We use skms stateoftheart groundmat software module and accurately determine the touch and step potentials. Earthing grid, is an arrangement in a plant which is very important for a few reasons, all of which are related to either the protection of people and equipment andor the optimal operation of the electrical system. Bs7354 1990 code of practice for design of high voltage open terminal stations. Etap is the most comprehensive enterprise solution for design. Grounding design calculations part sixteen electrical. A vertical rod is more effective electrode than a horizontal rod. National grid substations technical specification ngts 2. I am trying to design a ground grid, but i need to add a ground well a ground rod that is driven deep enough till it is in water, e. Ground grid design jghrist electrical 14 apr 08 08. Geometry of grounding grid with data relevant in this study this first iteration is without additional rods e. Etap model for earth mat design etap model for earth.
There are a variety of national and international standards available, which provide empirical formulae for the calculation of earthing design parameters and shock potential safety limits. Fault current computations may be obtained from the owner or calculated by ees consulting. Optimal substation ground grid design based on genetic algorithm and pattern search by qianzhi zhang a thesis presented in partial fulfillment of the requirements for the degree master of science approved november 2014 by the graduate supervisory committee. Subsequent chapters cover the types of voltages that must be addressed and how to design a ground grid. A simplified method for calculating the substation grounding grid resistance article pdf available in ieee transactions on power delivery 92. From the past, ground grid design without rods and with rods was carried out.
Jul 25, 2017 the isolated ground is a separate wire connected directly to the ground terminal of that device and goes back to a panel not necessarily the panel that feeds that receptacle, may be upstream panel. The primary objective of ground grid design is to ensure. Etap facilitates an engineer to carry out ground grid design as well as analysis with considerations specified in various standards such as ieee801986, ieee802000 and ieee6651995. Bhuj, india abstract substation grounding is a critical part of the overall electric power system. Hence substations in general can be considered as heart of overall power system. Substations volume x grounding a pdh online course. Here, the design uses etap electrical transient analyzer program software. Identifying and implementing costsaving design practices 3 fault magnitude the magnitude of the fault current into the earth via the substation ground grid is directly proportional to the ground potential rise gpr at the substation. Analytical methods for earth surface potential calculation. The epr is caused only by the current injected into the ground by the earthing grid. Student 2,3assistant professor 1,2,3 department of electrical engineering 1, 2, 3 g. The rod length is varied to determine the influence of rod length on gpr, furthermore, when the soil structure is twolayer structure, the optimum ground layer. In a uniform soil, the resistance can be calculated with an acceptable accuracy.
Chapter 1 is a general discussion of grounding issues. Earth grid impedance an accurate understanding of the earth grid impedance is critical to correctly assess the earthing system. Conductors a substation earthing grid will consist of a earthing system of bonded cross conductors. Earth grid commissioning for new electrical systems routine earth testing for preexisting systems high voltage safety compliance audits accreditations asnzs2067 asnzs3007 1016 0 267 373 earth grid design and testing. Photogrammetric control gps north dakota department of transportation, design division julian daysession no. A large grid in poor sandy rocky soil can be less effective, than a much. Calculationofimportantdesignparametersforgroundingsystemsi. Chapter 4 presents the initial design of the grounding system. It uses a generalpurpose finite element algorithm for potential analysis and graphical facilities to validate ground system efficiency. Grounding design calculations part fourteen electrical. After satisfying the step and touch voltage requirements, additional grid and ground rods conductors may be required. Integrated grounding, equipotential bonding and lightning. Omega red group are the uk market leaders in the specialist design, supply, installation, testing and maintenance of electrical earthing and lightning protection systems.
Abstract the main purpose of this paper is to acquaint the reader with various types of grounding systems prevalent in an electrical substation and their importance. The comparison between theoretical values and experimental values for various types of grounding grid performance at fixed depth is carried out 5,6. In this video, i mentioned the basic steps for designing power substation grounding grid using custom codeprogram made under matlab environment. For calculation of this current grid resistance and fault resistance are assumed to be zero. Etap model for earth mat design etap model for earth mat design. Site soil resistivity, the amount of earthing electrode in contact with the soil. International journal of engineering trends and technology. Optimal substation ground grid design based on genetic. Subsequent chapters cover the types of voltages that. Appendix f north dakota department of transportation. Effective grounding system design is important as it deals with. Design of grounding system for an electrical substation. Ees consulting provides ground grid design as part of the substation design based on ieee standard 80.
Therefore, the design is based on single line to ground fault current. Safety design of ground grid in distribution substation. Determination of maximum grid current a single line to ground fault is more common and causes more fault current as compared to a double line to ground fault. The ground grid systems module enables engineers to quickly and accurately design and analyze ground protection. Substation grounding design challenges and lessons learned.
Substations volume x grounding a pdh online course for. In a uniform soil, the resistance can be calculated with an acceptable accuracy using several simplifying assumptions 37. Earthing design of 11kv and 33kv rural substations in the uk. The cost optimal solution is picked up from the set of feasible solutions obtained and given in table 2. Soil testing and soil data is typically provided by others. The configuration of an installation of ground rod will be buried at 4 edges and the diagonal lines of the ground grid. Oct 30, 2012 in this video, i mentioned the basic steps for designing power substation grounding grid using custom codeprogram made under matlab environment.
The size of the soil model is calculated as a multiple of the grounding grid size and is closely dependent on the accuracy of calculations. Division of grid into smaller windows is not appropriate in the first design iteration. Flexible design methodologies allow for quick autodesigned layouts or very detailed schemes. Substation grounding grid design case study using matlab vikram patel1 a. Sonagra3 1pg student 2, 3assistant professor 1 2 3electrical department, g. Cold sites do not require any special design principles and the touch and step voltages are deemed to be safe by inference. Therefore, this number should be as close to the realworld. Successful operation of entire power system depends to a considerable extent on efficient and satisfactory performance of substations. Calculationofimportantdesignparametersforgroundingsystemsinsu.
The isolated ground is a separate wire connected directly to the ground terminal of that device and goes back to a panel not necessarily the panel that. To reduce step and touch voltages and to achieve an appropriate shielding effect about 20 db in the lightningrelevant frequency range however, a further reduction of the grid. Investigate of design and its details studies compute of fault current magnitude and duration ig, tf compute resistive of network grid rg, lc, lr control for network voltages and allowable range ig. Access above ground level shall be from mobile or fixed platforms though the latter may be accessed by. The distinguishing characteristic of a multipoint ground is the use of many interconnected grounding conductors into a loose grid configuration. For comparison of the calculations done by both techniques, the obtained results are shown in table 3. A ground grid mat study will determine if your substation grounding grid design is safe and will limit the touch and step potential to values below the ieee 80 standard ieee guide for safety in ac substation grounding limits. Two other important design parameters, which depend upon the value of the ground. Ground grid systems software ground grid design ieee 80. It is designed to help optimize grid design or reinforce existing grids of any shape.
In high and medium voltage air insulated substations ais the electromagnetic field, which causes are the static charges of bare cable and conductors and by the atmospheric conditions surges, induce voltages at nolive parts of the installation that create potential differences between metallic parts and ground and also between different points of. The fence is connected to a separate grounding conductor. The proper grounding of a substation is essential and very important for the following two reasons. High efficient multicore parallel calculation allows fast analysis of irregular largescale renewable applications. Power station grounding grid design using field methods. Bs 7354 code of practice for design of highvoltage openterminal substations. Design of earthing grounding system in a substation grid. Part 3 c ode of practice for the design of industrial type stairs, permanent ladders and walkways. Pdf design and analysis of substation grounding grid. Computer aided design of transformer stations grounding. Substation engineering power grid engineering, llc. All the ground rods are directly connected to the main ground grid by the exothermic welding method.
Power station grounding grid design using field methods 39 parameters as the construction materials of the grounding grid. Pge is committed to high quality services using a combination of internal and strategic external resources, and is ideally suited to the engineering, construction and design of power substations. This rise in voltage of the grounding grid is referred to as the ground potential rise gpr, and is proportional to the magnitude of the fault current, and the ground resistance of the grounding grid. Skm groundmat is a program for substation ground grid design and analysis. Whitepaper substation grounding identifying and implementing. The grounding grid provides a common ground for the electrical equipment as well all the metallic structures in the substation. The substation grounding system is an essential part of the every electrical system.
In general, it consists of a mesh of interconnected cylindrical conductors, horizontally buried and supplemented by ground rods vertically thrusted in specific places of the installation site 1. Grounding design calculations part sixteen electrical knowhow. Effects of ground grid configuration of two neighbouring. The cymgrd software is a substation grounding grid design and analysis program specially developed to help engineers optimize the design of new grids and reinforce existing grids, of any shape, by virtue of easy to use, builtin danger point evaluation facilities. The uniform and two layer soil structure for substation ground grid design is mostly used in india 4,5. This gives faults a lowresistance path through the concrete to the earth. Grounding of electrical substations for safety and neutral point by ground rods provides the lowest. Design of charts for ground resistance calculations of driven rods system in uniform and nonuniform soils o. Index terms electrical substation, engineering design, grounding systems, grid resistance, ground potential rise, mesh voltage, step potential, touch potential i. A multipoint ground is an alternate type of electrical installation that attempts to solve the ground loop and mains hum problem by creating many alternate paths for electrical energy to find its way back to ground. The cross section of the ground grid conductor is 240 mm 2, the grid dimension is 3m. Cost effective grounding grid design for substation. Rg pdf available in ieee transactions on power delivery 92.
Design of charts for ground resistance calculations of. Tylavsky, chair john undrill raja ayyanar arizona state university. Chapter 2 explains ground fault currents and chapter 3 covers grounding conductors. Grid design procedure we are assuming some data of substation for this case study and a computer modeling was developed to carry out the substation grounding grid design. Substation grounding grid design case study using matlab. Moreover, this software also provides finite element modeling fem of the ground grid for detailed analysis. The dimension of ground grid which presents the status of. Abstract substation grounding is a critical part of the overall electric power system.
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