Corrosion detection method and system for grounding grid

Abstract

The invention discloses a corrosion detection method and system for a grounding grid, and relates to the field of digital operation and maintenance of the grounding grid, and the method comprises the steps: firstly, dividing a plurality of measurement sub-domains according to the area of the grounding grid and a geographic region, obtaining corresponding soil resistivity and other physical and chemical parameters in a layering manner, and constructing a three-dimensional model of soil and the grounding grid; secondly, selecting a specific node by adopting a QR-pivot algorithm, injecting current, measuring a potential difference, and generating a part of elements of a node admittance matrix under the current working condition; thirdly, calculating a modal coefficient according to the part of elements so as to invert and reconstruct a complete node admittance matrix, and assigning the elements to each branch of the three-dimensional model of the soil and the grounding grid so as to obtain a numerical calculation model of the grounding grid; and finally, packaging the numerical calculation model of the grounding grid to obtain a digital twin model of the grounding grid, calculating the corrosion state of the grounding grid and the safety parameters of the grounding grid, and performing visual presentation to assist operation and maintenance personnel in accurately mastering the operation state of the grounding grid.

Description

Technical Field

[0001] This invention relates to the field of power equipment condition assessment technology, and in particular to a corrosion detection method and system for grounding grids. Background Technology

[0002] Grounding grids are crucial for protecting personnel and electrical equipment within substations. In my country, steel grounding grids are commonly used, but they are easily corroded by oxygen and microorganisms in the soil. Defects and even breakage caused by corrosion occur frequently, posing significant safety hazards to the safe operation of substations.

[0003] Existing methods often use grounding impedance measurement to estimate various safety parameters, but these methods suffer from significant errors. From a theoretical calculation perspective, the identification of corroded branches and the degree of corrosion based on the electrical network method and the magnetic field method is highly accurate. However, when performing current injection, potential measurement, and magnetic field measurement, the lack of theoretical basis for determining the injection and measurement points leads to poor inverse problem inversion accuracy. As a result, maintenance personnel still cannot adequately grasp the operating status of the grounding grid, leading to the existence of hidden dangers in the grounding grid. Digital twin technology has been explored and applied in the field of power equipment. Using digital twin models, dynamic and comprehensive perception of data that is difficult to directly measure from physical entities can be achieved, thereby realizing transparent operation of physical entities. Summary of the Invention

[0004] In view of the above-mentioned prior art, the present invention provides a corrosion detection method and system for grounding grids, which mainly solves the technical problems existing in the background art.

[0005] To achieve the above objectives, the technical solution of this invention is implemented as follows: On the one hand, the present invention provides a corrosion detection method for grounding grids, the method comprising the following steps: Step S1: Based on the area of ​​the grounding grid and its geographical location, multiple measurement sub-domains are delineated, and soil parameters are measured at different depths in each sub-domain. The measured soil parameters are iteratively used to derive the soil resistivity and other physicochemical parameters corresponding to each layer thickness, and a three-dimensional model of the soil and the grounding grid is constructed; Step S2: Use the QR-pivot algorithm to determine the location of a specific node in the grounding grid, inject excitation current into the specific node and measure the potential difference between the specific nodes to obtain some elements in the node admittance matrix under the current operating conditions; Step S3: Based on the known elements of the node admittance matrix under the current working conditions, calculate its modal coefficients and invert the modal coefficients to obtain the complete node admittance matrix under the condition of corrosion. Then, assign the elements of the complete node admittance matrix to each branch of the three-dimensional model of the soil and the grounding grid to obtain the numerical calculation model of the grounding grid. Step S4: Encapsulate the numerical calculation model of the grounding grid to obtain the digital twin model of the grounding grid. Calculate the corrosion state of the grounding grid based on the digital twin model of the grounding grid, and calculate the safety parameters of the grounding grid under the current corrosion state. Step S5: Compare the grounding grid safety parameters with the measured values. If they are consistent, keep the grounding grid digital twin model unchanged. If there are differences, update the grounding grid digital twin model.

[0006] As a preferred embodiment of the present invention, step S1, which iterates the measured soil parameters to obtain the soil resistivity and other physicochemical parameters corresponding to the thickness of each layer, specifically includes fitting the measured data to obtain the thickness, resistivity, porosity, water content, salinity, and pH value of each soil layer through an objective function.

[0007] in, J Let be the objective function. r i For the first i The resistivity of the soil layer h i For the first i The thickness of the soil layer, n For soil layers, r eq,j For the first j The apparent resistivity of the soil obtained from this measurement f j (·) is the function for calculating soil parameters. f (·) The calculated first j The apparent resistivity of the soil. l The regularization coefficient is used. The obtained physical and chemical parameters of each soil layer and the material parameters of the grounding grid are then used to assign values ​​to the three-dimensional model of the constructed grounding grid soil.

[0008] As a preferred embodiment of the present invention, the step S2 of determining the location of a specific node of the grounding grid using the QR-pivot algorithm specifically includes: assuming the grounding grid has... n For each node, the node admittance matrix under normal operating conditions is... :

[0009] in, This indicates a connection between node 1 and node 2. n Admittance of the branch; With respect to the nodal admittance matrix Perform singular value decomposition and based on the previous The cumulative sum of the singular values ​​of order 1 is listed first. n The sum of singular values ​​of order 1 is truncated if the proportion of singular values ​​in the cumulative sum is not less than 99.9%.

[0010] Among them, matrix and Each is a matrix The left and right singular matrices, The column vectors are matrices modality, Given a diagonal matrix, if the following conditions are met... If the cumulative sum of any element accounts for no less than 99.9% of the cumulative sum of all its elements, then the number of current injection points is directly taken as [value missing]. ; right The QR-Pivot transform yields the location of the current injection node:

[0011] in, For matrices The permutation matrix used in QR decomposition. and It is a matrix The decomposition results; It is a matrix composed of elements 0 and 1. The former The row number of the non-zero element in the column is... The location of each current injection point.

[0012] As a preferred embodiment of the present invention, step S3, which involves calculating the modal coefficients based on the nodal admittance matrix and performing inversion based on the modal coefficients to obtain the complete nodal admittance matrix under corrosion conditions, specifically includes: Sparse measurements of the nodal admittance matrix under the current operating conditions Y sp The modal coefficients were calculated. α， The formula is as follows: ; The complete nodal admittance matrix under corrosion conditions is obtained by inverting the nodal admittance matrix under the current operating condition using modal coefficients. Y inv The formula is as follows: .

[0013] As a preferred embodiment of the present invention, the calculation of the corrosion state of the grounding grid based on the digital twin model of the grounding grid in step S4 specifically includes: The node admittance matrix under the current operating conditions Y invBy comparing the node admittance matrix Y with that under normal, uncorroded conditions, corroded branches are identified through differences in element values. The degree of corrosion, i.e., the corrosion degree of branch ij, is calculated based on the magnitude of these differences. for:

[0014] in, To represent the admittance of the branch connecting node i and node j under the current operating condition, Let be the erosion branch admittance of the branch connecting node i and node j.

[0015] As a preferred embodiment of the present invention, the grounding grid safety parameters in step S4 include ground potential rise, contact voltage, and step voltage. The calculation of the grounding grid safety parameters under the current corrosion state specifically includes ground potential rise, contact voltage, and step voltage, and the calculation method is as follows:

[0016] in, s For conductivity, f For the grounding grid potential, J Current density; Let the reference potential at infinity be... f ref The surface of the equipment is f eq The potentials at step point 1 and step point 2 are respectively f 1 and f 2, then the ground potential rises to V. GPR = f - f ref The contact voltage is V touch = f - f eq The step voltage is V step = f 1- f 2.

[0017] On the other hand, the present invention provides a corrosion detection system for grounding grids, which is applied to the corrosion detection method for grounding grids. The system includes: a measurement module, a model calculation module, and a visualization module. The measurement module is used to measure the soil parameters of the grounding grid, the node current excitation and potential measurement, the grounding grid safety parameters measurement, and to send the data to the model calculation module. The model calculation module is used to establish a three-dimensional model of the grounding grid, calculate and assign values ​​to the structure and physicochemical parameters of each soil layer, invert the nodal admittance matrix, and further establish a numerical calculation model of the grounding grid. After the numerical calculation model is encapsulated and the interface file is configured, it becomes a digital twin model of the grounding grid. The corrosion state of the grounding grid and the safety parameters of the grounding grid under the current corrosion state are calculated based on the digital twin model of the grounding grid. The visualization module is used to construct a three-dimensional visualization model, visualize and render the grounding grid corrosion status data obtained by the calculation module, and visualize and present the grounding grid and soil measurement data obtained by the measurement module and the grounding grid safety parameters obtained by the calculation module.

[0018] The beneficial effects of this invention are as follows: 1. When injecting current into the grounding point and measuring the point position to invert the node admittance matrix, this invention utilizes the QR-Pivot algorithm, which theoretically provides the basis for the number of measurement points and the optimal location selection. Compared with existing methods, it significantly improves the inversion accuracy, that is, it improves the accuracy of grounding grid corrosion identification.

[0019] 2. The grounding grid digital twin model constructed in this invention is encapsulated in the form of DLL file + XML file and configured with interface file. It can be deployed to the software platform in the form of ZIP file and driven by monitoring data. Compared with the various grounding grid status calculation models at present, it can realize flexible deployment and driving on industrial Internet platform and software platform.

[0020] 3. This invention uses a software platform based on a B / S architecture to present a digital twin model of the grounding grid. It is driven by the measurement results of the hardware device through interface files. Maintenance personnel only need to view the software to grasp the operation and monitoring status of the grounding grid, avoiding a lot of testing and excavation work, reducing labor costs, improving maintenance efficiency, and realizing real-time perception of the corrosion status and safety parameters of the entire grounding grid, assisting maintenance personnel in ensuring the reliable operation of the grounding grid. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the steps involved in a corrosion detection method for a grounding grid. Figure 2 This is a schematic diagram of the structure of the digital twin model file for the grounding grid; Figure 3 This is a schematic diagram of a corrosion detection system for a grounding grid. Detailed Implementation

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. In the following description, the expression "some embodiments" refers to a subset of all possible embodiments; however, it should be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict.

[0023] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0024] It should be understood that the present invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Furthermore, the terminology used herein is intended only to describe particular embodiments and is not intended to limit the invention. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “compose” and / or “comprising,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0025] It should also be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "inner," "outer," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0026] To fully understand this invention, a detailed structure will be presented in the following description to illustrate the technical solution proposed by this invention. Optional embodiments of the invention are described in detail below; however, in addition to these detailed descriptions, the invention may have other embodiments.

[0027] Please refer to the attached document. Figure 1 On the one hand, the present invention provides a corrosion detection method for grounding grids, the method comprising the following steps: Step S1: Based on the area of ​​the grounding grid and its geographical location, multiple measurement sub-domains are delineated, and soil parameters are measured at different depths in each sub-domain. The measured soil parameters are iteratively used to derive the soil resistivity and other physicochemical parameters corresponding to each layer thickness, and a three-dimensional model of the soil and the grounding grid is constructed; In this embodiment, multiple measurement sub-domains are defined according to the grounding grid area and the geographical region, and the apparent resistivity of the soil at different depths is measured in each sub-domain, rather than being limited to measurements at different depths in a single area. The measured parameters include, but are not limited to, apparent resistivity, porosity, water content, salinity, and pH value.

[0028] Step S2: Use the QR-pivot algorithm to determine the location of a specific node in the grounding grid, inject excitation current into the specific node and measure the potential difference between the specific nodes to obtain some elements of the node admittance matrix under the current operating conditions; In this embodiment, when measuring the grounding grid state parameters, the excitation term is the current injected into a specific node, and the measurement term is the potential difference of the specific node.

[0029] Step S3: Based on the known elements of the node admittance matrix under the current working conditions, calculate its modal coefficients and invert the modal coefficients to obtain the complete node admittance matrix under the condition of corrosion. Then, assign values ​​to each branch of the three-dimensional model of the soil and grounding grid to the elements of the complete node admittance matrix to obtain the numerical calculation model of the grounding grid. Step S4: Encapsulate the numerical calculation model of the grounding grid to obtain the digital twin model of the grounding grid. Calculate the corrosion state of the grounding grid based on the digital twin model of the grounding grid, and calculate the safety parameters of the grounding grid under the current corrosion state. In this embodiment, please refer to the appendix. Figure 2 The numerical calculation model is encapsulated as a .DLL file and configured with an XML specification file. An interface file is also written, which provides input to the model and outputs the model calculation results to the software front end for visualization. The digital twin model is encapsulated as a .ZIP file. This .ZIP file is used as the digital twin model of the grounding grid.

[0030] The computational functions of the digital twin model are provided by the .DLL file; the parsing and description functions of the digital twin model are provided by the .XML file; and the interface for driving and calling the digital twin model is written by the .py file.

[0031] The interaction between the physical entity of the grounding grid and the twin model is based on the interface file. When there is a difference between the calculation results of the twin model and the measured data, the twin model parameters are updated.

[0032] Step S5: Compare the grounding grid safety parameters with the measured values. If they are consistent, keep the grounding grid digital twin model unchanged. If there are differences, update the grounding grid digital twin model.

[0033] In this embodiment, the measured values ​​are used to generate grounding grid observation lines according to the grounding grid drawings. Then, based on the drawn observation lines, parameters such as contact voltage, step voltage, and ground potential rise of the grounding grid are measured periodically.

[0034] As a preferred embodiment of the present invention, step S1, which iterates the measured soil parameters to obtain the soil resistivity and other physicochemical parameters corresponding to the thickness of each layer, specifically includes fitting the measured data to obtain the thickness, resistivity, porosity, water content, salinity, and pH value of each soil layer through an objective function.

[0035] in, J Let be the objective function. r i For the first i The resistivity of the soil layer h i For the first i The thickness of the soil layer, n For soil layers, r eq,j For the first j The apparent resistivity of the soil obtained from this measurement f j (·) is the function for calculating soil parameters. f (·) The calculated first j The apparent resistivity of the soil. l This is the regularization coefficient; its purpose is to avoid overfitting the parameters. From this, the thickness and resistivity of each soil layer can be obtained, and similarly, other soil parameters can be obtained, thus enabling the establishment of a grounding grid soil model.

[0036] The obtained physical and chemical parameters of each soil layer and the material parameters of the grounding grid are then used to assign values ​​to the three-dimensional model of the constructed grounding grid soil.

[0037] As a preferred embodiment of the present invention, the step S2 of determining the location of a specific node of the grounding grid using the QR-pivot algorithm specifically includes: assuming the grounding grid has... n For each node, the node admittance matrix under normal operating conditions is... :

[0038] in, This indicates a connection between node 1 and node 2. n Admittance of the branch; With respect to the nodal admittance matrix Perform singular value decomposition and based on the previous The cumulative sum of the singular values ​​of order 1 is listed first. n The sum of singular values ​​of order 1 is truncated if the proportion of singular values ​​in the cumulative sum is not less than 99.9%.

[0039] Among them, matrix and Each is a matrix The left and right singular matrices, The column vectors are matrices modality, Given a diagonal matrix, if the following conditions are met... If the cumulative sum of any element accounts for no less than 99.9% of the cumulative sum of all its elements, then the number of current injection points is directly taken as [value missing]. ; right The QR-Pivot transform yields the location of the current injection node:

[0040] in, For matrices The permutation matrix used in QR decomposition. and It is a matrix The decomposition results; It is a matrix composed of elements 0 and 1. The former The row number of the non-zero element in the column is... The location of each current injection point.

[0041] As a preferred embodiment of the present invention, step S3, which involves calculating the modal coefficients based on the nodal admittance matrix and performing inversion based on the modal coefficients to obtain the complete nodal admittance matrix under corrosion conditions, specifically includes: Sparse measurements of the nodal admittance matrix under the current operating conditions Y sp The modal coefficients were calculated. α， The formula is as follows: ; The complete nodal admittance matrix under corrosion conditions is obtained by inverting the nodal admittance matrix under the current operating condition using modal coefficients. Y inv The formula is as follows: .

[0042] As a preferred embodiment of the present invention, the calculation of the corrosion state of the grounding grid based on the digital twin model of the grounding grid in step S4 specifically includes: The node admittance matrix under the current operating conditions Y inv By comparing the node admittance matrix Y with that under normal, uncorroded conditions, corroded branches are identified through differences in element values. The degree of corrosion, i.e., the corrosion degree of branch ij, is calculated based on the magnitude of these differences. for:

[0043] in, To represent the admittance of the branch connecting node i and node j under the current operating condition, Let be the erosion branch admittance of the branch connecting node i and node j.

[0044] As a preferred embodiment of the present invention, the grounding grid safety parameters in step S4 include ground potential rise, contact voltage, and step voltage. Calculating the grounding grid safety parameters under the current corrosion state specifically includes:

[0045] in, s For conductivity, f For the grounding grid potential, J Current density; Let the reference potential at infinity be... f ref The surface of the equipment is f eq The potentials at step point 1 and step point 2 are respectively f 1 and f 2, then the ground potential rises to V. GPR = f - f ref The contact voltage is V touch = f - f eq The step voltage is V step = f 1- f 2.

[0046] In this embodiment, when step S7 determines that the node admittance matrix has changed, i.e. the corrosion state of the twin model has been updated, the corresponding numerical calculation model is updated, the grounding grid digital twin model is updated based on the corresponding numerical calculation model, and the grounding grid corrosion state and grounding grid safety parameters are calculated based on the updated grounding grid digital twin model.

[0047] Please refer to the attached document. Figure 3On the other hand, the present invention provides a corrosion detection system for grounding grids, which is applied to the corrosion detection method for grounding grids. The system includes: a measurement module, a model calculation module, and a visualization module. The measurement module is used to measure the soil parameters of the grounding grid, the node current excitation and potential measurement, the grounding grid safety parameters measurement, and to send the data to the model calculation module. In this embodiment, the communication unit in the measurement module can convert different communication protocols and finally send the measurement results of each measurement module to a specific MQTT server using the MQTT communication protocol and JSON data format.

[0048] The model calculation module is used to establish a three-dimensional model of the grounding grid, calculate and assign values ​​to the structure and physicochemical parameters of each soil layer, invert the nodal admittance matrix, and further establish a numerical calculation model of the grounding grid. After the numerical calculation model is encapsulated and the interface file is configured, it becomes a digital twin model of the grounding grid. The corrosion state of the grounding grid and the safety parameters of the grounding grid under the current corrosion state are calculated based on the digital twin model of the grounding grid. The visualization module is used to construct a three-dimensional visualization model, visualize and render the grounding grid corrosion status data obtained by the calculation module, and visualize and present the grounding grid and soil measurement data obtained by the measurement module and the grounding grid safety parameters obtained by the calculation module.

[0049] In this embodiment, the visualization module uses a B / S architecture to present the digital twin model of the grounding grid. Specifically, based on WebGL, it performs 3D visualization of the grounding grid and soil in .obj data format on the browser side, allowing for rotation, scaling, translation, and disassembly / separation. On the 3D visualization model, it presents the grounding grid and soil measurement data obtained by the measurement module and the grounding grid corrosion status data obtained by the model calculation module, and renders the data according to the corrosion situation. By clicking, users can dynamically view and test the ground potential rise, contact voltage, and step voltage at any location in the entire grounding grid under various working conditions.

[0050] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for detecting corrosion of a grounding grid, characterized in that, The method includes the following steps: Step S1: Based on the area of ​​the grounding grid and its geographical location, multiple measurement sub-domains are defined, and soil parameters are measured at different depths in each sub-domain. The measured soil parameters are iteratively used to derive the soil resistivity and other physicochemical parameters corresponding to each layer thickness, and a three-dimensional model of the soil and the grounding grid is constructed. Step S2: Use the QR-pivot algorithm to determine the location of a specific node in the grounding grid, inject excitation current into the specific node and measure the potential difference between the specific nodes to obtain some elements of the node admittance matrix under the current operating conditions; Step S3: Based on the known elements of the node admittance matrix under the current working conditions, calculate its modal coefficients and invert the modal coefficients to obtain the complete node admittance matrix under the condition of corrosion. Then, assign the elements of the complete node admittance matrix to each branch of the three-dimensional model of the soil and the grounding grid to obtain the numerical calculation model of the grounding grid. Step S4: Encapsulate the numerical calculation model of the grounding grid to obtain the digital twin model of the grounding grid. Calculate the corrosion state of the grounding grid based on the digital twin model of the grounding grid, and calculate the safety parameters of the grounding grid under the current corrosion state. Step S5: Compare the grounding grid safety parameters with the measured values. If they are consistent, keep the grounding grid digital twin model unchanged. If there are differences, update the grounding grid digital twin model.

2. The corrosion detection method for a grounding grid according to claim 1, characterized in that, In step S1, the measured soil parameters are iterated to obtain the soil resistivity and other physicochemical parameters corresponding to the thickness of each layer. Specifically, this includes fitting the measured data to a target function to obtain the thickness, resistivity, porosity, water content, salinity, and pH value of each soil layer. in, J Let be the objective function. ρ i For the first i The resistivity of the soil layer h i For the first i The thickness of the soil layer, n For soil layers, ρ eq,j For the first j The apparent resistivity of the soil obtained from this measurement f j (·) is the function for calculating soil parameters. f (·) The calculated first j The apparent resistivity of the soil. λ The regularization coefficient is used. The obtained soil physicochemical parameters and grounding grid material parameters were then used to assign values ​​to the constructed three-dimensional model of the soil and grounding grid.

3. The corrosion detection method for a grounding grid according to claim 2, characterized in that, The step S2, which uses the QR-pivot algorithm to determine the location of a specific node in the grounding grid, specifically includes: assuming the grounding grid has... n For each node, the node admittance matrix under normal operating conditions is... : in, This indicates a connection between node 1 and node 2. n Admittance of the branch; With respect to the nodal admittance matrix Perform singular value decomposition and based on the previous The cumulative sum of the singular values ​​of order 1 is listed first. n The sum of singular values ​​of order 1 is truncated if the proportion of singular values ​​in the cumulative sum is not less than 99.9%. Among them, matrix and Each is a matrix The left and right singular matrices, The column vectors are matrices modality, Given a diagonal matrix, if the following conditions are met... If the cumulative sum of any element accounts for no less than 99.9% of the cumulative sum of all its elements, then the number of current injection points is directly taken as [value missing]. ; right The QR-Pivot transform yields the location of the current injection node: in, For matrices The permutation matrix used in QR decomposition. and It is a matrix The decomposition results; It is a matrix composed of elements 0 and 1. The former The row number of the non-zero element in the column is... The location of the current injection point.

4. The corrosion detection method for a grounding grid according to claim 3, characterized in that, Step S3, which involves calculating the modal coefficients based on the nodal admittance matrix and then inverting the modal coefficients to obtain the complete nodal admittance matrix under corrosion conditions, specifically includes: Sparse measurements of the nodal admittance matrix under the current operating conditions Y sp The modal coefficients were calculated. α， The formula is as follows: ; The nodal admittance matrix under the current operating condition is inverted using modal coefficients to obtain the complete nodal admittance matrix under corrosion conditions. Y inv The formula is as follows: .

5. The corrosion detection method for a grounding grid according to claim 4, characterized in that, The calculation of the corrosion state of the grounding grid based on the digital twin model of the grounding grid in step S4 specifically includes: The node admittance matrix under the current operating conditions Y inv By comparing the node admittance matrix Y with that under normal, uncorroded conditions, corroded branches are identified through differences in element values. The degree of corrosion, i.e., the corrosion degree of branch ij, is calculated based on the magnitude of these differences. for: in, To represent the admittance of the branch connecting node i and node j under the current operating condition, Let be the erosion branch admittance of the branch connecting node i and node j.

6. The corrosion detection method and system for a grounding grid according to claim 5, characterized in that, In step S4, the grounding grid safety parameters include ground potential rise, contact voltage, and step voltage. The calculation of these parameters under the current corrosion state specifically includes: ground potential rise, contact voltage, and step voltage, calculated as follows: in, σ For conductivity, φ For the grounding grid potential, J Current density; Let the reference potential at infinity be... φ ref The surface of the equipment is φ eq The potentials at step point 1 and step point 2 are respectively φ 1 and φ 2, then the ground potential rises to V. GPR = φ - φ ref The contact voltage is V touch = φ - φ eq The step voltage is V step = φ 1- φ 2.

7. A corrosion detection system for a grounding grid, wherein the system is applied to the corrosion detection method for the grounding grid according to any one of claims 1 to 6, characterized in that, The system includes: a measurement module, a model calculation module, and a visualization module; The measurement module is used to measure the soil parameters of the grounding grid, measure the node current excitation and potential, measure the safety parameters of the grounding grid, and send the data to the model calculation module. The model calculation module is used to establish a three-dimensional model of the soil and grounding grid, calculate and assign values ​​to the structure and physicochemical parameters of each soil layer, invert the nodal admittance matrix, and further establish a numerical calculation model of the grounding grid. After the numerical calculation model is encapsulated and the interface file is configured, it becomes a digital twin model of the grounding grid. The corrosion state of the grounding grid and the safety parameters of the grounding grid under the current corrosion state are calculated based on the digital twin model of the grounding grid. The visualization module is used to construct a three-dimensional visualization model, visualize and render the grounding grid corrosion status data obtained by the calculation module, and visualize and present the grounding grid and soil measurement data obtained by the measurement module and the grounding grid safety parameters obtained by the calculation module.

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