Grounding Grids for High-Voltage Stations
ABSTRACT Grounding grids are used in high-voltage stations when rocky ground makes the use of driven ground rods impractical. The characteristics of grounding grids are investigated in this paper, and the results are applied to the basic design elements of this type of grounding system.
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ABSTRACT: Referring to the 1976 edition of IEEE Std 80, this paper examines the basic premises of IEEE gradient method and of simplified equations for determining the touch and step voltages in the corner mesh of a grounding grid. Re-examination of the prirncipal assumptions yields a new simiplified formula for Km which performs the calculation with less error. A beneficial effect of ground rods is evaluated in view of the present equation for the current irrregularity factor Ki. A brief analysis of the effect of a crush-stone overlay upon the allowable surface voltage above and beyond a grounding grid, is also icluded. A review of work done by others related to the methods of Std 80 includes a discussion of equations and of some critical aspects involved. A computer-produced series, comparing the performance of the old simplified and non-simplified equations for-Km with the improved ones and with the equations suggested by Thapar and Nagar, Zuker- man, Zink, and Nahman, concludes Part I of this two-part report. Its purpose is to provide a framework for updating and refining Appendix of the Guide which is presently under revision.IEEE Transactions on Power Apparatus and Systems 02/1984;
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ABSTRACT: The paper presents graphical data for the calculation of ground grid resistance, corner mesh potential and corner step potential for a restricted class of ground grids. The restricted class of ground grids are similar to those considered in the IEEE Guide for Safety In Substation Grounding, IEEE Standard 80-1976, where the primary restrictions are uniform soil, rectangular grid shape, and uniform conductor spacing. The data presented represents the computer analysis of over 2,385 ground grid configurations using the method of moments (also called a finite element analysis) computer algorithm GRID developed at Georgia Tech under EPRI sponsorship. This computer algorithm has been validated with several field measurement programs. The graphical data is for square grids with square meshes. Simple equations are presented to extend this data to rectangular grids with rectangular meshes.IEEE Transactions on Power Apparatus and Systems 10/1983;
Conference Proceeding: A review of methods for grounding grid analysis[show abstract] [hide abstract]
ABSTRACT: This paper presents a brief review of the most important methods available for the grounding grid analysis. This includes numerical methods intended for the grounding grid direct current, time-harmonic current and transient current energization. Emphasis will be given to the methods involving transient grounding grid analysis. Available numerical methods will be surveyed according to the implemented soil model, e.g. homogenous soil, horizontally and vertically stratified multilayer soil as well as exceptionally heterogeneous soil. In that regard, various possible treatments of the boundary between soil layers are discussed. Here, image methods feature prominently in a solution to this problem. Whence, several possible image methods are reviewed. Additionally, numerical methods are surveyed according to the theoretical background approach. Here, one can make a clear distinction between circuit approach, transmission line approach, electromagnetic theory approach and hybrid approach. Numerical methods for the transient analysis of grounding grids are also reviewed in regards to the domain of the solution. Therefore, they could be regarded as frequency domain and time domain methods. Fast Fourier transform algorithm is seen as a conventional way of crossing between frequency and time domains. Major advantages and disadvantages of both approaches are pointed out as well.Software, Telecommunications & Computer Networks, 2009. SoftCOM 2009. 17th International Conference on; 10/2009