Abstract: This paper describes a node pair selection scheme
in relay-aided multiple source multiple destination communication
system based on stable marriage problem. A general case is assumed
in which all of source, relay and destination nodes are equipped
with multiantenna and carry out multistream transmission. Based
on several metrics introduced from inter-node channel condition,
the preference order is determined about all source-relay and
relay-destination relations, and then the node pairs are determined
using Gale-Shapley algorithm. The computer simulations show
that the effectiveness of node pair selection is larger in multihop
communication. Some additional aspects which are different from
relay-less case are also investigated.
Abstract: This paper presents a fault identification, classification and fault location estimation method based on Discrete Wavelet Transform and Adaptive Network Fuzzy Inference System (ANFIS) for medium voltage cable in the distribution system.
Different faults and locations are simulated by ATP/EMTP, and then certain selected features of the wavelet transformed signals are used as an input for a training process on the ANFIS. Then an accurate fault classifier and locator algorithm was designed, trained and tested using current samples only. The results obtained from ANFIS output were compared with the real output. From the results, it was found that the percentage error between ANFIS output and real output is less than three percent. Hence, it can be concluded that the proposed technique is able to offer high accuracy in both of the fault classification and fault location.
Abstract: This paper discusses the performance of critical
trajectory method (CTrj) for power system transient stability analysis
under various loading settings and heavy fault condition. The method
obtains Controlling Unstable Equilibrium Point (CUEP) which is
essential for estimation of power system stability margins. The CUEP
is computed by applying the CTrjto the boundary controlling unstable
equilibrium point (BCU) method. The Proposed method computes a
trajectory on the stability boundary that starts from the exit point and
reaches CUEP under certain assumptions. The robustness and
effectiveness of the method are demonstrated via six power system
models and five loading conditions. As benchmark is used
conventional simulation method whereas the performance is compared
with and BCU Shadowing method.
Abstract: Currently, several soft switching topologies have been studied to achieve high power switching efficiency, reduced cost, improved reliability and reduced parasites. It is well known that improvement in power electronics systems always depend on advanced in power devices. The IGBT has been successfully used in a variety of switching applications such as motor drives and appliance control because of its superior characteristics.
The aim of this paper is focuses on simulation and explication of the internal dynamics of IGBTs behaviour under the most popular soft switching schemas that is Zero Current Switching (ZCS) environments.
The main purpose of this paper is to point out some mechanisms relating to current tail during the turn-off and examination of the response at turn-off with variation of temperature, inductance L, snubber capacitors Cs, and bus voltage in order to achieve an improved understanding of internal carrier dynamics. It is shown that the snubber capacitor, the inductance and even the temperature controls the magnitude and extent of the tail current, hence the turn-off time (switching speed of the device).
Moreover, it has also been demonstrated that the ZCS switching can be utilized efficiently to improve and reduce the power losses as well as the turn-off time. Furthermore, the turn-off loss in ZCS was found to depend on the time of switching of the device.
Abstract: In this work, an experimental technique is applied
for the measurements of the vibrations and deformation of a test
transformer core. Since the grid voltage contains some higher
harmonics, in addition to a purely sinusoidal magnetisation of the
core the presence of third harmonic is also studied. The vibrations of
the transformer core for points as well as the surface scan of the leg
show more deformation in the corners of the leg than the middle of
the leg. The influence of the higher harmonic of the magnetisation
on the core deformation is also more significant in the corners of the
leg. The core deformation shape under a sinusoidal magnetisation
with a higher harmonic is more wavy and fluctuating than that under
a purely sinusoidal magnetisation.
Abstract: This paper deals with a stabilization problem for
multi-agent systems, when all agents in a multi-agent system receive
the same broadcasting control signal and the controller can measure
not each agent output but the sum of all agent outputs. It is
analytically shown that when the sum of all agent outputs is bounded
with a certain broadcasting controller for a given reference, each agent
output is separately bounded: stabilization of the sum of agent outputs
always results in the stability of every agent output. A numerical
example is presented to illustrate our theoretic findings in this paper.
Abstract: This paper studies a robust stabilization problem of a
single agent in a multi-agent consensus system composed of identical
agents, when the network topology of the system is completely
unknown. It is shown that the transfer function of an agent in a
consensus system can be described as a multiplicative perturbation
of the isolated agent transfer function in frequency domain. From an
existing robust stabilization result, we present sufficient conditions for
a robust stabilization of an agent against unknown network topology.
Abstract: This paper presents a nonparametric method to obtain the hazard rate “Bathtub curve” for power system components. The model is a mixture of the three known phases of a component life, the decreasing failure rate (DFR), the constant failure rate (CFR) and the increasing failure rate (IFR) represented by three parametric Weibull models. The parameters are obtained from a simultaneous fitting process of the model to the Kernel nonparametric hazard rate curve. From the Weibull parameters and failure rate curves the useful lifetime and the characteristic lifetime were defined. To demonstrate the model the historic time-to-failure of distribution transformers were used as an example. The resulted “Bathtub curve” shows the failure rate for the equipment lifetime which can be applied in economic and replacement decision models.
Abstract: This paper deals with the novel intelligent bio-inspired control strategies, it presents a novel approach based on an optimal fuzzy immune PID parameters tuning, it is a combination of a PID controller, inspired by the human immune mechanism with fuzzy logic. Such controller offers more possibilities to deal with the delayed systems control difficulties due to the delay term. Indeed, we use an optimization approach to tune the four parameters of the controller in addition to the fuzzy function; the obtained controller is implemented in a modified Smith predictor structure, which is well known that it is the most efficient to the control of delayed systems. The application of the presented approach to control a three tank delay system shows good performances and proves the efficiency of the method.
Abstract: With the current rise in the demand of electrical energy, present-day power systems which are large and complex, will continue to grow in both size and complexity. Flexible AC Transmission System (FACTS) controllers provide new facilities, both in steady state power flow control and dynamic stability control. Thyristor Controlled Series Capacitor (TCSC) is one of FACTS equipment, which is used for power flow control of active power in electric power system and for increase of capacities of transmission lines. In this paper, a Backstepping Power Flow Controller (BPFC) for TCSC in multimachine power system is developed and tested. The simulation results show that the TCSC proposed controller is capable of controlling the transmitted active power and improving the transient stability when compared with conventional PI Power Flow Controller (PIPFC).
Abstract: Packaging for vanadium redox flow battery is one of the key elements for successful implementation of flow battery in the electrical energy storage system. Usually the bulky battery size and low energy densities make this technology not available for mobility application. ThereforeRFB with improved packaging size and energy capacity are highly desirable. This paper focuses on the study of packaging improvement for unit cell V-RFB to the application on Series Hybrid Electric Vehicle. Two different designs of 25cm2 and 100cm2 unit cell V-RFB at same current density are used for the sample in this investigation. Further suggestions on packaging improvement are highlighted.
Abstract: This paper proposes frequency offset (FO) estimation
schemes robust to the non-Gaussian noise for orthogonal frequency
division multiplexing (OFDM) systems. A maximum-likelihood (ML)
scheme and a low-complexity estimation scheme are proposed by
applying the probability density function of the cyclic prefix of
OFDM symbols to the ML criterion. From simulation results, it is
confirmed that the proposed schemes offer a significant FO estimation
performance improvement over the conventional estimation scheme
in non-Gaussian noise environments.
Abstract: This paper presents the optimal design and simulation of a grid-connected Photovoltaic (PV) system to supply electric power to meet the energy demand by Electrical Department in University of Tripoli Libya. Solar radiation is the key factor determining electricity produced by photovoltaic (PV) systems. This paper is designed to develop a novel method to calculate the solar photovoltaic generation capacity on the basis of Mean Global Solar Radiation data available for Tripoli Libya and finally develop a system design of possible plant capacity for the available roof area. MatLab/Simulink Programming tools and monthly average solar radiation data are used for this design and simulation. The specifications of equipments are provided based on the availability of the components in the market. Simulation results and analyses are presented to validate the proposed system configuration.
Abstract: This paper presents a simulation and mathematical model of stand-alone solar-wind-diesel based hybrid energy system (HES). A power management system is designed for multiple energy resources in a stand-alone hybrid energy system. Both Solar photovoltaic and wind energy conversion system consists of maximum power point tracking (MPPT), voltage regulation, and basic power electronic interfaces. An additional diesel generator is included to support and improve the reliability of stand-alone system when renewable energy sources are not available. A power management strategy is introduced to distribute the generated power among resistive load banks. The frequency regulation is developed with conventional phase locked loop (PLL) system. The power management algorithm was applied in Matlab®/Simulink® to simulate the results.
Abstract: Distributed generation units (DGs) are grid-connected or stand-alone electric generation units located within the electric distribution system at or near the end user. It is generally accepted that centralized electric power plants will remain the major source of the electric power supply for the near future. DGs, however, can complement central power by providing incremental capacity to the utility grid or to an end user. This paper presents an efficient power dispatching model for hybrid wind-Solar power generation system, to satisfy some essential requirements, such as dispersed electric power demand, electric power quality and reducing generation cost and so on. In this paper, presented some elements of the main parts in the hybrid system; and then made fundamental dispatching strategies according to different situations; then pointed out four improving measures to improve genetic algorithm, such as: modify the producing way of selection probability, improve the way of crossover, protect excellent chromosomes, and change mutation range and so on. Finally, propose a technique for solving the unit's commitment for dispatching problem based on an improved genetic algorithm.
Abstract: The integration of wide variety of communication services is made possible with invention of 3G technology. Code Division Multiple Access 2000 operates on various RF channel bandwidths 1.2288 or 3.6864 Mcps (1x or 3x systems). It is a 3G system which offers high bandwidth and wireless broadband services but its efficiency is lowered due to various factors like fading, interference, scattering, absorption etc. This paper investigates the effect of diversity (MRC), roll off factor in Root Raised Cosine (RRC) filter for the BPSK and QPSK modulation schemes. It is possible to transmit data with minimum Inter symbol Interference and within limited bandwidth with proper pulse shaping technique. Bit error rate (BER) performance is analyzed by applying diversity technique by varying the roll off factor for BPSK and QPSK. Roll off factor reduces the ISI and diversity reduces the Fading.
Abstract: This paper presents a regression model for interval type-2 fuzzy sets based on the least squares estimation technique. Unknown coefficients are assumed to be triangular fuzzy numbers. The basic idea is to determine aggregation intervals for type-1 fuzzy sets, membership functions of whose are low membership function and upper membership function of interval type-2 fuzzy set. These aggregation intervals were called weighted intervals. Low and upper membership functions of input and output interval type-2 fuzzy sets for developed regression models are considered as piecewise linear functions.
Abstract: Visually impaired people find it extremely difficult to
acquire basic and vital information necessary for their living.
Therefore, they are at a very high risk of being socially excluded as a
result of poor access to information. In recent years, several attempts
have been made in improving the communication methods for
visually impaired people which involve tactile sensation such as
finger Braille, manual alphabets and the print on palm method and
several other electronic devices. But, there are some problems which
arise in such methods such as lack of privacy and lack of
compatibility to computer environment. This paper describes a low
cost Braille hand glove for blind people using slot sensors and
vibration motors with the help of which they can read and write emails,
text messages and read e-books. This glove allows the person
to type characters based on different Braille combination using six
slot sensors. The vibration in six different positions of the glove
which matches to the Braille code allows them to read characters.