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Showing 3 results for Cooperative
Cooperative Orthogonal Space-Time-Frequency Block Codes over a MIMO-OFDM Frequency Selective Channel
M. Rezaei, A. Falahati,
Volume 12, Issue 1 (3-2016)
Abstract

In this paper, a cooperative algorithm to improve the orthogonal space-timefrequency block codes (OSTFBC) in frequency selective channels for 2*1, 2*2, 4*1, 4*2 MIMO-OFDM systems, is presented. The algorithm of three node, a source node, a relay node and a destination node is formed, and is implemented in two stages. During the first stage, the destination and the relay antennas receive the symbols sent by the source antennas. The destination node and the relay node obtain the decision variables employing time-space-frequency decoding process by the received signals. During the second stage, the relay node transmits decision variables to the destination node. Due to the increasing diversity in the proposed algorithm, decision variables in the destination node are increased to improve system performance. The bit error rate of the proposed algorithm at high SNR is estimated by considering the BPSK modulation. The simulation results show that cooperative orthogonal space-time-frequency block coding, improves system performance and reduces the BER in a frequency selective channel.


Cooperative Decision Making of DERs in a Joint Energy and Regulation Market in Presence of Electric Vehicles
S. Arefi Ardakani, A. Badri,
Volume 13, Issue 4 (12-2017)
Abstract
Today due to increasing and evolving of electrical grids, the optimal and profitable energy production is among producers' major concerns. Thus, conventional ways of production and trading energy are being replaced by modern economical procedures. In addition, distributed energy resources (DERs) in form of renewable and conventional resources as well as responsive loads play an important role in this issue. The mutual problem of DERs in joining power market is their rather small production compared to other units and intermittency of the corresponding resources. Forming coalition is an effective way to overcome DER difficulties for participating in power market. In this paper the problem of optimal bidding strategy of DERs integrated as a virtual power plant is investigated. Based on the proposed method, cooperative game is employed to obtain optimal DER outputs and the results are compared with individual non-cooperative bidding model. In order to mitigate the intermittent nature of renewable energies, existence of electric vehicles (EVs) as energy storage facilities in the proposed coalition is investigated. Due to the associated uncertainties regarding EVs and DERs, a stochastic optimization model is used. Finally, Shapley value method is employed to obtain corresponding allocated profits. Results show the eminence of forming coalition in terms of acquiring payoffs and optimal contributions.

A Novel Protection Method for UPFC Compensated Transmission Line Based on Cooperative Game Theory
M. Khalili, F. Namdari, E. Rokrok,
Volume 18, Issue 1 (3-2022)
Abstract
This paper presents a new single-end scheme to locate and protect faults on the compensated transmission line using the Unified Power Flow Controller (UPFC). The UPFC controllers have remarkable effects on the transient and steady-state components of the voltage and current signals. First of all, this study evaluates the impact of UPFC on Traveling Waves (TW) that pass through the UPFC location. Following that, the effects of UPFC’s harmonic on conventional protections will be investigated using the TW theory. A single-end method will be presented in the next stage to protect and locate the faults on the compensated transmission lines with UPFC. Moreover, an extraction technique (i.e., Discrete Wavelet Transform [DWT]) is used to process the current and voltage signals. As a branch of mathematics, cooperative game is employed in this study to represent the strategic interaction of different players in a context by predefined rules and outcomes. Additionally, this study made use of this theory to distinguish the extracted TWs from each other. The proposed method is assessed considering different fault situations with great variations in operating conditions accompanied by a UPFC placed at the midpoint of the line.

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© 2022 by the authors. Licensee IUST, Tehran, Iran. This is an open access journal distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license.