Transient analysis of coaxial cables using the skin effect approximationA+Bsqrt{s}

Wideband Impedance Matching in Transient Regime of Active Circuit Using Lossy Nonuniform Multiconductor Transmission Lines

“…In general, the impedance is a nonlinear function of frequency. Thus, the description of the frequency dependent loss is introduced by using the widely used Nahman approximation of the internal impedance Z int (s) = A + B √ s as in [12] and Qingjian formulation of conductance [13], where s is the Laplace transform variable.…”

“…In time domain and according to the expression of Z int in [12], the convolution product Z int (z, t) * I (z, t) becomes:…”

“…The solution of these equations starts with an initially relaxed line having zero voltages and currents values. First voltages along the line are solved for a fixed time from Equation (16) in terms of the previous solutions, and then currents are solved from Equation (12) in terms of these and previous values.…”

Analytic Approximation of Fault Current Contributions From Capacitive Components in HVDC Cable Networks

“…Other skin effect models for lower frequencies are the cylindrical skin effect [27] and the f m -law with 0 < m < 1 as described in [26]. The general case including dielectric losses is discussed in [28] and [26], and a model considering a non-zero dc resistance of the inner conductor is presented in [29]. However, the aforementioned models cannot be represented by closed form analytic expressions.…”

Análisis de formulaciones aproximadas de impedancia interna para el estudio de transitorios de alta frecuencia en cables subterráneos de alta tensión

“…La impedancia interna de conductores cilíndricos para grandes parámetros puede ser calculada mediante ciertos modelos aproximados, los cuales no involucran el cálculo de las funciones de Bessel, funciones de Bessel modificadas o funciones de Kelvin y por lo tanto permiten determinar la impedancia interna de una manera más sencilla con poco esfuerzo computacional. Sin embargo, estos modelos no son exactos y presentan cierto margen de error, por lo que son clasificados como modelos de baja precisión, tales como los propuestos por Nahman y Holt [9], Semlyen y Deri [10], Wedepohl y Wilcox [11]; y modelos de alta precisión, como los propuestos por Vujević, Boras y Sarajčev [12], Mingli y Yu [13], Knight [14].…”