Design and Optimization of Substation Grounding Grid for Ensuring the Safety of Personnel and Equipment

Abstract

Appropriate design of a substation grounding grid keeping in view of safety of equipment and personnel working area in or walking close to the substation is of great importance. Several steps are involved to design and developed a safe, effective and optimized grounding grid. IEEE Standard 80-2000 explains the terminologies, definitions, formulas and act as an important guide for substation grounding grid design. To date a number of substations grounding grid design intelligent software have already been developed by engineers of many commercial enterprises which takes well care of safety, reliability, continuity of services and optimization of the design. Such a software, e.g., Electrical Transient Analyzer Program (ETAP) has been utilized in this study which has achieved optimization in substation grounding grid design ensuring safety of personnel and equipment. The study utilized the Finite Element Method (FEM) of Ground Grid System (GGS) module of ETAP in combination with Sverak's variable space technique and showcased that 63.88% copper saving of ground rods could be achieved in comparison with a reference study of substation grounding grid. The method thus has become a very effective tool in substation grounding grid optimization.

Simulation of electromagnetic processes in the grounding system with a short circuit in the operating high-voltage substation

“…Literature analysis. Several works [4][5][6][7][8][9][10][11][12] are devoted to the issues of modeling electromagnetic processes that occur in the GS during the flow of emergency currents. In most cases, a mathematical model of the GS located in two-layer soil is used (in particular, with the help of [7], more than 1000 power facilities of Ukraine with voltage classes of 35-750 kV were calculated, and the software package [9,10] based on it is one of the most commercial versions popular in the world).…”

“…The method of integro-differential equations is based on the analytical solution of the problem of the electric field potential of a point current source [6,7,[9][10][11][12][13]. Programs based on this method with a two-layer electric soil structure are used to carry out calculations by the world's leading scientific research institutions and following the international standards IEEE Std.…”

“…From the existing world analogues [7][8][9][10][11][12] for determining the NP of GS of operating power stations and substations when the GS is located in three-layer soil, this software package is distinguished by:  the calculation of the electric field is based on the analytical solution of the problem of the electric field potential of a point current source in a three-layer half-space;…”

“…To create a calculation model the «LiGro» complex, in contrast to [7][8][9][10][11][12], has ample opportunities and allows to:  set in any node (see Fig. 6) its individual properties (voltage class, short circuit location, touch point, service point, experiment measurement point, neutral with setting the current in the neutral for each voltage class, base resistance, initial current in the node);…”

“…A working window of the software for multi-layer soils interpretation «VEZ-4A»  for the first layer at a depth of up to 1,6 m -34,5 ×m;  for the second layer at a depth from 1,6 m to 8,1 m -5,5 ×m; for the third layer at a depth from 8,1 m -1,85 ×m.To compare the calculation results with two-layer models, in particular, the IEEE model, the three-layer soil structure was reduced to an equivalent two-layer model: for the first layer at a depth of up to 1,9 m -29,39 ×m;  for the second layer at a depth from 1,9 m -2,37 ×m.The given initial data were entered into the «LiGro» software package, and a model of the GS of the studied substation was created. Fig.5shows the GS scheme, where the blue color indicates groundings located underground at the same depth, the green colorgroundings at varying depths, the purple/red colorbuildings and structures, and the metal construction of the substation equipment.To create a calculation model the «LiGro» complex, in contrast to[7][8][9][10][11][12], has ample opportunities and allows to:…”