A new frequency-dependent-model for cables

This paper deals with the inclusion of frequency effects (skin effect) in an enhanced transport delay model for electric cables of arbitrary length connected to a PWM-IGBT variable frequency drive (VFD), to better predict overvoltage peaks in the line during transient.The problem and the importance of predicting peak overvoltages to determine the appropriate insulation to be used by cables is addressed. Frequency-domain characterization of cables is considered. A function in the Laplace-s-domain is fitted to such characterized behavior by using genetic algorithms. From the step response of the cable, and using genetic algorithms (GA), an impulse function (propagation function) is derived. Such a function is used to predict frequency-dependent voltage and current in longer cables. Simulation and experimental results are provided.