Abstract

The calculation of frequency-dependent cable parameters is essential for simulations of transient phenomena in electrical power systems. The simulation of transients is more complicated than the calculation of currents and voltages in the nominal frequency range. The model has to represent the frequency dependency and the wave propagation behavior of cable lines. The introduced model combines an improved subconductor method for the determination of the frequency-dependent parameters and a PI section wave propagation model. The subconductor method considers the skin and proximity effect in all conductors for frequency ranges up to few megahertz. The subconductor method method yields accurate results. The wave propagation part of the cable model is based on a cascaded PI section model. A modal transformation technique has been used for the calculation in the time domain. The frequency-dependent elements of the related modal transformation matrices have been fitted with rational functions. The frequency dependence of cable parameters has been reproduced using a vector fitting algorithm and has been implemented into an resistor-inductor-capacitor network (RLC network) for each PI section. The proposed full model has been validated with measured data.

Highlights

  • The safe and reliable operation of cable systems requires the analysis of transient behavior of such systems

  • In order to avoid the difficulties by using frequency-dependent modal transformation matrices, Noda et al [14] have developed the line model directly in the phase domain

  • The frequency dependency of the capacitances can be generally neglected in an algorithm for frequency-dependent parameters

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Summary

Introduction

The safe and reliable operation of cable systems requires the analysis of transient behavior of such systems. In order to avoid the difficulties by using frequency-dependent modal transformation matrices, Noda et al [14] have developed the line model directly in the phase domain. In order to simplify the calculations, the universal line model uses a vector fitting algorithm [15,16], which approximates some of the line parameters (surge admittance and propagation constant) by rational functions. Another approach (alternatively to the vector fitting algorithm) for the approximation of the line parameters is based on the algorithm developed in Noda [17]. The differential equations to describe the voltages and currents along the cable are of the first order, which can be solved as state space equations

Fundamentals
Partial Subconductor Method
Frequency-Dependent Segmentation of Conductors
Earth Segmentation
Shield Segmentation
Calculation of Frequency-Dependent Impedances
System Impedances red
Impact of Semiconducting Layers
Main Insulation Capacitance
2.10.1. Earth Installation
2.10.2. Air Installation
Approach
Validation of the Full Frequency-Dependent Cable Model
Findings
Conclusions

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