In this paper, we propose an efficient modeling technique for incorporating surge arresters in finite-difference timedomain (FDTD) simulations of lightning-induced disturbances in power networks. Instead of using piecewise linear approximations for the V-I curve of an arrester, as usually done in the literature, we derive new updating equations for calculation of electric field components required at each FDTD time step. This is done in a semi-implicit manner where we first obtain a time-stepping relation of electric field based on the V-I curves of the arresters. The time-stepping relation in each time step is solved by the NewtonRaphson method to update the electric field components. The proposed technique is implemented into a nonuniform parallel FDTD code, which is used to simulate a three-phase distribution line of about 800 m equipped with lightning arresters and a neutral wire, installed at the International Center for Lightning Research and Testing at Camp Blanding Florida. The results of FDTD numerical simulations are found to be in excellent agreement with experimental data associated with triggered lightning.

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Purpose Tall towers have a high potential for being struck by lightning which is a major source of electromagnetic radiation with adverse effects on electric, electronic and telecommunication instruments. The paper aims to present an accurate method for predicting the radiated electromagnetic fields and current distribution along the lightning channel and the tower hit by the lightning. Design/methodology/approach The electromagnetic model is utilized to model the lightning channel and the tower is represented by lossy conducting wires. The finite difference time domain (FDTD) method is used to solve for the governing Maxwell’s equations. Due to the large computational space, the FDTD code is paralleled between several computer processors. To enhance the efficiency of the code, a non-uniform mesh is used, reducing the mesh length in the air-ground interface. For model evaluation, simulated current distribution along the lightning channel and tower, and the radiated electromagnetic fields are compared with the measurement data and those obtained using the engineering models. Findings The proposed modeling technique has proved to be more accurate than the conventional methods, particularly in the prediction of current distribution along the tall tower and the vertical component of the radiated electric field. Originality/value The main feature of the proposed technique is its ability to consider the impact of metallic structures in a large space around lightning channel on the predicted radiated electromagnetic fields, having no concern on computer memory requirements.

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