High Soil Resistivity Research Articles

Pemanfaatan Drainase (Saluran) Air Bekas Limbah Rumah Tangga sebagai Solusi untuk Penurunan Resistansi Pentanahan (Grounding)

This study aims to anticipate a high value of grounding resistance by utilizing drainage or waste water from household waste as a planting medium to reduce the value of grounding resistance. The research method used is an experimental method of testing and measuring at field locations. In this study, a round rod electrode is coated with copper, namely testing with one electrode rod and two electrode rods that are installed in parallel or better known as the use of a driven rod. The results showed a decrease in the value of the grounding resistance where the average value for 1 grounding rod was 18.32 ohms and 11.82 ohms for the measurement of 2 grounding rods installed in parallel. From the test results, there was a decrease in the resistance value of 59.52% for 1 electrode rod and a 51.75% decrease for 2 electrode rods, where the decrease in the resistance value in the field was caused by factors of water, humidity and used water minerals from household waste. In conclusion, housing with reddish yellow podzolic soil that is clay (high soil resistance) by utilizing water drainage is a solution to reduce grounding resistance.
 Keywords: Resistance, Drainage, Grounding (Grounding)

Innovative earthing systems for electric power substations using conductive nanoparticles

The earthing system is very important to safe human’s lives and protect power system from normal and abnormal faults. High soil resistivity regions is the main problem of installation the earthing systems in electric power substations to pass the current through the earth's surface. This paper has been overcome on high soil resistivity regions by penetrating conductive nanoparticles to have extremely low grounding resistance. Moreover, it has been succeeded to examine the methodology of the proposed Nano-Tech earthing systems in case of single rods, multiple rods and grids. Also, it has been defined optimal types and concentrations of nanoparticles for Nano-Tech grounding system to provide excellence protection for electrical substations with respect to built beneath of soil where substation is located. A comparative study has been discussed and analyzed the results of traditional and nanotechnology grounding systems.

Bare versus insulated conductors for improving the lightning response of interconnected wind turbine grounding systems

This paper investigates the lightning response of a pair of interconnected wind turbine grounding systems assuming their connection to be performed by a bare or insulated underground conductor. Typical first and subsequent stroke current waveforms are injected at one of the grounding systems and the transient response is studied for different soil resistivities considering frequency-dependent soil parameters. The ground potential rise (GPR) at the current injection point and the voltages transferred to the adjacent grounding system are calculated. GPR peak reductions are obtained using either a bare or insulated conductor, but the former is more effective. It is shown that when the wind turbine grounding systems are interconnected by a bare conductor, the GPR peak reduction is essentially due to the interconnecting wire. On the other hand, when the interconnection is made through an insulated conductor, the GPR reduction is related to the current that is partly diverted to the adjacent tower, especially for high resistivity soils. For an insulated interconnecting conductor and first lightning return-stroke currents, the adjacent grounding system also contributes to the GPR peak decrease.

On the Characterisations of the Impulse Breakdown in High Resistivity Soils by Field Testing

This paper presents experimental results of high-current impulse tests on six ground electrode configurations. A high impulse current generator is employed to inject different magnitudes of current into these rod electrodes, under both positive and negative impulse polarities. The effect of increasing the number of rod electrodes, hence the resistance at DC or steady-state (RDC), on the impulse response of ground electrodes is analysed. From the analysis of the results, it was found that the larger the size of rod electrodes, the less current-dependent Zimpulse becomes. The percentage of reduction of impulse impedance, Zimpulse from its steady state, and RDC values are found to be independent of impulse polarity. However, as the voltage magnitudes were increased, an occurrence of breakdown was seen, with higher breakdown voltage seen in negative impulse polarity in comparison to positive impulse polarity. Relatively, the higher the breakdown voltage is, seen in the ground electrodes subjected to negative polarity, the faster the time to breakdown is.

Land-use change affects soil hydro-physical properties in Mollisols of semiarid Central Argentina

The objective of the present study was to describe the relationships between soil physical properties and to identify variables that determine the pore system and hydrological functions which are specifically important in drought prone semiarid marginal croplands. We compared Mollisols under natural vegetation (NV) with their agriculture (AG) pairs in the central Argentinean Dry Pampas to obtain the range of values for variables that characterize the soil pore system. These were total carbon (OC), bulk density (BD), structural instability index (SII), volumetric weight of aggregates (VAW), total porosity (TP), macropores (Ma), saturated hydraulic conductivity (K), infiltration rate (IR), Dexter's S index (S), and least limiting water range (LLWR). To a depth of more than 23 cm, TP and Ma were considerably lower (~ 35% and 50% less, respectively) in AG versus NV. The changes in porosity and pore size resulted in 74% smaller IR and 65% lower K. The S index had mean values of 0.16 and 0.14 for the upper and middle layer respectively in NV; while for AG, these values were significantly lower (0.09 and 0.10, respectively). The LLWR was also lower in AG (21 and 59% less in the upper and middle layer, respectively), due to high soil resistance even at non-limiting BDs (1.17 and 1.32 g cm−3 for AG2 and AG1, respectively). Soil OC was positively correlated with TP, Ma, and S, and negatively correlated with BD and SII. Multiple regression models for S included SII, TP, and clay contents, while for LLWR the variables were OC, TP, and clay plus silt. Thus, these complex soil quality indices can be predicted by using simpler physical parameters, but texture and organic matter also have a strong effect on them. Moreover, our results contribute to a better understanding of the role of texture and organic matter in controlling soil physical quality and for maintaining soil-based ecosystem services.

Resistance Reduction Scheme for Tower Grounding with Conductive Cement

The construction conditions of transmission lines are becoming more and more difficult. It is necessary to find new ways to reduce the grounding resistance of poles and towers at high soil resistivity and small construction area. Conductive cement samples with graphite, stainless steel fibers, and their mixtures as conductive phases materials were prepared, the resistivity, flexural strength and compressive strength were tested, compared and analyzed. The graphite and stainless steel fiber conductive cement with better comprehensive performance was selected out for tower grounding. The application schemes of conductive cement for tower grounding were designed and compared, the partial wrapping scheme was selected and its application methods under different soil resistivity was analyzed. The analysis results can provide theoretical basis and guidance for the application of conductive cement in transmission tower grounding, the feasibility of scheme is proved by the field application.

Study of soil physical properties in UIN Sunan Gunung Djati campus area using geoelectrical resistivity method

Study of Soil physical properties are important characteristics of the soil. The description of soil physical properties is very important to investigation the function of the soil as a plant growth medium. The aim of this study was to determine the physical properties of the soil based on geoelectric resistivity data. The study was conducted in UIN Sunan Gunung Djati campus area. The method used in this study was geoelectrical resistivity of wenner configuration method. The results showed the value of resistivity, porosity and soil fraction. Range value of Soil resistivity was 50-800 Om. Soil porosity was 5-50%. The soil fraction component consists of coarse sand, fine sand and clay. Soil resistivity was inversely proportional to soil porosity. The high soil resistivity is likely due to the low soil moisture, causing generally campus area still open. Based on the soil fraction component, soil texture in the campus area tends to be Loam Sandy. It is good for aeration and water holding. This condition is very good for plant growth.

Effective Grounding of the Photovoltaic Power Plant Protected by Lightning Rods

This article discusses the lightning protection performance of a grounding grid for photovoltaic (PV) systems protected by independent lightning rods. Several grounding grid configurations are investigated, and the transferred voltages between the dc cables and supporting structures at different points in the PV system are evaluated using the finite difference time domain (FDTD) method. In the PV system without a dedicated grounding grid for supporting structures, the transferred voltage is very high, and is even worse if the soil resistivity is high. Installing a dedicated grounding grid, which is very costly in a large PV power plant, can reduce the amplitude of the transferred voltage and eliminate the residual voltage effectively. It is found that the arrangement using a bonding network is superior to other grounding improvement approaches in lightning protection. More importantly, the proposed approach is simple to implement and cost-effective. With the bonding network, the soil with high soil resistivity will not lead to severe overvoltage in the system. It is highly recommended to be adopted in the PV power plant protected by independent lightning rods.

Lightning Protection of Overhead Distribution Lines Installed on High Resistivity Soil

Lightning Protection of Overhead Distribution Lines Installed on High Resistivity Soil

Assessment of grounding grid for enhancing wind turbine service sustainability

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.

Effect of Impulse Polarity on a New Grounding Device with Spike Rods (GDSR)

The characterizations of grounding systems subjected to high impulse conditions are known to be dependent on the polarity, current to peak time and discharge time, as well as the electrical properties of the soil, and the grounding electrodes themselves. It is therefore important to investigate the behavior of grounding systems under high impulse conditions under negative impulse polarity, and compare it with positive impulse polarity results. Experimental test results for the same grounding systems installed with various earth electrodes at several sites under positive impulse polarity have previously been presented. In comparison, this paper presents the results of negative impulse polarity injected on the same grounding systems. It is found that a significant difference between positive and negative impulse polarities is observed for the grounding systems installed at high soil resistivity.

Investigation of Novel DC Wind Farm Layout During Continuous Operation and Lightning Strikes

This paper proposes a novel layout for a grid-connected DC wind farm (DCWF) and investigates the performance under continuous operation and direct lightning strikes particularly for high soil resistivity. The DCWF employs internal dc grid that supplies generated power to the host AC utility through high voltage direct current (HVDC) transmission link. The proposed layout ensures sustainability of power supply against potential interruptions of DCWFs either during normal conditions or lightning incidents to comply with grid codes regulations. During continuous operation, the proposed layout safeguards the entire DCWF cables against flow of return currents to avert derating of conductor ampacity. Besides, protects WT nacelle switchgear and entire interface converters against hazards of surge currents. Furthermore, an effective grounding system design is proposed to introduce a low impedance path for system return currents, minimize voltage drop across grounding impedance and thus maximize DCWF delivered power to the grid. A detailed system that sufficiently represents models of system cables, grounding network and interface converters is built to verify the proposed scheme significance. The obtained results assure the capability of proposed layout to cease return currents via cable sheath during continuous operation and provide superior mitigation of lightning-associated transient voltages and currents.

Sustaining electrification service from photovoltaic power plants during backflow lightning overvoltages

Photovoltaic (PV) systems are subjected to lightning strikes that contribute to losing their sustainable electrification service. Furthermore, they are subjected to backflow lightning overvoltages due to the installation in high soil resistivity areas, however, such the study is not aforementioned well in the literature. Therefore, the analyses and reductions of backflow lightning overvoltages are investigated in this paper, considering a PV power plant as an example installed in Taif city, KSA. All PV plant components are modeled using high-frequency models, in which they are such as air-termination, grounding system, surge protective devices, PV string, inverters, underground cables, and power transformers. To decrease the lightning overvoltages in the PV power plant, a modified PV grounding system design is introduced and evaluated. The evaluation is performed considering step voltage profiles using COMSOL Multiphysics and backflow lightning overvoltage magnitudes at different points in PV plant using ATP/EMTP. The results provide the motivation of studying backflow lightning overvoltages in PV plants and evidence of the efficacy of the proposed grounding system design in reducing the overvoltage magnitudes.

Comprehensive Design of an Earthing System for Broadlands Hydropower Station Switchyard

Broadlands Hydropower Project (BHP) harnesses the last hydropower potential of Kehelgamu-Maskeli Oya rivers with an installed capacity of 35 MW and 126 GWh annual energy generation. Excavation of the powerhouse switchyard site exposed to a bedrock formation with highly weathered granitic gneiss beneath a thin layer of scum soil top, resulting in an irregular high soil resistivity profile. Therefore, the main purpose of this research is to design a safe and effective grounding system for the switchyard of BHP, which can carry fault current into the ground without exceeding tolerable ground potential rise, ensuring the desired operation of protective & control devices so that not to endanger human & equipment. Owing to the nature of non-uniform high soil resistivity and limited land space for extension, this has become a great challenge. Research used two approaches, guidelines of conventional IEEE 80-2000 standards and Finite Element Method (FEM). Initially, resistivity measurement was conducted covering the entire area of concern. A soil model was prepared using orthodox horizontally stratified two-layer soil model using Sunde’s graphical technique based on measured data. Then the grounding grid was designed adhering to guidelines given in IEEE 80:2000 standard and observed high overall grid resistance, eventually exceeding the tolerable step and touch potential levels. Thereafter a soil model was prepared based on FEM which facilitates plot of accurate and smooth surface voltage distribution over the entire switchyard area. Applying fault current to these discrete finite elements and based on the first principle of Kirchhoff’s current distribution balance, the localized voltage distribution has been developed for the entire area and plotted using a self-developed MATLAB computer program. FEM model can trace the points where the touch and step potentials exceed safe limits in two-dimensional stratified grid, estimation of voltage gradients at boundary areas, which all are unable to track using conventional IEEE method. Accuracy of the model can further be increased by reducing the size of the soil element. Finally, several sensitivity studies were conducted so as to optimize the BHP switchyard grid design ensuring safe grid operation.

A Guideline on Designing a Safe and Appropriate Grounding System: A Review of Selected Papers

This study to review scientific articles from some of the international journal, published from 2005 to 2017. This study focused on articles that discuss how reduce grounding resistance. The article is discussed systematically, criticized, and analyzed. To secure the system from the disorder, we need to design a system. This system was later known with the grounding system. The criteria used in the review journal is focused in terms of: how reduce grounding resistance with electrode be planted a single or parallel, giving conductive material/reducing material, including some of the methods used in reduce grounding resistance specific to regions with high soil resistivity, and the obstacles faced. The discussion on the above issue is a major problem in the article. The article that reviewed published in language of United Kingdom from 2005 to 2017. The analysis of reviewing 20 journal produces two staples of the discussion is existing problems in the grounding system and optimal way in reduce grounding resistance. The reduction of resistance on the location of the grounding that have very high soil resistivity needs to be done, some way is offered in several articles that are discussed so that it could be a guideline the planners in designing a grounding system that is safe and appropriate for the system to be secured.

ANALISIS PERANCANGAN SISTEM PEMBUMIAN PADA GARDU KA 3267 DI PERUMAHAN NUSA DUA HIGHLAND

Planning for the grounding system of KA 3267 substation which has land limitations but has high soil resistance (?). High resistivity soils are required using plate, grid or mesh earthing systems. The purpose of this study was to find out an appropriate earthing system for securing the 3267 KA substation of its equipment. The results of measurements of soil resistance around the 3267 KA distribution substation in Nusa Dua Highland Housing in average >2 ? so that the prisoner soil type ? 251.2 ?-m. Based on the amount of resistance of the soil type, the recommended earthing system is the plate and grid earthing system. From the results of the calculation analysis, that the plate grounding system found 13 plates of 2 m x 1 m installed with a total cost of Rp. 33,800,000. While the earthing of the grid system is obtained a total grid length of 1000 m at a depth of 2 m in parallel to 3 grids at a cost of Rp. 38,690,000. The chosen earthing system is the more economical one, the plate system. To secure KA 3267 distribution substation in Nusa Dua Highland Housing with a resistivity value of 4.594 ? (? 5 ohms) for the type of limestone soils using a plate earthing system in parallel as many as 13 plates.

APPLYING ELECTROMAGNETIC FIELD ANALYSIS TO MINIMIZE THE EARTH RESISTANCE ON HIGH RESISTIVITY SOILS

Different optimization strategies to reduce the earth resistance in a high resistivity soil are discussed in this work and illustrated with a practical example. Finite Element simulations reproducing real-world conditions in terms of structure design and soil profiles have been made to evaluate the improvements that should be adopted to minimize earth resistance. We analyze an example of an earthing system of an array of four identical telescopes installed on high resistivity (k Omega. m order) soils with two different behaviors. In the first one, current dissipation occurs in an uniform soil. In the second one, a terrain with four layers of different resistivities is considered. This situation corresponds to a real world case of an observatory constructed in a volcanic terrain. It was found that the best strategy in each case differs: extend horizontal electrodes as far as possible from the foundation in the first case and combine these electrodes with buried vertical electrodes that connect with deep high conductive layers in the second. The results are discussed in terms of the achieved improvements depending on the modifications introduced in the main structure.

Sensitivity analysis of a single phase to ground fault system in connection with high impedance faults: A case study

Most of High-impedance faults (HIFs) occur due to broken conductors falling on high-resistivity desert soil in United Arab Emirates remain undetected due to incredibly low fault currents and endang...

Factors Determining the Effectiveness of a Wind Turbine Generator Lightning Protection System

As a result of the growing supply and demand for wind power, wind turbine generators are increasingly being installed at suboptimal sites that have high soil resistivity and high incidence of lightning strikes. This means that lightning protection systems for wind turbines are becoming a critical component of wind farm design. Not only do effective lightning protection systems ensure the safety of the physical wind turbine structure and human operators, they also protect the electrical and control systems installed inside wind turbine generators and safeguard the lives of human operators. This paper presents a framework to assess the effectiveness of wind turbine lightning protection systems at the wind farm design phase. Performing the analysis at this early stage reduces lightning-induced downtime, which leads to increased energy yield. Our results show that the grounding system plays a critical role in the wind turbine lightning protection system. For this reason, we also analyze various influential parameters of a grounding system design. We present results from full-wave electromagnetic simulations of the complete wind turbine grounding system, including the foundation.

Evaluating the overvoltage performance of an overhead line taking into account the frequency-dependence of its tower’s grounding electrodes with high soil resistivity

The paper demonstrates the importance of taking the frequency-dependence of the tower grounding impedance into account when studying the lightning performance of an overhead line located in an area with high soil resistivity. Towers’ impulse grounding impedance measurements and their rational approximations are used to construct a wideband model of the towers’ grounding electrodes in an EMTP-type software program.In order to examine the impact of tower grounding impedances, simulations of lightning strokes to the overhead line tower were performed using an EMTP-type tool in the following three different cases: constant grounding impedance of the tower hit by a lightning stroke, frequency-dependent tower grounding impedance and frequency-dependent tower grounding impedance for the tower equipped with a Line Surge Arrester (LSA) installed at the lowest phase.The simulations have shown the influence of the frequency-dependence of the tower grounding impedance on the level of the build-up voltage across the tower’s insulator string and consequently on the flashover occurrence in the observed configuration with a high soil resistivity.