Fast and Highly Accurate Algorithm for Calculating the Earth-Return Impedance of Underground Conductors

The earth-return impedance of underground conductors, whose expression was first derived by Pollaczek, is of particular importance for the study of the electromagnetic compatibility problems among the underground conductor system. In this paper, a fast and highly accurate algorithm is presented to calculate the Pollaczek´s integral. The high accuracy acquired by the proposed procedure is due to the fact that the tail of the Pollaczek´s integral is approximated by a sum of several exponential integrals, which in nature means that there is no truncation to the Pollaczek integral. The extensive comparison with published data indicates that the proposed algorithm is highly accurate and the computational time is reasonable.