scholarly journals Effect of Non-Homogeneous Soil Characteristics on Substation Grounding-Grid Performances: A Review

2021 ◽  
Vol 11 (16) ◽  
pp. 7468
Author(s):  
Navinesshani Permal ◽  
Miszaina Osman ◽  
Azrul Mohd Ariffin ◽  
Mohd Zainal Abidin Ab Kadir
Keyword(s):  
Soil Structure ◽  
System Analysis ◽  
Soil Characteristics ◽  
Design Parameters ◽  
Soil Conditions ◽  
Grounding System ◽  
Ground Resistance ◽  
Grounding Grid ◽  
Design Changes ◽  
Homogeneous Soil

Designing an effective grounding system for AC substations needs predetermination of ground resistance and ground potential distribution caused by fault current’s presence in the ground. Therefore, it is necessary to have a suitable grounding grid structure in the soil properties in which the grid is buried. Though the soil composition where the grounding grid is located is typically non-homogeneous, the soil is often presumed to be homogeneous due to the complexities of grounding system analysis in non-homogeneous soil. This assumption will lead to inaccuracies in the computation of ground resistance and ground potentials. Although extensive research has been done on non-homogeneous soil structure, comprehensive literature on grounding system performance in non-homogeneous soil is yet to be reviewed. Thus, this paper reviews the effect of non-homogeneous soil on the grounding system, with different soil characteristics in horizontal and vertical two-layer soil structure and the horizontal three-layer soil structure. In addition, the effect of design parameters on the grounding performance in non-homogeneous soil conditions for non-transient fault conditions is also studied. The significance of this study is that it provides a comprehensive review of grounding performance as grounding design changes and their effects as soil layers and their corresponding features change. This knowledge will be useful in developing safe grounding designs in non-homogeneous soil.

scholarly journals Optimization of substation grounding grid design for horizontal and vertical multilayer and uniform soil condition using Simulated Annealing method

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0256298
Author(s):  
Navinesshani Permal ◽  
Miszaina Osman ◽  
Azrul Mohd Ariffin ◽  
Navaamsini Boopalan ◽  
Mohd Zainal Abidin Ab Kadir
Keyword(s):  
Simulated Annealing ◽  
Soil Structure ◽  
Soil Layer ◽  
Minimum Cost ◽  
Soil Condition ◽  
Problem Formulation ◽  
Soil Conditions ◽  
Grounding System ◽  
Grounding Grid ◽  
Grounding Grids

Grounding systems are critical in safeguarding people and equipment from power system failures. A grounding system’s principal goal is to offer the lowest impedance path for undesired fault current. Optimization of the grounding grid designs is important in satisfying the minimum cost of the grounding system and safeguarding those people who work in the surrounding area of the grounded installations. Currently, there is no systematic guidance or standard for grounding grid designs that include two-layer soil and its effects on grounding grid systems, particularly vertically layered soil. Furthermore, while numerous studies have been conducted on optimization, relatively limited study has been done on the problem of optimizing the grounding grid in two-layer soil, particularly in vertical soil structures. This paper presents the results of optimization for substation grounding systems using the Simulated Annealing (SA) algorithm in different soil conditions which conforms to the safety requirements of the grounding system. Practical features of grounding grids in various soil conditions discussed in this paper (uniform soil, two-layer horizontal soil, and two-layer vertical soil) are considered during problem formulation and solution algorithm. The proposed algorithm’s results show that the number of grid conductors in the X and Y directions (Nx and Ny), as well as vertical rods (Nr), can be optimized from initial numbers of 35% for uniform soil, 57% for horizontal two-layer soil for ρ1> ρ2, and 33% for horizontal two-layer soil for ρ1< ρ2, and 29% for vertical two-layer soil structure. In other words, the proposed technique would be able to utilize square and rectangle-shaped grounding grids with a number of grid conductors and vertical rods to be implemented in uniform, two-layer horizontal and vertical soil structure, depending on the resistivity of the soil layer.

scholarly journals Calculation of Grounding Grids Parameter at Arbitrary Geometry

2017 ◽  
Vol 2 (2) ◽  
pp. 11
Author(s):  
Carlos L. B. Silva ◽  
Thyago G. Pires ◽  
Wesley P. Calixto ◽  
Diogo N. Oliveira ◽  
Luis A. P. Souza ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Computer Program ◽  
Arbitrary Geometry ◽  
Resistance Surface ◽  
Ground Resistance ◽  
Step Voltage ◽  
Grounding Grid ◽  
Grounding Grids ◽  
Homogeneous Soil ◽  
Touch Voltage

This paper deals with the computation of ground resistance, surface voltage, touch voltage and step voltage, to mesh with horizontal wires arranged in different angles. The computer program implemented used in the mathematical modeling is based on the method proposed by Heppe, which allows obtaining the grounding parameters for homogeneous soil and soil stratified in two layers. The results obtained with the proposed method will be compared with other methods in literature. Also will be presented the results of a grounding grid using wires at various angles.

Design of Grounding Grid According to IEEE Standards

2018 ◽  
pp. 158-186
Keyword(s):  
System Design ◽  
Design Procedure ◽  
Grounding System ◽  
Grounding Resistance ◽  
Computerized Analysis ◽  
Grounding Grid ◽  
Homogeneous Soil ◽  
Ieee Standards

This chapter contains the following points: design procedure of grounding system according to IEEE 80, methods for calculating the grounding grid resistance (Dwight's formula, Laurent and Niemann, Sverak's equation, Schwarz's Formula, Dawalibi, Mukhedkar's Formula, Chow and Salama's Formula, Nahman's Formula and Heppe's Method). It contains also the design of charts of grid earthing system and application of step and mesh potential in safe grounding system design. This chapter draws attention also to the following points: Grounding resistance of grounding system in non-homogeneous soil, calculations of maximum step and mesh voltages, estimation of minimum buried grid conductor length and finally computerized analysis in grounding design.

Influence of Driven Rods on Performance of Grounding Grids in Stratified Soils

2003 ◽  
Author(s):  
S. A. El-Drieny ◽  
I. A. Metwally ◽  
M. M. El-Saadawi
Keyword(s):  
Experimental Study ◽  
Soil Structure ◽  
Great Influence ◽  
Ground Resistance ◽  
Triple Layer ◽  
Grounding Grid ◽  
Scale Models ◽  
Grounding Grids ◽  
Mathematical Equations

The variation in soil structure has a great influence on the grounding grid performance. This influence can be measured in terms of ground resistance, touch and step potentials. This paper presents a comprehensive experimental study for the influence of adding driven rods on the performance of grounding grids. The study is applied on three constructed scale models. The models have been performed to simulate a single-, double- and triple-layer soils. A comparison between results obtained experimentally and that computed by mathematical equations is introduced.

Investigation of the Seismic Risk of Industrial Pipe Rack - Piping Systems Accounting for Soil-Structure Interaction

2019 ◽  
Author(s):  
George Karagiannakis ◽  
Luigi Di Sarno
Keyword(s):  
Soil Structure ◽  
Soil Structure Interaction ◽  
Design Parameters ◽  
Soil Conditions ◽  
Piping System ◽  
Seismic Action ◽  
Alluvial Deposits ◽  
Nonstructural Components ◽  
Structure Interaction ◽  
Piping Systems

Abstract Earthquake events have shown that industrial pipe racks lack of a completed design framework that encompasses contemporarily a number of uncertainties such as modelling, seismic action, design and analysis procedures as well as soil conditions. That being said, the seismic behaviour of piping systems has not been assessed up to par recognizing the potential effects of nonbuilding – nonstructural components interaction as well as soil conditions that constitute a decisive parameter particularly for structures that lie on alluvial deposits. In the present work, after reviewing European and American standards and technical literature upon design parameters, the seismic reliability analysis of two pipe rack – piping systems in decoupled and coupled case considering near- and far-field records as well as soil deformability is addressed. As it is illustrated, the classic nonlinear static analysis may overestimate the resistance of racks, common limit states of interstorey drift ratio cannot be applied and the behaviour factor selection may be unjustifiable. Also, soil-structure interaction affects detrimentally the response both of rack and piping system as depicted by the fragility functions.

scholarly journals Global earthworm distribution and activity windows based on soil hydromechanical constraints

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Siul A. Ruiz ◽  
Samuel Bickel ◽  
Dani Or
Keyword(s):  
Soil Structure ◽  
Mechanistic Model ◽  
Biophysical Model ◽  
Ecosystem Functions ◽  
Soil Conditions ◽  
Agricultural Systems ◽  
Occurrence Patterns ◽  
Additional Constraints ◽  
Earthworm Activity ◽  
Good Agreement

AbstractEarthworm activity modifies soil structure and promotes important hydrological ecosystem functions for agricultural systems. Earthworms use their flexible hydroskeleton to burrow and expand biopores. Hence, their activity is constrained by soil hydromechanical conditions that permit deformation at earthworm’s maximal hydroskeletal pressure (≈200kPa). A mechanistic biophysical model is developed here to link the biomechanical limits of earthworm burrowing with soil moisture and texture to predict soil conditions that permit bioturbation across biomes. We include additional constraints that exclude earthworm activity such as freezing temperatures, low soil pH, and high sand content to develop the first predictive global map of earthworm habitats in good agreement with observed earthworm occurrence patterns. Earthworm activity is strongly constrained by seasonal dynamics that vary across latitudes largely due to soil hydromechanical status. The mechanistic model delineates the potential for earthworm migration via connectivity of hospitable sites and highlights regions sensitive to climate.

Method for the estimation of soil structure in the vicinity of a grounding system

2015 ◽  
Vol 9 (7) ◽  
pp. 800-806 ◽  
Author(s):  
Wenxia Sima ◽  
Qing Yang ◽  
Bin Zhu ◽  
Peng Wu ◽  
Yang Bai ◽  
...  
Keyword(s):  
Soil Structure ◽  
Grounding System

scholarly journals Influence of Tillage on the Mollisols Physicochemical Properties, Seed Emergence and Yield of Maize in Northeast China

Agriculture ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 939
Author(s):  
Qiang Chen ◽  
Xingyi Zhang ◽  
Li Sun ◽  
Jianhua Ren ◽  
Yaru Yuan ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Physicochemical Properties ◽  
Northeast China ◽  
Soil Structure ◽  
Aggregate Stability ◽  
Maize Yield ◽  
Conventional Tillage ◽  
Soil Conditions ◽  
Emergence Period

Tillage practices are critical for sustaining soil quality necessary for successful crop growth and productivity, but there are only few studies for strip tillage (ST) in the Mollisols region of Northeast China at present. A long-term (≥10-year) study was carried out to investigate the influence of within the tilled row (IR) and between rows (BR) in ST (10-year), conventional tillage (CT, 14-year) and no tillage (NT, 14-year) treatments on soil physicochemical properties. Soil samples were taken in May of 2019 at 0–5, 5–10, 10–20 and 20–30 cm depths and used to analyze bulk density (BD), soil aggregate distribution and stability, and soil organic carbon (SOC). Meanwhile, our study also explored the differences in seed emergence, soil moisture, and temperature during the seed emergence period, and yield of maize (Zea mays L.) among the different treatments. Similar soil properties were observed between ST-BR and NT, which showed they had a significantly greater BD, >0.25 mm water stable aggregate content (WR0.25) (especially in the amount of >2 mm and 1–2 mm size proportion), aggregate stability, and SOC than ST-IR and CT-IR at a depth of 0–20 cm. By improving soil conditions of seedbed, ST-IR and CT-IR increased soil temperature above NT by 1.64 °C and 1.80 °C, respectively, and ST-IR had a slight greater soil moisture than CT-IR in the top 10 cm layer during the seed emergence period. Late maize seed emergence was observed NT in than ST-IR and CT-IR and the average annual yields in ST were slightly greater than NT and CT, but the differences were not significant. Our results also showed that CT-BR had a poor soil structure and lower SOC than other treatments at 0–30 cm depth. We conclude from these long-term experimental results that ST could improve soil water-heat conditions to promote seed germination, maintain soil structure, and increase the maize yield and it should be applied in the Mollisols region of Northeast China.

scholarly journals Grounding System Cost Analysis Using Optimization Algorithms

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3484 ◽  
Author(s):  
Jau-Woei Perng ◽  
Yi-Chang Kuo ◽  
Shih-Pin Lu
Keyword(s):  
Human Body ◽  
Rbf Neural Network ◽  
Grounding System ◽  
Grounding Resistance ◽  
Grounding Grid ◽  
Engineering Costs ◽  
System Data ◽  
And Performance ◽  
Touch Voltage ◽  
Resistance Value

In this study, the concept of grounding systems is related to the voltage tolerance of the human body (human body voltage tolerance safety value). The maximum touch voltage target and grounding resistance values are calculated in order to compute the grounding resistance on the basis of system data. Typically, the grounding resistance value is inversely proportional to the laying depth of the grounding grid and the number of grounded copper rods. In other words, to improve the performance of the grounding system, either the layering depth of the grounding grid or the number of grounded copper rods should be increased, or both of them should be simultaneously increased. Better grounding resistance values result in increased engineering costs. There are numerous solutions for the grounding target value. Grounding systems are designed to find the combination of the layering depth of the grounding grid and the number of grounded copper rods by considering both cost and performance. In this study, we used a fuzzy algorithm on the genetic algorithm (GA), multi-objective particle swarm optimization (MOPSO) algorithm, Bees, IEEE Std. 80-2000, and Schwarz’s equation based on a power company’s substation grounding system data to optimize the grounding resistance performance and reduce system costs. The MOPSO algorithm returned optimal results. The radial basis function (RBF) neural network curve is obtained by the MOPSO algorithm with three variables (i.e., number of grounded copper rods, grounding resistance value, and grounding grid laying depth), and the simulation results of the electrical transient analysis program (ETAP) system are verified. This could be a future reference for substation designers and architects.

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