Corrosion diagnosis system for grounding grid of transformer substation

Abstract

The invention relates to the technical field of power system safety detection, and provides a transformer substation grounding grid corrosion diagnosis system, which comprises a structure information acquisition module, which establishes an association relationship between nodes and branches through topology analysis and calculates an initial resistance parameter; the detection data acquisition module injects direct current through a selected reference node and measures port voltage; the parameter construction module calculates theoretical parameters and resistance variation based on the topological relation and the measurement current; the objective function construction module establishes a quadratic optimization objective function through the current change proportion; the constraint construction module sets a regularization constraint condition containing topological association; the quadratic programming solving module carries out iterative optimization by dynamically adjusting regularization parameters; and the corrosion diagnosis module performs grading evaluation according to the resistance change multiple and generates a visual result. The accuracy and efficiency of corrosion detection can be improved, and reliable guarantee is provided for safe operation of the transformer substation grounding grid.

Description

Technical Field

[0001] The present invention relates to the technical field of power system safety detection, and more particularly to a transformer substation grounding grid corrosion diagnosis system. Background Art

[0002] In modern power systems, the safety and reliability of substation grounding grids are key factors in ensuring the stable operation of power facilities. The primary function of a grounding grid is to ground electrical equipment within the substation, ensuring its safe operation, preventing damage from lightning strikes and overvoltage, and protecting personnel. However, over long-term operation, grounding grids are affected by a variety of factors, including the soil environment, corrosive media, and mechanical stress, leading to the gradual emergence of corrosion problems. Currently, the detection and diagnosis of grounding grid corrosion primarily relies on methods such as regular excavation inspections and local resistance measurements. These methods are not only time-consuming and labor-intensive, but also fail to fully and accurately reflect the overall corrosion status of the grounding grid. Problems are often only detected when corrosion is already severe, making early warning and precise location impossible.

[0003] Existing grounding grid corrosion detection technology is mainly based on the principle of resistance measurement, and the degree of corrosion is determined by comparing the resistance changes of the grounding grid. However, this method has some limitations. First, the traditional resistance measurement method can only obtain local information and it is difficult to fully reflect the corrosion situation of the entire grounding grid. Secondly, due to the complex topological structure of the grounding grid and the large number of branches, it is difficult to accurately distinguish the resistance changes caused by corrosion from the influence of other factors (such as contact resistance changes) by relying solely on resistance measurement. In addition, the existing technology lacks consideration of the topological structure and spatial correlation of the grounding grid during the corrosion diagnosis process, resulting in insufficient accuracy and reliability of the diagnostic results.

[0004] In the process of implementing the embodiments of the present invention, the inventors found that there are at least the following problems or defects in the existing technology: First, the existing detection method cannot achieve comprehensive and real-time monitoring of grounding grid corrosion, and it is difficult to meet the needs of substation operation and maintenance; second, there is a lack of effective corrosion diagnosis models, and it is impossible to accurately distinguish between resistance changes caused by corrosion and the influence of other factors; third, the existing technology fails to fully utilize the topological structure and spatial correlation information of the grounding grid, resulting in low accuracy and reliability of the diagnostic results. Summary of the Invention

[0005] The present invention provides a substation grounding grid corrosion diagnosis system, comprising:

[0006] Structural information acquisition module: used to obtain the topological relationship between nodes and branches of the grounding grid and construct the correlation matrix K = [a ij ] and calculate the branch resistance nominal value vector; where a ijRepresents the element in row i and column j of the incidence matrix K. When branch j flows out from node i, a ij =1; when flowing in, a ij =-1; in other cases, a ij =0;

[0007] Detection data acquisition module: used to select the reference node and inject DC current, measure the port voltage value between the accessible node and the reference node, and generate the port voltage measured value vector U′ and the injection current matrix I n ; Where U′ is the measured value vector of the port voltage, I n is the injection current matrix, n represents the relevant dimension or number of injection current and other parameters (specifically according to the matrix definition);

[0008] Parameter construction module: used to calculate the value of the correlation matrix K and the injection current matrix I according to the correlation matrix K and the injection current matrix I n Calculating the node voltage matrix, the branch current matrix theoretical value and the port resistance theoretical value vector, and calculating the port resistance measured value vector and the port resistance change ΔR based on the port voltage measured value vector U′;

[0009] Objective function construction module: used to construct a quadratic objective function, which is a minimization expression

[0010]

[0011] Among them, X is the current change ratio matrix, and the calculation formula is

[0012]

[0013] I b_cor is the branch current after corrosion, I b_0 is the branch current before corrosion, represents the Hadamard product; Y is the port resistance change vector; ΔR k is the branch resistance change vector;

[0014] Constraint building block: used to set linear inequality constraints A ineq ΔR k ≥b ineq and the equality constraint A eq ΔR k =b eq Among them, A ineq is the identity matrix, b ineq is the zero vector; A eq is the quadratic term matrix of the current change ratio, and the construction formula is A eq =X T X+γL, L is the Laplace matrix based on the grounding grid topology, γ = 0.1, which is used to enhance the resistance change correlation of spatially adjacent branches, beq is the transposed vector of the port resistance change;

[0015] Quadratic programming solver module: used to solve the quadratic objective function through an iterative algorithm, including setting the regularization parameter λ, the maximum number of iterations max_iter and the tolerance ε, and dynamically adjusting the H matrix and the f vector until the iteration stop condition is met;

[0016] Corrosion diagnosis module: used to calculate the ΔR k Calculate the resistance change multiple of each branch, determine the corrosion level according to the preset threshold, and generate visualization results.

[0017] Furthermore, the structure information acquisition module includes:

[0018] Correlation matrix construction unit: sets the reference direction of node i and branch j according to the grounding grid design drawing;

[0019] Branch parameter calculation unit: Calculate the nominal resistance value vector R0 = [R1, R2, ..., R b ] T , and generate the node conductance matrix Where R0 is the nominal resistance value vector, R b It represents the nominal resistance value of the b-th branch, where b is the total number of branches; is the branch conductance diagonal matrix, and its diagonal elements are The corresponding elements in , and the off-diagonal elements are 0.

[0020] Furthermore, the parameter construction module includes:

[0021] Theoretical value calculation unit: through the formula Calculate the node voltage matrix; where U is the node voltage matrix, is the node conductance matrix G n The inverse matrix of

[0022] Branch current calculation unit: through the formula Calculate the theoretical value matrix of branch current; where I b is the theoretical value matrix of branch current, K T is the transposed matrix of the incidence matrix K;

[0023] Port resistance theoretical value unit: through the formula

[0024]

[0025] Calculate the theoretical value vector of the port resistance; where R this the theoretical value vector of the port resistance, U(:,m) represents the mth column element in the node voltage matrix U (which can be understood as the node voltage value related to the accessible node m), I n (m,m) represents the injection current matrix I n The element at row m and column m in ;

[0026] Measured value conversion unit: through the formula

[0027]

[0028] Generate a port resistance measured value vector; wherein R′ is the port resistance measured value vector;

[0029] Change calculation unit: by formula ΔR=R′-R th Generates a vector of port resistance changes.

[0030] Furthermore, in the objective function construction module, the quadratic objective function is minimized by:

[0031]

[0032] Among them, X is the current change ratio matrix, and the calculation formula is:

[0033]

[0034] I b_cor is the branch current after corrosion, I b_0 is the branch current before corrosion, represents the Hadamard product; Y is the port resistance change vector; ΔR k is the branch resistance change vector.

[0035] Furthermore, the quadratic programming solution module performs the following steps:

[0036] Step S1: Initialize ΔR k =0, λ=1, number of iterations n=0; where λ is the regularization parameter;

[0037] Step S2: Construct H matrix as H=2X T X+λI, construct f vector as f=-2X T Y. Among them, H matrix is ​​used for quadratic programming solution, I is the identity matrix, and f vector is used for quadratic programming solution;

[0038] Step S3: Solve the quadratic objective function to satisfy A ineq ΔR k ≥0 and A eq ΔR k =Y T ;

[0039] Step S4: If Or n≥max_iter, then terminate the iteration; otherwise, update λ=λ×0.9, n=n+1 and return to step S2. Indicates ΔR k The infinity norm of the difference between the new value and the old value, ε is the tolerance, and max_iter is the maximum number of iterations.

[0040] Furthermore, the update rule of the regularization parameter λ is: when the objective function decrease rate is less than 5% in three consecutive iterations, λ = λ × 0.5; when ΔR k The L2 norm exceeds the threshold R max When λ=λ×1.2, where R max =10×mean(R0). Where mean(R0) represents the mean value of the resistance nominal value vector R0.

[0041] Furthermore, the corrosion diagnosis module includes:

[0042] Change multiple calculation unit: through the formula

[0043]

[0044] Calculate the resistance change multiple of each branch. Where k is the resistance change multiple of each branch, R 0_k is the nominal resistance value vector of the kth branch;

[0045] Corrosion grade judgment unit: classified according to the following rules: if 1≤k<3, it is mild corrosion, 3≤k<10 is moderate corrosion, k≥10 is severe corrosion;

[0046] Visualization unit: Maps branches to different colors according to corrosion level, generates a grounding grid topology overlay bar chart, and the bar height is proportional to the k value.

[0047] Furthermore, the corrosion level judgment unit further performs regional corrosion detection: if the k values ​​of five consecutive branches are all greater than 2 and are spatially adjacent, they are marked as a regional corrosion group and a warning signal is triggered.

[0048] Furthermore, the linear inequality constraint is A ineq ΔR k ≥b ineq ;

[0049] The equality constraint is A eq ΔR k =b eq ;

[0050] Among them, A ineq is the identity matrix, bineq is the zero vector; A eq is the quadratic term matrix of the current change ratio.

[0051] Furthermore, the linear inequality constraint A ineq It further includes a regional constraint sub-matrix, specifically: for a branch p within a specified area, set A ineq (p,p)=2 and b ineq (p) = R 0_p ×0.1, forcing the branch resistance change in this area to be no less than 10% of the nominal value; where A ineq (p,p) represents the linear inequality constraint matrix A ineq The element in row p and column p in b ineq (p) represents the zero vector b ineq The pth element in R 0_p is the nominal resistance value vector of the p-th branch in the specified area.

[0052] According to the above-mentioned embodiment of the present invention, there are at least the following beneficial effects: the substation grounding grid corrosion diagnosis system of the present invention can realize comprehensive and accurate monitoring of the corrosion status of the substation grounding grid. By constructing the topological relationship and correlation matrix of the grounding grid, combining current injection and voltage measurement technology, the system can generate detailed theoretical values ​​and measured values ​​of node voltage, branch current and port resistance, so as to accurately calculate the change in port resistance. Furthermore, the system uses a quadratic programming solution algorithm, combined with linear inequality constraints and equality constraints, to quantitatively analyze the corrosion status of the grounding grid, which can effectively distinguish the resistance change caused by corrosion from the influence of other factors, and improve the accuracy of corrosion diagnosis. In addition, the system also introduces the Laplace matrix to enhance the correlation between the resistance changes of adjacent branches in space, so that the diagnostic results are more in line with the actual operating conditions of the grounding grid, and provide strong support for the maintenance and management of the substation grounding grid.

[0053] The present invention also enables visualization of corrosion levels and regional corrosion detection. Based on the calculated branch resistance change factor and preset thresholds, the system automatically determines the corrosion level and visually displays the corrosion distribution of the grounding grid using color-coded bar charts, allowing operators to quickly understand the corrosion status. Furthermore, the system can detect corrosion in consecutive branches, identify regional corrosion clusters, and trigger early warning signals, providing a basis for early corrosion warning and targeted maintenance of substation grounding grids. This effectively reduces the impact of corrosion on substation operational safety and improves the reliability and cost-effectiveness of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily apparent by reading the following detailed description with reference to the accompanying drawings, in which several embodiments of the present invention are shown by way of example and not limitation, in which:

[0055] Figure 1 This is a structural diagram of a substation grounding grid corrosion diagnosis system provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0056] The principles and spirit of the present invention will be described below with reference to several exemplary embodiments. It should be understood that these embodiments are provided solely to enable those skilled in the art to better understand and implement the present invention, and are not intended to limit the scope of the present invention in any way. Rather, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0057] Those skilled in the art will appreciate that the embodiments of the present invention may be implemented as a system, apparatus, device, method, or computer program product. Therefore, the present invention may be implemented in the following forms: entirely in hardware, entirely in software (including firmware, resident software, microcode, etc.), or in a combination of hardware and software.

[0058] It should be noted that any number of elements in the drawings is for illustration only and not for limitation, and any naming is only for distinction and does not have any limiting meaning.

[0059] Reference below Figure 1 , Figure 1 This is a schematic diagram of the structure of a substation grounding grid corrosion diagnosis system provided by an embodiment of the present invention. Figure 1 As shown, a substation grounding grid corrosion diagnosis system 100 includes:

[0060] Structural information acquisition module 101: used to obtain the topological relationship between nodes and branches of the grounding grid and construct the correlation matrix K = [a ij ] and calculate the branch resistance nominal value vector. Among them, a ij Represents the element in row i and column j of the incidence matrix K. When branch j flows out from node i, a ij =1; when flowing in, a ij =-1; in other cases, a ij =0.

[0061] Detection data acquisition module 102: used to select a reference node and inject DC current, measure the port voltage value between the accessible node and the reference node, and generate the port voltage measured value vector U′ and the injection current matrix I n Among them, U′ is the measured value vector of the port voltage, In is the injection current matrix, and n represents parameters such as the relevant dimension or number of injection currents (specifically according to the matrix definition).

[0062] Parameter construction module 103: used to construct the parameters according to the correlation matrix K and the injection current matrix I n The node voltage matrix, the branch current matrix theoretical value and the port resistance theoretical value vector are calculated, and the port resistance measured value vector and the port resistance variation ΔR are calculated based on the port voltage measured value vector U′.

[0063] Objective function construction module 104: used to construct a quadratic objective function, which is a minimization expression

[0064]

[0065] Among them, X is the current change ratio matrix, and the calculation formula is

[0066]

[0067] I b_cor is the branch current after corrosion, I b_0 is the branch current before corrosion, represents the Hadamard product; Y is the port resistance change vector; ΔR k is the branch resistance change vector.

[0068] Constraint construction module 105: used to set linear inequality constraints A ineq ΔR k ≥b ineq and the equality constraint A eq ΔR k =b eq Among them, A ineq is the identity matrix, b ineq is the zero vector; A eq is the quadratic term matrix of the current change ratio, and the construction formula is A eq =X T X+γL, L is the Laplace matrix based on the grounding grid topology, γ = 0.1, which is used to enhance the resistance change correlation of spatially adjacent branches, b eq is the transposed vector of the port resistance change.

[0069] The quadratic programming solving module 106 is used to solve the quadratic objective function through an iterative algorithm, including setting the regularization parameter λ, the maximum number of iterations max_iter and the tolerance ε, and dynamically adjusting the H matrix and the f vector until the iteration stop condition is met.

[0070] Corrosion diagnosis module 107: used to calculate the ΔR kCalculate the resistance change multiple of each branch, determine the corrosion level according to the preset threshold, and generate visualization results.

[0071] It should be noted that the substation grounding grid corrosion diagnosis system of the present invention includes multiple modules, each of which is responsible for a specific function. First, the structural information acquisition module is used to obtain the node and branch topology relationship of the grounding grid, construct the correlation matrix K, and calculate the branch resistance nominal value vector. The correlation matrix K is a matrix that represents the relationship between nodes and branches, and the resistance nominal value vector represents the resistance value of each branch. The detection data acquisition module selects a reference node and injects DC current to measure the port voltage value, generate the port voltage measured value vector V′ and the injection current matrix I. The parameter construction module calculates the node voltage matrix, the branch current matrix theoretical value and the port resistance theoretical value vector based on the correlation matrix K and the injection current matrix I, and calculates the port resistance measured value vector and the port resistance change ΔR based on the port voltage measured value vector V′. The objective function construction module constructs a quadratic objective function to minimize the expression:

[0072]

[0073] Where X is the current change ratio matrix, and Y is the port resistance change vector. The constraint construction module sets linear inequality constraints and equality constraints. The quadratic programming solver module solves the quadratic objective function through an iterative algorithm, calculates the resistance change multiple of each branch, determines the corrosion level, and generates visualization results.

[0074] Specifically, the elements in the correlation matrix K represent the connection relationship between nodes and branches. When a branch flows out of a node, the element value is 1; when it flows into a node, the element value is -1; otherwise, it is 0. The nominal resistance value vector represents the resistance value of each branch. These values ​​can be calculated based on the branch material and length. The injection current matrix I represents parameters such as the relevant dimensions or frequency of the injection current. The node voltage matrix, the theoretical branch current matrix, and the theoretical port resistance value vector are calculated using the correlation matrix K and the injection current matrix I and are used for comparison with the measured values. The measured port resistance value vector V′ is obtained by measuring the port voltage value, and the port resistance change ΔR is the difference between the measured value and the theoretical value. The current change ratio matrix X in the objective function represents the change ratio of the branch current before and after corrosion, and the port resistance change vector Y represents the change in port resistance. Linear inequality constraints and equality constraints are used to limit the range and relationships of variables in the solution process.

[0075] Preferably, the structural information acquisition module can set the reference direction of nodes and branches through the grounding grid design drawings, and the branch parameter calculation unit can calculate the resistance nominal value vector based on the branch material and length. The detection data acquisition module can select multiple reference nodes for current injection and voltage measurement to improve the accuracy of the data. The parameter construction module can further refine the calculation method of the node voltage matrix and the branch current matrix, taking into account different current injection methods and measurement conditions. The objective function construction module can adjust the calculation method of the current change ratio matrix and the port resistance change vector according to different corrosion conditions. The quadratic programming solution module can set different regularization parameters, maximum number of iterations and tolerances to adapt to different corrosion diagnosis needs. The corrosion diagnosis module can generate various forms of visualization results based on the calculation results, such as charts, heat maps, etc., to facilitate operation and maintenance personnel to quickly understand the corrosion status of the grounding grid.

[0076] In some embodiments, the structure information acquisition module includes:

[0077] Correlation matrix construction unit: Set the reference direction of node i and branch j according to the grounding grid design drawing. When branch j flows out from node i, a ij =1, -1 when inflow, 0 otherwise.

[0078] Branch parameter calculation unit: Calculate the nominal resistance value vector R0 = [R1, R2, ..., R b ] T , and generate the node conductance matrix Where R0 is the nominal resistance value vector, R i represents the nominal resistance value of the i-th branch, and b is the total number of branches; is the branch conductance diagonal matrix, and its diagonal elements are The corresponding elements in , and the off-diagonal elements are 0.

[0079] It should be noted that the structural information acquisition module is the foundation of this system, and its core function is to construct the topological structure information of the grounding grid. Specifically, the association matrix construction unit sets the reference direction of nodes and branches based on the grounding grid design drawings. When a branch flows out of a node, the matrix element is assigned a value of 1; when it flows into a node, it is -1, and otherwise it is 0. The branch parameter calculation unit calculates the nominal resistance value vector based on the material and length of the branch and generates a node conductance matrix. The nominal resistance value vector is the initial value of the resistance of each branch of the grounding grid, while the node conductance matrix is ​​an inverse matrix based on the nominal resistance value and is used for subsequent current and voltage calculations. This information provides basic data support for the entire corrosion diagnosis system.

[0080] Specifically, the construction of the correlation matrix is ​​based on the topological structure of the grounding grid, where nodes represent the connection points of the grounding grid and branches represent the conductors connecting the nodes. The calculation of the resistance nominal value vector needs to take into account the material (such as copper, aluminum, etc.) and length of the branch, because these factors directly affect the resistance value of the branch. For example, the resistivity of copper conductors is low, while the resistivity of aluminum conductors is high. The node conductance matrix is ​​generated by the inverse matrix of the resistance nominal value vector, where the elements on the diagonal are the reciprocals of the resistance nominal values ​​and the off-diagonal elements are 0. This matrix form facilitates subsequent current distribution calculations and voltage drop analysis. In practical applications, these parameters can be adjusted and optimized according to the specific design and operation of the grounding grid.

[0081] Preferably, the correlation matrix construction unit can use automated tools to extract node and branch information from the grounding grid design drawings to reduce errors in manual input. For the branch parameter calculation unit, the influence of environmental factors (such as soil moisture and corrosive medium concentration) on the nominal value of resistance can be introduced to further improve the calculation accuracy. For example, in a high humidity environment, the resistance value of the grounding grid may decrease due to corrosion. In addition, the generation of the node conductance matrix can be calibrated in combination with actual measurement data to ensure its accuracy. In alternative solutions, the use of more complex network models (such as considering the coupling effect between branches) can be considered to improve the description accuracy of the grounding grid topology.

[0082] In some embodiments, the parameter building module includes:

[0083] Theoretical value calculation unit: through the formula Calculate the node voltage matrix. Where U is the node voltage matrix, is the node conductance matrix G n The inverse matrix, I n is the injection current matrix.

[0084] Branch current calculation unit: through the formula Calculate the theoretical value matrix of branch current. b is the theoretical value matrix of branch current, K T is the transposed matrix of the incidence matrix K.

[0085] Port resistance theoretical value unit: through the formula

[0086]

[0087] Calculate the theoretical value vector of the port resistance. th is the theoretical value vector of the port resistance, U(:,m) represents the mth column element in the node voltage matrix U (which can be understood as the node voltage value related to the accessible node m), I n (m,m) represents the injection current matrix I nThe element at row m and column m in .

[0088] Measured value conversion unit: through the formula

[0089]

[0090] Generate the port resistance measured value vector. Among them, R' is the port resistance measured value vector, U' is the port voltage measured value vector, I n is the injection current matrix.

[0091] Change calculation unit: by formula ΔR=R′-R th Generate the port resistance change vector. Among them, ΔR is the port resistance change vector, R' is the port resistance measured value vector, R th is the theoretical value vector of the port resistance.

[0092] It should be noted that the parameter construction module is the core component of the substation grounding grid corrosion diagnosis system. Its main function is to calculate the node voltage matrix, the theoretical values ​​of the branch current matrix, and the theoretical port resistance vector based on the grounding grid topology and detection data. By comparing these theoretical values ​​with the measured values, a quantitative basis for corrosion diagnosis can be provided. The theoretical value calculation unit calculates the node voltage matrix by multiplying the inverse of the node conductance matrix by the injection current matrix. The branch current calculation unit calculates the theoretical branch current matrix by operating the transpose of the correlation matrix on the node voltage matrix. The theoretical port resistance unit calculates the theoretical port resistance vector based on the relationship between the node voltage and the injection current. The measured value conversion unit converts the measured port voltage vector into the measured port resistance vector, while the variation calculation unit calculates the port resistance variation vector by taking the difference between the measured and theoretical values. These variations are key indicators for corrosion diagnosis.

[0093] Specifically, the calculation formula of the node voltage matrix is ​​U=G -1 I, where G is the node conductance matrix and I is the injection current matrix. The inverse matrix G of the node conductance matrix is -1 It is used to reflect the conductivity relationship between nodes, while the injection current matrix contains the specific parameters of current injection. The calculation formula of the branch current theoretical value matrix is ​​I line =K T G -1 I, where Kw is the transposed matrix of the correlation matrix. The calculation formula for the theoretical value vector of the port resistance is Here, U(:,m) represents the voltage associated with an accessible node in the node voltage matrix, while I(m,m) represents the current at the corresponding location in the injection current matrix. The measured port resistance vector is calculated as the ratio of the measured voltage to the injected current, while the port resistance change vector is the difference between the measured value and the theoretical value. These parameter settings and calculation methods provide accurate data support for corrosion diagnosis.

[0094] Preferably, the theoretical value calculation unit can adopt a more efficient matrix solution algorithm to improve the calculation speed and accuracy, such as using a sparse matrix solver to adapt to the calculation requirements of large-scale grounding grids. The branch current calculation unit can take into account the coupling effect between branches to further optimize the calculation accuracy of the current distribution. For the port resistance theoretical value unit, the influence of environmental factors (such as temperature and humidity) on the resistance can be introduced to make the theoretical value closer to the actual situation. In an alternative solution, the change in port resistance can be modeled and predicted in combination with a machine learning algorithm, thereby improving the accuracy and reliability of corrosion diagnosis.

[0095] In some embodiments, in the objective function building module, the calculation formula of the current change ratio matrix X is:

[0096]

[0097] Among them, I b_cor is the branch current after corrosion, I b_0 is the branch current before corrosion, represents the Hadamard product; the equality constraint matrix A eq The construction formula is

[0098] A eq =X T X, b eq =Y T

[0099] Among them, Y is the port resistance change vector, Y T Transpose its vector.

[0100] It should be noted that the objective function construction module is a key part of the substation grounding grid corrosion diagnosis system for quantifying the corrosion status. Its core function is to construct a quadratic objective function that minimizes the expression To optimize corrosion diagnosis results. The current change ratio matrix X is the Hadamard product (element-by-element multiplication) of the branch currents before and after corrosion, reflecting the change in branch current. The port resistance change vector Y is the difference between the measured and theoretical values, measuring the resistance change caused by corrosion. The branch resistance change vector ΔR is the variable to be solved, representing the degree of corrosion. The equation for constructing the equality constraint matrix, A = K + λL, is used. K is the correlation matrix, and L is the Laplace matrix based on the grounding grid topology. This matrix is ​​used to enhance the correlation between the resistance changes of spatially adjacent branches, thereby more accurately reflecting the actual distribution of corrosion.

[0101] Specifically, the calculation formula of the current change ratio matrix X is: Among them I corroded is the branch current after corrosion, I0 is the branch current before corrosion, and the Hadamard product Represents element-by-element multiplication. This calculation method can intuitively reflect the impact of corrosion on current distribution. In the construction of the equality constraint matrix A, the Laplace matrix L is generated based on the topological structure of the grounding grid. Its diagonal elements are the degrees of the nodes, and the off-diagonal elements are the connection relationships between the nodes. The parameter λ is a regulation factor used to control the influence of the Laplace matrix on the equality constraint, and its value is usually 0.1. In this way, the objective function not only considers the influence of the current change ratio, but also utilizes the spatial topological information of the grounding grid, enhancing the accuracy of corrosion diagnosis.

[0102] Preferably, a dynamic adjustment mechanism can be introduced into the calculation of the current change ratio matrix X to update the current ratio before and after corrosion in real time according to the changes in the corrosion degree. In the construction of the equality constraint matrix A, the Laplace matrix L can be optimized according to different grounding grid structures. For example, in complex networks, weight factors can be added to highlight the influence of key branches. In addition, the value of the parameter λ can be adjusted according to the actual corrosion situation. For example, the value of λ can be appropriately increased in areas with more severe corrosion to strengthen the constraints on spatial correlation. As an alternative, it is possible to consider introducing a multi-objective optimization method that takes into account both the corrosion degree and network stability to further improve the comprehensive performance of corrosion diagnosis.

[0103] In some embodiments, the quadratic programming solver module performs the following steps:

[0104] Step S1: Initialize ΔR k =0, λ=1, number of iterations n=0. Among them, ΔR k is the branch resistance variation vector, λ is the regularization parameter, and n is the number of iterations.

[0105] Step S2: Construct H matrix as H=2X T X+λI, construct f vector as f=-2X TY. Among them, H matrix is ​​used for quadratic programming solution, X is the current change ratio matrix, I is the identity matrix, f vector is used for quadratic programming solution, and Y is the port resistance change vector.

[0106] Step S3: Solve the quadratic programming problem Satisfy A ineq ΔR k ≥0 and A eq ΔR k =Y T .

[0107] Step S4: If Or n≥max_iter, then terminate the iteration; otherwise, update λ=λ×0.9, n=n+1 and return to step S2. Indicates ΔR k The infinity norm of the difference between the new value and the old value, ε is the tolerance, and max_iter is the maximum number of iterations.

[0108] It should be noted that the quadratic programming solution module is a key component of the substation grounding grid corrosion diagnosis system. Its main function is to solve the quadratic objective function through an iterative algorithm to determine the branch resistance change vector. In this module, the branch resistance change vector ΔR is first initialized to zero, the regularization parameter λ is 1, and the number of iterations is 0. Then, the H matrix and f vector are constructed for the quadratic programming solution. The H matrix is ​​constructed based on the current change ratio matrix X and the identity matrix I, while the f vector is based on the port resistance change vector Y. By solving the quadratic programming problem, the module can satisfy linear inequality constraints and equality constraints, ultimately obtaining corrosion diagnosis results.

[0109] Specifically, the initialization step of the quadratic programming solver module includes setting ΔR = 0, λ = 1 and the number of iterations k = 0. During the iteration process, the construction formula of the H matrix is ​​H = 2X T X+λI, where X is the current change ratio matrix and I is the identity matrix, which is used to regularize the solution process to avoid overfitting. The construction formula of vector f is f=-2X T Y, where Y is the vector of port resistance changes. The goal of the quadratic programming problem is to minimize At the same time, the linear inequality constraint AΔR≥b and the equality constraint CΔR=d are satisfied. The iterative termination conditions include when the infinite norm of the updated amount of ΔR is less than the set tolerance ∈ or the number of iterations reaches the maximum number of iterations k max Stop iteration when .

[0110] Preferably, the initial value of the regularization parameter λ can be adjusted according to the scale and complexity of the grounding grid. For example, for a large-scale grounding grid, the initial value of λ can be appropriately increased to enhance the regularization effect. During the iteration process, the value of λ can be dynamically adjusted. For example, when the rate of decrease of the objective function is lower than a certain threshold, the value of λ can be reduced to speed up the convergence. In addition, the maximum number of iterations k max The number of iterations can be set to 100 to 1000, depending on the degree of corrosion of the grounding grid and the required accuracy. Alternatively, an adaptive iterative algorithm can be introduced to dynamically adjust the iteration step size and direction based on the results of each iteration, thereby improving solution efficiency and accuracy.

[0111] In some embodiments, the updating rule of the regularization parameter λ is: when the objective function decrease rate is less than 5% in three consecutive iterations, λ = λ × 0.5; when ΔR k The L2 norm exceeds the threshold R max When λ=λ×1.2, where R max =10×mean(R0). Where mean(R0) represents the mean value of the resistance nominal value vector R0.

[0112] It should be noted that the update rule of the regularization parameter is an important mechanism for optimizing the solution process in the quadratic programming solution module. The core of this rule is to dynamically adjust the regularization parameter λ according to the rate of decrease of the objective function and the norm of the branch resistance change in the solution process. When the rate of decrease of the objective function is less than 5% in three consecutive iterations, it indicates that the current solution process may be stagnant or overfitting. At this time, λ is halved to enhance the regularization effect and prompt the solution process to jump out of the local optimal solution. When the L2 norm of the branch resistance change exceeds the threshold λ norm When , it indicates that the resistance change may be too large. At this time, λ is increased by 20% to suppress the excessive resistance change and ensure the rationality of the solution. norm Typically set to 10 times the mean of the nominal resistance vector R0. This setting is based on the initial resistance distribution of the ground grid and is used to balance solution accuracy and stability.

[0113] Specifically, the dynamic adjustment mechanism of the regularization parameter λ involves two key conditions. First, the calculation formula of the objective function descent rate is:

[0114]

[0115] Among them, f current and f previousare the objective function values ​​for the current and previous iterations, respectively. When the rate of decrease for three consecutive iterations is less than 5%, it indicates that the solution process may require a stronger regularization constraint, so λ is updated to λ×0.5. Secondly, the L2 norm of the branch resistance change is used to measure the overall scale of the resistance change, and its calculation formula is ||ΔR||2. When ||ΔR||2 exceeds the threshold λ norm When , it means that the resistance change may be too large, and it is necessary to suppress this change by increasing λ. In this case, λ is updated to λ×1.2. The mean of the resistance nominal value vector R0 is used to calculate the threshold λ norm , which is calculated as mean(R0), and a reasonable threshold range is set by multiplying it by 10.

[0116] Preferably, the threshold of the objective function drop rate can be dynamically adjusted according to the complexity and corrosion of the actual grounding grid. For example, in a grounding grid with severe corrosion, the drop rate threshold can be set to 3% or lower to trigger the adjustment of the regularization parameter earlier. norm , can be adjusted based on the resistance distribution range of the grounding grid. For example, in a grounding grid with a wide resistance distribution, the threshold can be appropriately increased by a factor of 15 or 20. Alternatively, an adaptive regularization parameter adjustment strategy can be introduced, such as combining a machine learning algorithm to predict the optimal λ value based on historical data, thereby further improving the efficiency and accuracy of the solution process.

[0117] In some embodiments, the corrosion diagnostic module includes:

[0118] Change multiple calculation unit: through the formula

[0119]

[0120] Calculate the resistance change multiple of each branch. Where k is the resistance change multiple of each branch, R 0_ k is the nominal resistance vector of the kth branch, ΔR k is the branch resistance change vector.

[0121] Corrosion grade judgment unit: classified according to the following rules: if 1≤k<3, it is mild corrosion, 3≤k<10 is moderate corrosion, and k≥10 is severe corrosion.

[0122] Visualization unit: Maps branches to different colors according to corrosion level, generates a grounding grid topology overlay bar chart, and the bar height is proportional to the k value.

[0123] It should be noted that the corrosion diagnosis module is the core part of the substation grounding grid corrosion diagnosis system for evaluating the degree of corrosion and outputting diagnostic results. The module quantifies the degree of corrosion by calculating the branch resistance change multiple and classifies the corrosion level according to the preset threshold. Specifically, the branch resistance change multiple is calculated by adding the branch resistance change vector to the resistance nominal value vector and then dividing it by the resistance nominal value vector. The corrosion level judgment unit divides the corrosion level into three levels: mild, moderate and severe corrosion based on the calculation results, thereby providing intuitive corrosion status information to operation and maintenance personnel. In addition, the visualization unit maps the corrosion level to the grounding grid topology map with different colors, and displays the branch corrosion level in the form of a bar chart. The bar height is proportional to the corrosion level, which is convenient for quickly identifying areas with severe corrosion.

[0124] Specifically, the calculation formula for the branch resistance change multiple is:

[0125]

[0126] Among them, R0 is the nominal value vector of branch resistance, ΔR is the branch resistance change vector. The classification standard of corrosion level is: when 1≤ΔR ratio When ΔR <3, it is mild corrosion, indicating that the corrosion degree is relatively light and has little impact on the performance of the grounding grid; when 3≤ΔR ratio When ΔR <10, it is moderate corrosion, indicating that the corrosion degree is moderate and needs attention; when ΔR ratio When ≥10, it is severe corrosion, indicating that the corrosion is serious and needs to be treated in time. In the visualization process, mild corrosion can be represented by green, moderate corrosion by yellow, and severe corrosion by red. The height of the bar graph is based on ΔR ratio The value of is adjusted dynamically to intuitively display the distribution of corrosion degree.

[0127] Ideally, the corrosion classification criteria can be adjusted based on the actual operating environment and safety requirements of the grounding grid. For example, in areas with severe corrosion, the upper limit for mild corrosion can be appropriately lowered to attract attention earlier. For visualization units, interactive features can be introduced, allowing operators to click on bar charts to view specific branch information and corrosion data.

[0128] Furthermore, Geographic Information System (GIS) technology can be used to combine corrosion diagnosis results with the substation's geographic location, providing a more intuitive display of regional corrosion distribution. Alternatively, corrosion severity can be determined by combining historical data with machine learning algorithms. This training model can automatically identify corrosion trends and potential risks, further improving the accuracy and reliability of diagnosis.

[0129] In some embodiments, the corrosion level judgment unit further performs regional corrosion detection: if the k values ​​of five consecutive branches are all greater than 2 and are spatially adjacent, they are marked as a regional corrosion group and a warning signal is triggered.

[0130] It should be noted that when performing corrosion diagnosis, the corrosion level judgment unit not only assesses the degree of corrosion of a single branch, but also further performs regional corrosion detection. The core of this function is to identify the corrosion of consecutive branches. When it detects that the resistance change multiple of five consecutive branches is greater than 2 and they are spatially adjacent, the system marks them as a regional corrosion cluster and triggers an early warning signal. This regional corrosion detection mechanism can effectively identify concentrated corrosion phenomena in a local area, thereby providing operation and maintenance personnel with a more comprehensive corrosion risk warning, helping to take targeted maintenance measures in advance.

[0131] Specifically, when identifying regional corrosion groups, the corrosion level judgment unit will check whether the resistance change multiple of the branch meets the conditions (i.e., greater than 2), and at the same time, combine the spatial position information of the branch to determine whether there is continuity. The continuity here means that in the topology of the grounding grid, the branches are physically connected to each other to form a local area. In terms of parameter setting, the threshold for the number of continuous branches is set to 5. This is because when five or more branches show significant corrosion at the same time, it usually indicates that the area may have a serious corrosion environment or potential corrosion factors. The resistance change multiple threshold is set to 2 because this value is already in the moderate corrosion range in the corrosion level classification, indicating that the degree of corrosion is more obvious. The triggering mechanism of the early warning signal is used to remind operation and maintenance personnel to focus on the corrosion situation in the area so that timely measures can be taken to prevent further deterioration.

[0132] The threshold for the number of consecutive branches can be adjusted based on the size and complexity of the grounding grid. For example, in a small grounding grid, the threshold can be set to 3 or 4 to detect potential regional corrosion issues earlier. The resistance change multiple threshold can be fine-tuned based on the severity of the actual corrosion environment. For example, in environments with high humidity or highly corrosive soil, the threshold can be appropriately lowered to 1.5 or 1.8.

[0133] Furthermore, alternative solutions could include the introduction of machine learning-based pattern recognition algorithms to automatically learn the characteristic patterns of corrosion distribution, thereby more accurately identifying regional corrosion clusters. Furthermore, early warning signals could be integrated with geographic information systems (GIS) to directly mark the location and severity of corrosion areas on substation maps, providing more intuitive decision support for operations and maintenance personnel.

[0134] In some embodiments, the linear inequality constraint A ineq It further includes a regional constraint sub-matrix, specifically: for a branch p within a specified area, set Aineq (p,p)=2 and b ineq (p) = R 0_p ×0.1, forcing the branch resistance change in this area to be no less than 10% of the nominal value. ineq (p,p) represents the linear inequality constraint matrix A ineq The element in row p and column p in b ineq (p) represents the zero vector b ineq The pth element in R 0_p is the nominal resistance value vector of the p-th branch in the specified area.

[0135] It should be noted that linear inequality constraints are used in the substation grounding grid corrosion diagnosis system to ensure the rationality and reliability of diagnostic results. Specifically, by introducing a regional constraint submatrix, the system can enforce constraints on the resistance change of branches within a specified area of ​​the grounding grid. For example, for branches within a specified area, the constraint requires that the resistance change be no less than 10% of the nominal value. This constraint mechanism prevents misjudgments caused by errors in the diagnostic model or local data anomalies, thereby more accurately reflecting the actual corrosion situation of the grounding grid, especially in specific areas known to be at risk of corrosion.

[0136] Specifically, in the construction of the linear inequality constraint matrix, for the branch i in the specified area, the corresponding element A(i,i) of the constraint matrix A is set to 2, and the corresponding element b(i) of the constraint vector b is set to in is the nominal resistance value of the i-th branch within a given area. This setting ensures that the resistance variation of branches within a region is at least 10% of the nominal value, thus avoiding underestimation of resistance variation due to overfitting of the diagnostic model. Furthermore, this constraint mechanism can be combined with actual operating data and historical corrosion history of the grounding grid to further optimize the constraint settings to accommodate differences in corrosion risk across different regions.

[0137] Preferably, the setting of linear inequality constraints can be further refined. For example, in areas with higher corrosion risks, the constraint ratio of resistance change can be appropriately increased, such as setting it to 15% or 20% of the nominal value, to more strictly monitor the corrosion situation. For the construction of the constraint matrix A, a weight factor can be introduced to adjust the constraint strength according to the importance of different branches. For example, for branches connecting key equipment, a higher weight can be given to ensure that its resistance change is more strictly monitored. In an alternative solution, the constraints can be dynamically adjusted in combination with real-time monitoring data. For example, the constraint ratio of resistance change can be updated in real time according to changes in environmental factors (such as humidity, soil pH), thereby improving the adaptability and accuracy of the diagnostic system.

[0138] In some embodiments, the equality constraint A eq ΔR k =b eq Among them, A ineq is the identity matrix, b ineq is the zero vector; A eq is the quadratic term matrix of the current change ratio.

[0139] A 7×7 grounding grid can be used for simulation testing to verify the effectiveness of corrosion diagnosis of multiple branches.

[0140] The above-mentioned embodiments of the present invention have the following beneficial effects: the substation grounding grid corrosion diagnosis system of the present invention can realize comprehensive and accurate monitoring of the corrosion status of the grounding grid. Through the structural information acquisition module, the system can obtain the node and branch topology relationship of the grounding grid, construct the correlation matrix and calculate the nominal value of the branch resistance. The detection data acquisition module can generate the port voltage measured value vector and the injection current matrix by injecting DC current and measuring the port voltage. The parameter construction module can calculate the node voltage matrix, the branch current matrix theoretical value and the port resistance theoretical value based on the correlation matrix and the injection current matrix, and further calculate the port resistance measured value vector and its change amount. The objective function construction module can construct a quadratic objective function, combine linear inequalities and equality constraints, and iteratively solve it through the quadratic programming solution module, and finally realize the calculation of the branch resistance change multiple and the judgment of the corrosion level.

[0141] The system of the present invention can also visualize corrosion status and detect regional corrosion. The corrosion diagnosis module automatically determines the corrosion level based on the calculated branch resistance change factor and a preset threshold. It then visually displays the corrosion distribution of the grounding grid using color-coded bar charts, allowing operators to quickly understand the corrosion status. Furthermore, the system can detect corrosion in consecutive branches, identify regional corrosion clusters, and trigger early warning signals, providing a basis for early corrosion warning and targeted maintenance of substation grounding grids. This effectively reduces the impact of corrosion on substation operational safety and improves the reliability and cost-effectiveness of the power system.

[0142] Furthermore, the storage medium of the embodiment of the present application stores program instructions that can implement all the above methods, wherein the program instructions can be stored in the above storage medium in the form of a software product, including a number of instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, or a terminal device such as a computer, a server, a mobile phone, or a tablet.

[0143] The above descriptions are merely some preferred embodiments of the present invention and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present invention is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also encompass other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the above-mentioned inventive concept. For example, a technical solution formed by mutually replacing the above-mentioned features with (but not limited to) technical features having similar functions disclosed in the embodiments of the present invention.

Claims

1. A substation grounding grid corrosion diagnosis system, characterized in that: Includes the following modules: Structural information acquisition module: used to obtain the topological relationship between nodes and branches of the grounding grid and construct the correlation matrix K = [a ij ], and calculate the branch resistance nominal value vector, where a ij Represents the element in row i and column j of the incidence matrix K. When branch j flows out from node i, a ij =1; when flowing in, a ij =-1; in other cases, a ij =0; Detection data acquisition module: used to select the reference node and inject DC current, measure the port voltage value between the accessible node and the reference node, and generate the port voltage measured value vector U′ and the injection current matrix I n ; Parameter construction module: used to calculate the value of the correlation matrix K and the injection current matrix I according to the correlation matrix K and the injection current matrix I n Calculating the node voltage matrix, the branch current matrix theoretical value and the port resistance theoretical value vector, and calculating the port resistance measured value vector and the port resistance change ΔR based on the port voltage measured value vector U′; Objective function construction module: used to construct quadratic objective function; Constraint building module: used to set linear inequality constraints and equality constraints; Quadratic programming solving module: used for solving the quadratic objective function through an iterative algorithm; Corrosion diagnosis module: used to calculate the resistance change multiple of each branch based on the solution results, determine the corrosion level according to the preset threshold and generate visual results.

2. The substation grounding grid corrosion diagnosis system according to claim 1, characterized in that: The structure information acquisition module includes: Correlation matrix construction unit: sets the reference direction of node i and branch j according to the grounding grid design drawing; Branch parameter calculation unit: Calculate the nominal resistance value vector R0 = [R1, R2, ..., R b ] T , and generate the node conductance matrix Where R0 is the nominal resistance value vector, R b It represents the nominal resistance value of the b-th branch, where b is the total number of branches; is the branch conductance diagonal matrix, and its diagonal elements are The corresponding elements in , and the off-diagonal elements are 0.

3. The substation grounding grid corrosion diagnosis system according to claim 2, characterized in that: The parameter building module includes: Theoretical value calculation unit: through the formula Calculate the node voltage matrix; where U is the node voltage matrix, is the node conductance matrix G n The inverse matrix of Branch current calculation unit: through the formula Calculate the theoretical value matrix of branch current; where I b is the theoretical value matrix of branch current, K T is the transposed matrix of the incidence matrix K; Port resistance theoretical value unit: through the formula Calculate the theoretical value vector of the port resistance; where R th is the theoretical value vector of the port resistance, U(:,m) represents the mth column element in the node voltage matrix U, I n (m,m) represents the injection current matrix I n The element at row m and column m in ; Measured value conversion unit: through the formula Generate a port resistance measured value vector; wherein R′ is the port resistance measured value vector; Change calculation unit: by formula ΔR=R′-R th Generates a vector of port resistance changes.

4. The substation grounding grid corrosion diagnosis system according to claim 3, characterized in that: In the objective function construction module, the quadratic objective function is minimized as follows: Among them, X is the current change ratio matrix, and the calculation formula is: I B_cor is the branch current after corrosion, I b_0 is the branch current before corrosion, represents the Hadamard product; Y is the port resistance change vector; ΔR k is the branch resistance change vector.

5. The substation grounding grid corrosion diagnosis system according to claim 4, characterized in that: The quadratic programming solver module performs the following steps: Step S1: Initialize ΔR k =0, λ=1, number of iterations n=0; where λ is the regularization parameter; Step S2: Construct H matrix as H=2X T X+λI, construct vector f=-2X T Y; where H is the matrix used for quadratic programming, I is the identity matrix, and f is the vector used for quadratic programming; Step S3: Solve the quadratic objective function to satisfy A ineq ΔR k ≥0 and A eq ΔR k =Y T ; Step S4: If Or n≥max_iter, then terminate the iteration; otherwise, update λ=λ×0.9, n=n+1 and return to step S2; wherein, Indicates ΔR k The infinity norm of the difference between the new value and the old value, ε is the tolerance, and max_ter is the maximum number of iterations.

6. The substation grounding grid corrosion diagnosis system according to claim 5, characterized in that: The updating rule of the regularization parameter λ is: when the objective function decrease rate is less than 5% in three consecutive iterations, λ = λ × 0.5; when ΔR k The L2 norm exceeds the threshold R max When λ=λ×1.2, where R max =10×mean(R0); Wherein, mean(R0) represents the mean value of the resistance nominal value vector R0.

7. The substation grounding grid corrosion diagnosis system according to claim 6, characterized in that: The corrosion diagnosis module includes: Change multiple calculation unit: through the formula Calculate the resistance change multiple of each branch; where k is the branch resistance change multiple, R 0_k is the nominal resistance value vector of the kth branch; Corrosion grade judgment unit: classified according to the following rules: if 1≤k<3, it is mild corrosion, 3≤k<10 is moderate corrosion, k≥10 is severe corrosion; Visualization unit: Maps branches to different colors according to corrosion level, generates a grounding grid topology overlay bar chart, and the bar height is proportional to the k value.

8. The substation grounding grid corrosion diagnosis system according to claim 7, characterized in that: The corrosion level judgment unit further performs regional corrosion detection: if the k values ​​of five consecutive branches are all greater than 2 and are spatially adjacent, they are marked as a regional corrosion group and a warning signal is triggered.

9. The substation grounding grid corrosion diagnosis system according to claim 8, characterized in that: The linear inequality constraint is A ineq ΔR k ≥b ineq ; The equality constraint is A eq ΔR k =b eq ; Among them, A ineq is the identity matrix, b ineq is the zero vector; A eq is the quadratic term matrix of the current change ratio.

10. The substation grounding grid corrosion diagnosis system according to claim 9, characterized in that: The linear inequality constraint A ineq It further includes a regional constraint sub-matrix, specifically: for a branch p within a specified area, set A ineq (p,p)=2 and b ineq (p) = R 0_p ×0.1, forcing the branch resistance change in this area to be no less than 10% of the nominal value; Among them, A ineq (p,p) represents the linear inequality constraint matrix A ineq The element in row p and column p in b ineq (p) represents the zero vector b ineq The pth element in R 0_p is the nominal resistance value vector of the p-th branch in the specified area.

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