Optimal Design of Grounding Systems of Electrical Networks

Abstract

With the growth of number and size of electrical networks, the need for an accurate and more versatile grounding system becomes more important. The importance of the accurate design is coming from both safety and financial considerations.

It is important that the substation ground has an effective grounding resistance, adequate current carrying capacity, and safety future for personnel and equipment.

To. design an accurate grounding system, it is essential to evaluate accurately the parameters of grounding system. The parameters of grounding system include modeling of soil resistivity, determining• the grounding resistance, calculating the step and touch potentials, and determining the size of grounding electrode.

Different methods with vanous techniques are presented over many years, to calculate accurately the grounding system parameters. The methods used may be analytical, computer-aided, or graphical method.

This thesis presents a comprehensive literature survey of the methods used to calculate the parameters of grounding system over about 25 years ago. The different methods are introduced exploring different assumptions, approximations, and the applied conditions of each method. Also the advantages and the disadvantages of each method, compared to the other methods, are •discussed. Our opinion of each method is remarked.

The measurement of soil resistivity is important m the design of a grounding system. The measurements cannot be used directly in the design.