الفهرس 
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Abstract
With the incessant increase of power systems capacity and voltage grade, the safety of grounding grid becomes more and more prominent. In every electrical installation, one of the most important aspects is the adequate grounding; more specifically the grounding of high voltage substation. Grounding, generally mean an electrical connection to the general mass of earth, the latter being a volume of soil, rock etc. whose dimensions are very large in comparison to the electricity system being considered. It is worth noting that, in Europe they tend to use the term “Earthing” whilst in North America, the term ”Grounding” is more common. Grounding system is one of the most important parts of the power plants and substation systems design, the main purpose of power system substation grounding grids is to maintain reliable operation and provide protection for personnel and equipment during fault conditions. In any substation planning, economical and effective grounding system plays an essential role since absence of effective grounding grid can result in mal-operation of protective devices and hazardous for operators and substation equipment. Therefore, in this thesis, evolutional technique for unequally spaced grounding grid design is suggested. The design is based on hybridization of Optimum Compression Ratio (OCR) and Particle Swarm Optimization (PSO) techniques. This new approach is purposed to control the grounding copper volume of the grounding system with the aid of controlling of unequally spaced grounding conductor lengths with respect to the safety measures. The proposed technique offers almost 20% of copper savings comparing with the optimum compression ratio method. It is found that each grid has its own OCR depending on the meshes number. Comparisons are done between grounding system using OCR technique, IEEE Std 80-2000 method and particle swarm optimization technique. The step, touch and ground potential rise are calculated and drawn in three dimensions’ graphs.