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 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.

Cathodic Protection of Grounding Grids

2018 ◽  
pp. 248-286
Keyword(s):  
Cathodic Protection ◽  
Galvanic Corrosion ◽  
Steel Corrosion ◽  
Uniform Corrosion ◽  
Grounding System ◽  
Grounding Grid ◽  
Grounding Grids ◽  
Corrosion Pitting ◽  
Impressed Current ◽  
Cathodic Protection System

This chapter contains the corrosion theory of grounding electrodes and basic electrochemistry in corrosion reactions. It contains also the forms of substation grounding grid corrosion (uniform corrosion, pitting corrosion, galvanic corrosion, microbial influenced corrosion), survey on corrosion rate of substation grounding grid, copper and steel corrosion rates, corrosion protection methods (coating, cathodic protection [CP]). The chapter contains also the methods of applying cathodic protection in grounding grids, anode selection, anode spacing, and impressed current in the grounding grid cathodic protection. Finally it contains the required information for design grounding system cathodic protection and sacrificial anode (galvanic) cathodic protection system design steps.

scholarly journals Evaluation of soil-structure interaction for structures subjected to earthquake loading with different types of foundation

2018 ◽  
Vol 162 ◽  
pp. 04026
Author(s):  
Mohammed Elwi ◽  
Bassman Muhammed ◽  
Nada Alhussiny
Keyword(s):  
Soil Structure ◽  
Response Spectrum ◽  
Soil Layer ◽  
Tall Buildings ◽  
Soil Structure Interaction ◽  
Soil Conditions ◽  
Building Frames ◽  
Structure Interaction ◽  
Different Types ◽  
Seismic Forces

However though the structures are supported on soil, most of the designers do not consider the soil structure interaction and its subsequent effect on structure during an earthquake. Different soil properties can affect seismic waves as they pass through a soil layer. When a structure is subjected to an earthquake excitation, it interacts the foundation and soil, and thus changes the motion of the ground. It means that the movement of the whole ground structure system is influenced by type of soil as well as by the type of structure. Tall buildings are supposed to be of engineered construction in sense that they might have been analyzed and designed to meet the provision of relevant codes of practice and building bye-laws. IS 1893: 2002 “Criteria for Earthquake Resistant Design of Structures” gives response spectrum for different types of soil such as hard, medium and soft. An attempt has been made in this paper to study the effect of Soil-structure interaction on multi storeyed buildings with various foundation systems. Also to study the response of buildings subjected to seismic forces with Rigid and Flexible foundations. Multi storeyed buildings with fixed and flexible support subjected to seismic forces were analyzed under different soil conditions like hard, medium and soft. The buildings were analyzed by Response spectrum method using software SAP2000. The response of building frames such as Lateral deflection, Story drift, Base shear, Axial force and Column moment values for all building frames were presented in this paper.

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.

scholarly journals PENGARUH KELEMBABAN TANAH TERHADAP TAHANAN PENTANAHAN STUDI KASUS PADA GARDU INDUK KEMAYORAN 150 kV

2020 ◽  
Vol 3 (1) ◽  
pp. 18-23
Author(s):  
Rahmawati Fajri Latiefa ◽  
Irzan Zakir ◽  
Massus Subekti
Keyword(s):  
Soil Moisture ◽  
Soil Condition ◽  
Soil Conditions ◽  
Grid System ◽  
Actual Measurement ◽  
Grounding System ◽  
Grounding Resistance ◽  
The Earth ◽  
System Method ◽  
Dry Soil

Abstract The value of grounding resistance at the substation should be 0 Ω or less than 1 Ω. The value of grounding resistance is influenced by the resistivity and the grounding system method used. the resistivity is influenced by external factors, one of which is the soil moisture. The purpose of this research are (i) to find the effect of soil moisture to grounding resistance with; (a) compare the actual measurements of grounding resistance between wet soil conditions and dry soil conditions; (b) compare actual measurement results, manual calculations, and ETAP 12.6 software on grid resistance between wet soil conditions and dry soil conditions. (ii) to find the effect that would occur if the grounding station resistance exceeds the IEEE Std 80-2000 standard value of less than 1 Ω. The research method is comparative quantitative. This research is measuring grounding resistance with driven rood system and with grid system during wet and dry soil conditions, and then calculate grid resistance of Kemayoran 150 kV Substation in dry and wet soil conditions using manual calculating based on IEEE Std 80 -2000, and calculating using ETAP 12.6 software. The result of measument grounding resistance with driven rood system show the value of grounding resistance is 27,72 Ω when dry soil condition and 18,92 Ω when wet soil condition, the measurement result of grounding resistance with grid system show the value of grounding resistance is 0.076 Ω when the soil condition is dry and 0.049 Ω during wet soil conditions, the manual calculation of grid resistance is 0.078 Ω for dry soil conditions and 0.056 Ω, and the ETAP calculation of grid resistance is 0.071 Ω for dry soil conditions and 0.051 Ω for wet soil conditions. Based on the results of this research, the conclusion is soil moisture can affect the value of grounding resistance, based on this research the dry soil condition of the earth resistance value is higher than the wet soil conditions. The value of earthquake grounding shall be less than 1 Ω due to minimize the earth potenial value (Ground Potensial Rise) which can cause dangerous voltage for humans. Abstrak Nilai tahanan pentaahan pada Gardu Induk harus mendekati 0 Ω atau kurang dari 1 Ω, dan dipengaruhi oleh tahanan jenis tanah dan metode sistem pentanahan yang digunakan. Tahanan jenis tanah dipengaruhi oleh faktor eksternal, salah satunya adanya kelembaban tanah. Tujuan dari penelitian ini adalah mengetahui pengaruh kelembaban tanah terhadap nilai tahanan pentanahan, dan mengetahui pengaruh yang akan terjadi jika tahanana pentanahan gardu induk melebihi nilai standar IEEE Std 80-2000 yaitu kurang dari 1 Ω. Penelitian ini melakukan pengukuran aktual tahanan pentanahan dengan sistem driven rood dan tahanan pentanahan dengan sistem grid saat kondisi tanah basah dan tanah kering, serta perhitungan tahanan pentanhan grid Gardu Induk Kemayoran 150 kV dalam kondisi tanah kering dan tanah basah dengan menggunakan perhitungan manual berdasarkan IEEE Std 80-2000, dan perhitungan menggunakan software ETAP 12.6. Dalam penelitian ini ditemukan bahwa kelembaban tanah dapat mempengaruhi nilai tahanan pentanahan, dengan berdasarkan saat kondisi tanah kering nilai tahanan pentanahan lebih tinggi dibandingkan saat kondisi tanah basah Hasil pengukuran tahanan pentanahan dengan sistem driven rood menunjukkan nilai tahanan pentanahan adalah 27,72 Ω saat kondisi tanah kering dan 18,92 Ω saat kondisi tanah basah, hasil pengukuran tahanan pentanahan dengan sistem grid menunjukkan nilai tahanan pentanahan adalah 0,076 Ω saat kondisi tanah kering dan 0,049 Ω saat kondisi tanah basah, hasil perhitungan manual tahanan grid adalah 0,078 Ω untuk kondisi tanah kering dan 0,056 Ω, dan hasil perhitungan ETAP tahanan grid adalah 0,071 Ω untuk kondisi tanah kering dan 0,051 Ω untuk kondisi tanah basah.

scholarly journals Effects of disk tillage on soil condition, crop yield and weed infestation

2011 ◽  
Vol 48 (No. 1) ◽  
pp. 20-26
Author(s):  
M. Birkás ◽  
T. Szalai ◽  
C. Gyuricza ◽  
M. Gecse ◽  
K. Bordás
Keyword(s):  
Winter Wheat ◽  
Crop Yield ◽  
Field Experiments ◽  
Soil Layer ◽  
Soil Condition ◽  
Perennial Weeds ◽  
Weed Infestation ◽  
Set Up ◽  
Different Levels

This research was instigated by the fact that during the last decade annually repeated shallow disk tillage on the same field became frequent practice in Hungary. In order to study the changes of soil condition associated with disk tillage and to assess it is consequences, long-term tillage field experiments with different levels of nutrients were set up in 1991 (A) and in 1994 (B) on Chromic Luvisol at G&ouml;d&ouml;ll&ouml;. The effects of disk tillage (D) and disk tillage combined with loosening (LD) on soil condition, on yield of maize and winter wheat, and on weed infestation were examined. The evaluation of soil condition measured by cone index and bulk density indicated that use of disking annually resulted in a dense soil layer below the disking depth (diskpan-compaction). It was found, that soil condition deteriorated by diskpan-compaction decreased the yield of maize significantly by 20 and 42% (w/w), and that of wheat by 13 and 15% (w/w) when compared to soils with no diskpan-compaction. Averaged over seven years, and three fertilizer levels, the cover % of the total, grass and perennial weeds on loosened soils were 73, 69 and 65% of soils contained diskpan-compaction.

scholarly journals Root Response to Soil Water Status via Interaction of Crop Genotype and Environment

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 708
Author(s):  
Phanthasin Khanthavong ◽  
Shin Yabuta ◽  
Hidetoshi Asai ◽  
Md. Amzad Hossain ◽  
Isao Akagi ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Root Distribution ◽  
Water Status ◽  
Soil Layer ◽  
Shoot Biomass ◽  
Soil Conditions ◽  
Crop Adaptation ◽  
Soil Moisture Status ◽  
Root Distributions

Flooding and drought are major causes of reductions in crop productivity. Root distribution indicates crop adaptation to water stress. Therefore, we aimed to identify crop roots response based on root distribution under various soil conditions. The root distribution of four crops—maize, millet, sorghum, and rice—was evaluated under continuous soil waterlogging (CSW), moderate soil moisture (MSM), and gradual soil drying (GSD) conditions. Roots extended largely to the shallow soil layer in CSW and grew longer to the deeper soil layer in GSD in maize and sorghum. GSD tended to promote the root and shoot biomass across soil moisture status regardless of the crop species. The change of specific root density in rice and millet was small compared with maize and sorghum between different soil moisture statuses. Crop response in shoot and root biomass to various soil moisture status was highest in maize and lowest in rice among the tested crops as per the regression coefficient. Thus, we describe different root distributions associated with crop plasticity, which signify root spread changes, depending on soil water conditions in different crop genotypes as well as root distributions that vary depending on crop adaptation from anaerobic to aerobic conditions.

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

SOIL CONDITIONS ASSOCIATED WITH ABSENCE OR SPARSE DEVELOPMENT OF APPLE ROOTS

1978 ◽  
Vol 58 (4) ◽  
pp. 961-969 ◽  
Author(s):  
D. H. WEBSTER
Keyword(s):  
Soil Condition ◽  
Soil Strength ◽  
Rooting Depth ◽  
Soil Porosity ◽  
Soil Conditions ◽  
Increase With Increase ◽  
Or Groups ◽  
Maximum Root ◽  
M 12 ◽  
Root Abundance

Within orchards or groups of similar samples, the abundance of apple roots [Formula: see text] diameter was related to total soil porosity (Sta). Below a boundary soil porosity, roots were sparse or absent, and above this porosity, maximum root abundance tended to increase with increase in soil porosity. Depending upon soil texture, this boundary porosity varied from 29 to 39%. A previously derived model, which estimates boundary soil porosity (Stc) as a function of texture, accounted for most of these differences. If the model was correct, all boundary Sta – Stc values should have been zero and in four of six groups of samples the derived values were zero, + 1 or − 1. The greater departures from the expected in the remaining two groups (− 2 and + 4) may have been due to a tolerance of M. 12 rootstock to poor aeration and incomplete exploitation of potential rooting depth, respectively. With the exception of M. 12, apple roots were sparse or absent in samples with less than 10% air porosity at a tension of 100 cm (S100 cm). Poor development of roots in these samples was predicted by the model. In many samples with S100 cm > 10% there were few or no roots. Soil strength of many samples was within the range known to interfere with root development. For the purpose of recognizing a soil condition that will prevent apple root growth, Sta – Stc appears to be superior to the other criteria examined, i.e. Sta, S100 cm or soil strength.

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