-circuit-mechanical multi-physics field coupling, which runs the GIL electromagnetic property detection method based on field-circuit-mechanical coupling as described in embodiment 1, including:

[0196] Model building module, used to build electromagnetic field-circuit-mechanical coupling mathematical model;

[0197] The simulation analysis module is used to divide the gas-insulated transmission line into engineering sections, establish a finite element two-dimensional simulation model, build an equivalent external circuit, obtain the external circuit port voltage matrix, and generate an electromagnetic characteristic detection model;

[0198] The electromagnetic response module is used to iteratively solve the electromagnetic characteristic detection model to obtain the transient electromagnetic response of each project section;

[0199] The abnormality verification module is used to detect whether there are abnormal electromagnetic responses in the gas-insulated transmission line during actual operation, simulate the electromagnetic stress of gas-insulated transmission line components, and verify the electromagnetic and mechanical properties of the gas-insulated transmission line.

[0200] To further clarify the technical solution of the present invention and the beneficial technical effects it brings, the following describes an application example. In one application example of the present invention, the electromagnetic characteristics of a GIL based on field-circuit-mechanical multi-physics coupling, as described in Example 1, were tested under normal operating conditions, single-phase short circuit conditions, and three-phase short circuit conditions.

[0201] The GIL finite element 2D simulation model built is as follows Figure 3 As shown, the model consists of a conductor and an aluminum alloy casing. Three conductors are located within different casing tubes and arranged horizontally and equidistantly. A 2D simulation model was established in the xy plane, with specific dimensional parameters as shown in Table 1. In this simulation model, both the conductor and casing are made of aluminum alloy, the insulating gas inside the casing is SF6, and the surrounding air domain is vacuum, simulating an ideal magnetic insulation boundary. Specific material properties are shown in Table 2.

[0202] Table 1 Geometric parameters

[0203] Parameter name describe Value / mm <![CDATA[R1]]> Shell outer radius 313 <![CDATA[r1]]> Shell inner radius 305 <![CDATA[R2]]> Conductor outer radius 50 <![CDATA[r2]]> Conductor inner radius 40 D Conductor eccentricity 780

[0204] Table 2 Material properties

[0205] Material Relative magnetic permeability Conductivity S / m SF6 1 0 Air 1 0 aluminum alloy 1 3.03

[0206] The GIL electromagnetic characteristic detection method based on field-circuit-mechanical multi-physics field coupling described in Example 1 of the present invention is used to build an equivalent external circuit simulating different working conditions. Figure 4 As shown in the figure, the process of solving electromagnetic force and electromagnetic stress in finite element software is as follows: Figure 2 As shown in the figure, after modeling and simulation analysis, the electromagnetic characteristics of GIL under different working conditions are obtained as follows Figure 5-Figure 7 As shown, it can be seen that the electromotive force frequency of the three-phase conductor is twice the power frequency (100Hz) and varies periodically. Four power frequency cycles were selected for electromagnetic force analysis, and the magnetic flux density at the same time of the two-phase current at t = 10ms and the randomly selected time of t = 74ms was selected for display. The specific electromagnetic characteristics are as follows:

[0207] The electromagnetic characteristics of GIL under normal working conditions are as follows: Figure 5 As shown in the figure, it can be seen that due to the horizontal symmetry of the B-phase conductor, the y-axis component force is close to 0, and the x-axis component force shows a periodic sinusoidal change. The electromagnetic force of phase B is affected by the superposition of the field strengths of phases A and C, and is distributed in a half-wave waveform. Phases A and C are symmetrical with respect to phase B, and the electromagnetic force change trends are the same, with a phase angle difference of π / 3. The specific maximum electromagnetic force occurrence time and value are as follows: Phase A: 13.4ms, 4.99N / m; Phase B: 4.2ms, 6.11N / m; Phase C: 10.0ms, 4.98N / m;

[0208] The electromagnetic characteristics of GIL under single-phase short circuit conditions are as follows: Figure 6 As shown in the figure, it can be seen that under the single-phase short-circuit condition, the phase current of the short-circuited phase increases rapidly, resulting in an increase in current density and magnetic flux density. Take the single-phase short circuit of phase B as an example: phase C instantly reaches the maximum short-circuit electromagnetic force of 104.98N / m at t=0, and then begins to decay. The instantaneous electromagnetic force of phase B at t=0 is 104.36N / m, and reaches the maximum short-circuit electromagnetic force of 133.79N / m at 4.8ms. The electromotive force change trends of phases A and C are similar, with a peak value difference of less than 20N and a phase angle difference of about 4π / 3. The maximum peak electromagnetic forces of the three-phase conductors are similar, but phase B has an obvious double peak feature. Therefore, during the transient period, the effective value of the electromotive force of phase B is significantly higher than that of phases A and C;

[0209] The electromagnetic characteristics of GIL under three-phase short circuit conditions are as follows: Figure 7As shown in the figure, the current in the three-phase conductors surges under the three-phase short-circuit condition, and the current density and magnetic flux density of each phase change in a similar manner to the power frequency steady-state condition. The maximum electromagnetic force on phase A occurs at 8ms, reaching a maximum of 1.09kN / m. The maximum electromagnetic force on phase B occurs at 8.8ms, reaching a maximum of 1.43kN / m. The maximum electromagnetic force on phase C occurs at 9.8ms, reaching a maximum of 0.39kN / m. The short-circuit electromagnetic force impact on each phase conductor varies greatly, with the ratio of the maximum impact electromagnetic force to the minimum impact electromagnetic force being as high as 3-4 times.

[0210] The electromagnetic stress of GIL conductor and supporting insulator is simulated by harmonic response analysis method, and the electromagnetic stress distribution is shown as follows: Figure 8 shown.

[0211] Compared with the prior art, the beneficial effects of the present invention include at least:

[0212] (1) The present invention can more accurately simulate the electromagnetic characteristics of GIL by constructing an electromagnetic field-circuit-mechanical coupling mathematical model.

[0213] (2) The present invention takes into account the interaction between electrical parameters and geometric structures. By sequentially coupling multi-physics field models and adopting harmonic response analysis, it can comprehensively consider the influence of electromagnetic forces on the GIL structure. It is applicable to GILs of different structures and lengths and has the advantages of wide applicability, fast calculation speed, and high precision.

[0214] (3) The present invention provides a guarantee for GIL short-circuit fault monitoring and safe and stable operation. It uses transient electromagnetic response and node transient electromagnetic force as the abnormality judgment criterion of GIL operation status to achieve real-time monitoring and fault diagnosis, which helps to timely discover potential problems, reduce the probability of faults, and improve the reliability and safety of the system.

[0215] The present disclosure may be a system, method and / or computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0216] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A GIL electromagnetic characteristics detection method based on field-circuit-mechanical coupling, characterized in that: The following steps are involved: Step 1: obtaining the magnetic vector potential and conductor eddy current of the gas-insulated transmission line based on the electromagnetic field mathematical model; Based on the mechanical mathematical model, the stiffness matrix of the magnetic vector potential, the stiffness matrix of the conductor eddy current, and the load matrix of the conductor conduction current in the gas-insulated transmission line are obtained; using the stiffness matrix of the magnetic vector potential, the stiffness matrix of the conductor eddy current, and the load matrix of the conductor conduction current, based on the circuit mathematical model, an electromagnetic field-circuit-mechanical coupling mathematical model is established; Step 2: Divide the actually operated gas-insulated transmission line into multiple engineering sections to establish a finite element two-dimensional simulation model of the gas-insulated transmission line; build an equivalent external circuit of the gas-insulated transmission line, connect the finite element two-dimensional simulation model with the equivalent external circuit, and obtain the external circuit port voltage matrix through simulation; the electromagnetic field-circuit-mechanical coupling mathematical model and the finite element two-dimensional simulation model are coupled through the external circuit port voltage matrix to obtain an electromagnetic characteristic detection model of the gas-insulated transmission line; Step 3: Iteratively solve the electromagnetic characteristic detection model to obtain the transient electromagnetic response of each engineering section, including magnetic flux density, current density and node transient electromagnetic force; Step 4: Use the calculated node transient electromagnetic force to detect whether there is any electromagnetic response anomaly in the gas-insulated transmission line during actual operation; use the harmonic response analysis method to simulate the electromagnetic stress of the gas-insulated transmission line components in the engineering section with electromagnetic response anomaly in the three-dimensional structural field, and verify the electromagnetic and mechanical characteristics of the gas-insulated transmission line.

2. The GIL electromagnetic characteristics detection method based on field-circuit-mechanical coupling according to claim 1, characterized in that: In step 1, the electromagnetic field mathematical model of the gas-insulated transmission line includes the electromagnetic field control equation, the electromagnetic field Poisson equation and the electromagnetic field energy storage; The electromagnetic field control equation is expressed as follows: Where: A is the magnetic vector potential; H is the magnetic field strength; J represents the current density flowing through the conductor of the gas-insulated transmission line, and J includes the conduction current J s and the eddy current J flowing through the shell e ; E is the induced electromotive force of the magnetic field; B is the magnetic induction intensity; is the gradient operator; The Poisson equation for the electromagnetic field is expressed as follows: Where: μ is the magnetic permeability; is the Laplace operator; The electromagnetic field energy storage is expressed as follows: Where: W is the electromagnetic field energy storage; Ω e is the integration domain at the e-th iteration; n is the number of iterations; x and y are the coordinates in the integration domain.

3. The GIL electromagnetic characteristics detection method based on field-circuit-mechanical coupling according to claim 1, characterized in that: In step 1, a circuit mathematical model of the gas-insulated transmission line is constructed based on the current constraint equation and loop voltage control equation of the gas-insulated transmission line; The current constraint equation is expressed as follows: Where: I a (t), I b (t), I c (t) are the cross-sectional currents of phase a, phase b, and phase c conductors at time t respectively; S a 、S b 、S c are the conductor cross sections of phase a, phase b, and phase c respectively; σ is the conductivity of the conductor; A is the magnetic vector potential; is the conductor potential; Using a three-phase power supply with a steady-state symmetrical power frequency for voltage control, the loop voltage control equation is expressed as follows: Where: u a (t),u b (t),u c (t) are the voltage drops across the conductors of phase a, phase b, and phase c at time t respectively; R a 、R b 、R c are the line resistances of phase a, phase b, and phase c of the external circuit respectively; L a 、L b 、L c are the line inductances of phase a, phase b, and phase c of the external circuit respectively; U is the voltage of the independent voltage source of the external circuit; are the conductor potentials of phase a, phase b, and phase c at time t respectively; ω is the three-phase power frequency; θ is the phase angle of the three-phase power supply voltage.

4. The GIL electromagnetic characteristics detection method based on field-circuit-mechanical coupling according to claim 1, characterized in that: In step 1, based on the dynamic equations and the interaction between the deformation and motion of each component of the gas-insulated transmission line, a mechanical mathematical model of the gas-insulated transmission line is constructed, which is expressed as the following formula: Where: [M] is the mass matrix of the mechanical mathematical model; [C] is the damping matrix of the mechanical mathematical model; [K] is the stiffness matrix of the mechanical mathematical model; {F(t)} is the function of the load vector of the mechanical mathematical model with respect to time; u are the acceleration vector, velocity vector and displacement vector of the mechanical mathematical model respectively.

5. The GIL electromagnetic characteristics detection method based on field-circuit-mechanical coupling according to claim 1, characterized in that: In step 1, the electromagnetic field-circuit-mechanical coupling mathematical model is constructed, including: Taking the magnetic vector potential A and the loop current I as unknown variables, the spatial discrete coupling equation of the transient electromagnetic field-circuit of the gas-insulated transmission line is obtained as the electromagnetic field-circuit-mechanical coupling mathematical model, which is expressed as the following formula: Where: K A and D represent the magnetic vector potential and the stiffness matrix of the eddy current in the conductor, respectively; F s The load matrix for the conductor conducting current; R and L are the resistance and inductance parameter matrices of the external circuit respectively; U s is the voltage matrix of the external circuit ports.

6. The GIL electromagnetic characteristics detection method based on field-circuit-mechanical coupling according to claim 1, characterized in that: Step 2 includes: Step 2.1, dividing the gas-insulated transmission line in actual operation into multiple engineering sections, and determining the size parameters and layout parameters of the gas-insulated transmission line; Step 2.2, based on the electromagnetic field mathematical model, a finite element two-dimensional simulation model of the gas-insulated transmission line is established using size parameters and layout parameters in finite element software; Step 2.3: Build an external circuit based on the electrical parameters of the gas-insulated transmission line, and simulate normal operating conditions, single-phase short-circuit conditions, and three-phase short-circuit conditions by opening and closing different switches; In step 2.4, the finite element two-dimensional simulation model is connected to the equivalent external circuit. The external circuit port voltage matrix under different working conditions is obtained through simulation, and the electromagnetic field-circuit-mechanical coupling mathematical model is connected through the port voltage matrix coupling.

7. The GIL electromagnetic characteristics detection method based on field-circuit-mechanical coupling according to claim 1, characterized in that: Step 3 includes: Step 3.1, using finite element simulation software, based on the finite element two-dimensional simulation model of the gas-insulated transmission line and the equivalent external circuit, simulate the electromagnetic characteristics of the gas-insulated transmission line under different operating conditions, including magnetic flux density and current density; In step 3.2, in each different engineering section, the node transient electromagnetic force is calculated using the real-time simulation data of current and magnetic field.

8. The GIL electromagnetic characteristics detection method based on field-circuit-mechanical coupling according to claim 7, characterized in that: The virtual work method is used to calculate the transient electromagnetic force on the conductor node, which is used as the load vector of the mechanical mathematical model and is expressed as follows: Where: s is the cross-sectional area of ​​the gas-insulated transmission line; V is the volume of the integration domain; B is the magnetic induction intensity; H is the magnetic field strength; h is the upper limit of magnetic field strength.

9. The GIL electromagnetic characteristics detection method based on field-circuit-mechanical coupling according to claim 1, characterized in that: In step 4, the frequency spectrum analysis method is used to detect the frequency of the node transient electromagnetic force. If the frequency of the node transient electromagnetic force is greater than 100 Hz, it is determined that there is an electromagnetic response anomaly.

10. A GIL electromagnetic characteristics detection system based on field-circuit-mechanical coupling, which runs the GIL electromagnetic characteristics detection method based on field-circuit-mechanical coupling according to any one of claims 1 to 9, characterized in that: include: Model building module, used to build electromagnetic field-circuit-mechanical coupling mathematical model; The simulation analysis module is used to divide the gas-insulated transmission line into engineering sections, establish a finite element two-dimensional simulation model, build an equivalent external circuit, obtain the external circuit port voltage matrix, and generate an electromagnetic characteristic detection model; The electromagnetic response module is used to iteratively solve the electromagnetic characteristic detection model to obtain the transient electromagnetic response of each project section; The abnormality verification module is used to detect whether there are abnormal electromagnetic responses in the gas-insulated transmission line during actual operation, simulate the electromagnetic stress of gas-insulated transmission line components, and verify the electromagnetic and mechanical properties of the gas-insulated transmission line.

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