MoM-SO: A Complete Method for Computing the Impedance of Cable Systems Including Skin, Proximity, and Ground Return Effects

IEEE Trans. Power Delivery

2016

Self Cite

An accurate knowledge of the per-unit length impedance of power cables is necessary to correctly predict electromagnetic transients in power systems. In particular, skin, proximity, and ground return effects must be properly estimated. In many applications, the medium that surrounds the cable is not uniform and can consist of multiple layers of different conductivity, such as dry and wet soil, water, or air. We introduce a multilayer ground model for the recently-proposed MoM-SO method, suitable to accurately predict ground return effects in such scenarios. The proposed technique precisely accounts for skin, proximity, ground and tunnel effects, and is applicable to a variety of cable configurations, including underground and submarine cables. Numerical results show that the proposed method is more accurate than analytic formulas typically employed for transient analyses, and delivers an accuracy comparable to the finite element method (FEM). With respect to FEM, however, MoM-SO is over 1000 times faster, and can calculate the impedance of a submarine cable inside a three-layer medium in 0.10 s per frequency point.

Section: Problem Definitionmentioning

confidence: 99%

Section: Surface Admittance For a Cable-hole Systemmentioning

confidence: 99%

See 1 more Smart Citation

Accurate Impedance Calculation for Underground and Submarine Power Cables Using MoM-SO and a Multilayer Ground Model

Patel

IEEE Trans. Power Delivery

2016

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“…In this paper, we present a novel reduced-order modeling scheme based on the Stratton-Chu formulation and the equivalence theorem to efficiently compute scattering from large arrays of scatterers made up of perfect electric conductors (PECs) in free space. This work is an extension of a similar idea proposed for a 2D transmission line problem [22]. In our method, each element of the array is modeled by a socalled macromodel that compactly represents the scattered field from the element.…”

Section: Arxiv:171202443v1 [Csce] 6 Dec 2017mentioning

confidence: 99%

A Macromodeling Approach to Efficiently Compute Scattering from Large Arrays of Complex Scatterers

Patel

IEEE Trans. Antennas Propagat.

Hum

2018

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Full-wave electromagnetic simulations of electrically large arrays of complex antennas and scatterers are challenging, as they consume large amount of memory and require long CPU times. This paper presents a new reduced-order modeling technique to compute scattering and radiation from large arrays of complex scatterers and antennas. In the proposed technique, each element of the array is replaced by an equivalent electric current distribution on a fictitious closed surface enclosing the element. This equivalent electric current density is derived using the equivalence theorem and it is related to the surface currents on the scatterer by the Stratton-Chu formulation. With the proposed approach, instead of directly solving for the unknown surface current density on the scatterers, we only need to solve for the unknowns on the equivalent surface. This approach leads to a reduction in the number of unknowns and better conditioning when it is applied to problems involving complex scatterers with multiscale features. Furthermore, the proposed approach is accelerated with the adaptive integral equation method to solve large problems. As illustrated in several practical examples, the proposed method yields speed up of up to 20 times and consumes up to 12 times less memory than the standard method of moments accelerated with the adaptive integral method.Index Terms-surface integral equation method, macromodel, equivalence theorem, adaptive integral equation method, multiscale problems, reduced-order modeling

“…As a result, only skin effect will exist in that conductor. We refer the reader to [7] for a detailed description of MoM-SO as well as its extension to multi-layered earth in [9].…”

Section: Approximate Representation By Tubular Conductorsmentioning

confidence: 99%

Inclusion of Wire Twisting Effects in Cable Impedance Calculations

Gustavsen

Høyer-Hansen

IEEE Trans. Power Delivery

et al. 2016

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Abstract-Cable series impedance modeling is widely applied in electromagnetic transients calculations and power loss calculations. The calculations are usually performed in a 2D frame using FEM or alternative approaches like MoM-SO, thereby losing the 3D effects imposed by twisting of wire screens and armors. One of the implications of using 2D modeling for three-core and closely packed single-core cables is that currents will always circulate among the individual wires of each wire screen or armor. However, in the case of twisted screens/armors where the wires are insulated from each other, such current circulation will in reality not exist. As a result, the calculated impedances become incorrect, as well as the induced currents and losses on individual conductors. A procedure is introduced for preventing such false current circulations in a 2D calculation frame by simple manipulation of the system impedance matrix. The approach is demonstrated for the modeling of single-core and three-core cables, with and without an external armor. It is shown that the representation of the wire screen/armor armor with respect to current circulations can substantially influence the calculated result, both for the 50/60 Hz impedance and the cable transient behavior. The use of tubular screen representations is also investigated.