2,311,098 research outputs found
RF power generation
This paper reviews the main types of r.f. power amplifiers which are, or may
be, used for particle accelerators. It covers solid-state devices, tetrodes,
inductive output tubes, klystrons, magnetrons, and gyrotrons with power outputs
greater than 10 kW c.w. or 100 kW pulsed at frequencies from 50 MHz to 30 GHz.
Factors affecting the satisfactory operation of amplifiers include cooling,
matching and protection circuits are discussed. The paper concludes with a
summary of the state of the art for the different technologies.Comment: 35 pages, contribution to the CAS - CERN Accelerator School:
Specialised Course on RF for Accelerators; 8 - 17 Jun 2010, Ebeltoft, Denmar
Magnetohydrodynamic power generation
Magnetohydrodynamic (MHD) Power Generation is a concise summary of MHD theory, history, and future trends. Results of the major international MHD research projects are discussed. Data from MHD research is included. Economics of initial and operating costs are considered
On-Site Wireless Power Generation
Conventional wireless power transfer systems consist of a microwave power
generator and a microwave power receiver separated by some distance. To realize
efficient power transfer, the system is typically brought to resonance, and the
coupled-antenna mode is optimized to reduce radiation into the surrounding
space. In this scheme, any modification of the receiver position or of its
electromagnetic properties results in the necessity of dynamically tuning the
whole system to restore the resonant matching condition. It implies poor
robustness to the receiver location and load impedance, as well as additional
energy consumption in the control network. In this study, we introduce a new
paradigm for wireless power delivery based on which the whole system, including
transmitter and receiver and the space in between, forms a unified microwave
power generator. In our proposed scenario the load itself becomes part of the
generator. Microwave oscillations are created directly at the receiver
location, eliminating the need for dynamical tuning of the system within the
range of the self-oscillation regime. The proposed concept has relevant
connections with the recent interest in parity-time symmetric systems, in which
balanced loss and gain distributions enable unusual electromagnetic responses.Comment: 10 pages, 13 figure
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Market Power and Technological Bias: The Case of Electricity Generation
It is difficult to elminated all market power in electricity markets and it is therefore frequently suggested that some market power should be tolerated: extra revenues contribute to fixed cost recovery,facilitate investment and increase security of supply. This suggestion implicitly assumes all generation technologiesbenefit equally from market power. We assess a mixture of conventional and intermittent generation, eg coal plants and wind power. If all output is sold in the spot market, then intermittent generation benefits less frommarket power than conventional generation. Forward contracts or option contracts reduce the levelof market power but bias against intermittent generators persists
Alternative power-generation systems
The present state of the art of thermal power systems is surveyed. Because of the great potential variety of thermal power systems, the heat sources, the power conversion systems, and the integration of thermal power systems with missions are treated sequentially
Spectrophotovoltaic orbital power generation
A subscale model of a photovoltaic power system employing spectral splitting and 1000:1 concentration was fabricated and tested. The 10-in. aperture model demonstrated 15.5% efficiency with 86% of the energy produced by a GaAs solar cell and 14% of the energy produced by an Si cell. The calculated efficiency of the system using the same solar cells, but having perfect optics, would be approximately 20%. The model design, component measurements, test results, and mathematical model are presented
Spectrophotovoltaic orbital power generation
A system with 1000 : 1 concentration ratio is defined, using a cassegrain telescope as the first stage concentration (270 x) and compound parabolic concentrators (CPC) for the second stage concentration of 4.7 x for each spectral band. Using reported state of the art (S.O.A.) solar cells device parameters and considering structural losses due to optics and beamsplitters, the efficiencies of one to four cell systems were calculated with efficiencies varying from approximately 22% to 30%. Taking into account cost of the optics, beamsplitter, radiator, and the cost of developing new cells the most cost effective system is the GaAs/Si system
Power quality improvements through power electronic interfaced distributed generation
In low-voltage distribution networks a large amount of single-phase nonlinear loads are connected. This leads to the combined presence of power system unbalance and harmonic distortion. The research presented in this paper focusses on these steady-state power quality problems. It uses a harmonic load flow program, implemented in symmetrical components, to investigate the influence of several single-phase inverter control strategies used to connect any kind of primary energy source to the grid. The influence of these single-phase distributed generation units in the three-phase four-wire distribution network is discussed by means of two recently formulated indicators that combine the power system unbalance and the existing harmonics
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