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This paper deals with an analytical solution of the time domain Pocklington integro-differential equation for the transient current flowing along the horizontal grounding electrode of finite length. The electrode is excited with an equivalent current source representing the lightning strike current. Presence of the earth–air interface is taken into account through the formulation, via simplified reflection coefficient arising from the modified image theory. The analytical solution is carried out using the Laplace transform and the Cauchy residue theorem, respectively. Results obtained by the analytical solution are compared to those calculated using numerical solution of the corresponding frequency domain Pocklington equation in conjunction with the Inverse Fast Fourier Transform. The results obtained via different methods agree satisfactorily. [ABSTRACT FROM PUBLISHER]

The calculation of voltages induced by external electromagnetic fields on multiconductor transmission lines (MTLs) has been the subject of several studies. In this paper, discrete equations for MTLs exposed to incident fields are derived based on the time-domain finite-element method and the backward differentiation formula. Based on these equations, a value-delivery table characterizing the MTLs is presented. Combining this table with modified node analysis formulation, it is convenient for analyzing the responses of transmission lines composed of complex termination networks or complex transmission-lines networks. The validity and efficiency of the proposed algorithm is demonstrated using several examples. Finally, a 1-km 35 kV overhead line above an imperfectly conducting ground is studied, and the influences of ground wire and a metal-oxide arrester to the lightning-induced voltage are both discussed. [ABSTRACT FROM PUBLISHER]

This paper presents a new approach for modeling of electrically thin conductive shields in the finite-difference time-domain (FDTD) method. The method is based on representation of the relation between the fields at two faces of the shield as an impedance boundary network condition (INBC) in the frequency domain. The INBC includes frequency-dependent self and mutual impedances which are approximated by series of partial fractions in terms of real or complex conjugate pole-residue pairs. A discrete time-domain INBC at the shield is generated, which is then incorporated within the FDTD method. The primary advantages of the proposed approach are: 1) the convolution equations are not used in the formulation, 2) the approximation applied for discretizing the Maxwell equation has second-order accuracy in time and first-order of accuracy in space, and 3) the stability of the method is governed by the classical Courant Friedrichs Lewy stability condition. Numerical examples are presented to validate the new method and to demonstrate its efficiency and accuracy. [ABSTRACT FROM PUBLISHER]

A procedure to synthesize a suitable biphasic composite material from the given Shielding effectiveness (SE) specifications is proposed herein. In particular, this paper presents an analytic approach for calculating parameters of a Debye-like equivalent homogeneous material, which meets the SE requirements in given frequency range. Establishing the relationship of the SE with the intrinsic material and morphological properties of a composite will make it possible to effectively find an equivalent homogeneous lossy Debye-like material model, starting from the given SE frequency characteristic. The Maxwell Garnett mixing rule is used to synthesize a composite made by aligned cylindrical inclusions. A few examples of how this procedure works are presented; validation by time domain numerical simulations is provided. [ABSTRACT FROM PUBLISHER]

This paper presents a new approach for modeling nonuniform lossy transmission lines. The proposed technique is based on the concept of Green’s function of the differential problem represented by the Telegrapher’s equations. The Green’s function of nonuniform one-dimensional problems is expanded in terms of the eigenfunctions of the uniform problem, yielding a rational macromodel that has a simple representation in the time-domain. The use of global basis functions also addresses the problem of space dependence of the per-unit-length parameters, completely avoiding to resort to any discretization technique. Several examples of single and coupled nonuniform lines are presented and the accuracy of the method is verified by comparison with reference results. [ABSTRACT FROM AUTHOR]

In this paper, a general domain expression is developed to calculate the horizontal electric field at the ground surface. The expression satisfies stricter conditions than the Cooray–Rubinstein (C-R) and Wait formulae. We proved that the new expression can be reduced into the first approximation of the C-R and Wait formulae. An evaluation that utilized the numerical results obtained by the three formulae was conducted to investigate the error caused by the assumptions made in the C-R and Wait formulae. Finally, the approximate method proposed by Caligaris, Delfino, and Procopio was utilized to evaluate the new formula and the C-R formula through comparison with the results obtained conventionally using the C-R formula. [ABSTRACT FROM PUBLISHER]

The time-domain counterpart of the Okoshi’s contour integral method is formulated with the aid of the reciprocity theorem of the time-convolution type. A numerical procedure for solving the time-domain reciprocity relation is proposed and validated using an analytical solution based on the eigenfunction expansion and the finite-integration technique. For the former, the time-domain counterpart of the classical double-summation formula for a rectangular power-ground structure is found and evaluated. [ABSTRACT FROM PUBLISHER]

A new subcell finite-difference time-domain model is presented to solve shielding problem. The field penetration through the nonperfectly conductive shield is modeled by two-port network equations in terms of frequency-dependent admittances which are rationalized by the vector fitting procedure. The resulting equations are used to synthetized an equivalent linear time invariant circuit which is analyzed directly in time domain without using convolution equations. This important aspect is the main novelty of the proposed procedure. [ABSTRACT FROM AUTHOR]