5,038 research outputs found
Efficient Database Generation for Data-driven Security Assessment of Power Systems
Power system security assessment methods require large datasets of operating
points to train or test their performance. As historical data often contain
limited number of abnormal situations, simulation data are necessary to
accurately determine the security boundary. Generating such a database is an
extremely demanding task, which becomes intractable even for small system
sizes. This paper proposes a modular and highly scalable algorithm for
computationally efficient database generation. Using convex relaxation
techniques and complex network theory, we discard large infeasible regions and
drastically reduce the search space. We explore the remaining space by a highly
parallelizable algorithm and substantially decrease computation time. Our
method accommodates numerous definitions of power system security. Here we
focus on the combination of N-k security and small-signal stability.
Demonstrating our algorithm on IEEE 14-bus and NESTA 162-bus systems, we show
how it outperforms existing approaches requiring less than 10% of the time
other methods require.Comment: Database publicly available at:
https://github.com/johnnyDEDK/OPs_Nesta162Bus - Paper accepted for
publication at IEEE Transactions on Power System
Efficiency of dispersive wave generation in dual concentric core microstructured fiber
We describe the generation of powerful dispersive waves that are observed
when pumping a dual concentric core microstructured fiber by means of a
sub-nanosecond laser emitting at the wavelength of~1064 nm. The presence of
three zeros in the dispersion curve, their spectral separation from the pump
wavelength, and the complex dynamics of solitons originated by the pump pulse
break-up, all contribute to boost the amplitude of the dispersive wave on the
long-wavelength side of the pump. The measured conversion efficiency towards
the dispersive wave at 1548 nm is as high as 50%. Our experimental analysis of
the output spectra is completed by the acquisition of the time delays of the
different spectral components. Numerical simulations and an analytical
perturbative analysis identify the central wavelength of the red-shifted pump
solitons and the dispersion profile of the fiber as the key parameters for
determining the efficiency of the dispersive wave generation process.Comment: 11 pages, 12 figure
Multi-speckle diffusing wave spectroscopy with a single mode detection scheme
We present a detection scheme for diffusing wave spectroscopy (DWS) based on
a two cell geometry that allows efficient ensemble averaging. This is achieved
by putting a fast rotating diffuser in the optical path between laser and
sample. We show that the recorded (multi-speckle) correlation echoes provide an
ensemble averaged signal that does not require additional time averaging. We
find the performance of our experimental scheme comparable or even superior to
camera based multi-speckle techniques that rely on direct spatial averaging.
Furthermore, combined with traditional two-cell DWS, the full intensity
autocorrelation function can be measured with a single experimental setup
covering more than 10 decades in correlation time.Comment: Submitted to PR
- …