2,354 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
Super-Poissonian noise in a Coulomb blockade metallic quantum dot structure
The shot noise of the current through a single electron transistor (SET),
coupled capacitively with an electronic box, is calculated, using the master
equation approach. We show that the noise may be sub-Poissonian or strongly
super-Poissonian, depending mainly on the box parameters and the gate. The
study also supports the idea that not negative differential conductance, but
charge accumulation in the quantum dot, responds for the super-Poissonian noise
observed.Comment: 4 Pages, 3 Figure
Polynomial mixing of a stochastic wave equation with dissipative damping
We study the long time statistics of a class of semi--linear wave equations
modeling the motions of a particle suspended in continuous media while being
subjected to random perturbations via an additive Gaussian noise. By comparison
with the nonlinear reaction settings, of which the solutions are known to
possess geometric ergodicity, we find that, under the impact of nonlinear
dissipative damping, the mixing rate is at least polynomial of any order. This
relies on a combination of Lyapunov conditions, the contracting property of the
Markov transition semigroup as well as the notion of --small sets
Data Optical Networking Architecture Using Wavelength-Division Multiplexing Method for Optical Sensors
Recently there has been a growth in the number of fiber optical sensors used for health monitoring in the hostile environment of commercial aircraft. Health monitoring to detect the onset of failure in structural systems from such causes as corrosion, stress corrosion cracking, and fatigue is a critical factor in safety as well in aircraft maintenance costs. This report presents an assessment of an analysis model of optical data networking architectures used for monitoring data signals among these optical sensors. Our model is focused on the design concept of the wavelength-division multiplexing (WDM) method since most of the optical sensors deployed in the aircraft for health monitoring typically operate in a wide spectrum of optical wavelengths from 710 to 1550 nm
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