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Home>Products>Journal and Reviews>I.R.E.E.>Latest issue
International Review of Electrical Engineering - August 2009 - Papers
International Review of Electrical Engineering - Papers
by Ghazanfar Shahgholian, Jawad Faiz, Mohsen Arezoomand Vol. 4. n. 4, pp. 513-523
Abstract - An uninterruptible power supply (UPS) system with two kinds of filters in the inverter output is ana¬lyzed and simulated. The purpose of a voltage controller for UPS inverters is to produce stable output voltage with low distortion under all loading condi¬ti¬o¬ns, particularly under nonlinear loads and load transients. The system modeled consists of the output filter, the control system and the single phase inverter. A state-space mathematical model for system is used. The results show that system voltage total har¬m¬onic distortion to less than 5% even when supplying non¬linear loads which draw current with a crest factor of 3. The simulation results are confirmed by the experimental results. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Uninterruptible Power Supply (UPS), Filter, Harmonic, Two-Port Network, Stability.
Vol. 4. n. 4, pp. 524-531
Abstract - A bidirectional dc-dc converter with high conversion ratio is presented in this paper to have the capability of bidirectional power flow. Two boost conversion stages are adopted in the converter to achieve high voltage step-up conversion. The other power flow direction can also be achieved in the proposed converter with low voltage step-down conversion. Comparison with the conventional boost converter with narrow turn-off period, the proposed converter has wide conversion ratio so that the higher or lower output voltage can be achieved. To reduce the switching losses and limit the voltage stress on the power switch, the boost type of active snubber is used in the converter. The resonance based on the output capacitance of power switch and resonant inductance at the transition interval will make the power switches to turn on at zero voltage switching (ZVS). The circuit configuration, principle operation, system analysis, and design consideration of the proposed converter are presented. Finally, experiments conducted on a laboratory prototype are presented to verify the effectiveness of the proposed converter. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Bidirectional converter, High conversion ratio.
Vol. 4. n. 4, pp. 532-538
Abstract - In this paper, a novel approach for harmonic optimization of a single-phase multilevel inverter is introduced. Firstly, a novel single-phase multilevel inverter structure is proposed and structural parts of the inverter are described. A simple switching strategy that uses a formula to calculate switching angles for obtaining multilevel voltage form is improved. Simulation and experimental results are given together for 7, 15, 31 and 63 levels. For harmonic optimization of proposed method, firstly general equation of Total Harmonic Distortion (THD) is obtained for n-level voltage wave. After obtaining the general equation of THD, four different analysis methods are used for THD optimization in multilevel voltage wave forms. The common point in all analyses is finding switching angles (αj) and level coefficients (kj) for obtaining multilevel output voltage that has minimal THD value. After finding optimum switching angles (αj) and level coefficients (kj), THD values are calculated and the results are given related to level number. All analysis methods are realized by proposed inverter structure and THD values of output voltage waves are measured by a harmonic analyzer. Proposed switching strategy is an analysis method which is simple and easily applicable compared to the other methods. It is seen that the method closely converges to the best solution that gives minimal THD value. Output voltage waves obtained by using proposed switching strategy are given up to 127-level, THD values are also measured and experimental results are given. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Total Harmonic Distortion, Harmonic Optimization, Multilevel Inverter.
Vol. 4. n. 4, pp. 539-546
Abstract - This paper presents direct thrust control (DTC) method of a linear induction motor (LIM) considering end effects based on machine flux and force estimation. We analyze in this work the influences of longitudinal end effects, while basing on a new approach. The approach consists in developing a new electric equivalent circuit. The developed DTC control scheme is based on the proposed mathematical model. Numerical simulations have been carried out to validate the proposed method. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Linear Induction Motor (LIM), Direct Thrust Control (DTC), Longitudinal End Effects, Estimation.
Vol. 4. n. 4, pp. 547-556
Abstract - In a front differential vehicle, Driving/Regeneration can be obtained by summing torques applied on rear wheels. On the other hand, unequal torques applied to rear wheels provides enhanced safety. For these aims, a model with seven degrees of freedom (7-DoF) and Dugoff’s tire model are considers. Also, ADVISOR model of engine, power-train subsystems, electrical machine and battery will be used. A simple PID Controller will be considered for driver modeling. Considering an electrical machine on each rear wheels, sliding mode and fuzzy controllers will be designed for direct yaw moment control and driving mode control respectively. Also regenerative braking torque will be applied by braking pedal directly. To reach these goals, an estimation of engine power and yaw rate error will be calculated to use in the controller. Forward simulation of vehicle, intelligent vehicle control based on road/driving condition and also synchronous control of driving/regeneration and stability enhancement are the advantages of this paper. Simulations performed in MATLAB/SIMULINK environment demonstrate that the proposed structure can effectively enhance the vehicle performance in different modes. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Fuzzy, Driving/Regeneration, Hybrid, Sliding mode controller.
Vol. 4. n. 4, pp. 557-563
Abstract - A Renewable Energy Vehicle Simulator (REVS) that enables to simulate renewable energy vehicles using combination of propulsion system and fuels by adapting library modules to suit particular applications has been developed. The simulation software predicts the energy use of the vehicle, taking into account the duty cycle and driver habits. Library modules have been developed to simulate the Plug-In Hybrid Electric Vehicle (PHEV) architecture as this platform offers energy scenario for cars and buses allowing combination of energy sources that include renewable electricity and renewable biofuels. This paper will discuss the methodology for designing system level vehicles using the REVS package. A series parallel HEV with a conventional ICE and power split transmission system has been designed using the simulation package. A fuzzy controller has been developed to simulate the driver and to command the acceleration and brake pedal. Another fuzzy controller has been employed to manage the power flow in hybrid vehicle. The energy management strategy has been applied through a rule-based fuzzy approach. Several rules are used to determine, based on the power demand value, how much power to get from electric motor if the power demand is positive. Simulation results of the vehicle will be presented for high and low capacity battery in various driving schedules. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Plug-In Hybrid Electric Vehicle, Simulator, Transportations, Control Strategies, Energy Flow, Renewable Energy Vehicle Simulator.
Vol. 4. n. 4, pp. 564-569
Abstract - Interior permanent magnet synchronous motors (IPMSMs) are attractive in hybrid electric vehicles (HEVs) because of the high efficiency and ability to operate in the field-weakening mode for extended speed range. In HEV application, under a driving schedule, the traction motor has to operate in both the constant-torque and constant-power regions due to the wide speed range. This paper aims to improve the IPMSM control technique in both aforementioned regions and maintain the ability to change between them quickly, by considering all factors affecting it such as the dc-link voltage, battery pack and electric motor maximum permissible currents, motor speed, and torque request. The maximum torque per ampere (MTPA) and field-weakening control techniques are chosen in the constant-torque and constant-power regions respectively. Thereafter, the proposed control technique is used to examine the IPMSM performances under city as well as highway driving conditions. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Hybrid Electric Vehicles, HEV, Interior Permanent Magnet Synchronous Motors (IPMSMs), Motor Drives.
Vol. 4. n. 4, pp. 570-576
Abstract - Further to introducing a multi-machine power system model, in this paper, we attempt to obtain the related linear equations around the operating point which are later used to determine the state equations and system modes. After that and through sensitivity analysis, the relation between system modes and network states are achieved which in turn, will lead to identifying the generators that require stabilizer installation. Using feedback from various system states, the optimal control method (LOC) is known as one of the effective methods of designing power system stabilizers. Due to inaccessibility of the majority of system states in a multi-machine power network, this paper suggests using system states estimated by Kalman filter for optimal control that avoids transmitting the remote system states which requires using telemetry channels. By using the proposed method, a practical sample is simulated and compared with another effective method. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Kalman Filter, Linear Optimized Control (LOC), Stabilizer, Synchronism, System Modes.
Vol. 4. n. 4, pp. 577-582
Abstract - In this paper, loss allocation problem in power systems is studied and a new method for transmission loss allocation in power systems is proposed. At first, using transmission line losses according to the bus current injection, the share of any busses in appointed transmission line losses production is determined. Then, considering the total available transmission line losses in the network, the share of any of the network buses from these total losses can be determined. In extracting the proposed method, the existing equations within the network have been used and no simplifying assumption has been employed. In this paper, using the sending and receiving power flow equations in the transmission line and its relation with the produced losses in transmission line, it is tried to determine the share of any network buses from the produced loses. Numerical test is performed on a standard power system for this method against some other famous loss allocation techniques. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Power markets, Transmission loss allocation, Line loss.
Vol. 4. n. 4, pp. 583-591
Abstract - In high penetration of Distributed Generation in the distribution network, new economic opportunities will emerge for Distribution Company, DISCO, in the wholesale market, such as exporting power to the transmission system and providing additional services. To use these opportunities, DISCO, while satisfying the internal demands, needs to aggregate DGs to compete in power market or respond to ISO requests. For this purpose, this paper proposes a method for extracting a single operating profile, a lumped financial model, for a DISCO at the connecting point to the transmission system. The proposed method is based on aggregation of cost function of all internal resources, while taking the distribution network constraints and losses into account. Moreover, the effects of technical constraints of the network, cost function of DGs, and hourly variation in the system load pattern on the created operating profile as well as functionality of DISCO in the wholesale market are fully investigated and reported. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Aggregated Model, Distributed Generation, Distribution System, DISCO.
Vol. 4. n. 4, pp. 592-600
Abstract - The
applications of available transfer capability (ATC) have received
considerable attention in restructured power systems. System operators
calculate and post ATC values for different time intervals considering
power system operation issues, including security issues. On the other
hand, competitive electricity market has added economic issues to
transmission services such that they could have different price, type
(recallable/non-recallable) and curtailment cost. The inclusion of
economic issues in ATC calculation to obtain NATC and RATC has not been
sufficiently addressed yet. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Available transfer capability, Transmission service, Security assessment.
Vol. 4. n. 4, pp. 601-609
Abstract - TThe work
aims to underline the prerogatives and the advantages of the Bayesian
approach in the reliability studies of the modern power electrical
systems. The new organization of the electric energy sector and the
consistent degree of technological innovation make the data more
uncertain related to the operation of the electric systems components
with the consequent lack of information for an efficient respect of the
reliability according to the classical approach. Such uncertainty
sometimes, concerns the same reliability models, adequately missing the
possibility of validates the models adaptation. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Reliability, Power system, Bayes theorem, Weibull model.
Vol. 4. n. 4, pp. 610-621
Abstract - This paper presents a novel approach for voltage sag indices monitoring based on instantaneous voltage estimation. The estimation uses traditional state estimation where redundant measurements are available. Main advantage of voltage sag indices monitoring is that it is used to calibrate stochastic methods. Also, monitoring data are principle information when analyzing a part of the system recently introduced or modified. This paper shows a possible for fault instance detection and fault location identification method for different line models utilizing residual analysis and topology error Processing. Lumped parameter transmission line modeling and distributed parameters transmission line modeling are developed to estimate instantaneous voltage in three-phase of power system in time domain. Magnitude and duration of voltage sag are estimated from the estimated instantaneous voltage of buses. The performance of the novel approach is tested on IEEE 14 bus system and the results are shown. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Voltage Sag (dip), State Estimation, Transmission Line Modeling, Residual analysis and Fault Type.
Vol. 4. n. 4, pp. 622-626
Abstract - The efficient distribution of reactive power in a power system is designed to maintain voltage within acceptable limits of operation and control the transmission losses. This article presents the problem of the optimal reactive power flow, using the particle swarm optimization method (PSO) and an application on the Western Algerian Transmission System 68 bus 220/60 kV. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Electrical network analysis, Optimal power flow, Load flow, Particle swarm optimization, Genetic algorithm, Optimization method, Transmission loss, Electrical network, Reactive power.
Vol. 4. n. 4, pp. 627-634
Abstract - The Gate – Controlled Series Capacitor (GCSC) is supposed to be an excellent tran¬smission line series compensator. In practical applications, the GCSC would be used typically for EHV transmission lines compensation, requiring high power GTO valves. To overcome the limit¬a¬tions due to the power range of the GTO valves, multi-module GCSC (MGCSC) can be used in a way that several small GCSCs are connected in series with one another in order to provide the de-sired series compensation level. This paper presents a detail analysis and evaluation of the MGCSC while the special emphasis is given to the harmonic analysis of this device showing that how much of harmonic levels are generated by this device, and how they can be reduced. In add-ition, the harmonics of the power system, to where the MGCSC is connected, is studied. In order to consider the subsynchronous resonance (SSR) phenomenon, which is a potential problem in series compensated transmission lines, all analysis are performed in the IEEE First Benchmark Model, a highly unstable power system to SSR, by studying the impact of the MGCSC on the SSR mitigation. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: FACTS, Multi-Module GCSC (MGCSC), Power system harmonics, THD.
Vol. 4. n. 4, pp. 635-641
Abstract - The rapid response feature of SVC can improve the steady state stability (or small signal stability) of power system, if it is located appropriately. In this paper, an index for identifying the location of SVC in large scale power system is proposed. The proposed index indicates modal controllability of the weak damping oscillatory modes. A multimachine linearized analysis for computation of the most dominant eigenvalues is done. Then, the most effective state variables on the given mode or eigenvalue are determined by participation factor analysis. The controllability of same state variable is calculated in all nodes of the network. The location index for each node is absolute value of controllability in same node. For evaluating the results, some computer simulations are done using MATLAB SIMULINK. The results demonstrate validity of proposed index. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Eigen analysis, Multimachine system, Power system stability, State Equations, Static VAR Compensator (SVC).
by B. Vahidi, R. Shariatinasab, J. Sh. Moghani Vol. 4. n. 4, pp. 642-648
Abstract - ZnO surge arresters have been used widely in high voltage systems to provide protection for power apparatus against overvoltages. ZnO surge arresters are continuously stressed at the system voltage. This stress can lead to fail the arrester. The probability of failure occurrence is dependent on the voltage distribution on arrester for different conditions. In the present paper effect of broken sheds, pollution on voltage and field distribution will be analyzed in 3-D configuration by using PC-OPERA 8.7 software. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Arrester, Electric Field, Pollution, Voltage Distribution, Three Dimensional, FEM.
by S. Ghazi Maghrebi, M. Lotfizad, M. Ghanbari Vol. 4. n. 4, pp. 649-653
Abstract - It is proposed, a new constellation, the non-rectangular quadrature amplitude modulation (NQAM) instead of the conventional quadrature amplitude modulation (QAM) in the Discrete Multi-Tone (DMT) system. These two constellations, with the same average power, are applied to 8 standard channels carrier service area (CSA#1 through CSA#8). The channels have burst noise; it means that the duration, power and the position of occurrence of the noise in the channel are variable. Based on the results of simulations, in the DMT system, the NQAM constellation has a better performance, in terms of the bit error rate (BER), with respect to the conventional QAM constellation with the same complexity for implementation Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: ADSL, Constellation, Cyclic prefix, DMT, QAM.
Vol. 4. n. 4, pp. 654-659
Abstract - Interconnected power systems are subject to low frequency oscillations. The oscillations can cause system-wide security concerns and have to be tackled in an adequate manner. To address this problem a detection scheme is needed. It has to enable early recognition of the system status and introduction of preventive and corrective procedures. In this paper a scheme based on power system modal identification is suggested. It includes estimation of modal information, such as frequency, damping and relative phase of modal components of the system’s response to changes in operation. For the purpose the matrix pencil method is used. It has a great practical value and can be used as a side-tool in power system control centers to help recognize dangerous swing interactions in the system. The paper gives the mathematical formulation of the method and illustrates its performance by means of a study case. Moreover, methodology of incorporation into traditional power system control framework is given. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Matrix pencil, Low frequency oscillations, System identification, System control.
Vol. 4. n. 4, pp. 660-669
Abstract - Reliability is one of the main salient assets of modern electronic systems and its improvement is of utmost importance in manufacturing high-reliability electronic products, especially in military and medical electronic systems. The design and development of reliable electronic products is a highly challenging task. Reliability improvement is possible through designing in reliability, derating of parts, and implementing a thorough testing program to achieve maximum reliability at minimum costs. Highly accelerated life testing in the initial stages of development and environmental stress screening programs for the later stages of product manufacturing and testing are practical tools to this end. In this paper, interconnect stress testing, derating of parts, destructive highly accelerated life testing and environmental stress screening programs developed for high reliability analog electronic products manufactured locally are presented. Optimal design is proposed using existing Rome Air Development Center's Environmental Stress Screening (RADC ESS) efficiency models. Results of printed circuit board (PCB) testing and actual highly accelerated lifetime testing (HALT) and environmental stress screening (ESS) testing of the printed circuit boards of the product are presented. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Accelerated Life Testing; Derating; Reliability; Thermal Cycling; Environmental Stress Screening; ESS Efficiency.
Vol. 4. n. 4, pp. 670-683
Abstract - This paper presents a review of the most important methods available for the grounding grid analysis. This includes numerical methods intended for the grounding grid direct current, time-harmonic current and transient current energization. Emphasis is given to the numerical methods involving transient grounding grid analysis. Available numerical methods are reviewed according to the implemented soil model, e.g. homogenous soil, horizontally and vertically stratified multilayer soil as well as exceptionally heterogeneous soil. In that regard, various possible treatments of the boundary between soil layers are discussed. Here, image methods feature prominently in a solution to this problem. Whence, several possible image methods are reviewed. Additionally, numerical methods are reviewed according to the theoretical background approach. Here, one can make a clear distinction between circuit approach, which might include a transmission line approach, and electromagnetic theory approach. Numerical methods for the transient analysis of grounding grids are also reviewed in regard to the domain of the solution. Therefore, they could be regarded as time domain and frequency domain methods. Fast Fourier transform algorithm is seen as a conventional way of crossing between frequency and time domains. Major advantages and disadvantages of both approaches are pointed out as well. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Electromagnetic models, Frequency domain, Grounding Grid Analysis, Image methods, Multilayer soil, Time domain
Vol. 4. n. 4, pp. 684-689
Abstract - In this paper possibilities to evaluate the condition of a transformer both with measurements and calculated data are compared. Several commercial off-line condition measurements for two power transformers are carried out. In the paper besides measurements, calculation based condition evaluation methodology adapted from loading standards is also studied. The calculation methodology is one alternative to monitor and evaluate a large population of the transformers systematically, if proven to be reliable for condition evaluation. In the studies the methodology is evaluated by utilising the annual loading characteristics as an input parameter to estimate the deterioration level of the insulation structure and loss of life for the studied transformers. The calculation results are compared with the measured data to give an indication about the usefulness of the calculation methods. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Transformer, condition measurements, loading standards.
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