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A good substation grounding grid is essential to ensure safety of personnel working in the substation, and also to protect the equipment to ensure continuous operation of the substation. The design of the substation grounding grid is often carried out to meet the IEEE Std 80-2000 requirements of grounding resistance, touch voltage and step voltage at an economical cost. However, the conventional grounding grid design is normally over calculated to meets these IEEE requirements without considering the total cost. The grounding grid is often costly to implement due to high number of grounding conductors and rods, and large area size of the interconnected bare conductors. In this study, Gravitational Search Algorithm (GSA) and Particle Swarm Algorithm (PSO) are proposed to achieve an effective grounding grid calculation. The reliability of these algorithms has been validated using a typical medium voltage substation grounding grid parameters. It was found both that GSA and PSO were capable to achieve a lower cost with of grounding grid with 29% cost saving as compared to the conventional calculation technique, without compromising the safety requirements of grounding grid.

Corrosion of grounding grids can affect the safe and reliable operation of power systems. In view of the corrosion problem of the grounding grid, this paper introduces the corrosion mechanism, which is chemical corrosion and electrochemical corrosion respectively. Then, three common grounding grid corrosion detection methods, such as electric network analysis method, electromagnetic field detection method and electrochemical method, are introduced. On this basis, the advantages and disadvantages of three methods are compared. Further prospects for the corrosion detection technology of the grounding grid are pointed out.

To make effective fault diagnosis of grounding grid , a new method using Self-Adaptive Particle Swarm Optimization (SAPSO) is proposed. Firstly, the grounding grid can be handled as a resistive network to establish fault diagnosis equations. Then the objective function based on minimum energy principle is added to lower the ill-condition of diagnostic equation. Next, according to optimization techniques, a new method of SAPSO is proposed to solve the corrosion diagnosis equations. The method takes advantage of the high global searching ability of SAPSO to obtain the optimal solution to the diagnosis model. By means of the analysis of the simulation, the correctness and reliability of the method have been verified.

Grounding grid is an important device which ensures the safe operation of substation. Its corrosion is influenced by various factors and the influence of these factors is varied. It is difficult to infer the relationship between the corrosion rate and its influencing factors, so this paper apply the grey clustering method of grey system theory in the grounding grid corrosion and gives an application instance and realizes it by MATLAB. The results demonstrate the practicality and effectiveness of the method mentioned in this paper. This method can provide reference for high reliability for related departments in the implementation of emergency situation due to grounding grid corrosion.

In order to improve the accuracy and efficiency of the fault location in grounding grids, a new method combing Extreme Learning Machine (ELM) with neural network was proposed. The method compares the voltages of different node to determine whether the branch is fault or not. The simulation results show that this method can save time and improve accuracy.

In Korea, where most of the sites are narrow in space and their earth resistivity is relatively high, the spaces between grounding conductors are likely to be designed narrow in order to lower ground resistance and dangerous voltage below to the permitted safety values. In addition, ground nets are in the shape of square or rectangle depending on the location and size of the facilities and ground contact area, and inner conductors are laid out in grids like the pattern of nets. Nevertheless, with the existing designs, the marginal voltage for safety gets higher as the area is extended further outside, in comparison with that of inner mesh grounding, thus causing much difficulty maintaining them equipotential, and there exist limits in the burial, grounding grid design considering the dangerous voltage of muti-layered model in the constrained sites, was studied.

This paper presents a genetic algorithm to optimize support vector machine parameters for grounding grid fault diagnosis method. Grounding grid is equivalent to a pure resistance model, extract characteristics of different kinds of corrision states, Using genetic algorithm optimize support vector machine kernel function parameters, achieve the identification of the type of failure mode, Grounding grid of 6 × 6 test can quickly detect the grounding grid corrosion, simulation results show that the method has higher accuracy than support vector machine.

A flexible anode and three graphite anodes were used to study cathodic protection in simulated grounding grid in the laboratory. The protection potential values and uniformities of these anodes were investigated under the same condition through potential detection at each grid node. The results showed that with flexible anode, the protection potential was 0·3 V less than that with graphite anode, the potential dispersion degree of each node was 0·1 times that with graphite anode, and no special demands were needed for the cathodic access points under the same condition. The potential dispersion degree of each node in grounding grid was influenced significantly by the cathodic access points when graphite was used as deep-well anode. The rational choice for cathode access points and increasing the depth of deep-well anode could decrease the potential differences and dispersion degree of each node. The impressed potential for realising the same protection potential with graphite anode was higher than that wi...

The grounding grid of some substation shows severely corrosion, which affects the safe running of power grid. Galvanized steel is widely used in grounding grid. However, the galvanized steel is easy to corrosion in alkaline soil. In this paper, the corrosion behavior of galvanized steel was studied through accelerated corrosion test of burying specimens in laboratory soils and the corrosion rate was measured by electrochemical test. The corrosion products and corrosion appearance were analyzed by means of SEM, and XRD. The results show that pitting corrosion and localized corrosion were observed on the surface of the galvanized steel, the corrosion products were rough and loose, indicating no protection, the corrosion products of galvanized steel were ZnO,FeO(OH),FeCl3,Zn3O(SO4)2,and ZnSO3·2.50H2O. Electrochemical test show that the corrosion rate of galvanized steel in the later corrosion stage is higher than in the initial corrosion stage.

Established a cross-validation of the model optimization algorithm in order to predict the corrosion rate of the grounding grid. Forward neural network input variables by principal component analysis to extract the main element, eliminating the correlation between variables; cross-validation method and change the termination of the neural network training conditions, the selection of network training model. The final simulation results show that, get a good grounding grid corrosion rate stability and generalization performance optimization prediction model can predict the corrosion rate of the grounding grid.

PurposeReliable grounding is an important condition for the stable operation of substations and cathodic protection is one of the electrochemical protection technologies for substation grounding grids. The purpose of this paper is to consider the design proposal, installation, construction requirements and monitoring methods for Hunan 220 kV substation grounding grid.Design/methodology/approachThis paper treated Hunan 220 kV substation grounding grid as a research object. The physical and chemical data of three soil samples were measured, German DIN50929 evaluation criteria were used to assess its corrosion and a sacrificial anode cathodic protection design was selected, based on advanced concepts.FindingsThe design proposal, installation, construction requirements and monitoring methods for the 220 kV substation grounding grid were clearly explained and recommended for implementation.Originality/valueThis paper has some guidance on design ideas and the selection method for substation sacrificial anode cathodic protection.

Aiming at the existing poor corrosion resistance, difficult transportation and construction of metal grounding material in transmission line grounding grid, this paper designed and prepared flexible graphite grounding materials based on carbon nanotubes modified technology. The performance of new grounding materials was analyzed and electrical performance experiments were carried out. The final trial site application example showed that the material can meet the practical engineering applications.

Previous work has proven that transient characteristics of a grounding grid was far more different than its performance at power frequency because of the inductance of the system and the soil ionization phenomena. In this paper, a test on a grounding grid of a 110 kV substation was conducted. Several parameters, such as waveform, peak value and injecting point of lightning, were altered to study their relationship with transient characteristics. Not only the impulse earthing resistance but also the voltage and current distribution of the conductors were analyzed. Characteristics of grounding grid between power frequency and higher frequency were compared.

External grounding grid is an effective measure to reduce grounding resistance of grounding grid. In order to meet the requirements of the grounding resistance in the most economical way, it is important to determine the distance and the area of the external grounding grid. Generally speaking, when the area is larger, the grounding resistance is smaller. When the distance of the external grounding grid increases, the grounding resistance decreases firstly and then increases. Therefore, there is a minimum of the external grounding grid area and the optimal distance to meet the requirements of the grounding resistance within the constraints. Also means to get the best economic design scheme that minimum material consumption and construction of the external grounding grid. In this paper, we establish the objective function of the minimum grounding resistance based on the area and the distance of the external grounding grid using the method of grounding grid unequal potential model. Through optimization theory and genetic algorithm optimization, the optimum parameters of the distance and the area size of the grounding grid are obtained. Provide important basis for the design of the grounding grid economically.

The transient characteristics of a grounding grid is very important for the safety of the equipment on it, which is quite different from the performance at power frequency. In this paper, based on numerical simulation, the factors due to the grounding grid that affect its transient performance were discussed. The methods to improve the transient performance of the grounding grid such as increasing the horizontal grounding conductors and vertical grounding conductors near the current injection point were presented. It shows that increasing the horizontal grounding conductors is such more effective than increasing vertical grounding conductors to decrease the ground potential rise and the potential difference in the grounding grid.

The article simulates the typical tower grounding resistance using CDEGS. First of all, it compares the difference between the flexible graphite grounding electrode, round steel and manganin, in power frequency grounding performance and impulse grounding performance. The results show that flexible graphite grounding electrode is slightly higher than the round steel in the power frequency grounding resistance. But due to its non-magnetism, weaker skin effect, the impulse grounding resistance is lower than that of the round steel. Thus, flexible graphite grounding electrode has good lightning protection grounding characteristics. Take an application of flexible graphite grounding electrode in typical transmission lines in Foshan demonstration project for example, the practical engineering construction process and technology of flexible graphite grounding electrode is introduced, providing references for other similar engineering and test.

Grounding grid is an essential means for the safety of operators and power apparatus in substation. Many approaches including transient electromagnetic method have been applied to diagnose faults in grounding grids. This paper investigated break point diagnosis of grounding grids with consideration of underground pipe. Based on the equivalent resistivity distribution characteristics, the grounding fault can be accurately located in the grounding grids. The influence of underground pipe on the distribution of equivalent resistivity is analyzed. Factors including underground pipe made of different materials and buried in different depth are discussed in detail. The results show that the underground pipe puts a great impact on fault diagnosis of grounding grids.

It is essential to consider the electrical safety protection distance when the mobile base station and the substation are building together. This paper makes an analysis from three aspects: the influence on the disturbance voltage of the secondary cable in substation when the station is struck by lightning; the influence on the base station grounding grid caused by the station switching operation and short circuit faults. According to the relevant national and international standards, the electrical parameters are calculated when the substation and mobile base station grounding grid connected in different ways and different distance. The conclusion of the paper provides a theoretical basis for engineering construction with much higher practical value. Meanwhile, it is of great significance to develop the win-win co-operation between the power and telecommunications operators and to explore the diversified businesses of electric power.

In order to equalize the electric potential distribution of the grounding grid surface, and improve the safety level of the grounding grid, method for optimal arrangement of conducts in the grounding grid is proposed in this paper. The calculation results about maximum touch voltages and mesh potentials show that the method can reduce touch voltage and equilibrium surface potential. It is shown that the design of the grounding grid is related to not only the soil environment, but also the rectangular shape. Comparing with other methods, the method proposed in the paper can reduce maximum touch voltage about 12%. This method also can be applied in a uniform and non-uniform soil, rectangular and square grounding grids. The optimize effect meets the related standards of the power industry.

When the current distribution changes due to the breakage in the grounding grid, the magnetic field in the vicinity of the grounding grid will change, hence the magnetic field on the ground above the grounding can be used to detect the breakage of the grounding. In the paper, the magnetic field forward problem of the grounding grid is described firstly, and simulations were carried out when the breakage was located at different position. Results indicate that the maximum change of the magnetic flux density occurs at different measuring point when the breakage was located at different position. To achieve a more convenient method to detect the grounding grid fault, the magnetic field inverse problem of the grounding grid is presented, which is the process to calculate the current flowing in the grounding grid according to the magnetic field strength, and the method based on the global regularization and Damped Gauss-Newton method to solve the inverse problem is described, with which the ill-posed and ill-conditioning characteristic of the inverse problem can be diminished. Then the fault state of the grounding grid can be confirmed in the following way. Firstly, inject a 10∼30A current into the grounding grid, measure the magnetic field strength or the magnetic flux density at the measuring points on the ground above the grounding grid, then the current distribution can be obtained by solving the inverse problem. If the parameters of the soil are known, the resistance distribution can be obtained, with which the fault state of the grounding grid and the location of the fault can be confirmed. An equivalent model to verify the inverse problem was set up, and results indicate that the global regularization can diminish the ill-posed and ill-conditioning characteristic of the inverse problem.

This paper describes the analysis technique of risk voltage around grounding electrode by new touch and step voltage measurement methods. We have analyzed three techniques for risk voltage measurement, such as footprint-electrode method, test-probe method, and simulated-personnel method. We have selected test-probe method considering applicability of site. In order to reduce error related to the location of the auxiliary electrode, we propose a new approach to perform risk voltage measurement with minimum errors and short auxiliary electrode distances. Field tests were carried out at a grounding grid. It can be concluded that the proposed method will be satisfactory for risk voltage measurement.

The improved transmission line (ITL) model of a grounding grid has been already used in engineering practice for a grounding grid transient analysis. This paper offers a progress to the ITL model of a grounding grid based on the finite element method (FEM), where ITL model is developed using FEM applied to the system of multi-conductor Telegrapher equations. In order to check accuracy of the proposed method, the results obtained using ITL approach has been compared to the results calculated using electromagnetic field approach and very good correlation has been obtained.

The paper deals with transient analysis of grounding grids using two different approaches, wire antenna theory and modified transmission line model. The Pocklington integro-differential equations, in frequency domain, arising from the wire antenna theory are numerically handled via the Galerkin–Bubnov variant of indirect Boundary Element Method (GB-IBEM), while the transient response was obtained using inverse Fourier transform. The modified transmission line equations are treated using the finite difference time domain (FDTD) method. Some illustrative numerical results are presented and discussed in the paper.

When we design the grounding grid, dangerous voltage ANSI/IEEE Std. 80 method has been commonly used in the domestic area. However, the suitability of the ground rules for the design environment available. However, the suitability of the ground rules for the design environment available. In this paper, sticks according to the electrode conductor in combination with the mesh in order to design the ground by the IEEE Std.80 was designed. So in this paper, we examined of IEEE Std. 80 touch voltage method marginal utility and we induced for those problems by comparison between IEEE Std. 80 touch voltage value and simulation experimentation value. Furthermore, this paper presents a new design grounding system method that complements the IEEE Std. 80 method.

An investigation into the optimal design of a substation grounding system for the transmission substation in Gaza City, Palestine has been carried out. A research into the most influential parameters on the effectiveness of the substation grid system has been performed and its results have been incorporated into the Gaza case study. Through modelling and simulating the power station in Gaza while considering some field data, an optimal substation grounding grid has been designed and has shown complete conformance to safety. It is thus considered that such a design will protect personnel in any area of the substation in addition to the installed machinery if the largest possible fault current was to traverse the earth.

The grounding grid buried in the earth will become a hidden danger to the safety of substations due to some faults of breaks or thinner conductors in corrosion. A novel method to get accurate status of grounding grid was proposed based on measuring magnetic induction intensity. The basic structure of grounding grid without working drawing was concluded, and the positions and the status of faults were diagnosed by this method. The completed detecting system, including hardware device of data measurement, diagnosis, and analysis software, was introduced concisely. The results of simulations and applications show that this method is simple and effective in the practical engineering.

There is a difference between the actual impedance of substations' ground grid under harmonic interference and that measured under power frequency. Especially under strong harmonic interference, the difference becomes more obvious between the actual one and that measured under power frequency. A method is proposed in this paper to calculate parameters of ground grid models by measuring the ground grid impedances under power frequency and then calculate those under harmonic interference. This method is capable of solving the problem that it is impossible to measure the actual grounding impedance of substations operating under harmonic waves. The feasibility of the method is verified by means of simulating calculations. After correcting by this method, the grounding impedance modulus error becomes less than 2% and the impedance angle error less than 10%. This method may be applied to the measurement and analysis of grounding impedances of substations under harmonic interference.

The grounding grid is a key part of substation protection, which provides safety to personnel and equipment under normal as well as fault conditions. Currently, the topology of a grounding grid is determined by assuming that its orientation is parallel to the plane of earth. However, in practical scenarios, the assumed orientation may not coincide with the actual orientation of the grounding grid. Hence, currently employed methods for topology detection fails to produce the desired results. Therefore, accurate detection of grounding grid orientation is mandatory for measuring its topology accurately. In this paper, we propose a derivative method for orientation detection of grounding grid in high voltage substations. The proposed method is applicable to both equally and unequally spaced grounding grids. Furthermore, our method can also determine the orientation of grounding grid in the challenging case when a diagonal branch is present in the mesh. The proposed method is based on the fact that the distribution of magnetic flux density is perpendicular to the surface of the earth when a current is injected into the grid through a vertical conductor. Taking the third order derivative of the magnetic flux density, the main peak coinciding with the position of underground conductor is accurately obtained. Thus, the main peak describes the orientation of buried conductor of grounding grid. Simulations are performed using Comsol Multiphysics 5.0 to demonstrate the accuracy of the proposed method. Our results demonstrate that the proposed method calculate the orientation of grounding grid with high accuracy. We also investigate the effect of varying critical parameters of our method.

Recently, the common grounding systems are adapted in most large structures. Since the ground resistance is insufficient to evaluate the performance of grounding systems, it is needed to measure grounding impedance. Even though the methods of measuring grounding impedance of large grounding systems are presented in IEEE standard 81.2, but they have not been described in detail. In this paper, we present the accurate method of measuring grounding impedance based on the revised fall-of-potential method and measurement errors due to earth mutual resistance and ac mutual coupling depending on locating test electrodes at remote earth were examined for the 15[m]15[m] grounding grid. As a result, the measurement error due to earth mutual resistance is decreased when the distance to auxiliary electrodes increased. To get rid of measurement errors due to mutual coupling, the potential lead should be installed at a right angle to the current lead. When the angle between the potential and the current leads is an acute angle or an obtuse angle, the mutual couple voltage is positive or negative, respectively. Generally, the measurement errors due to mutual coupling with an obtuse angle route are lower than those with an acute angle route.

A grounding grid is designed with the capacity to minimize the very fast transient overvoltage generated during switching operations in a Gas Insulated Substation (GIS). The methodology takes the reference from the IEEE Std. 80-2000 and contains detailed models of GIS and grounding grid. By means an iterative process, new elements are added to the grounding grid for reducing magnitude of a very fast transient overvoltage in different points of a substation. This permits to improve the levels of personal security and the protection of apparatus in the substation.

When we design the grounding grid, dangerous voltage IEEE Std. 80 method has been commonly used in the domestic area. However there is not appropriative examination of ground design environment. So in this paper, we examined of IEEE Std. 80 touch voltage method`s marginal utility and we induced corrective factor for those problems by comparison between IEEE Std. 80 touch voltage value and simulation experimentation value. Moreover, Logistic model`s corrective factor we proved the maximum accidental error has reduced less than 10[%].

The paper provides a procedure for experimental determination of the grounding grid impulse characteristics. The principles of forming the measuring scheme, disposition and characteristics of the equipment used are described. Some of the numerous experimental results for the square-shaped grounding grid are presented. The results have been obtained for various shapes, magnitudes and discharge points of the impulse currents and are related to the cases without soil ionization around the grid elements.

This article presents laboratory scale models developed to study the performance of grounding systems in uniform soil. Two parallel grids are investigated and correlated with a same mass grid having the same conductor material and extending over the same area at a depth equal to that of the upper grid. The experimental results demonstrate how the potential profiles and ground resistance are influenced by the grounding grid design such as number of meshes, grid depth and spacing between parallel grids. The effectiveness of the two parallel grids is compared with that of the upper grid only. The measured surface potential and ground resistance agreed satisfactorily with the present calculated values

In order to analyze the potential rise of grounding systems installed in buildings, a hemispherical grounding simulation system was studied. Potential rise was measured and analyzed regarding the shape and distance of the grounding electrodes by using this system. The system was composed of a hemispherical water tank, AC power supply, a movable potentiometer, and test grounding electrodes. The potential rise was measured in real time by the horizontal moving probe of the potentiometer. The test grounding electrodes were fabricated through reducing the grounding electrode installed in real buildings such as the ground rod, grounding grid and so on. The potential rise was displayed in a two-dimensional profile and was analyzed regarding the shapes of the ground electrodes. The potential rise of the grounding grid combined with a ground rod was the lowest of every grounding electrode tested. The proposed results can be applicable to evaluating ground potential rise in grounding systems, and the analytical data can be used to stabilize the electrical installations and prevent electrical disasters.

In this paper, we present how the finite element method (FEM) can be utilized to analyze the influence of an additional substance in the trenches surrounding the grounding grid's conductors on the grounding grid's performance. For this purpose, we modified the preliminarily existent FIELD_GS program code in such a way that the additional substance in the immediate vicinity along the grounding grid's conductors can be simulated. Different soil structures and various volumes of the additional substance in the soil have been analyzed to prove the suitability of surrounding the grounding grid's conductors in trenches with the additional substance instead of strewing a whole grounding grid's surface with the additional substance

In this paper we propose a new formalism for analyzing the transient behavior of grounding systems associated to substation structures (Faraday-cage) under lightning strokesin unsettled regime. The protective device to study is formed of a guard filet connected to a grounding grid by simple conductors called down conductors. Our formalism is based on the resolution of the propagation equation in potential on 3D. The purpose of our proposition is the direct analyzing in time domain and simple implementation. We compare the results obtained by this new approach to results published in literature.

This paper deals with the calculation of ground resistance, surface voltage, touch voltage and step voltage, to mesh with horizontal wires arranged in different angles. The mathematical modeling is based on the method proposed by Heppe, which allows obtaining the grounding parameters for soil stratified in two layers. Moreover, the results obtained by the Variable Currents Method (VCM) have been compared to traditional methods and the simplified method of ANSI-IEEE Std. 80/2013. They also present the results using a grounding grid non-symmetrical with conductors on various angles.

Ovaj rad daje opis raspodjela struja kvara unutar uzemljivačkog sustava visokonaponskog elektroenergetskog postrojenja. Nakon uvoda, u drugom poglavlju, slijedi definiranje dodirnog napona te napona koraka, govori se i o raspodjeli potencijala. U trećem poglavlju riječ je o uzemljenjima i uzemljivačima te njihovim vrstama. U četvrtom poglavlju govori se o redukcijskom faktoru i o načinima njegovog izračunavanja. U petom poglavlju izvršena je simulacija u programskom paketu CDEGS te je pomoću njega dobivena na uvid raspodjela struja kvara iz koje je izračunat redukcijski faktor This paper gives description of the fault current distribution in the grounding grid of high voltage power installation. After the introduction in the second chapter touch voltage, step voltage and potential distribution are defined. Third chapter is about grounding, grounding grids and their types. The fourth chapter deals with split factor, and ways to calculate split factor. In the fifth chapter a simulation in software package CDEGS are conducted. Using the software package CDEGS fault current distribution and split factor are obtained