402,657 research outputs found
Comparative Evaluation between Direct Connected and VSC-HVDC Grid Connected Wind Farm
Nowadays, the penetration level of wind power generation plants has reached a high level. The double Fed Induction Generator (DFIG) based wind turbines are the most preferred type, due to their advantages. Following the impact of wind power plant onto power system, they are now requested by the utilities through grid codes to participate to the grid support and stabilization. For the safety of network operations, an evaluation of DFIG grid connection methods is needed to provide a performance platform in grid connection interface choice and grid codes requirement.This paper presents a comparative study of dynamic behavior of two methods of DFIG wind turbine connection to the grid: direct method and the connection through high voltage direct current transmission system (VSC-HVDC), during the fault. Keywords: Mathematical model of DFIG, fault ride-through (FRT)/ low voltage ride-through (LVRT) requirement, impact of FRT/LVRT on wind farm, VSC-HVDC, MATLAB/Simulations
On Rational Interpolation-Based List-Decoding and List-Decoding Binary Goppa Codes
We derive the Wu list-decoding algorithm for Generalised Reed-Solomon (GRS)
codes by using Gr\"obner bases over modules and the Euclidean algorithm (EA) as
the initial algorithm instead of the Berlekamp-Massey algorithm (BMA). We
present a novel method for constructing the interpolation polynomial fast. We
give a new application of the Wu list decoder by decoding irreducible binary
Goppa codes up to the binary Johnson radius. Finally, we point out a connection
between the governing equations of the Wu algorithm and the Guruswami-Sudan
algorithm (GSA), immediately leading to equality in the decoding range and a
duality in the choice of parameters needed for decoding, both in the case of
GRS codes and in the case of Goppa codes.Comment: To appear in IEEE Transactions of Information Theor
On the Existence of Optimal Exact-Repair MDS Codes for Distributed Storage
The high repair cost of (n,k) Maximum Distance Separable (MDS) erasure codes
has recently motivated a new class of codes, called Regenerating Codes, that
optimally trade off storage cost for repair bandwidth. In this paper, we
address bandwidth-optimal (n,k,d) Exact-Repair MDS codes, which allow for any
failed node to be repaired exactly with access to arbitrary d survivor nodes,
where k<=d<=n-1. We show the existence of Exact-Repair MDS codes that achieve
minimum repair bandwidth (matching the cutset lower bound) for arbitrary
admissible (n,k,d), i.e., k<n and k<=d<=n-1. Our approach is based on
interference alignment techniques and uses vector linear codes which allow to
split symbols into arbitrarily small subsymbols.Comment: 20 pages, 6 figure
Topological Subsystem Codes
We introduce a family of 2D topological subsystem quantum error-correcting
codes. The gauge group is generated by 2-local Pauli operators, so that 2-local
measurements are enough to recover the error syndrome. We study the
computational power of code deformation in these codes, and show that
boundaries cannot be introduced in the usual way. In addition, we give a
general mapping connecting suitable classical statistical mechanical models to
optimal error correction in subsystem stabilizer codes that suffer from
depolarizing noise.Comment: 16 pages, 11 figures, explanations added, typos correcte
New Codes on Graphs Constructed by Connecting Spatially Coupled Chains
A novel code construction based on spatially coupled low-density parity-check
(SC-LDPC) codes is presented. The proposed code ensembles are described by
protographs, comprised of several protograph-based chains characterizing
individual SC-LDPC codes. We demonstrate that code ensembles obtained by
connecting appropriately chosen SC-LDPC code chains at specific points have
improved iterative decoding thresholds compared to those of single SC-LDPC
coupled chains. In addition, it is shown that the improved decoding properties
of the connected ensembles result in reduced decoding complexity required to
achieve a specific bit error probability. The constructed ensembles are also
asymptotically good, in the sense that the minimum distance grows linearly with
the block length. Finally, we show that the improved asymptotic properties of
the connected chain ensembles also translate into improved finite length
performance.Comment: Submitted to IEEE Transactions on Information Theor
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