Research On Under Complex Conditions Grounding System

The grounding system is one of important components of power system, to which much attention is always paid. There are two main functions of grounding grid:(1)Providing a benchmark ground;(2)When the power system fault occurs, it can let the non-normal current go quickly to curb the greatest potential of grounding unlimited increasing which is very important in equipment and personal protection.Therefore, correctly realizing the lightning transient performances of grounding devices is the fundament of lightning protections of power systems.The main work of this paper has the following aspects:(1)This paper introduces an intermediate amount of ground parameter calculation Green’s function, analyze its importance and its derive formula to solve.(2)This paper introduces the genetic algorithm detail, followed this a physical model for earth structure is established based on genetic algorithm and mathematical formulas, this laid a theoretical foundation of ground system.(3)Utilized by Fourier transform, the impulse current is changed into different components of frequencies. The calculation method for grounding systems regarded as an unequipotential is based on method of field-circuit coupling theory. The current response of grounding grid can be calculated in these frequency components. Finally the time-domain response and the impactive grounding impedance can be received by Fourier inverse transform.(4)Otherwise, the methods discussed in this dissertation are applied to analyze the lightning impulses grounding grids. Detailed conclusions about the impulse characteristics of grounding systems under versatile grids size, soil, and grids tentative.