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Conference on electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Anoy Saha Arian Azizi Mona Ghassemi Department of Electrical and Computer Engineering Zero Emission Realization of Optimized Energy Systems (ZEROES) Laboratory The University of Texas at Dallas Richardson TX USA

Future generations of electrified aircraft, such as more electric aircraft (MEA) and all-electric aircraft (AEA), will require high-power-delivery and low-system-mass electric power systems (EPS). Designing aircraft cables confronts thermal challenges due to the limited heat transfer by convection at a cruising altitude of 12.2 km (18.8 kPa) for wide-body aircraft. These thermal challenges are exacerbated by implementing bipolar MVDC EPSs which are formed of two adjacent power cables, conventionally. In this regard, coaxial geometry for cables can be evaluated as a solution to this problem. In this paper, a coaxial MVDC power cable is, for the first time, designed with inner and outer conductors carrying the same ampacity of 1000 A when the voltage of the inner and outer conductors is −5 kV and +5 kV, respectively. This design compares the effectiveness of coaxial power cables to the conventional arrangement of bipolar MVDC cable systems. This study will analyze three case studies to determine if a coaxial geometry is better than a conventional arrangement for a bipolar MVDC cable system or not. According to the findings of this study, coaxial cable requires thicker insulation and more conductors to maintain the same maximum electric field norm within cable insulation and ampacity. As a result, coaxial cables result in a greater mass and cross-sectional area than standard bipolar cables. For the envisaged AEA, the investigation in this paper addresses questions about the performance of coaxial geometry for bipolar MVDC power cables.

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Transmission Expansion Planning (TEP)-Based Unconventional High Surge Impedance Loading (HSIL) Line Design Concept

Transmission Expansion Planning (TEP)-Based Unconventional H...

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Annual North-American Power Symposium

作者： Babak Porkar Mona Ghassemi Mushfiqul Abedin Khan Department of Electrical and Computer Engineering Zero Emission Realization of Optimized Energy Systems (ZEROES) Laboratory The University of Texas at Dallas Richardson TX USA

This paper develops a new concept that we call transmission expansion planning (TEP)-based unconventional high surge impedance loading (HSIL) line design. To date, these two areas (TEP and transmission line design) have been conducted separately. For TEP, planners typically use the electrical parameters of a few standard conventional line designs to study planning scenarios, and then, the final candidate line is constructed. In such a sequence, cost-effective scenarios often do not meet the technical criteria of load flow. In this paper, we will study whether this sequence can be overturned; namely, can a transmission expansion planner get optimal line parameter values that lead to the most cost-effective scenario, and then have a transmission line with those parameters be designed? Although this cannot currently be realized through conventional designs, in this paper, we demonstrate that it is a possibility if breakthrough designs for transmission lines are used by shifting phase configurations and subconductors into unconventional HSIL arrangements, leading to the optimal line parameters determined by TEP.

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Transmission Expansion Planning via Unconventional High Surge Impedance Loading (HSIL) Lines

Transmission Expansion Planning via Unconventional High Surg...

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Annual North-American Power Symposium

作者： Bhuban Dhamala Mona Ghassemi Department of Electrical and Computer Engineering Zero Emission Realization of Optimized Energy Systems (ZEROES) Laboratory The University of Texas at Dallas Richardson TX USA

Transmission expansion planning (TEP) plays a vital role in ensuring the reliable and efficient operation of power systems, especially with the growing demand for electricity and the integration of renewable energy sources. This paper focuses on applying unconventional high surge impedance loading (HSIL) lines in transmission expansion planning and compares their outcomes with conventional line-based transmission expansion planning. Starting with a 17 bus- 500 kV power system connected by a conventional transmission line, the objective is to connect a new load located in a new bus, bus #18, to the existing 17-bus power system via two approaches: using conventional lines and incorporating unconventional HSIL lines. By comparing the number of lines required for the conventional and unconventional approaches, maintaining almost identical conductor volume per circuit, the effectiveness of unconventional HSIL lines in TEP is evaluated where using only two unconventional HSIL lines is sufficient to connect 1000 MW load demand at bus 18 while three lines are required when using the conventional design.

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A Cuboid Geometry Design for MVDC Power Cables for Using in Future All Electric Wide Body Aircraft

A Cuboid Geometry Design for MVDC Power Cables for Using in ...

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Conference on electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Arian Azizi Anoy Saha Mona Ghassemi Department of Electrical and Computer Engineering Zero Emission Realization of Optimized Energy Systems (ZEROES) Laboratory The University of Texas at Dallas Richardson TX USA

Designing high-power-delivery and low-system-mass electric power systems (EPS) is a major goal to achieve the next generation of electrified aircraft. As one of its major components, cables must be redesigned to obtain high-power-density and low-system-mass EPS. Among challenges in designing aircraft cables such as arc and arc tracking, partial discharges (PD), and thermal management, the latter is decisive since the thermal properties of the cable determine its maximum ampacity. The maximum permissible current of a cable depends on radiative and convective heat transfers from its surface to the ambient environment. At the cruising altitude (12.2 km) of wide-body aircraft where the air pressure is 18.8 kPa, the convective heat transfer is greatly reduced which results in a reduction in maximum permissible current. Moreover, both radiative and convective heat transfers depend on the surface area of the cable. One way to increase the heat transfers and compensate for the reduction of convective heat transfer from a limited air pressure is to change the geometry of the cable. The cuboid geometry design provides a larger contact area with the ambient environment for the same cross-section area, so it is expected that the heat transfer will increase compared to conventional cylindrical cables, and in turn, the maximum power carrying capacity of the cable will be larger. Here, the question is whether the hypothesis is true, and if so, how much improvement can be expected. The purpose of this paper is to answer these questions and, for the first time, an MVDC (5 kVdc) high power (1 kA) cuboid shape cable is designed for future AEA to increase the maximum permissible current of the cable.

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A New Unusual Bundle and Phase Arrangement For Transmission Line To Achieve Higher Natural Power

A New Unusual Bundle and Phase Arrangement For Transmission ...

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Annual North-American Power Symposium

作者： Mushfiqul Abedin Khan Mona Ghassemi Department of Electrical and Computer Engineering Zero Emission Realization of Optimized Energy Systems (ZEROES) Laboratory The University of Texas at Dallas Richardson TX USA

In conventional lines, subconductors are located symmetrically on an identical circle in each phase. The number of subconductors in a bundle, the radius of the bundle circle, and the radius of each subconductor, are chosen so that the maximum electric field strength on the sub conductors, $E_{max}$ , is limited to the permissible field strength on the conductor surface, $E_{p r},\left(E_{max } \leq\right. E_{pr})$ , which is determined by the corona discharge limitation requirement. In this paper, we show that by shifting phase configurations and subconductors into unusual/unconventional arrangements that are geometrically optimized within the space, high power density designs can be achieved. A novel bundle and phase arrangement of a 500 kV transmission line is presented in this paper, resulting in higher natural power than conventional design.

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Calculation of Audible Noise and Radio Interference for Unconventional High Surge Impedance Loading (HSIL) Transmission Lines

Calculation of Audible Noise and Radio Interference for Unco...

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Conference on electrical Insulation and Dielectric Phenomena, (CEIDP)

Corona discharges cause power loss, audible noise (AN), radio interference (RI), and television interference (TVI), all of which should be considered during transmission line design. Unconventional high surge impedance loading (HSIL) lines have been shown to have the potential to produce greater natural power than conventional lines and conventional HSIL lines. More than one conductor is used in conventional extra high voltage (EHV) lines, typically more than 300 kV, to form bundled conductors which reduce the electrical field on the subconductors and, as a result, reduce corona effects. In conventional lines, the number of subconductors symmetrically placed on a circle and bundle radius are determined based on corona effects considerations. Using a larger bundle circle and increasing the number of subconductors lead to greater natural power, resulting in conventional HSIL lines. Therefore, in conventional HSIL lines, bundled conductors are used not only to address corona effects but also to increase natural power. Using smaller conductors for conventional HSIL lines keeps costs close to conventional lines. In conventional HSIL lines, subconductors are still symmetrically placed on a circle while unconventional HSIL lines have subconductors placed at any point in space. Unconventional HSIL lines can lead to more natural power than conventional HSIL lines. In this paper, AN and RI for unconventional HSIL lines are calculated and discussed.

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The Significance of Accurate Needle Electrode Geometry Definitions in Discharge Plasma Finite-Element Simulations: A Comparative Analysis

The Significance of Accurate Needle Electrode Geometry Defin...

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Conference on electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Mohammad Hamidieh Mona Ghassemi Department of Electrical and Computer Engineering Zero Emission Realization of Optimized Energy Systems (ZEROES) Laboratory The University of Texas at Dallas Richardson TX USA

This paper aims to explore the significance of accurately defining the geometry of needle electrodes in gas discharge plasma finite-element simulations and evaluate the sensitivity and responsiveness of simulation outputs to different needle electrode shapes. Using a hydrodynamic (drift-diffusion) model and COMSOL Multiphysics software, a comprehensive numerical analysis is performed to investigate the influence of six needle geometries (hyperbolic, elliptic, and circle-with-tangents) with an equal radius of curvature on negative air discharge plasma characteristics. The study aims to establish a comparative understanding of how the defined geometries relate to the behavior of the discharge plasma. Various aspects, including the properties of Trichel pulses, the spatiotemporal evolution of charged species, and the electrical field distribution, are explored.

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A Test System for Transmission Expansion Planning Studies Meeting the Operation Requirements Under Normal Condition as Well as all Single Contingencies

A Test System for Transmission Expansion Planning Studies Me...

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Annual North-American Power Symposium

This paper presents a 17-bus 500 kV test system for transmission expansion planning (TEP) studies. An actual 500 kV transmission line geometry was used for the overhead lines of this system. Although many test systems have been introduced for different types of power system analysis, those especially for TEP studies at a transmission voltage level, not distribution voltage level, are few. To the best of our knowledge, the introduced test systems for TEP studies, either those combined with electricity market problems or those used to connect a new load or generation to an existing power grid, consider the studies under only normal condition. However, for TEP studies it is needed that a test system meets voltage drop and line loading limits criteria under normal condition as well as all single contingencies, and in this regard, addressing the latter, all single contingencies, is challenging. This paper addresses this technical gap, introducing a 17-bus test system at a transmission voltage level, 500 kV, that meets requirements under normal condition as well as all single contingencies. In addition to presenting all details of this new test system, load flow results under normal condition as well as the worst single contigency are presented. For studies on the TEP, this test system can be an invaluable resource.

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Geometric Graph Filters and Neural Networks: Limit Properties and Discriminability Trade-offs

arXiv

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arXiv 2023年

作者： Wang, Zhiyang Ruiz, Luana Ribeiro, Alejandro Department of Electrical and Systems Engineering University of Pennsylvania PA United States Computer Science & Artificial Intelligence Laboratory MIT MA United States

This paper studies the relationship between a graph neural network (GNN) and a manifold neural network (MNN) when the graph is constructed from a set of points sampled from the manifold, thus encoding geometric information. We consider convolutional MNNs and GNNs where the manifold and the graph convolutions are respectively defined in terms of the Laplace-Beltrami operator and the graph Laplacian. Using the appropriate kernels, we analyze both dense and moderately sparse graphs. We prove non-asymptotic error bounds showing that convolutional filters and neural networks on these graphs converge to convolutional filters and neural networks on the continuous manifold. As a byproduct of this analysis, we observe an important trade-off between the discriminability of graph filters and their ability to approximate the desired behavior of manifold filters. We then discuss how this trade-off is ameliorated in neural networks due to the frequency mixing property of nonlinearities. We further derive a transferability corollary for geometric graphs sampled from the same manifold. We validate our results numerically on a navigation control problem and a point cloud classification task. © 2023, CC0.

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Influence of Solid Dielectric Permittivity on Positive Streamer Characteristics in a Liquid-Solid Composite Dielectric

Influence of Solid Dielectric Permittivity on Positive Strea...

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Conference on electrical Insulation and Dielectric Phenomena, (CEIDP)

This paper presents a numerical investigation of positive streamers in a liquid-solid composite dielectric system, specifically in the context of wet-mate DC connectors. The study focuses on the influence of different materials and relative permittivity values of the solid dielectric on streamer behavior. The study employs a non-dimensionalized electric field-dependent molecular ionization streamer model to describe the initiation and propagation of streamers within a needle-sphere electrode system. A 2D-axisymmetric COMSOL model is utilized, where a solid tube-like dielectric is placed near the needle tip in an electrode system filled with transformer oil. The effects of varying relative permittivity values on the electric field distribution, streamer propagation velocity, ionization and attachment rates, and spatiotemporal evolution of charged species (electrons, positive ions, and negative ions) are studied. By analyzing these aspects, the paper aims to enhance the understanding of streamer dynamics and provide valuable information for optimizing the design and performance of equipment utilizing liquid-solid composite dielectric systems.

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