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This paper presents an online method to monitor the conditions of substation grounding grid. The proposed method utilizes phase-to-ground faults occurring in downstream feeders as test current sources and the neutral of a specially selected feeder as the electrode for GPR (ground potential rise) measurement. The measured fault currents and GPRs are then used to estimate substation grounding grid impedance. The method, once established, can monitor the grounding grid impedance continuously and automatically, and the trend of the impedance change can be observed. As a result, the proposed method can yield much more reliable information on the substation grounding conditions. The method also overcomes many disadvantages of the offline methods. The proposed idea, algorithm, and hardware setup are described in the paper. Factors contributing to measurement errors are investigated in detail.

Due to the impedance characteristic of conductor, the ground potential rise is different within grounding grid when impulse current is injected. When staff touches objects with different GPR at the same time, the GPD will be applied to human body, leading to potential personal safety problem. The impact of GPD on human body needs to be evaluated. The method of moment was used to calculate the ground potential rise of grounding grid under impulse current. By regarding the human body as a resistance, the current flowing through it because of ground potential difference was obtained. Methods based on current amplitude and electrical charge was used to evaluate personal safety. The effects of injecting current waveform, injecting position, soil resistivity, grounding conductor and grounding grid structure on ground potential difference and safe current threshold were studied. Results show the ground potential difference near injecting point may pose a threat to personal safety. The evaluation method based on electrical charge was recommended. In field test, the injecting point of grounding grid should be far away from corners, and staff should be kept away from the injecting point, so as to mitigate the risk of ground potential difference on personal safety.

In this paper, a wind turbine service sustainability is achieved by assessing grounding grids under steady-state and lightning-based transient conditions. An effective grounding grid is designed concerning IEC61400-24 standard, where Taif city, Saudi Arabia is considered a farming place. However, high soil resistivity is a challenge during the design. To accomplish the study, apparent resistivities are measured using Wenner method, in the field. A framework of multi-layer soil modeling is performed using the Sunde model, and it is optimally solved using the genetic algorithm. Using the optimal stratified soil, the wind turbine grounding system is assessed considering grounding resistances, electric potentials, and step voltages. The break-point effect is evaluated considering the designed grounding system. Then, the lightning-based transient study is investigated for both the healthy grid and break-point considerations. COMSOL Multiphysics and ATP/EMTP were used to accomplish simulations and modeling. The results ensure the effectiveness design of the assessed grounding system.

Grounding grid configuration which, is key to its fault diagnosis, changes continuously with the extension in a substation. Furthermore, older substations grounding grid configurations are unknown. Existing literature regarding configuration detection mainly accounts for the magnetic field that required a gradient to locate the grounding conductor. The gradient of raw measurement in the substation vicinity enhances electromagnetic noise and distorts the results. Therefore, in this paper, we have developed a new algorithm, Configuration Detection of Grounding Grid (CDGG) based on the static electric field and the concept of ordered pairs to draw the configuration of the unknown grounding grid. Unlike, the practiced magnetic field, the electric field does not require a gradient. The maximum electric field value indicates the location of a grounding conductor. The connection between nodes is verified by measuring the electric field on the circle. Furthermore, the proposed algorithm also locates any diagonal conductor in the configuration. Mathematical reasoning and simulation results illustrate that our proposed algorithm is feasible to draw the configuration of the unknown grounding grid.

It is important to ensure that a grounding system is designed with a low magnitude of earth resistance, so the protection system can divert the large fault current to earth effectively. The performances and protection level of a grounding system need to be acknowledged as the condition of soil structure changes with different soil characteristics. At present, there is a lack of systematic guide or standards for grounding grid designs that consider non-uniform soil and its impact on the grounding systems. By computing the grid safety threshold parameters consisting of the grid impedance, step, and touch voltages, a comparison has been made between uniform soil and two-layer soil models. Where the competence and level of safety of the grounding systems depend on the soil attributes, the significant impact of various soil conditions is seen. The evaluations on performance and safety assessment in two-layer soil conditions hold the novelty and originality as there is no such comparison and discussion have been made to date. These comparisons would help in forecasting the behavior and safety of the grounding system in various soil environments, which would provide engineers with additional expertise to design an effective and secure grounding system. This research would contribute to the existing body of knowledge by differentiating and predicting the performance of a grounding system when the characteristics of the soil differ significantly from uniform soil as most of the standards and guidelines only consider uniform soil while designing a grounding system, owing to its complexity at the site.

To balance the potential distribution on the surface of a substation, an equal spacing arrangement of the grounding grid conductors is not an economical solution. The implementable solution is an unequal placement of its constituent elements. The design methodologies of such a configuration are complex and require computer-assisted numerical analysis. This paper proposes and validates a very simple method, based on an arithmetic progression, of arranging the conductors of the grounding grid that guarantees the reduction of touch and step voltages, ensures the efficiency of the material used and has no limitations on its applicability for atypical substation surfaces (too large or too small), respectively for few or many parallel conductors. To certify the method, the proposed algorithm is analyzed, through the CYMGRD Substation Grounding Program, and compared to the technologies currently applied, for the substation grounding grid presented as an example in the IEEE Guide for Safety in AC Substation Grounding 80™- 2013 standard.

The analysis of adjacent grounding systems under lightning currents which is responsible for many safety problems to human beings and damages to devices is very important. In this study, the behaviours of such grounding grids under lightning conditions which are not well documented in the literature are analysed using the multi-conductor transmission line method in a two-layer soil model. To achieve this goal, the expressions related to the study of a single grounding grid extracted from the recent study of the authors are developed to be appropriate to the analysis of adjacent grounding systems under lightning currents. Also, through the representation of the connectivity matrix, the analysis of the adjacent grounding grids with any size and degree of complexity is facilitated. Furthermore, the behaviours of the adjacent grounding grids under different lightning and soil characteristics are examined and some conclusions are derived.

The grounding grid is the cornerstone for maintaining the safe operation of the power system. The grounding network acts as a concealed project, and its invisible characteristics make the defects difficult to be detected, which causes major safety hazards in the system. Thus accurate diagnosis of grounding grid corrosion is vital in electrical engineering. A diagnosis method for grounding grid corrosion based on branch voltage disturbance is proposed in this paper, which can judge the location and degree of corrosion through branch voltage disturbance before and after corrosion. Firstly, the sensitivity of branch voltage to branch resistance of the grounding grid is analyzed. Secondly, a diagnostic model based on branch voltage disturbance is established, and the corresponding regularity between peak voltage disturbance and the corrosion state of the grounding grid branch is developed. Finally, it is verified by experiments that this method can effectively diagnose the corrosion of the grounding grid.

Transient electromagnetic (TEM) method is a reliable means of non-destructive testing for fault diagnosis of grounding grid in substation. In view of the small transmitter loop of the TEM system and many measuring points and survey lines of grounding grid detection in substation. This study presents a fast solution to TEM apparent resistivity imaging for grounding grid detection using artificial neural networks. The input -output mapping relation of neural network is established based on TEM response characteristics of the grounding grid. The built network could map the recorded TEM data of grounding grid detection and quickly obtain the resistivity image. The proposed method offers accuracy and fast computation for the resistivity imaging of grounding grid. Feasibility and technical attractiveness of the proposed method in fast imaging of apparent resistivity is investigated with the measurement of grounding grids in the actual substations. It can be used in real time so that the recorded TEM data in substation can be calculated without re-training, which avoids time-consuming inversion computation. The rapid processing of massive data and submitting the detection results of the grounding grid to customers rapidly and in real time, which is expectation for a modern power industry.

Nondestructive testing of substation grounding grids is an issue that has increasing importance. The traditional EMI method transforms the condition of the undergrounding conductors to the surficial induced electric signal in the sensing coil. However, The EMI signals excited by multiple coexisted faults combining with other unknown noises surrounding the substation often cause the failure of detection. Therefore, the observed EMI signals rather complex and cannot be used directly. To address this problem, the separation of individual signatures from the mixture is posed as an SCBSS problem. To extract the induced signal, an EEMD-based EMI method is proposed. The desired signal is then reconstructed to visualize the structure of the grounding grids by a virtual instrument that consists of DAQ and digital signal processing modules. The numerical simulation and practical experiments are employed. The results show the proposed method can be used to effectively detect the topological structure of grounding grid in real substations' electromagnetic environment.

The grounding grid is an important part of ensuring the safety of power plants and substations, and its performance is directly related to the safety of people, equipment and power grids. After the grounding grid is running, due to the concealment of the project, it lacks sufficient technical means to evaluate it after it is put into operation, which has caused many difficulties for equipment operation, personnel safety and grounding grid maintenance. In order to solve the above problems, this paper uses CDEGS software to simplify the modeling of the grounding grid of a substation, and evaluates the performance of the grounding grid by analyzing the soil resistance layered model, touch voltage, step voltage and other parameters of the grounding grid, and give an optimization plan.

Based on the actual measured soil resistivity in a substation, this paper uses CDEGS to calculate and analyze the effects of deep well grounding, oblique well grounding, and small well grounding on improving the grounding performance of the grounding grid. Through the comparison of main parameters such as grounding resistance, ground potential rise, touch voltage and step voltage, it can be known: The oblique well grounding can play the role of a deep well grounding, and it can also effectively expand the area of the grounding grid without the need for land acquisition, and the mutual shielding effect of the oblique grounding electrode is much smaller than that of the deep grounding electrode; The small well grounding is more effective in terms of the effect of the touch voltage at the edge of the substation.

This paper gives the different grounding mat design modifications and the impact on the design parameters of these modifications. Different modifications in different cases like case 1: grounding mat design without earth electrodes, case 2: grounding mat design with the electrodes at the corner of mat, case 3: grounding mat design with compression ratio without earth electrode, and case 4: grounding mat design with compression ratio and earth electrodes have been applied with the application of ETAP 16.0.0 version software. The primary framework of the grounding mat solidly depends upon, \( R_{g} \), \( V_{\text{touch}} \), \( V_{\text{step}} \), and ground potential rise (GPR). These quantities are of great concern for safety of any grounding system. Here, our main concern is to minimize the design quantities by inserting electrodes and by changing the compression ratio to meet the standard safety regulations annunciated in various guidelines and standards. Here, in this paper, homogeneous soil model is considered for designing the grounding mat.

In order to ensure the safe and stable operation of the substation, it is necessary to test and evaluate the substation grounding grid. In the actual measurement process, since the overhead ground wire is difficult to disconnect from the ground network, in order to obtain accurate measurement results, it is necessary to consider the influence of the shunt phenomenon on the grounding resistance measurement of the grounding network. In recent years, the resistance measurement method with short lead wire has gained wide attention due to the advantages brought by its shorter measurement leads. Based on the backward measurement method with short lead wire, this paper considers the influence of the shunt coefficient on its measurement results, proposes a correction formula through theoretical derivation, and proposes an improved method of it, which is verified by simulation. The improved method proposed in this paper improves its accuracy while preserving advantages of the original method, and it has certain significance for the measurement of large-scale grounding grids.

As referred to the safety of people, the metallic fence of a substation is an object of special care. The substation fence is subject to a potential rise as well as to direct contact with people and animals, which is a hazardous situation. The connection of the fence to the substations grounding grid, the sectioning of the fence through isolated parts and the design of a specific fence grounding system are then necessary items for a well-designed project. This paper presents the procedure for calculating the potential rise in a metallic fence, also a report of good fence designing practices, verifying such procedure with an example from the literature.

As one of the important equipment to ensure the normal operation of substation, the performance of grounding grid has been highly concerned. In recent years, researchers propose that the theory of electromagnetic induction can be used to diagnose and identify the corrosion fault of substation grounding grid. In this paper, a fault classification model based on LS-SVM optimized by PSO is proposed to identify the corrosion fault of grounding grid. Firstly, the wavelet packet transform principle is used to filter the original data, and the wavelet packet energy is used to construct the fault eigenvalue as the input of the fault classification model. Based on LS-SVM, a corrosion fault classification model is constructed, and particle swarm optimization method is used to optimize the parameters of the model, which solves the problem of traditional SVM parameter optimization. Through the practical application in substation, the model proposed in this paper can identify the corrosion of grounding grid conductor without excavation and power failure, which provides an effective scheme for engineering application.

Substation design that refers to IEEE Standard 80–2000 can be carried out through manual calculation. Considering that there are lot of data involved used and also repeated calculations, it will be very difficult and requires high accuracy. Therefore, a computer-based computing system is needed to solve this problem. This paper discusses an application modelling of LabViewgraphical user interface to provide convenience in designing the substation grounding grid. Some options have been developed such as grounding grid resistance calculation method, conductor diameters determination, grounding grid selection with ground rod and without ground rod and weight body. The effect of any changes in design can be known directly and compared with limit of the touch voltage and the step voltage allowed. For validation, the model used data from Std. 80–2000 and compared with some design model already existed. As a result of this application, grounding grid design process will be easy, more accurate, and faster.

The ground potential will rise abnormally when impulse current injects into grounding grid if a converter substation is struck by lightning or there exist short-circuit faults. Transient ground potential rise (TGPR) could couple to the cable core wire through conductive and near-field coupling ways and it will invade the secondary system eventually. Taking those two coupling ways into consideration, this paper builds a simulation model describing the technisim on how TGPR couples to the secondary cables in an UHVDC converter substation and searches for the best grounding way for suppressing disturbance voltage in secondary cables’ cores caused by TGPR. Through simulation and test, for a single cable harness with armor double-ended grounded, we propose that cable’s shielding sheath should be grounded only in protecting cabin. For a four-segment cable, we find the best grounding way is that for the harness segment between protecting cabin and terminal box, we should guarantee armor double-ended in both sides while shielding sheath be grounded only in protecting cabin, for the segment between terminal box and operating cabinet, we should guarantee armor double-ended in both ends while shielding sheath be grounded only in terminal box, what’s more, the armor and sheath among operating cabinets should be grounded only in phase B’s cabinet.

This study presents the comparative analysis of three grounding grid configurations to find the optimum grid design in terms of safety parameters. Square grid, rectangular grid and L-shape grid, buried in two-layer soil model are taken in this study. Same grounding area is considered to design three different configurations of grounding grid. Effect of different grid designs, shapes and dimensions on grounding system performance is noticed. Equal and unequal spaced grounding grids for each shape are designed and it is found that unequally spaced rectangular grid gives better results than other considered designs. Study shows that rectangular grid has minimum value of grounding system resistance, grounding potential rise and mesh voltage in comparison of square and L-shape grid. ANSI/IEEE standard 80–2000 are used to designing the grids and all safety constraints are followed as mentioned in the slandered. Good agreements are found with unequal spaced rectangular grounding grid in comparison of square and L-shape grid. Two-layer soil structure is considered in the analysis. Vertical rods are placed at the periphery of the grid.

In order to solve the impact of test point offset on the grounding network corrosion fault diagnosis results, Simulate offset conditions using PSCAD, Comparative analysis of fault diagnosis results of fully measurable branches. Find the law that implies it and propose a method of calculating the test points at different offset levels. According to the method, the original large-change sensitivity nonlinear fault diagnosis mathematical model and the hybrid particle swarm optimization algorithm are improved. Simulation experiments show that the improved fault diagnosis algorithm is accurate and effective for solving the grounding grid corrosion diagnosis problem of test point offset.

The grounding device plays performs the role of releasing a lightning current and a fault current in the power system, and the corrosion of the conductor will cause damage to the grounding body, which threatens the safe operation of the power system. The grounding grid corrosion detection technology and equipment guarantee the safe operation of the power system. This paper discusses the research status of grounding corrosion and topological detection in detail and introduces the basic principles, research difficulties and existing problems of the methods such as the electric network method, electromagnetic field method, electrochemical method, ultrasonic detection method and electromagnetic imaging method. The methods of electromagnetic imaging and time difference positioning proposed in recent years have been also discussed in detail. The paper points out that the application of grounding grid corrosion detection distance engineering still faces great challenges and that multi-disciplinary, multi-information fusion, new sensing technology, big data platforms and intelligent computing will be the trends to follow in research on grounding grid fault, corrosion detection and life prediction.

With the continuous development of high-speed railways, more and more electronic equipment is introduced into high-speed railway traction substations, and the grounding grid is an important facility to ensure the normal operation of electrified railways and the safety of people and equipment in the station. The safety performance evaluation of the grounding grid of high-speed railway traction substation is essential for the design of the grounding engineering. In this study, The safety performance of the grounding grid wasevaluated by a method of moment under a power frequency grounding fault and the lightning strike of the substation. The results show that while the grounding impedance of the traditional evaluation standard grounding grid meets the requirements, the contact voltage under the grounding grid power frequency grounding fault and the mesh potential difference under the lightning strike do not meet the safety standard.

The lightning impulse behavior of substation grounding grids plays a very important role in lightning protection of substations and the grounding design of the grounding grid around the down leads has great influence on it. This paper analyzed the lightning impulse behavior of substation grounding grids with different grounding designs around the down lead, including the connection points, local refinement and layout of vertical grounding poles around down leads. Results showed that special designs around down leads including multi-point connection, local refinement and vertical grounding poles could improve the transient behavior of substation grounding grid. Meanwhile only increasing the number of vertical grounding poles cannot improve the transient behavior significantly.

Considering urban substations ground grid diagnosis, some real-physical constraints result in measurement process challenges: 1) limited length between electrodes used to measure the equivalent impedance of the grounding system; 2) to determine the current that flows from ground grid conductors to the earth; and 3) to determine the grid resistance. In this scenario, an adequate diagnosis of the safety offered by the ground grid under test when a ground fault occurs is not a trivial task. This article describes a methodology that allows a reliable diagnosis regarding the safety provided by a substation ground grid. The methodology is applied to the parameters obtained in performed field tests. The method has two steps. First, the fall-of-potential method with reduced distances between electrodes is used to determine the equivalent impedance of the grounding system. Then, the ground current is obtained. In both stages, optimization techniques are applied to the specific equations that govern the phenomenon under investigation. Comparative case studies considering real-life data illustrate the effectiveness of the method.

Today with increase in use of microgrid, appropriate grounding design is needed for it. In this paper it is done by considering different grounding shapes for the MG. For this purpose, paper evaluates the performances of triangular, rectangular, square, L shape and T shape grounding design considering uniform and two layer soil structure. Influence of diverse designs on safety parameters such as touch voltage and step voltage are examined. Investigation is done with the help of ETAP based finite element method and for its authentification, results obtained by it are substantiated with analytical results obtained through IEEE standard 80-2013. As per the results obtained, triangular shape performs better. Also, this paper reveals the touch and step potential profiles for different shapes.

The grounding grid of a substation is important for the safety of substation equipment. Especially to address the difficulty of parameter design in the auxiliary anode system of a grounding grid, an algorithm is proposed that is an optimization algorithm for the auxiliary anode system of a grounding grid based on improved simulated annealing. The mathematical model of the auxiliary anode system is inferred from the mathematical model of cathodic protection. On that basis, the parameters of the finite element model are optimized with the improved simulated annealing algorithm, thereby the auxiliary anode system of a grounding grid with optimized parameters is structured. Then the algorithm is proven as valid through experiments. The precision of the optimized parameters is improved by about 1.55% with respect to the Variable Metric Method and the Genetic Algorithm, so it can provide a basis for parameter design in the auxiliary anode system of a grounding grid.

Studying the frequency and impulse characteristics of grounding grids is of great reference value for the optimal design of the substation. As the frequency increasing, the variation trend of the grounding resistance under different conditions is not same, which is affected by many factors. Therefore, this study focuses on the influence of grounding grid sizes, sparsity, soil resistivity, and grounding material on frequency and impulse characteristics. Based on these factors, the corresponding value of the grounding resistances at different frequencies and the impulse resistances are obtained by simulation. The trends of grounding resistances under different factors are analysed by using the dispersion mechanism. The simulation results show that the impulse grounding resistance will decrease with the increase of the grounding grid sizes and the conductor radius, or will decrease with the decrease of the spacing and the soil resistivity. With the increasing in frequency, the inductance effect of grounding resistance is strengthened, and the effect of soil resistivity and grounding grid parameters on grounding resistance become remarkable.

The mathematical models proposed in the literature are used to determine the grounding resistance value for electrical installations. These models are mathematical expressions that change according to grounding type and the mechanical properties of the grounding system elements. Besides, the inclusion of nonlinear terms is another important issue in the modeling studies. For the modeling of nonlinear systems and the analysis of the faults that may occur, the finite element analysis (FEA) approach provides realistic results. In the present study, the simulation of a grid fault that may occur in the grounding system of a sample wind turbine (WT) is modeled by 2D electrostatic solver in FEA software. The simulation results prove that the findings are similar to the realistic faults in the grounding system. © 2019 Published by peer-reviewed open access scientific journal.

By analyzing the lightning protection and grounding requirements of the respective systems of the communication base station and the power tower, the impact of the towers on their respective systems is analyzed. By establishing a simulation calculation model of the shared tower’s grounding grid, a mature algorithm is used to analyze the current distribution of the typical shared tower. And ground potential distribution, so as to obtain the degree of influence of the equipment when the respective system is struck by lightning. According to the impact, the lightning protection grounding technical requirements and common scheme of the shared iron tower are proposed.

Substation grounding has proved to be a vital action in high voltage substations for safety of persons and equipment. This paper first describes the potential impacts of increasing the earth fault current of high voltage transformers substations more than the designed value on the performance of the grounding system of these substations. New designing methods for system grounding are suggested in this paper to avoid such problems. These proposed new methods aim at designing and constructing the grounding grid system in a way such that it can accommodate the system expansion more easily and safely. A real case 66/11 kV substation is considered as a case study and ETAP 12.6 is used as a simulation tool. The IEEE 80-2000std is adopted as a reference standard for design.

The metro stray current will flow through the neutral point of the transformer from the grounding grid in the soil, causing the transformer DC bias phenomenon. In order to effectively evaluate the influence of metro stray currents on the transformers, the traction current in metro, the “rail-current drainage net-earth” grounding network structure, and the DC bias current loop were equivalent, so a resistance model for the transformer DC bias caused by stray current was built. Then the dynamic equation of transformer neutral point current with time and metro train position was established, and the neutral point current can be solved by LU decomposition. The software CDEGS was used to build train and transformer simulation model. By comparative analyzing the transformer neutral point current between the simulation results and the calculation results of the proposed modeling method, the model error was small, which can be effectively applied to the evaluation of transformers affected by metro stray current.

The following paper presents an overview of the current state of art on the subject of Gas Insulated Substation (GIS) technology in order to understand the necessity of the grounding grid design models. Furthermore, different studies regarding existing applied technologies are considered in order to create an accurate review on GIS grounding models. For a better understanding of current GIS modeling methods an evaluation of the procedures regarding GIS grounding system design is conducted. The focus was to identify a suitable model technique for the GIS assemble and to obtain a proper grounding grid design procedure.

In this paper, the present situation of secondary system grounding in substation is comprehensively analyzed, some improvement measures are put forward, such as perfecting setting of secondary grounding grid, improving anti-interference ability of secondary equipment, canceling insulated copper bar in cabinet, making clear grounding mode of cable shielding layer, increasing protection of the weak electrical signal cable, have solved the problem of grounding frequently occurring in engineering.

Individual and equipment accidents of substations are mainly caused by the ground potential rise and the uneven voltage. The consequences of an accident are affected by lots of random elements, such as the type of the grounding faults, the magnitude of the fault current, the duration of the fault clearance time and the withstand voltage of equipment. While the traditional threshold means by judging the resistance of the grounding system, makes it difficult to accurately evaluate the risk of grounding system. Therefore, this paper presents a comprehensive method to calculate and assess the risk of grounding grid, especially for the equipment safety which has not been discussed before. Firstly three kinds of characteristic parameters was proposed which relate closely to individual and equipment safety, namely, the step voltage (Us), the contact voltage (Ut), and the ground potential difference (GPD), to calculate the risk of individual and equipment safety. Afterwards, the security level of the ground system was obtained according to the as low as reasonably practicable (ALARP criteria).

In this paper, development of a data processing software for grounding grid fault diagnosis of power substation based on the state response analysis (SRA) with impulse current is introduced. The SRA method with impulse current for grounding grid of power substation is described in detail firstly. Then the main function of the developed software used to analyze and display the measured current and voltage waveshapes is presented, including data loading, data display, parameter calculation, database management and correlation analysis to achieve fault diagnosis for grounding grid of power substation. At last, two examples of tests to the grounding grids with filed measured data are shown. All of that provides an effective technical support for grounding grid fault diagnosis based on the SRA.

The corrosion diagnosis of grounding grid can locate the corroded branches and provide guidance for the maintenance and repair of the grounding grid. This paper proposed the electrical impedance tomography (EIT) method on the corrosion diagnosis of grounding grid and described how it works. Firstly, the inverse problem model of the electrical impedance tomography on grounding grid is developed. Secondly, in order to weaken the ill-posedness of the inverse problem, a Newton iterative algorithm with Tikhonov regularization is proposed to solve the problem. Then, due to the high resistivity contrast between the soli and steel and the large size of imaging region, this paper presents the method of soil-separation and block-diagnosis to accomplish these problems. Finally, field experiments were carried out to verify the effectiveness of the proposed method and the results show that the location and degree of the corrosion in the grounding grid can be easily judged from the imaging results.

Grounding grid is an indispensable important component in the substation, which has important meaning for protecting the personal safety, equipment safety and system safety. Due to the grounding grid is always in the complex soil, it faced the varying degrees of corrosion threat. When the soil resistivity is high, engineers usually use an impressed current cathodic protection (ICCP) system to suppress corrosion. But the existing design and installation process of ICCP systems has some drawbacks. Engineers can only get the effect of the system after ICCP systems installed and run. If the effect is not up to standard, they need to re-design and re-install, which will waste a lot of manpower and resources. This paper mainly analyses the ICCP systems and proposes a new method to design the substation grounding grid ICCP systems by COMSOL Multiphyscis simulation software, which can effectively solve the above problems.

The behavior of grounding systems excited by high-current show great differs from that at low-frequency and low-current. Simulation of high-current draining to earth require accurate modeling of tower grounding system. The current model cannot meet this requirement. This paper proposed an accurate time-varying nonlinearly model of grounding systems established by ATP-EMTP, aiming at simulating the impulse characteristic of grounding systems. The results indicated that the strong agreement between the model and experimental values. At the end of this paper come to the calculation that the active length of the grounding bodies ray is 40 m in the grounding grid. And increasing the ray length infinitely is not conducive to reducing the impulse grounding resistance. The results above can be used for optimizing the grounding grid and selecting the length of grounding bodies ray.

Grounding system plays very important role in AC substation station for person and equipment safety. Proper design of grounding system is achievable by following IEEE Std-80 on safety in AC substation grounding but novice professionals find it not easy to use. The advantage of this paper presents evaluation of grounding system for AC substation by case studies presentation thus easing the understanding of IEEE Std-80 and its usage. This was carried out by using homegrown Sub-ground software with capability to identify the safety status of a grounding system design procedures. The grounding system is evaluated with six different cases. Different parameter is changed in each case to observe the result of the grounding system. The result shows that there are several important parameters in designing a grounding system. The parameters are grounding grid size, number of parallel rod, level of fault current, crush rock layer, cross sectional area of ground rod and level of soil resistivity. The tolerable and calculated step and touch voltage as well as the mesh voltage of the grounding system are presented in manner to tutor novice professionals on AC grounding system design. Last but not least the software developed in the laboratory useful for novice professionals training for AC substation grounding system.

As the large grounding grid occupies large area, the potential difference on the grounding grid is obvious, and the proportion of inductive components in the grounding impedance is larger. Then the design and the operation of the grounding grid are different from the small grounding grid. The paper studies the characteristics of resistive component and inductive component in the grounding impedance of the large grounding grid. The factors affecting the grounding impedance and the features of the large grounding grid are discussed. The results can provide a technical reference for design, operation and maintenance of the large grounding grid.

This paper presents the design of grounding grid system for substations. In last past years the design engineers follows steps of grounding grid design as per IEEE standard 80–2013, which is complicated process. This digital application is mainly concerned with development of Standalone software with using Visual Studio, named by “Grounding Grid Designer”, which calculated accurate grounding system as per guidelines given by IEEE standard 80–2013. After applying this computer aid application the complexity as well as time will reduces. This paper mainly conduct three mostly applicable grounding grid design:-Square Shape, Rectangular Shape, and L-shape. After developed software, the results obtained by standalone software is compared by sample calculation of square grid with ground rods design which is given into the IEEE 80–2000 standard in Annex B.

The configuration is essential to diagnose the status of the grounding grid, but the orientation of the unknown grounding grid is ultimately required to diagnose its configuration explicitly. This paper presents a transient electromagnetic method (TEM) to determine grounding grid orientation without excavation. Unlike the existing pathological solutions, TEM does not enhance the surrounding electromagnetic environment. A secondary magnetic field as a consequence of induced eddy currents is subjected to inversion calculation. The orientation of the grounding grid is diagnosed from the equivalent resistivity distribution against the circle perimeter. High equivalent resistivity at a point on the circle implies the grounding grid conductor and vice versa. Furthermore, various mesh configurations including the presence of a diagonal branch and unequal mesh spacing are taken into account. Simulations are performed using COMSOL Multiphysics and MATLAB to verify the usefulness of the proposed method.