18,848 research outputs found
Voltage Multistability and Pulse Emergency Control for Distribution System with Power Flow Reversal
High levels of penetration of distributed generation and aggressive reactive
power compensation may result in the reversal of power flows in future
distribution grids. The voltage stability of these operating conditions may be
very different from the more traditional power consumption regime. This paper
focused on demonstration of multistability phenomenon in radial distribution
systems with reversed power flow, where multiple stable equilibria co-exist at
the given set of parameters. The system may experience transitions between
different equilibria after being subjected to disturbances such as short-term
losses of distributed generation or transient faults. Convergence to an
undesirable equilibrium places the system in an emergency or \textit{in
extremis} state. Traditional emergency control schemes are not capable of
restoring the system if it gets entrapped in one of the low voltage equilibria.
Moreover, undervoltage load shedding may have a reverse action on the system
and can induce voltage collapse. We propose a novel pulse emergency control
strategy that restores the system to the normal state without any interruption
of power delivery. The results are validated with dynamic simulations of IEEE
-bus feeder performed with SystemModeler software. The dynamic models can
be also used for characterization of the solution branches via a novel approach
so-called the admittance homotopy power flow method.Comment: 13 pages, 22 figures. IEEE Transactions on Smart Grid 2015, in pres
Study of optimum discrete estimators in measurement analysis
Study of statistical techniques for obtaining estimates of true data parameters uses discrete measured quantities containing random error. These techniques develop estimation procedures as an iterative algorithm for digital computation in real time
Low-scale inflation in a model of dark energy and dark matter
We present a complete particle physics model that explains three major
problems of modern cosmology: inflation, dark matter and dark energy, and also
gives a mechanism for leptogenesis. The model has a new gauge group
that grows strong at a scale eV. We focus on the
inflationary aspects of the model. Inflation occurs with a Coleman-Weinberg
potential at a low scale, down to \sim 6\times 10^5\gev, being compatible
with observational data.Comment: 5 two-column pages, RevTex4; two reference added and minor changes
made in the text; published in JCA
Multiple-Input Multiple-Output Gaussian Broadcast Channels with Common and Confidential Messages
This paper considers the problem of the multiple-input multiple-output (MIMO)
Gaussian broadcast channel with two receivers (receivers 1 and 2) and two
messages: a common message intended for both receivers and a confidential
message intended only for receiver 1 but needing to be kept asymptotically
perfectly secure from receiver 2. A matrix characterization of the secrecy
capacity region is established via a channel enhancement argument. The enhanced
channel is constructed by first splitting receiver 1 into two virtual receivers
and then enhancing only the virtual receiver that decodes the confidential
message. The secrecy capacity region of the enhanced channel is characterized
using an extremal entropy inequality previously established for characterizing
the capacity region of a degraded compound MIMO Gaussian broadcast channel.Comment: Submitted to the IEEE Transactions on Information Theory, July 200
Methods for injection error analysis and their comparison Scientific report no. 13
Formulation of direct and adjoint methods of trajectory injection error in vector matrix notation and compariso
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