DESIGN AND OPTIMIZE SUBSTATION GROUNDING GRID BASED ON IEEE STD. 80 - 2000 USING GUI AND MATLAB CODES

摘要

Substation grounding grid design requires a simple, but accurate tool to compute the parameters that guarantees safety of personnel during earth faults. In this article, a Graphical User Interface (GUI) with an interactive computer program using MATLAB 7.10 version has been developed. The developed tool allows the computations of the total grid conductor length required for the earth grid to meet the step and touch potential criterion for safety. The interactive method versatility has allowed configuring the grid according to the availability of land space and value of the native soil resistivity. Calculations of minimum cross sectional Area of grounding conductors are presented. Simple Optimization technique using iterative search are applied to optimal design of grounding grid (conductors and rods as well) to satisfy tolerable safe touch and step voltages. Inequality constraints of ground potential rise (GPR), ground resistance (Rg), step voltage (Estep) and touch voltage (Etouch), are based on latest edition of ANSI/IEEE Std. 80-2000. The viability of results of developed tool are compared with world-wide softwares like ETAP and CYMGRD and showed to be reliable, friendly user interface, easy and practical tool for calculations of Ground grid design. All approved shapes (Square, Rectangle, Triangle, L and T shapes) based on IEEE 80 guidelines and procedures are implemented and tested. Executable versions may be obtained after generating C/C++ plus header files code from MATLAB codes to run standalone.