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International Conference on systems and control (ICSC)

作者： Bilel Dhouib Moncef Triki Mohamed Ali Zdiri Hsan Hadj Abdallah Electrical engineering department Sfax engineering school Control & energy management laboratory Sfax engineering school Sfax Tunisia Electrical Engineering Department Sfax laboratory of sciences and techniques of automatic & computer engineering (Lab-STA) Sfax engineering school Sfax Tunisia Electrical engineering department Sfax engineering school control & energy management laboratory Sfax engineering school Sfax Tunisia

With the increasing need for sustainable energy sources, wind power has gained prominence as a clean and renewable option. Nevertheless, incorporating wind power into the electrical grid at a significant scale can have a considerable impact on the dynamic behavior of the power system, leading to heightened operational uncertainties. The expanding requirement for power network connection to wind farms has led to the occurrence of rotor angle fluctuations and frequency instability. This paper utilizes a Static Synchronous Compensator (STATCOM) along with a multi-band power system stabilizer (MB-PSS) to assess the transient stability of a power grid. To demonstrate the system's efficiency under fault conditions, such as triple line-to-ground faults (LLLG), a nine-bus, three-machine test network incorporating a Doubly Fed Induction Generator (DFIG) has been employed. The system's performance has been evaluated through MATLAB/Simulink simulations, which reveal that the combination of STATCOM with MB-PSS produces superior results in enhancing transient stability when compared to the scenarios of using STATCOM alone or not using it at all.

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A Comparative Study on Partial Discharge and Dielectric Strength of MMEI Flat Samples under AC and DC Conditions at Atmospheric Pressure

A Comparative Study on Partial Discharge and Dielectric Stre...

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IEEE Green Energy and systems Conference (IGESC)

作者： Saikat Chowdhury Anoy Saha Md Asifur Rahman 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

ISBN: (数字)9798350379617

ISBN: (纸本)9798350379624

The shift towards electrifying transportation systems has become a pivotal strategy in achieving net-zero emissions, driving extensive adoption across the transportation sector. Consequently, the aviation industry is transitioning to all-electric aircraft (AEA). For AEA, an electric power system (EPS) that delivers high power while maintaining low system mass is crucial. Cables are vital components in this future EPS, and one way to reduce their weight is by operating at higher voltages. However, designing insulation systems for higher voltages poses challenges due to increased partial discharge (PD) activity in harsh aviation environments characterized by extremely low pressures and moisture levels. To address these challenges, multilayer multifunction electrical insulation (MMEI) systems have been developed, offering higher breakdown strength compared to single-layer insulation systems. Our previous study proposed some novel MMEI designs for medium voltage direct current (MVDC) power cables capable of operating at low pressures. In this paper, the PD characteristics of these designed MMEI systems are analyzed using the OMICRON MPD 800 under both AC and DC conditions on flat samples. Additionally, the dielectric strength for AC and DC is tested and compared using the Weibull distribution method.

关键词： Partial discharges Insulation Breakdown voltage Transportation Power system stability Discharges (electric) Weibull distribution Aircraft Stress Standards

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Carbon-Aware Computing in a Network of Data Centers: A Hierarchical Game-Theoretic Approach

arXiv

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arXiv 2024年

作者： Breukelman, Enno Hall, Sophie Belgioioso, Giuseppe Dörfler, Florian The KTH Royal Institute of Technology School of Electrical Engineering and Computer Science Division of Decision and Control Systems Malvinas väg 10 StockholmSE-100 44 Sweden The Automatic Control Laboratory Department of Electrical Engineering and Information Technology ETH Zurich Physikstrasse 3 Zürich8092 Switzerland

Over the past decade, the continuous surge in cloud computing demand has intensified data center workloads, leading to significant carbon emissions and driving the need for improving their efficiency and sustainability. This paper focuses on the optimal allocation problem of batch compute loads with temporal and spatial flexibility across a global network of data centers. We propose a bilevel game-theoretic solution approach that captures the inherent hierarchical relationship between supervisory control objectives, such as carbon reduction and peak shaving, and operational objectives, such as priority-aware scheduling. Numerical simulations with real carbon intensity data demonstrate that the proposed approach successfully reduces carbon emissions while simultaneously ensuring operational reliability and priority-aware scheduling. © 2024, CC BY-NC-ND.

关键词： Carbon

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Influence of Rise Time on the Aging of Electric Machine Windings

Influence of Rise Time on the Aging of Electric Machine Wind...

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Conference on electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Easir Arafat Md Asifur Rahman Farzana Islam 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

ISBN: (数字)9798350366679

ISBN: (纸本)9798350366686

This study examines how fast rise times, which are common in modern power electronics and drive systems, affect the aging of electric machine windings. It focuses on how to ensure these windings can last longer and work reliably in electrical systems. A twisted pair magnet wire with insulation commonly used in wound machines was used to get experimental data to understand how different voltage waveforms can influence endurance testing of motor insulation systems powered by inverters. Unlike past studies that looked at comparatively slower rise times and fewer repetitions, this research specifically addresses the challenges posed by next-generation wide bandgap (WBG)-based conversion systems. These systems operate at very high speeds, up to 100 kV/μs, and switch frequencies up to 500 kHz, where both frequency and rise time are crucial factors affecting insulation aging over time.

关键词： Insulation Time-frequency analysis Electric machines Windings Voltage Switches Aging Reliability engineering Wire Testing

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Accurate, provable, and fast nonlinear tomographic reconstruction: A variational inequality approach

arXiv

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arXiv 2025年

作者： Lou, Mengqi Verchand, Kabir Aladin Fridovich-Keil, Sara Pananjady, Ashwin Georgia Institute of Technology School of Industrial and Systems Engineering United States School of Electrical and Computer Engineering United States University of Cambridge Statistical Laboratory United Kingdom Stanford University Department of Electrical Engineering United States

We consider the problem of signal reconstruction for computed tomography (CT) under a nonlinear forward model that accounts for exponential signal attenuation, a polychromatic X-ray source, general measurement noise (e.g. Poisson shot noise), and observations acquired over multiple wavelength windows. We develop a simple iterative algorithm for single-material reconstruction, which we call EXACT (EXtragradient Algorithm for Computed Tomography), based on formulating our estimate as the fixed point of a monotone variational inequality. We prove guarantees on the statistical and computational performance of EXACT under practical assumptions on the measurement process. We also consider a recently introduced variant of this model with Gaussian measurements, and present sample and iteration complexity bounds for EXACT that improve upon those of existing algorithms. We apply our EXACT algorithm to a CT phantom image recovery task and show that it often requires fewer X-ray projection exposures, lower source intensity, and less computation time to achieve similar reconstruction quality to existing methods. © 2025, CC BY.

关键词： computerized tomography

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Location of Shield Wires for Unconventional High Capacity Transmission Lines

Location of Shield Wires for Unconventional High Capacity Tr...

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Proceedings of the IEEE Dallas Circuits and systems Workshop (DCAS)

作者： Saikat Chowdhury Babak Porkar 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

ISBN: (数字)9798350349535

ISBN: (纸本)9798350349542

To achieve net-zero emission in America by 2050, high voltage transmission capacity must expand ~60% by 2030 and triple by 2050 to connect further wind and solar facilities to demand. This expansion requires a capital investment in transmission capacity of $360 billion by 2030 and $2.4 trillion by 2050. Considering the high cost of building transmission lines, innovations toward high-capacity overhead lines have been targeted to reduce the number of transmission lines required. In our previous studies, we introduced unconventional high-capacity transmission lines. To realize these novel transmission lines, various aspects of line design should be studied, and this paper addresses determining the location and number of shield wires to protect these novel lines against lightning strikes. Lightning-induced overvoltage across line insulators is one of the key factors in power system outages. The design meets the shielding failure flashover rate (SFFOR) $\leq 0.05/100$ km-years for all three phases of the unconventional high-capacity transmission line. Brown-Whitehead equations were used to measure and analyze the striking distance for vertical strokes.

关键词： Technological innovation Power transmission lines Net zero Wires Lightning Flashover Transmission line measurements

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High Power Density, Cost-Effective HVDC Cables for Power Transmission on the Moon

High Power Density, Cost-Effective HVDC Cables for Power Tra...

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IEEE Texas Power and Energy Conference (TPEC)

作者： 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

The need for lunar surface power is expected to grow to megawatt levels, which is in line with NASA's objective of building a long-term human presence on the moon that can house more than 100 people. As humanity seeks to establish a long-term presence on the moon and construct lunar habitats or bases, the importance of efficient and dependable power transmission on the moon becomes crucial. Power lines of varied lengths and power transfer capacities are needed for a lunar-based power system to link the various power generation, energy storage, and load facilities dispersed over the lunar surface. Developing power lines with high power density, while considering weight, volume, safety, cost-effectiveness, and reliability in the harsh lunar environment, poses a significant challenge. Three potential locations for power lines on the lunar surface can be considered: above the surface, on the surface, or below the surface. The extreme lunar environment, characterized by factors such as temperature variation, micrometeoroid bombardment, and ionizing radiation, limits the effectiveness of the first two methods for power transfer on the moon. Underground deployment offers both safety and convenience. Using the COMSOL Multiphysics software, this work proposes a novel method for designing and assessing affordable bipolar HVDC cables for power transmission below the lunar surface with an emphasis on its electrical insulation difficulties. At a voltage level of up to ±10 kV, the cables are intended to transfer power at two different levels: medium power (500 kW), and high power (1 MW). These specially designed cables offer a viable solution for power transmission on the moon, as they are capable of functioning effectively in harsh lunar conditions.

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Characterizing Nonlinear Field Dependent Conductivity Layers to Mitigate Electric Field Within (U)WBG Power Modules Under High Frequency, High Slew Rate Square Voltage Pulses

Characterizing Nonlinear Field Dependent Conductivity Layers...

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IEEE Texas Power and Energy Conference (TPEC)

作者： Pujan Adhikari 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

A vast majority of research on (U)WBG power modules has been going on to implement nonlinear resistive field grading material on metal-brazed substrates in reducing the electric field that is maximum at triple points (TPs). However, nearly all investigations have been conducted under either DC or 50/60 $\mathbf{H}_{\mathbf{Z}}$ sinusoidal AC voltages, even though the actual operation of envisioned (U)WBG power modules involves high-frequency square voltages with high slew rates. It has been validated by several studies that fast rise times of square voltages rapidly degrade the breakdown strength of insulation materials, leading to premature failure. Therefore, this paper introduces a nonlinear resistive field grading material or field-dependent conductivity (FDC) layer around the TP and metal edges to evaluate the electric field mitigation under a high frequency and high slew rate square voltage. The modeling and simulation of both coated and uncoated (U)WBG substrates were performed in COMSOL Multiphysics to assess the electric field reduction with the nonlinear FDC layer. The improvement of reduction in electric field under 100 kHz high slew rate square voltage is compared with that of 60 Hz. The results reveal a significant decrease in field stress at the TP, even under square voltages with fast rise times and high frequencies, when applying a nonlinear FDC coating, as opposed to the uncoated substrate. The influence of switching field $(\mathbf{E}_{\mathbf{b}})$ and nonlinearity coefficient $(\alpha)$ of nonlinear FDC layer is studied under 100 kHz square voltage, and it is concluded that $\alpha$ and $\mathbf{E}_{\mathbf{b}}$ should be more than 10 and less than 8 kV/mm, respectively to achieve effective performance of resistive field grading material.

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MVDC Bipolar Power Cables with Rectangular Geometry Design for Envisaged All-Electric Wide-Body Aircraft

MVDC Bipolar Power Cables with Rectangular Geometry Design f...

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IEEE Texas Power and Energy Conference (TPEC)

Designing power cables that provide high power and low system mass is one of the major goals in achieving the future all-electric wide-body aircraft. Radiative and convective heat transfers from a cable's surface to the surrounding air determine how much current is permitted to flow through it. At a cruising altitude of 12.2 km (18.8 kPa) for wide-body aircraft, the limited heat transfer by convection poses thermal issues for the design of aircraft cables. These thermal challenges are exacerbated for bipolar electric power systems (EPS), which are usually made up of two power lines next to each other. The cable's surface area affects both convective and radiative heat transfers. Changing the shape of the cable is one technique to improve heat transfers and compensate for the reduced convective heat transfer caused by low air pressure. In comparison to cylindrical and cuboid cables, the rectangular geometry design gives a bigger contact area with the surrounding atmosphere for the same cross-section area, hence it is anticipated that the heat transfer would rise and as a result, the cable's maximum power-carrying capability will be higher. The purpose of this paper is to design ±5 kV bipolar MVDC power cables with rectangular geometry to raise the maximum current carrying capacity of the cable and analyze its performance with bipolar cylindrical and cuboid geometries.

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A Test System Meeting Requirements Under Normal and Contingency Conditions at Multiple Loadings for Transmission Expansion Planning

A Test System Meeting Requirements Under Normal and Continge...

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Proceedings of the IEEE Dallas Circuits and systems Workshop (DCAS)

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

ISBN: (数字)9798350349535

ISBN: (纸本)9798350349542

This paper introduces a high-voltage test system tailored specifically for transmission expansion planning (TEP). The network incorporates long transmission lines, and the line series impedance and shunt admittance for each line are computed utilizing the equivalent $\pi$ circuit model for long transmission lines to account for the distributed nature of line parameters. The proposed test system offers technically feasible load flow solutions under normal and all single contingency conditions for three distinct loading scenarios: peak, dominant, and light loading conditions. As the real power system is subject to various loading scenarios and should be effectively operable under all conditions, this test system accurately replicates the properties of real power systems. The test system introduced in this paper can be a valuable resource for TEP research.

关键词： Technical requirements Power transmission lines Loading Contingency management High-voltage techniques Planning Power system reliability

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