70,904 research outputs found
Market-based Control of Air-Conditioning Loads with Switching Constraints for Providing Ancillary Services
Air-conditioning loads (ACLs) are among the most promising demand side
resources for their thermal storage capacity and fast response potential. This
paper adopts the principle of market-based control (MBC) for the ACLs to
participate in the ancillary services. The MBC method is suitable for the
control of distributed ACLs because it can satisfy diversified requirements,
reduce the communication bandwidth and protect users' privacy. The modified
bidding and clearing strategies proposed in this paper makes it possible to
adjust the switching frequency and strictly satisfy the lockout time constraint
for mechanical wear reduction and device protection, without increasing the
communication traffic and computational cost of the control center. The
performance of the ACL cluster in two typical ancillary services is studied to
demonstrate the effect of the proposed method. The case studies also
investigate how the control parameters affect the response performance, comfort
level and switching frequency.Comment: 5 pages, conferenc
Distributed Optimal Frequency Control Considering a Nonlinear Network-Preserving Model
This paper addresses the distributed optimal frequency control of power
systems considering a network-preserving model with nonlinear power flows and
excitation voltage dynamics. Salient features of the proposed distributed
control strategy are fourfold: i) nonlinearity is considered to cope with large
disturbances; ii) only a part of generators are controllable; iii) no load
measurement is required; iv) communication connectivity is required only for
the controllable generators. To this end, benefiting from the concept of
'virtual load demand', we first design the distributed controller for the
controllable generators by leveraging the primal-dual decomposition technique.
We then propose a method to estimate the virtual load demand of each
controllable generator based on local frequencies. We derive incremental
passivity conditions for the uncontrollable generators. Finally, we prove that
the closed-loop system is asymptotically stable and its equilibrium attains the
optimal solution to the associated economic dispatch problem. Simulations,
including small and large-disturbance scenarios, are carried on the New England
system, demonstrating the effectiveness of our design
Application of a simplified thermal-electric model of a sodium-nickel chloride battery energy storage system to a real case residential prosumer
Recently, power system customers have changed the way they interact with public networks, playing a more and more active role. End-users first installed local small-size generating units, and now they are being equipped with storage devices to increase the self-consumption rate. By suitably managing local resources, the provision of ancillary services and aggregations among several end-users are expected evolutions in the near future. In the upcoming market of household-sized storage devices, sodium-nickel chloride technology seems to be an interesting alternative to lead-acid and lithium-ion batteries. To accurately investigate the operation of the NaNiCl2 battery system at the residential level, a suitable thermoelectric model has been developed by the authors, starting from the results of laboratory tests. The behavior of the battery internal temperature has been characterized. Then, the designed model has been used to evaluate the economic profitability in installing a storage system in the case that end-users are already equipped with a photovoltaic unit. To obtain realistic results, real field measurements of customer consumption and solar radiation have been considered. A concrete interest in adopting the sodium-nickel chloride technology at the residential level is confirmed, taking into account the achievable benefits in terms of economic income, back-up supply, and increased indifference to the evolution of the electricity market
The BOOMERANG North America Instrument: a balloon-borne bolometric radiometer optimized for measurements of cosmic background radiation anisotropies from 0.3 to 4 degrees
We describe the BOOMERANG North America (BNA) instrument, a balloon-borne
bolometric radiometer designed to map the Cosmic Microwave Background (CMB)
radiation with 0.3 deg resolution over a significant portion of the sky. This
receiver employs new technologies in bolometers, readout electronics,
millimeter-wave optics and filters, cryogenics, scan and attitude
reconstruction. All these subsystems are described in detail in this paper. The
system has been fully calibrated in flight using a variety of techniques which
are described and compared. It has been able to obtain a measurement of the
first peak in the CMB angular power spectrum in a single balloon flight, few
hours long, and was a prototype of the BOOMERANG Long Duration Balloon (BLDB)
experiment.Comment: 40 pages, 22 figures, submitted to Ap
An Overview of Broadband communication over Power Lines
Broadband over power lines are Systems for carrying
data on conductors used for electric power
transmission. Power line communication technologies
can be used for different applications ranging from
home automation to internet access.
With the spread of broadband technologies in the last
few years, there are yet significant areas in the world
that do not have access to high speed internet, as
compared with the few internet service providers in
existence, the additive expenditures of laying cables
and building necessary infrastructure to provide DSL
in many areas most especially rural areas is too great.
But if broadband is served through power lines
considering the fact that it exist all over the country,
there will be no need to build new infrastructure.
Therefore, anywhere there is electricity, there could
also be broadband.
Broadband over Power line is designed to offer an
alternative means to provide high speed internet
access, voice over Internet protocol (VOIP) and other
broadband services, using medium and low voltage
lines to reach customers and businesses by combining
the principle of wireless networking, modems and
Radio. Researchers and developers have created ways
to transmit data over power lines into homes at
speeds between 500kilobits and 3 megabits per
second which is equivalent to the cable DSL (Digital
Subscriber Line) and this is achieved by modifying
the present power grids with specialized equipments.
With this knowledge, the broadband power line
developers could partner with power companies and
Internet service providers to bring broadband to
everyone with access to electricity
CUSTARD (Cranfield University Space Technology Advanced Research Demonstrator) - A Micro-System Technology Demonstrator Nanosatellite. Summary of the Group Design Project MSc in Astronautics and Space Engineering. 1999-2000, Cranfield University
CUSTARD (Cranfield University Space Technology And Research Demonstrator) was
the group design project for students of the MSc in Astronautics and Space
Engineering for the Academic Year 1999/2000 at Cranfield University. The project
involved the initial design of a nanosatellite to be used as a technology
demonstrator for microsystem technology (MST) in space. The students worked
together as one group (organised into several subgroups, e.g. system,
mechanical), with each student responsible for a set of work packages. The
nanosatellite designed had a mass of 4 kg, lifetime of 3 months in low Earth
orbit, coarse 3-axis attitude control (no orbit control), and was capable of
carrying up to 1 kg of payload. The electrical power available was 18 W (peak).
Assuming a single X-band ground station at RAL (UK), a data rate of up to 1 M
bit s-1 for about 3000 s per day is possible. The payloads proposed are a
microgravity laboratory and a formation flying experiment.
The report summarises the results of the project and includes executive
summaries from all team members. Further information and summaries of the full
reports are available from the College of Aeronautics, Cranfield University
Nimbus power systems /1960 - 1969/
Power supply subsystems for use on Nimbus satellite progra
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