Assessment of earthing system location for wind turbines using finite element method

Abstract

A new proposal for the assessment of earthing system location used for wind turbines is presented. This proposal depends on the simulation of the electric field as well as the calculation of current density at the ground surface above the earthing system and distribution inside the soil when the wind turbine is exposed to high voltage. The electrical potential simulation around the earthing system of wind turbine using ring earth electrode with and without auxiliary vertical rods was also studied. Accurate calculations and simulation of the electric field are prerequisite for the simulation of current density. The electric field distribution is obtained by calculating the electric potential in three-dimensional domain surrounding the earthing system using Finite Element Method. The boundary conditions satisfy both Dirichlet's and Neumann's equations. The simulated electrodes are energized with one per unit voltage to be available for different types of applied potential. The resistance of the earthing system is calculated. This simulation model shows reasonably close agreement which gives confidence in predicting the assessment of the earthing grid location which is around 66.6% out of the total depth length of the affected domain. Different types of soils were checked to satisfy this ratio of the location assessment. The results showed that the vertical component of electrical field intensity and current density were improved at the assessment location of the earthing grid.