Search results for "Power engineering"

Field Reconstruction for Modeling Multiple Faults in Permanent Magnet Synchronous Motors in Transient States

2021

Conventional field reconstruction model (FRM) for electrical machines has proved its main strength in efficient computations of magnetic fields and forces in healthy permanent magnet synchronous machines (PMSM) or faulty machines in steady states. This study aims to develop a magnet library of different magnet defects and include inter-turn short-circuit (ITSC) in the FRM for PMSM. The developed FRM can model a combination fault between ITSC, and magnet defect in a PMSM in transient states. Within the framework, an 8-turn ITSC was modelled in both finite element analysis (FEA) and FRM, and then identified by the extended Park’s vector approach. The air-gap magnetic field reproduced b…

Neutron-Induced Effects on a Self-Refresh DRAM

2022

International audience; The field of radiation effects in electronics research includes unknowns for every new device, node size, and technical development. In this study, static and dynamic test methods were used to define the response of a self-refresh DRAM under neutron irradiation. The neutron-induced effects were investigated and characterised by event cross sections, soft-error rate, and bitmaps evaluations, leading to an identification of permanent and temporary stuck cells, single-bit upsets, and block errors. Block errors were identified in different patterns with dependency in the addressing order, leading to up to two thousand faulty words per event, representing a real threat fr…

Organisering og intern prissetting i Agder Energi Tjenester AS

2003

Hovedoppgave i Industriell økonomi og informasjonsledelse, Høgskolen i Agder, Grimstad Et karakteristisk trekk ved den økonomiske utviklingen de senere årene er den økte fokuseringen på lønnsomhet. Oppdelingen av foretaket i selvstendige ansvarsenheter og desentralisering av resultatansvaret, har vært viktige elementer i en strategi for økt lønnsomhet. Fordi dette motiverer hele organisasjonen til økt lønnsomhet, og fordi det gir bedre muligheter til å identifisere hvilke områder foretaket taper og tjener penger på. Dette gjelder også for energisektoren. I denne oppgaven har vi tatt for oss AET, som er et datterselskap i AE. AET leverer støttetjenester til AE. Oppgaven har som mål å drøfte …

2014

This paper considers the parameter estimation for linear time-invariant (LTI) systems in an input-output setting with output error (OE) time-delay model structure. The problem of missing data is commonly experienced in industry due to irregular sampling, sensor failure, data deletion in data preprocessing, network transmission fault, and so forth; to deal with the identification of LTI systems with time-delay in incomplete-data problem, the generalized expectation-maximization (GEM) algorithm is adopted to estimate the model parameters and the time-delay simultaneously. Numerical examples are provided to demonstrate the effectiveness of the proposed method.

A Simulation Analysis of VSM Control for RES plants in a Small Mediterranean Island

2020

The paper presents an application of Virtual Synchronous Machine control for managing inverter-interfaced renewable energy sources in a small Mediterranean island not supplied by the main grid. In the proposed analysis, the island's renewables-based generators area assumed interfaced to the grid by voltage source converters with a swing controller and a vector-current controller with two different options for the reference current for regulating the voltage at the Point of Common Coupling and the active power output. The system, modeled in PScad environment, allows to verify the response of the renewables-based generators with VSM control in the presence of a fault in the grid.

Josephson-based Threshold Detector for Lévy-Distributed Current Fluctuations

2019

We propose a threshold detector for Lévy-distributed fluctuations based on a Josephson junction. The Lévy-noise current added to a linearly ramped bias current results in clear changes in the distribution of switching currents out of the zero-voltage state of the junction. We observe that the analysis of the cumulative distribution function of the switching currents supplies information on both the characteristics' shape parameter α of the Lévy statistics. Moreover, we discuss a theoretical model, which allows characteristic features of the Lévy fluctuations to be extracted from a measured distribution of switching currents. In view of these results, this system can effectively find an appl…

Optical Probing (EOFM/TRI): A large set of complementary applications for ultimate VLSI

2013

International audience; Electro Optical Techniques (EOFM: Electro Optical Frequency Mapping and EOP: Electro Optical Probing) and Dynamic Light Emission Techniques (TRE: Time Resolved Emission and TRI: Time Resolved Imaging) are dynamic optical probing techniques widely used at IC level for design debug and defect localization purpose. They can pinpoint the origin of timing issue or logic fault in up to date CMOS devices. Each technique has its advantages and its drawbacks allowing a common set of applications and more specific ones. We have been involved in the development of the most advanced techniques related to EOFM and TRI on various devices (down to 28nm technology). What we can expe…

A Comparison of Special Bonding Techniques for Transmission and Distribution Cables under Normal and Fault Conditions

2021

In this article, a review of the existing special bonding techniques for medium voltage and high-voltage cables is presented. Special bonding techniques have the purpose of reducing sheath currents, thereby limiting copper losses and the reduction of the ampacity of cables. The literature review shows various bonding techniques and how these have evolved over the years thanks to new technologies. Simulations of each technique are performed in MATLAB/Simulink, to compare their strengths and drawbacks both under normal conditions and in the presence of a single-line-to-ground fault.

State feedback control against sensor faults for Lipschitz nonlinear systems via new sliding mode observer techniques

2011

This paper investigates the problem of simultaneous state and fault estimation and observer-based fault tolerant controller design for Lipschitz nonlinear systems with sensor failure. A new estimation technique is presented in this paper to deal with this design problem. In the proposed approaches, the original system is first augmented by a descriptor model transformation, then a new Proportional and Derivative sliding mode observer technique is developed to obtain accurate estimations of both system states and sensor faults. The designing observer is generalized from the PD observer in [3], but is not a trivial extension. Based on the state estimates, a observer-based control strategy is …

Detection and Discrimination of Inter-Turn Short Circuit and Demagnetization Faults in PMSMs Based on Structural Analysis

2021

This paper presents a fault diagnosis method based on structural analysis of permanent magnet synchronous motors (PMSMs), focusing on detecting and discriminating two of the most common faults in PMSMs, namely demagnetization and inter-turn short circuit faults. The structural analysis technique uses the dynamic mathematical model of the PMSM in matrix form to evaluate the system’s structural model. After obtaining the analytical redundancy using the over-determined part of the system, it is divided into redundant testable sub-models. Four structured residuals are designed to detect and isolate the investigated faults, which are applied to the system in different time intervals. Finally, th…