An efficient technique for the evaluation of lightning-induced voltage in a cylindrical vessel containing charged oil

This paper proposes a numerical procedure, based on a mixed circuit-field approach to compute the transient and spatial potential distributions inside vessels containing flammable liquids, induced by a direct lightning strike. The circuit model is used to simulate the metallic vessel as an equivalent electrical network, which is solved by the SPICE simulator. In this way, it is possible to compute the transient potential distribution on the external vessel walls. These potential values are the boundary conditions of the partial differential equation system, valid at the inner of the container, which is solved by the finite-difference time-domain method. The model takes into account the transient and nonuniform volume charge density inside the liquid and the temporal accumulation of charges at the air/liquid interface. A validation of the proposed method, in the absence of liquid, is furnished. The transient and spatial distributions of the potential in the container are analyzed in order to detect possible hazards.