Efficient Evaluation of Earth Return Impedances of Arbitrary Conductor Arrangements With a Horizontally Multilayered Soil

The evaluation of the earth return mutual impedance of arbitrary conductor arrangements with a horizontally multilayered nonmagnetic soil is of great significance when the electromagnetic compatibility is concerned. To evaluate the earth return impedance accurately and efficiently, a semianalytical approach is proposed in this paper. With the proposed approach, the expression of the earth return impedance, which includes a complex highly oscillatory integrand, is divided into two parts, i.e., the definite and the tail integral. The definite integral is evaluated by using the moment technique and the tail integral is evaluated by using the exponential integrals with an asymptotic integrand. The numerical examples show that the proposed algorithm can evaluate the earth return impedance with various parameters and arbitrary conductor arrangements accurately and efficiently and the required computational time of the proposed approach is almost independent of the geometric and electric parameters.