A method, apparatus, device and medium for suppressing direct induction voltage

Abstract

The application discloses a direct current induced voltage suppression method, device, equipment and medium, the method comprises the following steps: acquiring geometric size data of a bipolar direct current line tower, constructing a two-dimensional subdivision model according to the geometric size data, and extracting basic data; calculating the corona onset field strength under a preset conductor roughness coefficient, and determining the boundary condition; according to the basic data, the corona onset field strength and the boundary condition, combining the two-dimensional subdivision model, iteratively calculating the node charge density corresponding to the non-outage conductor; based on the boundary field strength constraint equation, calculating the boundary normal field strength of the surface of the outage conductor; according to the node charge density and the boundary normal field strength, determining the total amount of ion flow; according to the total amount of ion flow and the maximum allowable voltage of the non-outage conductor, determining the resistance value of the grounding resistor, and connecting the non-outage conductors in equipotential after grounding through the grounding resistor, so as to realize the suppression of the direct current induced voltage of the non-outage conductor on the outage conductor, and improve the power transmission safety.

Description

Technical Field

[0001] This invention relates to the field of voltage suppression technology, and more particularly to a method, apparatus, device, and medium for suppressing DC induced voltage. Background Technology

[0002] Currently, with the rapid growth of national electricity demand and the significant regional differences in clean energy power generation networks, the electromagnetic environment around DC transmission lines is attracting increasing attention. After high-voltage transmission lines are put into operation, they generate induced voltage and current through electric and magnetic field coupling. The induced voltage and current of high-voltage transmission lines increase significantly with the voltage level, and under adverse weather conditions, they may exceed the limits of national electromagnetic environment control standards. When the electric field strength on the surface of a high-voltage transmission line exceeds the air breakdown strength, corona discharge and high-frequency pulse currents will occur on the conductor surface, causing strong interference to telecommunications facilities such as radio communications and television signal transmission.

[0003] Icing on transmission lines, leading to line breaks and tower collapses, has been a major factor affecting power transmission in parts of Hunan, Guangxi, Yunnan, and Guizhou during the winter and spring seasons. For DC lines, to address the icing problem, de-icing devices are typically connected to unenergized lines, introducing kiloampere-level DC current into the unenergized lines to melt the ice.

[0004] However, in the case of corona formation on the DC line, the ion flow collected on the out-of-operation line will cause the line potential to rise, and its maximum value is far higher than the withstand voltage of the DC de-icing device, resulting in a reduction in power transmission safety. Summary of the Invention

[0005] This invention provides a method, apparatus, device, and medium for suppressing DC induced voltage, which solves the technical problem that when a DC line experiences corona, the ion flow collected in the out-of-operation line causes the line potential to rise, with the maximum value far exceeding the withstand voltage of the DC de-icing device, leading to a reduction in power transmission safety.

[0006] The first aspect of this invention provides a method for suppressing DC induced voltage, relating to bipolar DC line towers, wherein the bipolar DC line towers include out-of-operation conductors and non-out-of-operation conductors, and the method includes:

[0007] Obtain the geometric dimensions of the bipolar DC transmission tower, construct a two-dimensional mesh model based on the geometric dimensions, and extract the basic data;

[0008] Calculate the corona initiation field strength under the preset conductor roughness coefficient and determine the boundary conditions;

[0009] Based on the basic data, the initiation field strength, and the boundary conditions, and combined with the two-dimensional subdivision model, the nodal charge density corresponding to the non-stop conductor is iteratively calculated.

[0010] Based on the boundary field strength constraint equation, the boundary normal field strength on the surface of the decommissioned conductor is calculated;

[0011] The total ion flow is determined based on the node charge density and the boundary normal field strength.

[0012] The resistance value of the grounding resistor is determined based on the total ion flow and the maximum allowable voltage of the non-operational conductor, and the grounding resistor is used to connect the non-operational conductors at the same potential.

[0013] Optionally, the steps of obtaining the geometric dimension data of the bipolar DC transmission tower, constructing a two-dimensional mesh model according to the geometric dimension data, and extracting basic data include:

[0014] Obtain the geometric dimensions of bipolar DC transmission line towers;

[0015] A two-dimensional computational model is obtained by modeling based on the aforementioned geometric dimensions;

[0016] The field is discretized using the two-dimensional computational model described by the triangular element degree, and a two-dimensional partitioning model is constructed.

[0017] Extract the basic data corresponding to the location of the non-out-of-service conductor and the out-of-service conductor from the two-dimensional subdivision model.

[0018] Optionally, the step of calculating the corona initiation field strength under a preset conductor roughness coefficient and determining the boundary conditions includes:

[0019] The corona initiation field strength under the preset conductor roughness coefficient is calculated by substituting the preset conductor roughness coefficient into the Peek formula.

[0020] The nominal field potential is determined by responding to user input information and combining it with the simulated charge method.

[0021] The ground potential, non-outage conductor potential, and outage conductor potential are extracted from the user input information, and combined with the nominal field potential to determine the boundary conditions.

[0022] Optionally, the step of iteratively calculating the nodal charge density corresponding to the non-shutdown conductor based on the basic data, the corona initiation field strength, and the boundary conditions, combined with the two-dimensional partitioning model, includes:

[0023] Based on the number of elements and nodes in the two-dimensional mesh model, a finite element discrete equation is constructed.

[0024] The finite element discrete equations are solved using the aforementioned basic data to determine the node potentials of each node.

[0025] The current continuity model is solved by combining the node potentials with the basic data to determine the space charge density corresponding to each node.

[0026] Determine whether the space charge density satisfies the halo field strength and the boundary conditions;

[0027] If so, the node where the non-outage line is located is located, and the node charge density corresponding to the node where the non-outage line is located is determined from the space charge density.

[0028] Optionally, it also includes:

[0029] If not, adjust the potential boundary according to the preset test potential step size;

[0030] Adjust the surface charge density of the conductor according to the described corona induction field strength;

[0031] Jump to the step of solving the finite element discrete equation using the basic data to determine the node potential of each node.

[0032] Optionally, the step of determining the total ion current based on the node charge density and the boundary normal field strength includes:

[0033] The node ion current density corresponding to each node is determined by using the node charge density and the node normal field strength corresponding to each node, combined with the preset ion current density calculation formula.

[0034] By superimposing the ion current densities of all the nodes, the ion current density per unit length is obtained;

[0035] The total ion current is obtained by calculating the product of the ion current density and the total length of the line.

[0036] Optionally, the step of determining the value of the grounding resistor based on the total ion current and the maximum allowable voltage of the non-operational conductor, and then grounding the off-line conductors through the grounding resistor after equipotential bonding, includes:

[0037] The target resistance value is obtained by calculating the ratio between the maximum allowable voltage of the non-shutdown conductor and the total ion current.

[0038] The long-term operating allowable power is obtained by calculating the product between the maximum allowable voltage and the total ion current.

[0039] Select the target resistance value and the grounding resistance corresponding to the long-term allowable operating power;

[0040] After connecting the out-of-service conductors at the same potential, they are grounded through the grounding resistor.

[0041] A second aspect of the present invention provides a device for suppressing DC induced voltage, relating to a bipolar DC line tower, the bipolar DC line tower comprising out-of-operation conductors and non-out-of-operation conductors, the device comprising:

[0042] The basic data acquisition module is used to acquire the geometric dimension data of bipolar DC line towers, construct a two-dimensional subdivision model according to the geometric dimension data, and extract basic data.

[0043] The corona initiation field strength calculation module is used to calculate the corona initiation field strength under a preset conductor roughness coefficient and determine the boundary conditions.

[0044] The charge density iterative calculation module is used to iteratively calculate the nodal charge density corresponding to the non-stop conductor based on the basic data, the corona initiation field strength and the boundary conditions, combined with the two-dimensional partitioning model.

[0045] The boundary normal field strength determination module is used to calculate the boundary normal field strength on the surface of the deactivated conductor based on the boundary field strength constraint equation.

[0046] The total ion current determination module is used to determine the total ion current based on the node charge density and the boundary normal field strength.

[0047] The resistor grounding module is used to determine the resistance value of the grounding resistor based on the total ion current and the maximum allowable voltage of the non-operational conductor, and to ground the non-operational conductors through the grounding resistor after connecting them at the same potential.

[0048] A third aspect of the present invention provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the method for suppressing DC induced voltage as described in any of the first aspects of the present invention.

[0049] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed, implements the method for suppressing DC induced voltage as described in any of the first aspects of the present invention.

[0050] As can be seen from the above technical solutions, the present invention has the following advantages:

[0051] This invention acquires the geometric dimensions of bipolar DC transmission towers, constructs a two-dimensional meshed model based on the geometric dimensions, and extracts basic data. It calculates the corona initiation field strength under a preset conductor roughness coefficient and determines the boundary conditions. Based on the basic data, corona initiation field strength, and boundary conditions, and combined with the two-dimensional meshed model, iteratively calculates the nodal charge density corresponding to the non-operational conductors. Based on the boundary field strength constraint equation, it calculates the boundary normal field strength on the surface of the non-operational conductors. Based on the nodal charge density and boundary normal field strength, it determines the total ion current. Based on the total ion current and the maximum allowable voltage of the non-operational conductors, it determines the grounding resistance value and connects the non-operational conductors at equipotential bonding, grounding them through the grounding resistance. This suppresses the DC induced voltage on the non-operational conductors on the non-operational conductors, improving transmission safety. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a flowchart illustrating the steps of a method for suppressing DC induced voltage according to Embodiment 1 of the present invention.

[0054] Figure 2 A schematic diagram of a physical model of a bipolar DC circuit provided in an embodiment of the present invention;

[0055] Figure 3 This is a schematic diagram of field discretization provided in an embodiment of the present invention;

[0056] Figure 4 This is a flowchart illustrating the steps of a method for suppressing DC induced voltage according to Embodiment 2 of the present invention.

[0057] Figure 5 A schematic diagram of a first-order triangular unit provided in an embodiment of the present invention;

[0058] Figure 6 A schematic diagram showing the resistance, current, and power of the outage line under different voltage conditions, provided in an embodiment of the present invention;

[0059] Figure 7 This is a structural block diagram of a DC induced voltage suppression device provided in Embodiment 3 of the present invention. Detailed Implementation

[0060] This invention provides a method, apparatus, device, and medium for suppressing DC induced voltage, which addresses the technical problem that, in the event of corona in a DC line, the ion flow collected in the out-of-operation line causes the line potential to rise, with the maximum value far exceeding the withstand voltage of the DC de-icing device, leading to a reduction in power transmission safety.

[0061] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0062] Please see Figure 1 , Figure 1 This is a flowchart illustrating the steps of a method for suppressing DC induced voltage according to Embodiment 1 of the present invention.

[0063] This invention provides a method for suppressing DC induced voltage, relating to bipolar DC line towers, which include out-of-operation conductors and non-out-of-operation conductors. The method includes:

[0064] Step 101: Obtain the geometric dimension data of the bipolar DC line tower, construct a two-dimensional subdivision model according to the geometric dimension data, and extract the basic data;

[0065] Non-outage lines refer to lines that are energized and operated on the same pole;

[0066] A line that is out of service refers to a line that is suspended on the same tower and is in a state of power outage for de-icing.

[0067] In this embodiment of the invention, the size data of DC power towers can be obtained by geometric measurement or point cloud scanning. A two-dimensional calculation model is constructed according to the size data, and the calculation model is discretized by triangular elements to obtain a two-dimensional partitioned model. Basic data such as node element relationships, boundary node numbers, and node horizontal and vertical coordinates are extracted from the model.

[0068] Among them, bipolar DC line towers can be like Figure 2 As shown, the geometric dimensions are shown in Table 1 below:

[0069]

[0070] Table 1

[0071] Field discretization refers to the operation of dividing the area where the DC power pole is located using a certain meshing method. The mesh can be triangular elements. The divided area is centered on the DC power pole, with a semicircle formed by a predetermined radius and the ground as its boundary. The result of the meshing is as follows: Figure 3 As shown.

[0072] Step 102: Calculate the corona initiation field strength under the preset conductor roughness coefficient and determine the boundary conditions;

[0073] In this embodiment of the invention, the induced voltage on the out-of-operation line under the strongest corona initiation condition of the non-out-of-operation line can be determined during the historical data statistics process. The conductor roughness coefficient at this time is used as the preset conductor roughness coefficient for the strongest corona initiation condition. The corona initiation field strength under this preset conductor roughness coefficient is calculated by combining the Peek formula, and the corresponding boundary conditions are determined in the generated two-dimensional mesh model.

[0074] The strongest corona induction condition for non-outage lines is defined as the corona induction field strength corresponding to a conductor roughness coefficient of 0.35. This value is selected based on the fact that the conductor roughness coefficient is usually higher than 0.4, and considering environmental influences, the margin is appropriately increased to 0.35.

[0075] Step 103: Based on the basic data, the initiation field strength and boundary conditions, and combined with the two-dimensional meshing model, iteratively calculate the nodal charge density corresponding to the non-stop conductor.

[0076] After obtaining the basic data, corona initiation field strength, and boundary conditions, the corresponding finite element discrete equations can be determined by combining the two-dimensional mesh model. The Poisson equation and the current conservation law equation can then be solved. Iterative analysis is then performed to determine whether the calculated nodal charge density satisfies the convergence conditions established by the corona initiation field strength and boundary conditions. If satisfied, the nodal charge density corresponding to the non-shutdown conductor can be obtained.

[0077] Step 104: Calculate the boundary normal field strength on the surface of the deactivated conductor based on the boundary field strength constraint equation;

[0078] When calculating the nodal charge density, the boundary normal field strength on the surface of the deactivated conductor can be further calculated based on the boundary field strength constraint equation.

[0079] Step 105: Determine the total ion current based on the nodal charge density and the boundary normal field strength;

[0080] After calculating the charge density and normal field strength at each node, the ion current density at each node can be further calculated. The total ion current density at the location of the out-of-service line is then superimposed to obtain the ion current density per unit length. Finally, the total ion current is calculated by combining this with the total length of the out-of-service line conductor.

[0081] Step 106: Determine the value of the grounding resistor based on the total ion flow and the maximum allowable voltage of the non-operational conductors, and then connect the non-operational conductors at the same potential to the ground through the grounding resistor.

[0082] After obtaining the total ion current and the maximum allowable voltage of the non-shutdown conductor, the resistance value of the grounding resistor and the corresponding long-term operating allowable power can be determined by calculating the ratio and multiplication between the two. After selecting the corresponding grounding resistor and connecting the non-shutdown conductor to equipotential bonding, the grounding resistor is connected to perform the grounding operation, thereby suppressing the DC induced voltage of the non-shutdown conductor on the shutdown conductor.

[0083] In this embodiment of the invention, geometric dimension data of bipolar DC transmission towers are acquired, a two-dimensional meshing model is constructed based on the geometric dimension data, and basic data is extracted; the corona initiation field strength under a preset conductor roughness coefficient is calculated, and boundary conditions are determined; based on the basic data, corona initiation field strength, and boundary conditions, combined with the two-dimensional meshing model, the nodal charge density corresponding to the non-operational conductor is iteratively calculated; based on the boundary field strength constraint equation, the boundary normal field strength on the surface of the non-operational conductor is calculated; based on the nodal charge density and the boundary normal field strength, the total ion current is determined; based on the total ion current and the maximum allowable voltage of the non-operational conductor, the resistance value of the grounding resistor is determined, and the non-operational conductors are connected at the same potential and grounded through the grounding resistor, thereby suppressing the DC induced voltage on the non-operational conductor on the non-operational conductor and improving power transmission safety.

[0084] Please see Figure 4 , Figure 4 This is a flowchart illustrating the steps of a method for suppressing DC induced voltage according to Embodiment 2 of the present invention.

[0085] This invention provides a method for suppressing DC induced voltage, relating to bipolar DC line towers, which include out-of-operation conductors and non-out-of-operation conductors. The method includes:

[0086] Step 201: Obtain the geometric dimension data of the bipolar DC line tower, construct a two-dimensional subdivision model according to the geometric dimension data, and extract the basic data;

[0087] Optionally, step 201 may include the following sub-steps:

[0088] Obtain the geometric dimensions of bipolar DC transmission line towers;

[0089] A two-dimensional computational model is obtained by modeling based on geometric dimensions;

[0090] A two-dimensional computational model with triangular unit degree is used to discretize the field and construct a two-dimensional partitioning model;

[0091] Extract basic data corresponding to the locations of non-out-of-service conductors and out-of-service conductors from the two-dimensional subdivision model.

[0092] In this embodiment of the invention, geometric dimension data can be obtained by scanning and measuring the distances between each conductor on the bipolar DC line tower and the tower and the ground, such as... Figure 2 As shown.

[0093] Further modeling based on this geometric data yields a two-dimensional computational model. Then, triangular elements are used to discretize the field domain of the two-dimensional computational model, resulting in the following... Figure 3 The two-dimensional meshed model is shown. The locations of non-operational and operational conductors are extracted from the two-dimensional meshed model. Voltage parameters related to their operating conditions within the two-dimensional meshed model are extracted, such as the voltage of the lower conductor at a height H0 above the ground on the right side being +500kV, the voltage of the upper conductor at a height H1+H0 above the ground on the right side being -500kV, the voltage of the uppermost conductor on the right side being 0V, the allowable voltage for the de-icing equipment being 20kV, as well as node element relationships, boundary node numbers, and node horizontal and vertical coordinates.

[0094] Step 202: Calculate the corona initiation field strength under the preset conductor roughness coefficient and determine the boundary conditions;

[0095] Optionally, step 202 may include the following sub-steps:

[0096] The corona initiation field strength under the preset conductor roughness coefficient is calculated by substituting the preset conductor roughness coefficient into the Peek formula.

[0097] The nominal field potential is determined by responding to user input information and combining it with the simulated charge method.

[0098] The ground potential, non-out-of-service conductor potential, and out-of-service conductor potential are extracted from the user input information, and combined with the nominal field potential to determine the boundary conditions.

[0099] In this embodiment of the invention, the strongest corona induction condition for a non-outage line is defined as the corona induction field strength corresponding to a conductor roughness coefficient of 0.35. This value is selected based on the fact that the conductor roughness coefficient is generally higher than 0.4, and considering the environmental impact, the margin is appropriately increased, and it is taken as 0.35.

[0100] Dizziness field strength E onset After determining the roughness coefficient, it can be calculated using the Peek formula. The positive and negative ion mobility K is assumed to be a constant in finite element calculations, where K0... + =1.5e-4m 2 / V·sec,K - =1.7e-4m 2 / V·sec. The composite coefficient R is assumed to remain constant in the calculation, R = 2e-12m 2 / sec.

[0101] The artificial boundary potential is the nominal field potential, which is solved by the simulated charge method; the conductor potential... (U is the conductor operating voltage); ground potential The levitation potential assumption is a type of boundary condition. in To test the potential, the calculation was performed using cyclic substitutions in steps of 1kV from 0 to 150kV. The corona induction field strength E... onset The Kaptzov condition is satisfied, meaning that after the conductor becomes corona-inducing, the electric field strength on the conductor surface remains unchanged.

[0102] Step 203: Based on the basic data, the initiation field strength and boundary conditions, and combined with the two-dimensional subdivision model, iteratively calculate the nodal charge density corresponding to the non-stop conductor.

[0103] Optionally, step 203 may include the following sub-steps:

[0104] Based on the number of elements and nodes in the two-dimensional mesh model, the finite element discrete equations are constructed.

[0105] The finite element discrete equations are solved using basic data to determine the nodal potentials of each node;

[0106] The current continuity model is solved by combining nodal potentials with basic data to determine the space charge density corresponding to each node;

[0107] Determine whether the space charge density satisfies the halo field strength and boundary conditions;

[0108] If so, locate the node where the non-outage line is located, and determine the node charge density corresponding to the node where the non-outage line is located from the space charge density.

[0109] Furthermore, step 203 may also include the following sub-steps:

[0110] If not, adjust the potential boundary according to the preset test potential step size;

[0111] Adjust the charge density on the conductor surface according to the intensity of the corona initiation field;

[0112] The jump proceeds to the step of solving the finite element discrete equations using basic data to determine the node potentials of each node.

[0113] Solving using the forward process, i.e., solving the Poisson equation:

[0114] The computational speed of the upstream finite element method mainly depends on solving the Poisson equation. Assume that after one discretization of the computational domain, m elements and n nodes can be generated. The finite element discretization equations are as follows:

[0115]

[0116] In the formula, i = 1, 2, ..., n; Let Ω be the shape function of unit e. e Let ε be the element field, ρ be the dielectric constant, and ρ be the nodal charge density.

[0117] The equations after finite element discretization can be rewritten in matrix form:

[0118]

[0119] The following discussion addresses the substitution of forced boundary conditions. Let the potential of boundary node i be u. i When substituting it in, the elements S on the main diagonal of the coefficient matrix are... ii Set the value to 1, set all other elements in row i and column i to zero, and change the right-hand side to the given potential value u. i The right-hand side of the remaining equations is simultaneously subtracted from the product of the node potential and the coefficient in the corresponding i column before processing.

[0120] As can be seen, discretization using the finite element method essentially requires solving a homogeneous linear system of equations. Here, S is the total coefficient matrix (also known as the stiffness matrix), which is a symmetric sparse matrix. Because the program needs to handle the issue of conductors grounded through large resistances in the bipolar ion flow field, it is necessary to cyclically substitute the floating potential to calculate the corresponding ion flow. Each time a potential is substituted, the system of equations needs to be solved repeatedly to achieve convergence through iterative calculations. Traditional ICCG or SOR-PCG calculations using iterative methods are relatively slow; this calculation program uses a direct method combining node optimization sorting and orthogonal decomposition, improving speed by more than 10 times.

[0121] During node optimization sorting, the `symamd` function from the `suitesparse` (sparse matrix library) is called. Because the stiffness matrix remains constant each time the potential of the suspended conductor is modified for calculation, the obtained matrix can be processed first through node optimization sorting, and then orthogonal decomposition can be used for calculation in each loop. Node optimization sorting only needs to be performed once. The formation of the stiffness matrix determines which positions in the sparse matrix contain non-zero elements, and a dynamic array is used to store these elements.

[0122] The symamd function requires the dimension of the matrix as input, the row index of the non-zero element when stored in columns, and the sum of the non-zero elements when stored in columns.

[0123] The symamd function returns a permutation vector, which rearranges the elements of the corresponding rows and columns according to the element order of the permutation vector.

[0124] When performing orthogonal decomposition, the speed of each calculation step can be greatly improved because the number of non-zero elements is reduced.

[0125] The reverse solution process, i.e., solving the current conservation law equation:

[0126] According to the calculation principle of the all-upwind scheme, the space charge on a node is transferred by the upwind unit to which it belongs. Figure 5 The method for determining the windward element of node M in the first-order triangular element given is as follows:

[0127] b i v Mx +c i v My ≤0 (i=L,N)

[0128] In the formula, v Mx v My b is the directional component of the charge velocity vector at node M; i c i This is the derivative of the unit shape function with respect to the x and y coordinates.

[0129] In the upwind finite element method, taking the calculation of positive charge as an example, numerical discretization is performed on the node M to be determined, and we have:

[0130]

[0131] In the formula, S e Let be the area of ​​the triangular unit.

[0132] In the windward element, only the charge density at node M is unknown, so it can be viewed as solving a quadratic equation. When solving for the charge density of one polarity, it is assumed that the charge density of the other polarity at all nodes is known. The larger of the two solutions to the equation is taken as the space charge density at node M.

[0133] In the reverse computation, the node charge density is determined by its upstream element, specifically by the charge densities of the other two nodes within that upstream element. Therefore, the order in which node charge density is updated directly affects the algorithm's convergence speed. In windless conditions, positive charges are updated along the direction of charge movement, following a descending potential order, with nodes sorted and updated according to potential. Conversely, negative charges are updated in ascending potential order. In windy conditions, the wind field is analogous to the electric field, forming a virtual composite scalar potential. Nodes are sorted according to the magnitude of this composite scalar potential, establishing the node charge update order. Since the wind exerts the same force on both positive and negative charges, while the electric field exerts opposite forces, the update order for positive and negative charges is no longer completely reversed in windy conditions. However, the element numbers associated with each node should be recorded before computation to facilitate searching for its upstream elements. Using this method, the node charge update order does not need to consider the finite element mesh topology, resulting in lower computational complexity, ease of implementation, and the ability to strictly update charges along the direction of charge movement, leading to faster algorithm convergence.

[0134] Each forward and backward calculation of the conductor completes one iteration. At this point, the obtained solution (composite electric field strength and charge density) needs to be verified to determine if it is the desired solution. The verification of the solution includes the convergence of the boundary conditions and the charge density at each point in space. The first type of boundary condition is a forced boundary condition, which has already been automatically satisfied during the forward calculation process. Therefore, it is only necessary to verify the convergence of the second type of boundary condition and the charge density at each point in space.

[0135] The computation is considered to have converged when the following two conditions are met, the calculation result is the solution, and the calculation ends:

[0136]

[0137]

[0138] In the formula, E max ρ is the maximum electric field strength on the surface of the conductor; n (i) represents the charge density calculation result of the nth iteration; ρ s+ ρ s- These represent the maximum values ​​of the positive and negative charge densities on the surface of the conductor, respectively.

[0139] For the multi-pole circuit in this calculation, the charge density at each point in space when each pole exists alone is calculated simultaneously outward from the surface of each conductor. The convergence degree of the calculated charge density for each pole is judged. Only when all conditions are met is the charge density considered to be convergent and stable; otherwise, the calculation is repeated. The total charge density at each point is obtained by adding the calculated charge densities of each conductor.

[0140] When this condition cannot be met, the surface charge density of the conductor is corrected:

[0141]

[0142] After correction, the calculation starts again from the forward process until the required accuracy is met.

[0143] For the multi-pole circuit in this calculation, the charge density at each point in space when each pole exists alone is calculated simultaneously outward from the surface of each conductor. The convergence degree of the calculated charge density for each pole is judged. Only when all conditions are met is the charge density considered to be convergent and stable; otherwise, the calculation is repeated. The total charge density at each point is obtained by adding the calculated charge densities of each conductor.

[0144] It should be noted that the polar conductor is a non-outage line, while the suspended conductor is an outage line.

[0145] Step 204: Calculate the boundary normal field strength on the surface of the deactivated conductor based on the boundary field strength constraint equation;

[0146] In this embodiment of the invention, the boundary normal field strength of the suspended conductor surface can be obtained by calculating according to the boundary field strength constraint equation.

[0147] The Poisson equation for an electrostatic field is:

[0148]

[0149] The boundary conditions are:

[0150]

[0151] In the formula, Let ψ be a given potential on the first kind of boundary Γ1, and ψ be a given function of the second kind of boundary Γ2. The boundary value problem for the unknown quantity is as follows:

[0152]

[0153] In the formula, Ω represents the computational domain of the electrostatic field. The Lagrange functional J, equivalent to the above boundary value problem, is:

[0154]

[0155] In the two-dimensional region, the field Ω is discretized using first-order triangular elements, and its interpolation basis functions are:

[0156]

[0157] In the formula, S e a is the area of ​​the triangular unit; i b i c iThe interpolation coefficients corresponding to node i are determined by the coordinates of the three nodes of the triangular element. The element potentials in the functional are constructed using an interpolation method. With ρ e Approximate solution:

[0158]

[0159] ρ e (x,y)=N L ρ L +N M ρ M +N N ρ N (7)

[0160] The first type of boundary nodes are numbered last. The finite element equation for solving the nodal potentials using the extrema of the Lagrange functional is as follows:

[0161]

[0162] In the formula, Φ is the column vector of the node potentials to be determined; u is the column vector of the known node potentials on the first type of boundary; F2 is the known right-hand column vector; F1 is the unknown right-hand column vector, which contains the normal component of the electric field intensity on the first type of boundary to be determined; S 11 S 21 and S 22 H1 and H2 are the stiffness matrices after partitioning; H1 and H2 are the known column vectors on the right side of the partitioned structure. The formula for calculating the potential of the node to be determined is:

[0163]

[0164] The column vector of normal electric field intensity on the first kind of boundary E n This can be given by F1:

[0165] KE n =-F1 (10)

[0166] In the formula, K is the stiffness matrix on the first type of boundary, and its formula in two-dimensional calculation is:

[0167]

[0168] In the formula, k and n represent nodes on the boundary adjacent to node m, and l km and l mn Let km and mn represent the lengths of line segments respectively. According to equations (8) to (11), the boundary normal field strength can be obtained:

[0169] E n =-K -1 (S 21 Φ+S 22 u-H2) (12)

[0170] Step 205: Determine the total ion current based on the nodal charge density and the boundary normal field strength;

[0171] Optionally, step 205 may include the following sub-steps:

[0172] The node ion current density corresponding to each node is determined by using the node charge density and node normal field strength corresponding to each node, combined with the preset ion current density calculation formula.

[0173] By superimposing the ion current densities of all nodes, the ion current density per unit length is obtained.

[0174] The total ion current is obtained by calculating the product of the ion current density and the total length of the line.

[0175] In this embodiment of the invention, the ion current density at each node can be calculated using the ion current density calculation formula. Adding up the ion current densities at all nodes on the suspended conductor yields the ion current density per unit length.

[0176] i m =ρ m KE m (l km +l mn ) / 2

[0177] Where, ρ m Represents nodal charge density, K represents ion mobility, and E represents nodal charge density. m The normal field strength at node m is represented by k and n, which represent the nodes adjacent to node m on the boundary. km and l mn Let km and mn represent the lengths of line segments respectively.

[0178] Calculate the product of ion current density and total line length to obtain the total ion current. For non-outage lines, take the maximum operating voltage U according to the actual operating conditions. max .

[0179] The ion flow rate is measured in A / km. Multiplying this value by the total length of the line will give the total ion flow rate I.

[0180] Step 206: Calculate the ratio between the maximum allowable voltage of the non-shutdown conductor and the total ion current to obtain the target resistance value;

[0181] Step 207: Calculate the product between the maximum allowable voltage and the total ion current to obtain the long-term operating allowable power;

[0182] In this embodiment of the invention, the target resistance value R is:

[0183] R = U max / I

[0184] The long-term operating allowable power P is:

[0185] P = IU max

[0186] Step 208: Select the target resistance value and the grounding resistance corresponding to the long-term allowable power;

[0187] Step 209: After connecting the out-of-service conductors to the same potential, ground them through a grounding resistor.

[0188] In this embodiment of the invention, only three suspended conductors connected at equipotentially through a high-resistance grounding point are considered. The operating voltage and corona induction field strength of the conductors are determined, and the suspended conductor potentials from 0 to 150 kV are cyclically substituted into the calculation as a type of forced boundary condition. Following the steps described above for calculating the ion current density, the grounding current is obtained. Dividing the suspended conductor potential by the current yields the grounding resistance. Based on the changes in the suspended conductor potential, curves showing the current and resistance versus voltage can be plotted. Using a one-dimensional interpolation function in MATLAB, the corresponding voltage and power curves can be derived from the resistance. Based on the voltage limit requirements, the corresponding resistance and power can be obtained. Considering different situations, a set of resistance-voltage / power curves are obtained by changing the conductor operating voltage or the conductor roughness coefficient. Based on the upper voltage limit and by combining all curves, the size of the bleeder resistor and the long-term operating power of the resistor are selected.

[0189] After obtaining the target resistance value and the allowable long-term operating power, a grounding resistor with the same target resistance value and the allowable long-term operating power can be selected. After connecting all out-of-operation conductors at equipotential, grounding is performed through the grounding resistor to suppress the induced voltage on the conductor.

[0190] In this embodiment of the invention, geometric dimension data of bipolar DC transmission towers are acquired, a two-dimensional meshing model is constructed based on the geometric dimension data, and basic data is extracted; the corona initiation field strength under a preset conductor roughness coefficient is calculated, and boundary conditions are determined; based on the basic data, corona initiation field strength, and boundary conditions, combined with the two-dimensional meshing model, the nodal charge density corresponding to the non-operational conductor is iteratively calculated; based on the boundary field strength constraint equation, the boundary normal field strength on the surface of the non-operational conductor is calculated; based on the nodal charge density and the boundary normal field strength, the total ion current is determined; based on the total ion current and the maximum allowable voltage of the non-operational conductor, the resistance value of the grounding resistor is determined, and the non-operational conductors are connected at the same potential and grounded through the grounding resistor, thereby suppressing the DC induced voltage on the non-operational conductor on the non-operational conductor and improving power transmission safety.

[0191] Please see Figure 7 , Figure 7A structural block diagram of a DC induced voltage suppression device according to Embodiment 3 of the present invention is shown.

[0192] This invention provides a DC induced voltage suppression device, relating to a bipolar DC line tower, the bipolar DC line tower including out-of-operation conductors and non-out-of-operation conductors, the device comprising:

[0193] The basic data acquisition module 701 is used to acquire the geometric dimension data of bipolar DC line towers, construct a two-dimensional subdivision model based on the geometric dimension data, and extract basic data.

[0194] The corona initiation field strength calculation module 702 is used to calculate the corona initiation field strength under a preset conductor roughness coefficient and determine the boundary conditions;

[0195] The charge density iterative calculation module 703 is used to iteratively calculate the nodal charge density of non-stop conductors based on the basic data, corona initiation field strength and boundary conditions, combined with a two-dimensional partitioning model.

[0196] The boundary normal field strength determination module 704 is used to calculate the boundary normal field strength on the surface of the deactivated conductor based on the boundary field strength constraint equation.

[0197] The total ion current determination module 705 is used to determine the total ion current based on the nodal charge density and the boundary normal field strength.

[0198] The resistor grounding module 706 is used to determine the resistance value of the grounding resistor based on the total ion current and the maximum allowable voltage of the non-operational conductors, and to ground the non-operational conductors by connecting them at the same potential through the grounding resistor.

[0199] Optionally, the basic data acquisition module 701 is specifically used for:

[0200] Obtain the geometric dimensions of bipolar DC transmission line towers;

[0201] A two-dimensional computational model is obtained by modeling based on geometric dimensions;

[0202] A two-dimensional computational model with triangular unit degree is used to discretize the field and construct a two-dimensional partitioning model;

[0203] Extract basic data corresponding to the locations of non-out-of-service conductors and out-of-service conductors from the two-dimensional subdivision model.

[0204] Optionally, the halo field strength calculation module 702 is specifically used for:

[0205] The corona initiation field strength under the preset conductor roughness coefficient is calculated by substituting the preset conductor roughness coefficient into the Peek formula.

[0206] The nominal field potential is determined by responding to user input information and combining it with the simulated charge method.

[0207] The ground potential, non-out-of-service conductor potential, and out-of-service conductor potential are extracted from the user input information, and combined with the nominal field potential to determine the boundary conditions.

[0208] Optionally, the charge density iterative calculation module 703 is specifically used for:

[0209] Based on the number of elements and nodes in the two-dimensional mesh model, the finite element discrete equations are constructed.

[0210] The finite element discrete equations are solved using basic data to determine the nodal potentials of each node;

[0211] The current continuity model is solved by combining nodal potentials with basic data to determine the space charge density corresponding to each node;

[0212] Determine whether the space charge density satisfies the halo field strength and boundary conditions;

[0213] If so, locate the node where the non-outage line is located, and determine the node charge density corresponding to the node where the non-outage line is located from the space charge density.

[0214] Optionally, the charge density iterative calculation module 703 is also specifically used for:

[0215] If not, adjust the potential boundary according to the preset test potential step size;

[0216] Adjust the charge density on the conductor surface according to the intensity of the corona initiation field;

[0217] The jump proceeds to the step of solving the finite element discrete equations using basic data to determine the node potentials of each node.

[0218] Optionally, the total ion current determination module 705 is specifically used for:

[0219] The node ion current density corresponding to each node is determined by using the node charge density and node normal field strength corresponding to each node, combined with the preset ion current density calculation formula.

[0220] By superimposing the ion current densities of all nodes, the ion current density per unit length is obtained.

[0221] The total ion current is obtained by calculating the product of the ion current density and the total length of the line.

[0222] Optionally, the resistor grounding module 706 is specifically used for

[0223] The target resistance value is obtained by calculating the ratio between the maximum allowable voltage of the non-outage conductor and the total ion current.

[0224] The long-term operating allowable power is obtained by calculating the product between the maximum allowable voltage and the total ion current.

[0225] Select the grounding resistance corresponding to the target resistance value and the allowable long-term operating power;

[0226] After connecting the out-of-service conductors to the same potential, ground them through a grounding resistor.

[0227] This invention provides an electronic device, including a memory and a processor. The memory stores a computer program, which, when executed by the processor, causes the processor to perform the steps of a DC induced voltage suppression method as described in any embodiment of this invention.

[0228] This invention provides a computer-readable storage medium storing a computer program thereon, which, when executed, implements a method for suppressing DC induced voltage as described in any embodiment of this invention.

[0229] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the above-described device and module can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0230] In the several embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0231] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0232] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0233] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0234] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for suppressing DC induced voltage, characterized in that, The method relates to bipolar DC transmission line towers, which include out-of-service conductors and non-out-of-service conductors, and includes: Obtain the geometric dimensions of the bipolar DC transmission tower, construct a two-dimensional mesh model based on the geometric dimensions, and extract the basic data; Calculate the corona initiation field strength under the preset conductor roughness coefficient and determine the boundary conditions; Based on the basic data, the initiation field strength, and the boundary conditions, and combined with the two-dimensional subdivision model, the nodal charge density corresponding to the non-stop conductor is iteratively calculated. Based on the boundary field strength constraint equation, the boundary normal field strength on the surface of the decommissioned conductor is calculated; The total ion flow is determined based on the node charge density and the boundary normal field strength. The resistance value of the grounding resistor is determined based on the total ion flow and the maximum allowable voltage of the non-operational conductor, and the grounding resistor is used to connect the non-operational conductors at the same potential.

2. The method according to claim 1, characterized in that, The steps of obtaining the geometric dimension data of the bipolar DC transmission tower, constructing a two-dimensional mesh model according to the geometric dimension data, and extracting basic data include: Obtain the geometric dimensions of bipolar DC transmission line towers; A two-dimensional computational model is obtained by modeling based on the aforementioned geometric dimension data; The two-dimensional computational model is discretized using triangular elements to construct a two-dimensional partitioned model. Extract the basic data corresponding to the location of the non-out-of-service conductor and the out-of-service conductor from the two-dimensional subdivision model.

3. The method according to claim 1, characterized in that, The steps of calculating the corona initiation field strength under a preset conductor roughness coefficient and determining the boundary conditions include: The corona initiation field strength under the preset conductor roughness coefficient is calculated by substituting the preset conductor roughness coefficient into the Peek formula. The nominal field potential is determined by responding to user input information and combining it with the simulated charge method. The ground potential, non-outage conductor potential, and outage conductor potential are extracted from the user input information, and combined with the nominal field potential to determine the boundary conditions.

4. The method according to claim 1, characterized in that, The step of iteratively calculating the nodal charge density corresponding to the non-shutdown conductor based on the basic data, the corona initiation field strength, and the boundary conditions, combined with the two-dimensional partitioning model, includes: Based on the number of elements and nodes in the two-dimensional mesh model, a finite element discrete equation is constructed. The finite element discrete equations are solved using the aforementioned basic data to determine the node potentials of each node. The current continuity model is solved by combining the node potentials with the basic data to determine the space charge density corresponding to each node. Determine whether the space charge density and the halo field strength satisfy the boundary conditions; If so, locate the node where the non-stop conductor is located, and determine the node charge density corresponding to the node where the non-stop conductor is located from the space charge density.

5. The method according to claim 4, characterized in that, Also includes: If not, adjust the potential boundary according to the preset test potential step size; Adjust the surface charge density of the conductor according to the described corona induction field strength; Jump to the step of solving the finite element discrete equation using the basic data to determine the node potential of each node.

6. The method according to claim 1, characterized in that, The step of determining the total ion current based on the node charge density and the boundary normal field strength includes: The node ion current density corresponding to each node is determined by using the node charge density and the boundary normal field strength corresponding to each node, combined with the preset ion current density calculation formula. By superimposing the ion current densities of all the nodes, the ion current density per unit length is obtained; The total ion current is obtained by calculating the product of the ion current density and the total length of the line.

7. The method according to claim 1, characterized in that, The step of determining the value of the grounding resistor based on the total ion current and the maximum allowable voltage of the non-shutdown conductor, and then grounding the shut-down conductors through the grounding resistor at the same potential, includes: The target resistance value is obtained by calculating the ratio between the maximum allowable voltage of the non-shutdown conductor and the total ion current. The long-term operating allowable power is obtained by multiplying the maximum allowable voltage and the total ion current. Select the target resistance value and the grounding resistance corresponding to the long-term allowable operating power; After connecting the out-of-service conductors at the same potential, they are grounded through the grounding resistor.

8. A device for suppressing DC induced voltage, characterized in that, The invention relates to bipolar DC transmission line towers, which include out-of-service conductors and non-out-of-service conductors. The device includes: The basic data acquisition module is used to acquire the geometric dimension data of bipolar DC line towers, construct a two-dimensional subdivision model according to the geometric dimension data, and extract basic data. The corona initiation field strength calculation module is used to calculate the corona initiation field strength under a preset conductor roughness coefficient and determine the boundary conditions. The charge density iterative calculation module is used to iteratively calculate the nodal charge density corresponding to the non-stop conductor based on the basic data, the corona initiation field strength and the boundary conditions, combined with the two-dimensional partitioning model. The boundary normal field strength determination module is used to calculate the boundary normal field strength on the surface of the deactivated conductor based on the boundary field strength constraint equation. The total ion current determination module is used to determine the total ion current based on the node charge density and the boundary normal field strength. The resistance grounding module is used to determine the resistance value of the grounding resistor based on the total ion current and the maximum allowable voltage of the non-operational conductor, and to ground the non-operational conductors through the grounding resistor after connecting them at the same potential.

9. An electronic device, characterized in that, The device includes a memory and a processor, wherein the memory stores a computer program that, when executed by the processor, causes the processor to perform the steps of the method for suppressing DC induced voltage as described in any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed, it implements the method for suppressing DC induced voltage as described in any one of claims 1-7.

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