141,455 research outputs found
Uninterruptible Energy Production in Standalone Power Systems for Telecommunications
No full textA continuously energy production is the most difficult and important feature to be guaranteed when designing a standalone power system for telecommunications. This paper focuses on a standalone power system for telecommunications already proposed in the literature, combining the most mature generators and technologies related to renewable energies and environment friendliness. It is important to know the operational problems, the best way to solve them and how to apply efficient maintenance. Reliability studies based on existent applications of renewable generators (some of them used in standalone power systems) help to know what to expect from their operational behaviour and to reduce time and costs in maintenance tasks. Notwithstanding their undoubted importance, they are not much recognised in literature, yet. The paper presents a brief review based on the few reliability reports about wind and photovoltaic systems available in the literature. Contributions and important aspects are discussed having in mind all the obstacles to achieve an uninterruptible power supply
Physics, limits and application of the newly proposed deep depletion SOI power devices
No full textThe behaviour of a deep depletion SOI LDMOS is thoroughly analyzed in this paper. Deep depletion of the substrate for a SOI device has been recently proposed as an innovative technique to design power devices featuring a transient breakdown higher than the static breakdown. The deep depletion is a dynamic effect that allows the design of a whole new generation of SOI power devices providing improved performances. Eligible applications are power conditioning circuits in which the device sustains transient voltages higher than bus voltage such as the flyback converter and the resonant circuits. In this paper numerical simulations are used to analyze the behaviour of the device together with the effect of temperature and substrate carrier generation time on the duration of the transient breakdown phase. Numerical results show that the newly proposed "deep depletion SOI device", a SOI power LDMOS using P substrate, exhibit 190V static breakdown voltage while sustains transient overvoltages up to 290V. Furthermore, mixed-mode simulation of a complete Class E resonant converter using the proposed deep depletion SOI device is presented
On the class-F power amplifier design
No full textPower-amplifier class-F operation is investigated and revised, evidencing the fundamental importance of the harmonic-generating mechanism and the limitations imposed by the device input and output nonlinearities on the ideal class-F behavior. Closed-form expressions are derived for the major design quantities, together with the optimum fundamental and third-harmonic loading of the active device. A design procedure, making use of the derived expressions, is presented and the deviations from the ideal behavior are discussed. Sample designs, making use of a fall nonlinear device model and commercial analysis software, are carried out to demonstrate the effectiveness of the analysis and the design procedure. It is shown, both analytically and using commercial nonlinear simulations, that blind application of commonly used, idealized class-F harmonic terminations can cause unexpected detrimental results. (C) 1999 John Wiley & Sons, Inc
Power, F E, VX23974
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/411501Surname: POWER. Given Name(s) or Initials: F E. Military Service Number or Last Known Location: VX23974. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 29038.227212
Item: [2016.0049.43765] "Power, F E, VX23974
Four-wire Shunt Active Power Filter With Adaptive Selective Current Compensation
No full textThis paper presents simulated and experimental results obtained with a four-wire shunt active power filter fully controlled with neural networks. This research is focused on a current compensation method based on adaptive linear elements (adalines), which are powerful and simple neural networks. © 2005 IEEE.2005347353El Shatshat, R., Kazerani, M., Salama, M.M.A., Modular approach to active power-line harmonic filtering (1998) Proceedings of the 29th Annual IEEE Power Electronics Specialists Conference (PESC), 1, pp. 223-228Rukonuzzaman, M., Nakaoka, M., Adaptive neural network based harmonic current compensation in active power filter (2001) Proceedings of the International Joint Conference on Neural Networks (IJCNN), 3, pp. 2281-2286Vazquez, J.R., Salmeron, P., Active power filter control using neural network technologies (2003) IEE Proceedings - Electric Power Applications, 150 (2), pp. 139-145Marafão, F.P., Mattavelli, P., Buso, S., Deckmann, S.M., Repetitive-based control for selective active filters using discrete cosine transform (2004) Journal of the Brazilian Power Electronics Society (Revista da Sociedade Brasileira de Eletrônica de Potência), 9 (1), pp. 29-36Mattavelli, P., Fasolo, S., A closed-loop selective harmonic compensation for active filters (2000) Proceedings of the 15th Annual IEEE Applied Power Electronics Conference and Exposition (APEC), 1, pp. 399-405Haykin, S., (1999) Neural Networks - A Comprehensive Foundation, , Prentice HallHagan, M.T., Demuth, H.B., Beale, M., (1995) Neural Network Design, , PWS Publishing CompanyWidrow, B., Winter, R., Neural nets for adaptive filtering and adaptive pattern recognition (1996) Computer, 21 (3), pp. 25-39Widrow, B., Lehr, M.A., 30 years of adaptive neural networks: Perceptron, madaline, and backpropagation (1990) Proceedings of the IEEE, 78 (9), pp. 1415-1442M. G. Villalva, E. Ruppert F., Current controller with artificial neural network for 3-phase 4-wire active filter, in Proceedings of the 35th Annual IEEE Power Electronics Specialists Conference (PESC), 2004M. G. Villalva., E. Ruppert F., Current controller with 3-D SVPWM for 3-phase 4-wire active filters, IASME Transactions, 1, no. 2, april, 2004Marafão, F.P., Deckmann, S.M., Pomilio, J.A., Machado, R.Q., Software-based PLL model: Analysis and applications (2004) Proceedings of the Brazilian Automatics Conference (Congresso Brasileiro deAutomática
Second-Order Filter-Based Inertia Emulation (SOFIE) for Low Inertia Power Systems
No full textPublisher Copyright: © 1986-2012 IEEE.The massive integration of power electronic converters into the power grid has led to a decrease in the mechanical inertia of power systems, causing an increase in the rate of change of frequency (RoCoF) that may lead to stability problems. The scientific community has focused on developing grid-forming control techniques, although their implementation implies a significant change in the firmware of the converter. Grid-supporting approaches, on the other hand, are an interesting alternative to add frequency support to the grid while preserving the original control structure of the converter. This article proposes three new grid-supporting control techniques based on the dynamic behaviour of a synchronous machine (SM) and its equivalence with a second-order low-pass filter. They endow the converter with the capability of providing synthetic inertia, damping, droop-based p/f primary response and virtual reactance. The dynamics of the proposed implementations are compared with a reduced-order synchronous machine by means of time-domain simulations and in-depth state-space-based small signal analyses. Besides, their operation is validated in a nine-bus low-inertia power system. Hardware-in-the-loop (HIL) laboratory results are used to validate experimentally the proposed techniques.Peer reviewe
Artificial optical emissions at HAARP for pump frequencies near the third and second electron gyro-harmonic
No full textInternational audienceHigh-power high-frequency radio waves beamed into the ionosphere cause plasma turbulence, which can accelerate electrons. These electrons collide with the F-layer neutral oxygen causing artificial optical emissions identical to natural aurora. Pumping at electron gyro-harmonic frequencies has special significance as many phenomena change their character. In particular, artificial optical emissions become strongly reduced for the third and higher gyro-harmonics. The High frequency Active Auroral Research Program (HAARP) facility is unique in that it can select a frequency near the second gyro-harmonic. On 25 February 2004, HAARP was operated near the third and passed through the second gyro-harmonic for the first time in a weakening ionosphere. Two novel observations are: firstly, a strong enhancement of the artificial optical emission intensity near the second gyro-harmonic, which is opposite to higher gyro-harmonics; secondly, the optical enhancement maximum occurs for frequencies just above the second gyro-harmonic. We provide the first experimental evidence for these effects, which have been predicted theoretically. In addition, irregular optical structures were created when the pump frequency was above the ionospheric critical frequency.Keywords. Active experiments ? Auroral ionosphere ? Wave-particle interaction
Impact of wind power on the unit commitment, operating reserves and market design
No full textPaper presented at the 2011 IEEE Power and Energy Society General Meeting, San Diego, CA, 24-29 July 2011This article highlights and demonstrates the new requirements variable and partly unpredictable wind power will bring to unit commitment and power system operations.
Current practice is described and contrasted against the new requirements. Literature specifically addressing questions about wind power and unit commitment related power system operations is surveyed. The scope includes forecast errors, operating reserves, intra-day markets, and sharing reserves across interconnections. The discussion covers the critical issues arising from the research.Science Foundation Irelandau, ti, ke, ab, co - TS 10.04.1
An approach to harmonic load- and source-pull measurements for high-efficiency PA design
No full textHigh-efficiency power-amplifier design requires numerous efforts to investigate both input and output harmonic terminations effects. A simplified theoretical approach to clarify the relevance of such terminations is presented here, and design criteria to improve efficiency for high-frequency applications are briefly discussed. An advanced active load/source-pull test-bench has been used to validate theoretical harmonic tuning techniques, characterizing an active device. The adopted optimization strategy is presented, together with measured results obtained with a medium-power 1-mm MESFET at 1 GHz. Input second harmonic impedances effects are stressed, showing a drain efficiency spread between 37%-49% for a fixed input power level, corresponding to 1-dB compression. Finally, as predicted by the presented theory, after input second harmonic tuning, further improvements are obtained, increasing fundamental output load resistive part, demonstrating an additional drain efficiency enhancement, which reaches a level of 55% at 1-dB compression
Investigation of Aperture Coupled Microstrip Antenna to Obtain a High Efficient Active Integrated Antenna by Using Class F and Inverse Class F Power Amplifiers
No full textIn wireless communications and radar systems, there are requirements for high efficiency, small size, low cost, and wide bandwidth of transmitter front –end usage for commercial and also military applications. Active integrated antenna (AIA) could satisfy almost all the requirements. The overall objective of the proposed research is to model, optimise, and design a compact and high efficient AIA using an aperture coupled microstrip antenna (ACMA) by integrating with a power amplifier (PA). Research on ACMA has been focused on the transmissions line (TL) model (TLM) and full wave electromagnetic (EM) model analysis. The full wave investigation is rigorous and elegant but because the dimension of the physical model and the value of the circuit elements are interdependent, the design of the antenna is still difficult. TLM analysis has lower accuracy but easier to analysis and optimise than full wave EM model analysis. To increase the accuracy, the challenge is the coupling ratios between feed/slot, and slot/patch where no unique solution at the moment exists. In this thesis, a novel and simplified method has been produced to investigate these ratios using Scattering (S) parameters. A dual frequency ACMA has been designed to verify these results. Research on the class F and inverse class F PAs is carried out by a novel and simplified load/pull method. A new design method of harmonic load matching network has been presented using lump elements and TLs. Both linear and nonlinear modelling has been investigated. High power added efficiency (PAE) and high gain which are up to 60% and 12dB have been obtained. Finally AIAs have been produced based on previous investigation on class F, inverse class F PAs and a broadband circular polarized ACMA design with 350 MHz bandwidth and 8.5 dB gain at 2 GHz
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