33 research outputs found
MoM-SO: a Complete Method for Computing the Impedance of Cable Systems Including Skin, Proximity, and Ground Return Effects
The availability of accurate and broadband models for underground and
submarine cable systems is of paramount importance for the correct prediction
of electromagnetic transients in power grids. Recently, we proposed the MoM-SO
method for extracting the series impedance of power cables while accounting for
skin and proximity effect in the conductors. In this paper, we extend the
method to include ground return effects and to handle cables placed inside a
tunnel. Numerical tests show that the proposed method is more accurate than
widely-used analytic formulas, and is much faster than existing proximity-aware
approaches like finite elements. For a three-phase cable system in a tunnel,
the proposed method requires only 0.3 seconds of CPU time per frequency point,
against the 8.3 minutes taken by finite elements, for a speed up beyond 1000 X.Comment: This paper has now been published in the IEEE Trans. on Power
Delivery in Oct. 2015, vol. 30, no. 5, pp. 2110-2118. DOI:
10.1109/TPWRD.2014.237859
Proximity-Aware Calculation of Cable Series Impedance for Systems of Solid and Hollow Conductors
Wide-band cable models for the prediction of electromagnetic transients in
power systems require the accurate calculation of the cable series impedance as
function of frequency. A surface current approach was recently proposed for
systems of round solid conductors, with inclusion of skin and proximity
effects. In this paper we extend the approach to include tubular conductors,
allowing to model realistic cables with tubular sheaths, armors and pipes. We
also include the effect of a lossy ground. A noteworthy feature of the proposed
technique is the accurate prediction of proximity effects, which can be of
major importance in three-phase, pipe type, and closely-packed single-core
cables. The new approach is highly efficient compared to finite elements. In
the case of a cross-bonded cable system featuring three phase conductors and
three screens, the proposed technique computes the required 120 frequency
samples in only six seconds of CPU time.Comment: Update: This paper has been accepted for publication in the IEEE
Transactions on Power Delivery. DOI: 10.1109/TPWRD.2014.233099
A Novel Single-Source Surface Integral Method to Compute Scattering from Dielectric Objects
Using the traditional surface integral methods, the computation of scattering
from a dielectric object requires two equivalent current densities on the
boundary of the dielectric. In this paper, we present an approach that requires
only a single current density. Our method is based on a surface admittance
operator and is applicable to dielectric bodies of arbitrary shape. The
formulation results in four times lower memory consumption and up to eight
times lower time to solve the linear system than the traditional PMCHWT
formulation. Numerical results demonstrate that the proposed technique is as
accurate as the PMCHWT formulation.Comment: Submitted to IEEE Antennas and Wireless Propagation Letters on
November 18, 201
Fast Computation of the Series Impedance of Power Cables with Inclusion of Skin and Proximity Effects
We present an efficient numerical technique for calculating the series
impedance matrix of systems with round conductors. The method is based on a
surface admittance operator in combination with the method of moments and it
accurately predicts both skin and proximity effects. Application to a
three-phase armored cable with wire screens demonstrates a speed-up by a factor
of about 100 compared to a finite elements computation. The inclusion of
proximity effect in combination with the high efficiency makes the new method
very attractive for cable modeling within EMTP-type simulation tools.
Currently, these tools can only take skin effect into account.Comment: Submitted for publication to IEEE Transactions on Power Delivery.
Update: Published in IEEE Transactions on Power Delivery with the revised
title of "An Equivalent Surface Current Approach for the Computation of the
Series Impedance of Power Cables with Inclusion of Skin and Proximity
Effects