Modeling Large-Size Round Steel Plates With Surface PEEC Method for Lightning Transient Analysis

The round steel plate is the basic component of the external floating roof tank structure. Modeling large-size round steel plates is essential for analyzing the lightning response of external floating roof tanks. This article builds time-domain equivalent circuit models for round steel plates excited by the lightning current. First, a meshing scheme is presented to generate sector and cylindrical surface cells, which make use of the distribution characteristics of the currents and voltages on the round steel plates. Then, the surface partial element equivalent circuit (PEEC) approach is applied to model the plate. A method of calculating the equivalent surface impedance is proposed, which converts the frequency dependence of the skin effect into impedance based on the time domain. Finally, the time-domain surface PEEC approach is validated by the indirect time-domain solution based on the Fourier transform and the commercial software using the finite-difference time-domain technique, respectively. The comparisons show that the calculation results of different methods are consistent with each other. However, the proposed method in this article can greatly enhance the computational efficiency while meeting the accuracy requirements. It has great significance to the study of lightning protection for external floating roof tank.