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International Review on Modelling and Simulations  Vol. 4 N. 1---- Part A

International Review on Modelling and Simulations  Vol. 4 N. 1---- Part B

 

 

go to top    International Review on Modelling and Simulations (Vol. 4 N. 1)  - February 2011 - Papers (Part A)

 

 

 

go to top    International Review on Modelling and Simulations (Vol. 4 N. 1)  - February 2011 - Papers (Part B)

 

 

 

 

 

 

International Review on Modelling and Simulations - Papers (Part A)

 

go to top   Analysis and Simulation of a New Three Phase LLCC Resonant Inverter for Fuel Cell Applications
         by Budi Yanto Husodo, Makbul Anwari, Shahrin M. Ayob, Taufik

          Vol. 4. n. 1, pp. 1-9

        

Abstract - In this paper a new three phase LLCC resonant inverter for fuel cell applications is discussed. The proposed system consists of two power stages, which are boost dc-dc converter and three-phase bridge inverter with resonant tank. The boost dc-dc converter is controlled by adjusting its duty cycle to supply and maintain particular dc input voltage to the bridge inverter due to polarization characteristic of fuel cell. The resonant tank is operated at its geometric mean frequency to achieve unity voltage gain so that the output voltage of the inverter will not be affected by load variation. Hence, no external feedback is needed for the three-phase bridge inverter, thus simplifying the control of the inverter. The operating principle of the three-phase resonant inverter is analyzed and Matlab/Simulink simulation is conducted based on the analysis. The simulation shows that resonance has been achieved and the output voltage of the inverter is not influenced by load variation. Resonance technique for the proposed inverter is also shown to result in Zero Voltage Switching (ZVS). Furthermore, the inverter has very low THD of output voltage and output current.
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Keywords:  Fuel Cell, Power Electronics, LLCC Resonant Inverter, Soft Switching.

 

 

go to top   A New Switching Algorithm for Proposed Multilevel Z-Source Inverter
         by Mohamad Reza Banaei, Ali Reza Dehghanzadeh

          Vol. 4. n. 1, pp. 10-16

        

Abstract - This paper proposes a new switching algorithm for topology of Z-source based cascaded multilevel inverter. In this topology the output voltage is not limited to DC voltage source similar to traditional cascaded multilevel inverter and can be increased with Z network shoot-through states control due to in switching algorithm the traditional zero states turn in to shoot-through states sometimes. Besides, it is more reliable against short circuit. In the proposed topology, each basic unit consists of one DC voltage source, one Z-source and single H-bridge. In this paper the operating principle, switching algorithm and characteristics of proposed topology are presented and performance of suggested topology in the closed-loop control scheme is described in the Dynamic Voltage Restorer (DVR) structure. The performance of suggested inverter and switching algorithm are validated with simulation results using MATLAB/SIMULINK software.
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Keywords:  Cascaded H-Bridge Inverter, Switching Algorithm, DVR, Z-Source, Voltage Boosting.

 

 

go to top   Single-Phase Unity Power Factor Unipolar PWM Rectifier Using DSP
         by H. Denoun, N. Benamrouche, S. Haddad, S. Meziani, S. Ait Mamar

          Vol. 4. n. 1, pp. 17-22

        

Abstract - This paper aims to apply sinusoidal pulse width modulation (SPWM) technique to control PWM rectifier achieving by that unity power factor and reducing the harmonic current of the non linear load. The proposed control technique has the advantage of reducing switching frequency. The control structure has been developed and implemented on a DSP (micro-controller TMS320LF2407). Both pc simulations and experiments demonstrate the performance of this SPWM scheme in association with the single phase PWM rectifier.
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Keywords:  Digital Signal Processor (DSP), Matlab Simulation, Single-Phase Rectifier, Unipolar PWM Modulation, Unity Power-Factor.

 

 

go to top   Thermal Modeling of Semiconductors in a Three-Level NPC DTC Inverter
         by Tatu Musikka, Markku Niemelä, Juha Pyrhönen

          Vol. 4. n. 1, pp. 23-34

        

Abstract - Simulated junction temperatures of the semiconductor switches of a three-level Neutral Point Clamped (NPC) inverter applying Direct Torque Control (DTC) are addressed in this paper. The temperatures are defined by using simple power loss calculation methods, and the thermal network of the component is considered as a one-dimensional partial fraction RC network. The emphasis of this paper is on unequal thermal stressing between the different components of the NPC DTC inverter. Verification of the model is based on the use of well-known calculation and estimation methods.
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Keywords:  IGCT, Three-level inverter, Thermal model.

 

 

go to top   VHDL-AMS Modeling of the Current Distortions Compensator for ASIC Implementation Design
         by R. Benachour, S. Latreche, M. E. H. Latreche, C. Gontrand

          Vol. 4. n. 1, pp. 35-41

        

Abstract - The latest development of the AC motor control drive is based on digital implementation of a control algorithm and an important supervision and control functions as well as; short circuit protection, over voltage protection and current distortion compensation, etc.
Different hardware-software implementations of the current distortions compensation are used. One of these software techniques is based on an average model of voltage source inverter. This technique is characterized by a good quality of the currents supplied the motor and a high performance of motor mechanical torque.
This paper, studies a digital application specific integrated circuit ASIC implementation of the current distortions compensating function by high level behavioral model using VHDL-AMS. This model is associated to the Direct Torque Control DTC hardware description model. This improvement can avoid the complexity and provide compensation in real time. It offers in addition smaller size and lower cost.
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Keywords:  ASIC, Behavioral Model, Current Distortions Compensation, DTC, VHDL-AMS, VSI.

 

 

go to top   A D-Q Synchronous Frame Controller for Single-Phase Inverter-Based Islanded Distributed Generation Systems
         by S. Golestan, M. Ramezani, M. Monfared, J. M. Guerrero

          Vol. 4. n. 1, pp. 42-54

        

Abstract - This paper deals with the design of a synchronous reference frame control strategy for single-phase inverter-based islanded distributed generation systems. Since, the implementation of these regulators requires a minimum of two independent phases in the system, a second orthogonal phase is generated using a first order all pass filter. The essence of the proposed control strategy is to use a SRFPI controller to regulate the output voltage, together with a simple inner capacitor current regulating loop to stabilize the system and a voltage-feedforward loop to improve the system robustness. A detailed design procedure for the proposed control strategy is presented based on a frequency-response approach. Practical implementation aspects and the phase margin of the system are taken into account during the design process. Extensive simulations confirm the validity of the proposed strategy.
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Keywords:  Distributed Generation, Single Phase Inverter, Synchronous Frame.

 

 

go to top   New Hybrid Multicell Inverter Topology with Minimum Number of Switches for a Dynamic Voltage Restorer
         by Ali Ajami, Mehdi Armaghan

          Vol. 4. n. 1, pp. 55-62

        

Abstract - This paper presents the Dynamic Voltage Restorer (DVR) based on new hybrid multicell inverter topology. This inverter is based on a new cell obtained from the mixture of the two most popular multicell topologies, Flying Capacitor (FC) and Cascaded Multicell (CM) inverter. The new cell provides a high number of output levels, high modularity, low number of components and low losses. The proposed medium voltage DVR is designed to protect loads at power distribution systems. Simulation carried out by using MATLAB/SIMULINK software. Simulation results show the performance of the proposed DVR and prove the validity of the proposed topology. It is concluded that the proposed DVR works well both in balance and unbalance conditions of voltages.
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Keywords:  Hybrid Multicell Inverter, Dynamic Voltage Restorer, Voltage Sag, Voltage Swell.

 

 

go to top   Grid Codes Requirements for the Connection of Wind Power Plants to the Turkish Electricity Network
         by Ömer Gül

          Vol. 4. n. 1, pp. 63-73

        

Abstract - In this study, the grid codes requirements for the connection of the wind power plants to Turkey’s electric network are mentioned. Recently, it is given importance to generate electrical energy from the renewable energy resources in Turkey in order to prevent the foreign-source dependency in the energy resources and to ensure the variety of resources through a sustainable environmental management. The electrical energy generation from wind that is clean and renewable is the most rapidly growing renewable resource. The installed capacity of wind is expected to reach to 1000 MW by the end of 2010 and to 20.000MW in 2023. Since the wind power plants having a different characteristic than the conventional power plants are disseminated more and more on each passing day, the existing grid codes remain inadequate for the connection of the wind turbines to the electric network. The determination of the network connection criteria for the wind power plants is essential in terms of the dissemination of the energy generation from Wind in Turkey’s energy market that has been liberalized after restructuring. The new regulations are required in order to restrict the negative effects of the wind power plants on the transmission and distribution system and to protect the system reliability. In this study, the current regulations on the connection of the wind power plants to the network are evaluated, the defects are determined and the recommendations on the new requirements are made.
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Keywords:  Wind Power Plant, Technical Requirements, Interconnection, Grid Codes, Turkey.

 

 

go to top   Improvement of Voltage Unbalance and Voltage Sag in Radial Distribution Systems Using DG
         by Ali Saidian, Mehrdad Heidari, Davar Mirabbasi, Ehsan Gharibreza

          Vol. 4. n. 1, pp. 74-78

        

Abstract - Most of the dispersed generation systems (DGS) have smaller installation capacity and have to be connected to the distribution network to supply electric power into the utility as well as local loads. When the DG is interconnected in parallel with the utility distribution system, some operating conflicts might arise that affect the system power quality. This paper investigate the effect of DG on the distribution network, with more focusing on power quality issues especially voltage quality issues like voltage sag and voltage unbalance. To confirm this subject, simulation results are provided to reveal the effect of DG on power quality. The purpose of the simulation is to study the effect of different sizes of synchronous DG on voltage regulation, voltage sag and voltage unbalance in two cases: without local load and with RL local load. The simulation is performed using MATLAB/SIMULINK.
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Keywords:  Distributed Generation (DG), Voltage Unbalance, Voltage Sag.

 

 

go to top   Voltage Compensation and Fault Current Limiting with Z-Source Based Dynamic Voltage Restorer
         by M. Najafi, M. Hoseynpoor, M. Siahi, R. Ebrahimi

          Vol. 4. n. 1, pp. 79-84

        

Abstract - Dynamic voltage Restorer (DVR) is applied to optimize the power quality aspects such as voltage sag compensation. Recently, the application of Z-source inverter is proposed in order to optimize DVR operation. This inverter makes DVR to operate appropriately when the energy storage device’s voltage level severely falls. Here, the Z-source inverter based DVR is proposed to compensate voltage disturbance at the PCC and to reduce the fault current in downstream of DVR. By calculating instantaneous current magnitude in synchronous frame, control system recognizes if the fault exists or not, and determines whether DVR should compensate voltage disturbance or try to reduce the fault current. The proposed system is simulated under voltage sag and swell and short circuit conditions. The simulation results show that the system operates correctly under voltage sag and short circuit conditions.
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Keywords:  Dynamic Voltage Restorer, Z-Source Inverter, Voltage Disturbance, Fault Current.

 

 

go to top   Transmission Loading Relief(TLR) and Hour-Ahead ATC in Deregulaed Power System
         by Ch.Sunil kumar, J.Amarnath, P.S Subramanyam

          Vol. 4. n. 1, pp. 85-92

        

Abstract - This paper illustrates the relationship between Transmission Loading Relief (TLR) and Available Transfer Capability (ATC), and present possible approaches to reduce the need to invoke TLR procedures while improving the utilization of the transmission system. In open-access electricity markets the reservations of transmission services are based on the data resulting from the off-line computation of ATC. When ATC data is inaccurate or misused, security violations can emerge and cause operators and operation planners to invoke TLR procedures. In this paper ideas are demonstrated on 7-bus system and results have been presented and analyzed.
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Keywords:  Hour-Ahead ATC, Off-Line ATC, Transmission Loading Relief (TLR).

 

 

go to top   Direct Search Method for Solving Dynamic Economic Dispatch Problems
         by S. Ganesan, S. Subramanian

          Vol. 4. n. 1, pp. 93-103

        

Abstract - This paper presents a simple methodology to solve Dynamic Economic Dispatch (DED) problems. The main objective is to determine the most economic dispatch of on line generating units with the predicted load demands over a certain period of time. The DED is formulated as a second order dynamic optimization problem that takes into the consideration of the ramp rate limits of the generating units. The simplified methodology optimizes or provides the most economic schedule of generation for each interval in the scheduling time horizon hence the minimization of the total fuel cost is achieved. The feasibility of the proposed methodology is demonstrated for solving the dynamic economic dispatch problem with suitable test systems. The unit operation constraint, prohibited operating zone and transmission loss are considered for the practical applications. The simulation results are compared with the recent reports in terms of solution quality. Numerical simulation results indicate an improvement in total fuel cost saving and hence the superiority of the proposed is also revealed for dynamic economic dispatch problems.
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Keywords:  Dynamic Economic Dispatch, Prohibited Operating Zones, Ramp Rate Limits, Sequential Approach, Transmission Loss.

 

 

go to top   Power System Demand Management Contract Design: a Comparison between Game Theory and Artificial Neural Networks
         by Nnamdi I. Nwulu , Murat Fahrioglu

          Vol. 4. n. 1, pp. 104-112

        

Abstract - Demand management in power systems is one of the many innovative ideas introduced recently for the efficient management of our burgeoning energy needs. The major aim of demand management programs is to control an ever increasing demand for electric power among customers. Controlling customers demand for electric power will bring about load relief for electric utilities and an overall improvement of power system security. There exists a wide variety of demand management programs. Recently demand management contracts have been designed in which incentives are offered to customers who willingly sign up for load interruption. In this scenario the incentive offered to the customer should be greater than the cost of interruption while simultaneously making it beneficial for the utility. Mechanism design from Game theory has hitherto been used in the design of such contracts. This paper proposes a novel idea where an artificial neural network is designed to select the optimal contract. Our designed artificial neural model uses the back propagation learning algorithm with useful system parameters serving as the input and the output the value of the contract. The results obtained from Game theory using mechanism design are used to benchmark the results obtained from this artificial neural network. Furthermore our results show that artificial neural networks are an attractive option for contract design as they require less computational procedures than game theory without much of a compromise on accuracy.
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Keywords:  Artificial Neural Networks, Back Propagation Learning Algorithm, Demand Management, Game Theory, Mechanism Design.

 

 

go to top   On the Use of the Finite Element Formulation of the Impedance Boundary Condition in Shielded and Multiconductor Power Cables
         by A.M. El-Sawy Mohamed

          Vol. 4. n. 1, pp. 113-119

        

Abstract - The paper presents two developed finite element formulations of the impedance boundary condition (IBC) based on the variational approach to solve two-dimensional (2D) eddy current problems, especially at high frequencies. The first formulation is used in the solution of the eddy current in a solid circular conductor carrying an alternating current. The second formulation which is based on the integrodifferential approach is developed and successfully applied to compute the resistances and inductances per unit length of both single-core and 3-phase power cables. To show the validity of the proposed formulations, the obtained results are compared to analytical and published results.
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Keywords:  Eddy Currents, FE-Formulation, IBC Formulation, Power Cables.

 

 

go to top   Assessment of Reduction in Losses by Distributed Generation Penetration in a Radial Network: a Case Study
         by Akash Davda, Dr. M.D.Desai, Dr. B.R.Parekh

          Vol. 4. n. 1, pp. 120-124

        

Abstract - Conventional Transmission and Distribution systems do not envisage at present any generation on consumer side. However, with the enactment of Indian Electricity Act 2003 and due to the major changes in the Power Sector and the fast move towards liberalization of the energy markets, utilities are inclined to install small capacity generating units to distribution systems. Integration of small capacity generators at load points in the existing electrical network will have impact on voltage regulation, losses, reserve capacity of network etc. In this paper, Renewable Distributed Generators (RDGs) are introduced at a suitable location of a heavily loaded distribution network to minimize distribution losses. Case study has been performed on a real 3.4 MVA distribution system of a particular area of Gujarat state. A methodology has been developed for citing the RDGs at a suitable location in the Network.
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Keywords:  Distribution Losses, Forward / Backward Sweep, Renewable Distributed Generators, Voltage Regulation.

 

 

go to top   Power Quality Considerations of high Penetration of CFL on Distribution Power System
         by Ali M. Eltamaly

          Vol. 4. n. 1, pp. 125-132

        

Abstract - In This paper a new methodology for determining the influence of heavy loads from compact florescent lamps (CFLs) on distribution system is introduced. Thirty eight samples, consisting of 10 CFL in each sample were selected for practical test for 15,000 hours operation to determine the lamps’ performance. New comparison indices were introduced to rank the CFLs depending on the power system and consumers requirements. A new simulation model in PSIM simulation program for CFL is used to study the power quality of the power system for different loading of the CFLs. The actual simulation model interacts with the variation of the supply voltage due to voltage drop in the series impedance of the feeders and transformers. Simulation results show that the power quality of the distribution system is affected by a high CFLs loads.
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Keywords:  Compact Florescent Lamp, THD, Power Quality, Distribution System, Simulation Model.

 

 

go to top   Modelling and Simulation of Transmission Line Tower Grounding Impulse Characteristics
         by Z. M. Stojković

          Vol. 4. n. 1, pp. 133-140

        

Abstract - This work presents the application of the developed software tool, formed using the powerful MATLAB® technical computing software and the programming language Visual C++, which enables the modelling and simulation of transmission line tower grounding impulse characteristics. Various grounding models used for estimation of impulse characteristics are discussed. Special attention is dedicated to the nonlinear model, which more realistically takes into account the soil ionization influence. The performed models are convenient for implementation into the existing programs for the estimating lightning performance of transmission lines. Basic elements of the software tool are described. The practical and educational aspects of the software application are denoted, as an important part for designers applying Computer-Aided Design / Engineering (CAD / CAE) in Power Systems.
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Keywords:  Grounding, Modelling, Simulation, Software, Transmission Line.

 

 

go to top   TCSC Efficiency Assessment in Lines Overload Reduction during Fault Contingency
         by M. Najafi, M. Siahi, M. Hoseynpoor, R. Ebrahimi

          Vol. 4. n. 1, pp. 141-145

        

Abstract - In this paper we initially introduce a method to determine the optimum allocation of installing one or more thyristor controlled series capacitor. The target function to determine the TCSCs installing place is reducing power system lines overload during fault contingency. After determining TCSCs optimum installation place, their success rate in reducing lines overload is studied by a new following index, transmitting index and it is presented that in oppose to our expectation, TCSCs do not have a great roll in reducing lines overload during fault contingency. TCSC installation effect on amount of load shedding reduction is also presented as a new subject to keep buses voltage stability. IEEE 14&30 bus power systems are selected as the studied systems and mentioned analysis are applied on this system.
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Keywords:  Thyristor Controlled Series Capacitor (TCSC), TCSC Allocation, Fault Contingency, Lines Overload, Load Shedding.

 

 

go to top   Application of Evolutionary Algorithms for SSSC-based Controller Optimization to Improve Power System Stability
         by Mehdi Peyvandi

          Vol. 4. n. 1, pp. 146-156

        

Abstract - Nowadays, genetic algorithms (GA) and particle swarm optimization (PSO) are most famous optimization techniques among various modern heuristic optimization techniques. Since the two approaches are supposed to find a solution to a given objective function but employ different strategies and computational effort, it is appropriate to compare their performance. This paper presents the application and performance comparison of PSO and GA optimization techniques, for Static synchronous series compensator (SSSC)-based controller design for both single-machine infinite-bus (SMIB) and multi-machine power system. By minimizing the time-domain based objective function, in which the deviation in the oscillatory rotor speed of the generator is involved; stability performance of the system is improved. The non-linear simulation results are presented under wide range of operating conditions; disturbances at different locations to show the effectiveness and robustness of the proposed controller and their ability to provide efficient damping of low frequency oscillations.
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Keywords:  Genetic Algorithm, FACTS, SSSC, Particle Swarm Optimization, Power System Stability.

 

 

go to top   Dynamic Model of a Hybrid Distributed Generation System based on PEM Fuel Cell and Micro-Turbine
         by Seyed Morteza Alizadeh, Mostafa Sedighizadeh, Vahid Hajiaghayi Tabalvandani

          Vol. 4. n. 1, pp. 157-163

        

Abstract - In this work, we presented a dynamic model of Micro – Turbine Generation System (MTGS) in grid connected operation. In the second stage, we applied Fuel Cell in MTGS to improve the system outputs from the view point of fluctuation of the signals. The dynamic model of the MTGS consists of four main parts: micro – turbine, PM generator, converter and network. At first, we considered a dynamic model for the micro – turbine. The model input signal is rotor speed. and the output of the model is turbine torque which is a driving force for the PM generator. The voltage across the stator terminals of the generator has a very high frequency. A thyristor rectifier rectifies this high frequency AC voltage to 800 V DC. The DC voltage is inverted back to 50HZ AC by means of an IGBT inverter, and then filtered to reduce harmonics generated by the inverter. The novelty of this work is the use of a subsystem based on Fuel Cell as a DC link between rectifier and converter. We used a Proton Exchange Membrane (PEM) Fuel Cell stack feeding an average value 800 VDC DC/DC converter. In previous works, a capacitor was used as a DC link. Comparing to the previous works, which used a capacitor as a DC link, showed that the output signals of the system improved noticeably when we used a subsystem based on Fuel Cell as a DC link. The fluctuation of active and reactive power injected to the grid decreased very much. Using a fuel cell subsystem had also positive effects on some other outputs such as current of each phase in line side converter control.
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Keywords:  Distributed Generation, Fuel Cell, Inverter, Micro-Turbine, Permanent Magnetic Synchronous Generator, Rectifier.

 

 

go to top   Optimum Allocation of Distributed Generations based on Efficiency Scores using Data Envelopment Analysis
         by A. Moradkhani, M. Simab, E. Alishahi, M. K. Sheikh-El-Eslami

          Vol. 4. n. 1, pp. 164-170

        

Abstract - Distributed generations (DGs) can help in reducing the cost of electricity to the costumer and promote system technical characteristics such as loss reduction, voltage profile and reliability indices improvement. Proper location of DGs in power systems is important for obtaining their maximum potential benefits. In this paper, a new method is presented for optimal allocation and sizing of distributed generation units in order to minimize losses and to improve the reliability index and voltage profile in distribution systems. Initially, in this paper a methodology based on nodal price for finding optimum size of DG is presented. Optimal placement is based on the efficiency scores which are estimated from data envelopment analysis (DEA). In this research energy loss rate, voltage profile and expected energy not supplied (EENS) are considered as inputs and the cost of DG is considered as output for define a model of DEA to measure the efficiency of install DG in each bus. The tabu search algorithm is used to obtain EENS in order to minimizing the outage cost of customer. The proposed algorithm is tested on a 33 bus test feeder to show the applicability of the method.
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Keywords:  Data Envelopment Analysis, Distributed Generation, Distribution Networks, Nodal Price.

 

 

go to top   Demand Side Solution for Transmission Congestion Relief in Competitive Environment
         by T.T Nguyen, Ashkan Yousefi

          Vol. 4. n. 1, pp. 171-179

        

Abstract - Recently, a massive focus has been made on demand response (DR) programs, aimed for electricity price reduction, transmission lines congestion resolving, security enhancement and market performance improvement. The paper develops a method for transmission line congestion management using demand side approach. In the proposed method the mathematical model for incentive-based demand response program is developed and in the next step these market based programs are used as an effective tools for reducing the congestion cost in the electricity market. The IEEE 30 bus test system is used to demonstrate the effectiveness of the proposed method.
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Keywords:  Congestion Management, Demand Response, Interruptible Load.

 

 

go to top   Modeling and Evaluating of Protection Schemes based on Petri Nets
         by A. Jalilvand, R. Noroozian, A. Ashouri

          Vol. 4. n. 1, pp. 180-187

        

Abstract - In this paper, Petri nets have been used for modeling and evaluating of protection schemes of electric power system. By this approach, the processing time of information is reduced and the accuracy of fault detection procedure is increased. Simulation results show that Petri nets make possible the statistical analyzing and evaluation of protection systems operation.
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Keywords:  Petri Nets, Modeling, Protection System, Monitoring, Uncertainty.

 

 

go to top   Microgrids Control in Islanding Mode Operation considering a Hybrid Model of Distributed Generation Units of Wind and Fuel Cell
         by Hamidreza Mansoori, Seyedmohamad Sadeghzadeh, Mohamadreza Ebrahimi

          Vol. 4. n. 1, pp. 188-195

        

Abstract - This paper presents the control of microgrids electrical parameters of voltage and frequency in islanding mode of operation in a hybrid model of distributed generation units of wind and fuel cell.
Islanding mode conveys the meaning of separation some part of power system and its independent functioning. This phenomenon has negative impact on the network such as too much dependency of isolated network voltage and frequency on the amount of load and its kind.
This paper tries to investigate these negative effects and propose a proper solution. The suggested method utilizes power electronic converters and a proper design to propose an ideal controller. to provide a better insight of proposed method, it is implemented on a 13-modified bus IEEE distribution network, consisting of a hybrid model of distributed generation units of wind and fuel-cell by simulation in PSCAD/EMTDC software.
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Keywords:  Microgrid, Distributed Generation, Islanding Mode Operation, Power Electronic Converters, Voltage And Frequency Control.

 

 

go to top   Development of BSDC Index Application for Analysis of Voltage Instability in the Presence of Voltage Dependent Loads
         by Shahriar Abasi, Farid Karbalaei

          Vol. 4. n. 1, pp. 196-201

        

Abstract - In this paper, an algorithm for diagnosis of voltage collapse point is proposed. The algorithm is based on load characteristics, voltage and current measurements. When all loads at a bus are voltage independent type, the voltage collapse point coincides with Maximum Loading Point. In maximum loading point, with voltage and current changes, apparent power delivered to the bus does not increase. In these conditions, BSDC index that is based on the apparent power difference at the bus equals 0 in the voltage collapse point.
If load characteristics are not considered, the BSDC cannot detect the voltage collapse point. In this paper an improved version of the BSDC for diagnosis of the voltage collapse when a part of the load is voltage dependent, is proposed. This modification is based on dividing the load into voltage dependent and independent parts. The algorithm is simple enough to implement in a protective relay. The presented algorithm was tested on the IEEE 30 - bus test system. The results show the problem of the old method and the correction made by the proposed method.
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Keywords:  Voltage Collapse, Bus S Difference Criterion, Voltage Instability, Local Measurement.

 

 

go to top   A Hybrid Solution using Distributed Passive Filters and UPQC to Improve Power Quality in Dispersed Generation Systems
         by Amir R Naderipour, Alireza Jalilian

          Vol. 4. n. 1, pp. 202-206

        

Abstract - This paper presents a hybrid power quality solution in a test system consisting of distributed passive filters, an Universal Power Quality Conditioner (UPQC) and Distributed Generation (DG) units. In the system, single passive filters are designed and connected to eliminate main harmonics and compensate reactive power for each nonlinear load. The UPQC is utilized for voltage unbalance compensation and cancellation of the remaining current harmonics at the point of common coupling of the power distribution system. Configuration of the test system, nonlinear loads, DGs, active filters and UPQC and their modeling in Matlab software are presented in this paper. Matlab implementation of the control system based on dq reference frame theory is also described. Frequency response of the given system is performed and presented to study the issue of resonance under harmonic conditions. Simulation results are demonstrated and confirmed the effectiveness of the proposed configuration in simulated test system. It is shown that the UPQC rating can be reduced in the proposed configuration due to the reactive power compensation using passive filters.
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Keywords:  Passive Filters, UPQC, DG, Load Unbalance, Power Quality.

 

 

go to top   Arcing Fault Detection for a Double Busbar Metal Enclosed Switchgear
         by Nur ‘Ain Maiza Ismail, Abdullah Asuhaimi Mohd Zin, Sazali P Abdul Karim

          Vol. 4. n. 1, pp. 207-213

        

Abstract - Arcing fault issues have increased concern and awareness of many people in different background. The effect it causes leads to the development of arc fault detectors. Arc fault detector is associated with overcurrent relay in older switchgear system to improve speed performance of switchgear protection system. In this paper, a new design of arc fault detector for double busbar metal-enclosed medium voltage switchgear is introduced to develop a better arc fault detection in terms of selectivity. A position sensor is associated concurrently with light and current detector in providing a tripping signal to the corresponding circuit breaker. The circuit is designed using Boolean algebra approached and simulated in MATLAB Simulink. Simulation results are observed to verify the performance of the arc fault detector in terms of solving false tripping problems.
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Keywords:  Arc Protection, Double Busbar Switchgear.

 

 

go to top   DG Allocation Using Clonal Selection Algorithm (CSA) to Minimize Losses and Improve Voltage Security
         by A. Khanjanzadeh, M. Sedighizadeh, A. Rezazadeh

          Vol. 4. n. 1, pp. 214-219

        

Abstract - The purpose of this paper is to minimize losses and improving voltage security by DG allocation based on Clonal Selection Algorithm (CSA).The exigency for flexible electric system, Energy saving, Loss minimizing and environmental effects are providing motivation to the development of distributed generation. These days Scientists research shows that 30% of Generation of electrical energy is distributed. This subject caused to perform more studies about DG. It is obvious that losses are in any network, but DG be able to minimize the losses. The allocation of DG has the main effect of voltage improve and loss minimizing on the system. Finally the results are compared to Genetic Algorithm.
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Keywords:  Distributed Generation, Voltage Security, DG Allocation, Clonal Selection Algorithm, Genetic Algorithm.

 

 

go to top   Dual Functional UPQC to Improve Power Quality and Injection of Photovoltaic Array Power to Grid
         by S. Sajedi, T. Karimi, F. Khalifeh, Z. Khalifeh

          Vol. 4. n. 1, pp. 220-227

        

Abstract - In this paper the design of combined operation of UPQC and PV array is proposed. The proposed system is composed of series and shunt inverters, PV array connected to DC link by boost converter which is able to compensate the voltage sag and swell and voltage interruption, harmonics and reactive power in both islanding and interconnected modes. The proposed system is able to inject the active power to grid in addition to its ability in improvement of power quality in point of common coupling. Also it can provide a part of sensitive load power during voltage interruption. The results of simulation in MATLAB/SIMULINK software show that the mentioned system operates correctly.
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Keywords:  Unified power quality conditioner (UPQC), Photovoltaic array (PV), Interconnected mode, Islanding mode, Maximum power point tracking (MPPT).

 

 

go to top   The Effect of Solid State Fault Current Limiter in Distribution Grid with Distributed Generations
         by A. R. Fereidouni, B. Vahidi, T. Hosseini Mehr

          Vol. 4. n. 1, pp. 228-235

        

Abstract - Distributed generation (DG) is predicted to play an increasing role in the electric power system of the near future. DGs are being introduced to power systems to secure the electric power supply. However, expose of DG, can alter the fault current during a grid disturbance and disturb the existing distribution protection system. After connecting DG, part of the system may no longer be radial, which means the coordination might not be hold. This will give rise to fault current which is normally greater than interrupt capability of reclosers and fuses. The degree of the problem tends to increase when several DG sources are installed in the system. The introduction of Solid State Fault Current Limiters (SSFCLs) becomes an effective way for suppressing such a high short-circuit current fault in distribution systems. In this paper a solid state fault current limiter (SSFCL) application is proposed to minimize the effect of the DG on the distribution protection system in a radial system during a fault. Simulation is accomplished in PSCAD/EMTDC.
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Keywords:  Solid State Fault Current Limiter, Distribution System, Distributed Generation, Recloser-Fuse Coordination.

 

 

go to top   Inter-Phase Power Controllers Application to Reduce Transmission Network Short Circuit Level: System Planning and Engineering Considerations
         by Mehdi S. Naderi, J. Beiza, N. Taghizadegan

          Vol. 4. n. 1, pp. 236-240

        

Abstract - In the steady state condition, an IPC controls power flow by setting PST phase angle. In this paper, an efficient algorithm is presented to specify location and the IPC parameters as a fault current limiter including angels of phase shifting transformer (PST) and reactances of the reactor and the capacitor. As a case study, the algorithm is applied to Tehran Regional Electric Company (TREC) to reduce the Short Circuit Level (SCL) of critical transmission substations. The transient stability studies are performed in the transmission network with the installed IPC to verify the effective current limiting characteristic of IPC.
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Keywords:  IPC, Fault Current Limiting, Transient Stability.

 

 

go to top   A New Control Strategy for Achieving Minimum Power Injection of Dynamic Voltage Restorer
         by A. O. Al-Mathnani, H. Shareef, A. Mohamed, M. A. Mohd Ali, M. A. Hannan

          Vol. 4. n. 1, pp. 241-248

        

Abstract - This paper presents a new DVR design and a control mechanism to minimize active power injection and forced the load voltage to be in phase with grid voltage during the sag, swell and short outage for the non linear load. The control technique incorporates a short time delay and mitigates the harmonic distortion during the charging of the energy storage capacitor. The new design is based on two continuous vector control. It extracts the fundamental components of the measured voltage and current using a 12 switch inverter connected in parallel to improve the time response. The proposed control method is tested on an 11 kV distribution system. Photovoltaic source with a boost converter is included to support the DC source during voltage sag. It shows that the proposed method improve the in-phase compensation technique, minimum active power and response for nonlinear loads.
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Keywords:  Two Continuous Vector Control, Dynamic Voltage restorer, Voltage Sag.

 

 

go to top   A Fast Computational Technique to Trace V – Q Curve Using Broyden – Shamanski Method
         by K. Chandrasekar, Dr. N. V. Ramana

          Vol. 4. n. 1, pp. 249-254

        

Abstract - The V – Q curve analysis has been widely used for voltage stability studies by many power system utilities over the past years. The power flow technique used to trace V – Q curve is conventional Newton Raphson (NR) method. Though NR method is accurate, it needs high computational time due to the presence of repeated Jacobian inverses. This paper investigates a novel approach to solve power flow using Broyden – Shamanski method with Sherman – Morrison formula (BSS) to trace V – Q curve which eliminates the drawback of NR method without compromising accuracy. Simulation test is carried on IEEE 14, 30, 57 and 118 bus test systems using NR and BSS method. Results indicate that the computational time for tracing V – Q curve using the proposed BSS method is far less when compared to that of conventional NR method.
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Keywords:  Broyden – Shamanski, Newton Raphson, Power Flow, V – Q curve, Voltage Stability.

 

 

 

International Review on Modelling and Simulations - Papers (Part B)

 

 

go to top   On Some Numerical Methods for the Non Linear Transport Equation in 3D
         by Abdallah Tamrabet, Abdelouahab Kadem

          Vol. 4. n. 1, pp. 255-261

        

Abstract - In this paper the simulation of the phenomenon of homogeneous and isotropic turbulent flow in free-surface channels is studied in 3D.The method of finite volumes is used to solve the non linear transport equations (convection-diffusion problem) which are equations of quantity of motion, kinetic energy, dissipation, and tracking the volume fraction of each fluid in the whole filed. Numerical results are obtained by two models, the multiphasic model V.O.F (Volume of Fluid) and the model for turbulence.
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Keywords:  Numerical Simulation, Finite Volume, Nonlinear Transport Equation, VOF Model.

 

 

go to top   Multi-Scale Multi-Physics Modeling of Bundled Multiwalled Carbon Nanotube Interconnects
         by Omar F. Mousa, Jaber A. Abu Qahouq

          Vol. 4. n. 1, pp. 262-269

        

Abstract - CNTs (Carbon Nanotubes) has exceptional electrical, mechanical, and thermal properties. Most importantly, both experimental and numerical studies proved that when CNTs is used as metal or semiconductor material, the performance of such systems is tremendously improved. This paper aims at modeling the electrical and magnetic behavior of Bundled Multi-walled Carbon Nanotubes interconnects for on-chip power delivery among other applications. Simulation and modeling on the multi-scale and multi-physics are conducted by performing Extended Finite Element Time Domain and Extended Finite Difference Time Domain methods analysis in a hybrid model approach and by utilizing ANSYS®/MAXWELL® 3D software for the first time. The analysis, modeling, and simulation are used as a tool to derive the governing relationship of CNTs by considering the nonlinearity of the mechanism of interfacial bonding with other materials when subjected to current and voltage excitation. The results of the model are verified by experimental results from the literature.
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Keywords:  Carbon Nanotube; Interatomic Potential; Finite Elements; Finite Difference, Modeling; Simulation; Bmwcnt; Mwcnt; Swcnt; Vias; Pillars; Interconnect; Power Delivery.

 

 

go to top   Electromagnetic Analysis of Railguns by Numerical Simulations
         by Mehdi Peyvandi, Mehrdad Jafarboland, Mohsen Zafarani

          Vol. 4. n. 1, pp. 270-278

        

Abstract - Nowadays, the armature transition is one of problems in railguns. Many kinds of mechanism were proposed by researchers to predict or explain armature transition phenomena. And many types of railgun were invented. In this paper, three types of railgun, including simple railgun, parallel-augmented railgun and muzzle-fed railgun, are investigated with numerical simulations. Since current density is the decisive factor to transition velocity, this study focuses on the current distribution in armature. The inductance gradient of railgun and magnetic field distribution are also investigated. In order to simplify simulations, rails and armature are considered in each simulation, and armatures of railgun are same. The Maxwell 3D modular of Ansoft corp. was utilized as the program code. The simple railgun is selected as the benchmark, and the other two types were compared with it. In the simulation of parallel-augmented railgun, two current sources (500kA, 60Hz) were connected to inner rails and outer rail independently. In muzzle-fed railgun simulation, the same current source as in simple railgun was connected to rails. Based on simulation results, conclusions are drawn that augmented railgun has the highest inductance gradient and the largest launcher efficiency. But the current density at rear part of armature is larger than that of simple railgun if the currents flowing through inner rails and outer rail are equal. The inductance gradient of muzzle-fed railgun is the smallest, but the current density at armature shoulder is the largest. Projectiles of muzzle-fed railgun will face the greatest magnetic flux density.
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Keywords:  Inductance Gradient, Muzzle-Fed, Parallel-Augmented, Projectile, Railgun.

 

 

go to top   Discrete Wavelet Decomposition Applied to Position Sensor Default Detection on a PMSM Traction Drive
         by Manef Bourogaoui, Houda Ben Attia Sethom

          Vol. 4. n. 1, pp. 279-286

        

Abstract - This paper focuses on position sensor default detection on a Permanent Magnet Synchronous Motor (PMSM) traction drive. The proposed detection method consists in using Discrete Wavelet Transform technique (DWT), based on Multiresolution Analysis (MRA). The default considered is a position sensor disturbance induced by a high level external noise. The disturbance effects on the traction drive operation are studied. The multiresolution analysis is applied to stator current signals to detect the disturbance which affects the measured position. Simulation results prove the effective detection of the disturbance occurrence using DWT technique.
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Keywords:  PMSM, Position Sensor, Disturbance, Detection, Multiresolution Analysis.

 

 

go to top   Multiobjective Optimal Design of Transformer using Bacterial Foraging Algorithm
         by S. Subramanian, S. Padma

          Vol. 4. n. 1, pp. 287-294

        

Abstract - Transformer is a static electromagnetic device that transfers electrical energy from one level to another by magnetic coupling. This serves very important link between the electrical energy generation and its utilization. The optimal design emphasizes for the effective performance of transformer. The transformer design involves a number of parameters that makes the problem more complex and non linear and the efficient methods are need for the optimal design. The optimal design is not only involve the minimization of cost but also the maximization of performance or efficiency. In this paper a Multi Objective Bacterial Foraging Algorithm (MOBFA) has been developed for the optimal design of transformers. The effectiveness of the proposed method is tested with the suitable sample transformers and the simulation results are compared with the recent reports. Numerical results indicate that the proposed MOBFA outperforms the existing methods in terms of solution quality.
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Keywords:  Transformer Design, Cost, Efficiency, Multi Objective Optimization, Bacterial Foraging Algorithm.

 

 

go to top   Transient-State Modeling of Distribution Transformers
         by Mehdi Bigdeli, Ebrahim Rahimpour, Masoud Khatibi

          Vol. 4. n. 1, pp. 295-302

        

Abstract - In this paper, a black box model is proposed to analyze the transient state of distribution transformers. This model is capable of showing the frequency characteristics of the transformer under various conditions of the terminals connections up to the frequency domain of almost 1.2 MHz. In addition, this model has satisfactory abilities in illustrating the characteristic of the wave transferred to the consumer side and it can be employed in studying the over voltages produced in the transformers terminals as the result of striking the lightning waves. In order to investigate the validity as well as the accuracy of the proposed model, a 6300/420 V, 2500 KVA distribution transformer is selected for the research. First, required experiments are performed on this transformer and then, using the measurements results and applying the modal analysis, the model parameters are obtained. Comparing the results of the model and the measurements findings shows that the proposed model can be utilized for transient studies in distribution networks.
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Keywords:  Distribution Transformer, Transient State, Black Box model, Modal Analysis.

 

 

go to top   Improve the Performance of Linear Induction Motors by Independent Control for Testing Aircraft and Submarine Models
         by Abdolamir Nekoubin

          Vol. 4. n. 1, pp. 303-309

        

Abstract - One of applications of double sided linear induction motor is for investigating about aerodynamic conditions of aircraft and submarine hydrodynamic conditions, instead of real size model, models with smaller size can be moved with appropriate speed by linear induction motor above the water surface or inside of the water channel test. As a special and distinct feature, the linear induction motor generates attractive force between the primary and secondary members in addition to the propulsive force, which brake the motion during accelerating as well as imposes the control problem owing to the coupled flux and motion dynamics with the advantage of reducing the possibility of derailment. In this paper, the flux and motion dynamics for independent control of attraction and propulsion force is decoupled. This control strategy allows high performance to be achieved from linear induction motor.
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Keywords:  Independent Control, Attractive Force, Linear Motors, Motion Dynamics.

 

 

go to top   Parameter Estimation of Three Phase Transformer based on Bacterial Foraging Algorithm
         by S.Subramanian, S. Padma

          Vol. 4. n. 1, pp. 310-317

        

Abstract - Due to the importance of transformers to power systems, investments in studies are justified in order to develop mathematical models to better understand equipment characteristics. The methodology used in this study consisted of the traditional open and short-circuit tests (OC and SC tests) of the three phase transformer to estimate the equivalent circuit parameters based on Bacterial Foraging Algorithm (BFA).The performance characteristics, such as efficiency and voltage regulation are considered along with the name plate data in order to minimize the error between the estimated and measured data. The estimation procedure is demonstrated with a sample three phase transformer and the results are compared against the conventional method. Results of experiments show that the proposed method to accelerate the convergence of the estimation and improve the accuracy of the parameters.
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Keywords:  Three Phase Transformer, Parameter Estimation, Bacterial Foraging Algorithm.

 

 

go to top   Application of D-STATCOM to Improve the Power Quality and Transient Operation of Induction Motor
         by Amin Sarijali, Murtaza Farsadi

          Vol. 4. n. 1, pp. 318-324

        

Abstract - This paper discusses the operation of a distribution static compensator (D-STATCOM) based on three leg voltage source converter (VSC) in three. Phase four wire distribution systems. This device causes power quality improvement under unbalanced load, and regulates voltage when an induction Motor in system starts up.
The proposed controller of D-STATCOM mitigates the neutral current and compensates harmonics current, reactive power, and balances the system. The insulated gate bipolar transistor (IGBT) based VSC is supported by a capacitor and is controlled for the required compensation of the load current. The performance of the three phase four wire D-STATCOM simulated in PSCAD/EMTDC soft ware.
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Keywords:  D-STATCOM, Power Quality Improvement, Voltage Source Converter (VSC), Induction Motor, Active Filter.

 

 

go to top   Models and Simulations for Reconfigurable Magnetic-Coupling Thrusters Technology
         by O. Chocron, H. Mangel

          Vol. 4. n. 1, pp. 325-334

        

Abstract - This paper describes the theory and experiments of a new technology for re-orienting propellers of underwater thrusters and thus, vectoring AUV thrust. The principle is to extend the potentialities of magnetic-coupling motor shafts by adding degrees of freedom in their kinematics. The idea is to redirect the propeller and therefore, the thrust vector to a desired direction without moving the whole thruster body. The focus of this work is to understand how does behave the magnetically transmitted coupling torque with regard to the new kinematics of the propeller shaft. After justifying the concept, reviewing existing AUV locomotion systems, we introduce the theory underlying this thruster technology and bring numerical simulations for two design examples. Some experimental results are given for a laboratory set up, then for an existing and reconfigured thruster that confirm the insights brought by the theory. The feasibility of this technique is then discussed based on potential integration and developments on real AUVs. The conclusion marks these results as an interesting step to achieve full 3D smooth control of agile AUVs in near future.
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Keywords:  AUV Vectorial Thrust, Magnetic-Coupling, Modelling, Simulation, Experiments.

 

 

go to top   Computation of the Parameters of a Slot-Embedded Conductor Using the Finite Element Formulation of the Impedance Boundary Condition
         by A. M. El-Sawy Mohamed

          Vol. 4. n. 1, pp. 335-341

        

Abstract - The finite element variational formulation of the impedance boundary condition (IBC) is developed and applied to solve two-dimensional eddy current problems, especially at high frequencies in electrical machines. This formulation is used to compute the ac resistance and the self inductance per unit length of a reverse ‘T’ slot-embedded conductor and a simple slot-embedded conductor. The proposed IBC formulation is very efficient, because it does not change the sparsity of the finite element global matrix as well as it has minimized the computing cost such as computer memory and central processing unit time. The obtained results of both the finite element method (FEM) and the developed IBC formulation are compared to published results.
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Keywords:  Eddy Currents, FE-Formulation, IBC Formulation, Slot-Embedded Conductor.

 

 

go to top   Modeling and Comparison of Traction Transformers based on the Utilization Factor Definitions
         by Mohsen Kalantari, Mohammad Javad Sadeghi, Siamak Farshad, Seyed Saeed Fazel

          Vol. 4. n. 1, pp. 342-351

        

Abstract - Electric railways inject undesirable harmonics and large negative sequence component to the utility grid due to their essential characteristics (i.e. non-linear, non-sinusoidal, non-symmetrical, and non-continuity). Traction transformers with a special connection (i.e. Single-phase, V/V, Wye-Delta, Scott, and Le-Blanc) are one of the best solutions to limit the above drawbacks and also improve the efficiency and power factor of the utility grid. They have been selected on the basis of electrical performance, physical profile of the network, and economics issues. Traction load variation, negative sequence component, load harmonic currents, power factor, and efficiency as effective electrical parameters were investigated for aforementioned traction transformers. However, there are other influential and important parameters in the electrical railway systems which are not considered in the research works. Therefore, this paper defines these factors (utilization factors of the traction transformer and transmission line) as mathematical equations and then investigates the impacts of harmonic components and unbalance loading on these factors.
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Keywords:  Traction Transformer, Unbalance Loading, Line Utilization Factor, Transformer Utilization Factor.

 

 

go to top   Analysis of UPQC with Super-Capacitor to Power Quality Enhancement and Energy Storage
         by S. Sajedi, T. Karimi, F. Khalifeh, Z. Khalifeh

          Vol. 4. n. 1, pp. 352-357

        

Abstract - This paper proposes a new configuration of UPQC (Unified Power Quality Conditioner) that consists of the DC/DC converter and the super-capacitors for compensating the voltage interruption. The proposed UPQC can compensate the reactive power, harmonic current, voltage sag and swell, voltage unbalance, and the voltage interruption. The performance of proposed system was analyzed through simulations with MATLAB\SIMULINK software. The proposed system can improve the power quality at the common connection point of the non-linear load and the sensitive load.
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Keywords:  Unified Power Quality Conditioner (UPQC), Voltage Interruption, DC/DC Converter, Super-Capacitor.

 

 

go to top   Modeling and Simulation of Centrifugal Gas Compressor Using Adaptive Neuro-Fuzzy Inference System: Application to the Modeling and Simulation of the Industrial Packages
         by Mohsen Hayati, Seyd Mohammad Jamshidi, Abbas Rezaei

          Vol. 4. n. 1, pp. 358-363

        

Abstract - In this paper, the modeling and simulation of a centrifugal gas compressor based on adaptive neuro-fuzzy inference system (ANFIS) is presented. A hybrid learning algorithm consists of back-propagation and least-squares estimation is used for training. Structures of the ANFIS are developed and trained in MATLAB 7.0.4 program. This model can reduce the computational time while keeping the accuracy of physics-based model. The compact models with ANFIS allow the fast and accurate system level simulation of the Industrial Packages.
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Keywords:  Compressor, Artificial Neural Network, Adaptive Neuro-Fuzzy Inference System, Fuzzy System.

 

 

go to top   Theoretical Investigation on the Thermal Performance of two-Phase Heat Spreaders including Parallel Microchannels
         by J. Mansouri, S. Maalej, M.B.H. Sassi, M.C. Zaghdoudi

          Vol. 4. n. 1, pp. 364-379

        

Abstract - A detailed mathematical model of a two-phase heat spreader with axial microchannels is developed in which the fluid flow is considered along with the heat and mass transfer processes during evaporation and condensation. The model is based on the equations for the mass, momentum and energy conservation, which are written for the evaporator, adiabatic, and condenser zones. The model, which permits to simulate several shapes of microchannels, can predict the maximum heat transfer capacity of the two-phase heat spreader, the optimal fluid mass, and the temperatures and pressure gradients along the microchannel. The effect of shear stresses at the free liquid surface in a microchannel due to the frictional liquid-vapor interaction on the liquid flow is taken into consideration. The heat transfer through the liquid films in both evaporator and condenser is accounted for in the model, which is described with respect to the disjoining pressure, interfacial thermal resistance, surface roughness, and curvature. The thermal resistances of the evaporator and condenser are determined by accounting for the longitudinal distribution of the meniscus curvature, which is dependent on heat load and heat spreader inclination.
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Keywords:  Electronics Cooling, Mini Heat Pipes, Capillary Structure, Microchannels.

 

 

go to top   X-FEM Method for Crack Growth Modelling: Concepts and Computer Implementation
         by Y. Abdelaziz, R. Abderrahmani, A. Chabani, T. Rikioui

          Vol. 4. n. 1, pp. 380-387

        

Abstract - In this work, we present a method for modeling crack growth without re-meshing X-FEM. It covers the formulation and implementation of XFEM, and discusses various aspects of the approach. Concepts of the level set method and the extended finite element are explained, and there is a discussion on the enrichment models. It provides a number of simple instructions and step-by-step procedures for a wide range of engineering applications. These simple guidelines, in combination with other freely available XFEM source codes can be used to further advance the existing XFEM capabilities, and to provide a launching pad for future improvements and developments. A numerical experiment is provided to demonstrate the effectiveness and robustness of the XFEM implementation.
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Keywords:  Singularity, Crack, Fracture, XFEM, LSM, Implementation.

 

 

go to top   Degenerated Finite Element Modelling: Effect of Size
         by Y. Abdelaziz, R. Abderrahmani, A. Chabani,T. Rikioui

          Vol. 4. n. 1, pp. 388-390

        

Abstract - On the basis of fracture mechanics, a numerical study has been considered in order to study the effect of size of degenerated finite element in modeling the singularity near the crack tip. It allows to numerically estimating of the stress intensity factors, for Central Notched specimen, by using two techniques of modeling (finite element standard and degenerated finite elements). This work makes it possible to confirm the aptitude of the degenerated finite elements to model the singularity accurately existing in the vicinity of the cracks.
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Keywords:  Degenerated Finite Element, Size, Singularity, Crack, Stress Intensity Factors.

 

 

go to top   Robust Maximum Power Point Tracking for Fast Changing Environmental Conditions
         by H. Abouobaida, M. Cherkaoui, M. Ouassaid

          Vol. 4. n. 1, pp. 391-396

        

Abstract - In this paper , we study a system consisting of a photovoltaic (PV) array panel, dc-to-dc switching converter and a battery. A backstepping PWM controller is developed to maximize the power of the solar generating system.
The controller tracks a desired array voltage designed online by using MPPT algorithm, by varying the duty cycle of the switching converter. The stability of the control algorithm is demonstrated by means of Lyapunov analysis. Representative numerical results demonstrate that the power system can be controlled to track the maximum power point of the photovoltaic array panel.
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Keywords:  Maximum Power Point Tracking, Solar Power Generation, Robust Control, Lyapunov, PWM.

 

 

go to top   Using H∞ State Estimation for a Cold Flow Circulating Fluidized Bed on Standpipe
         by Seyed Mohammad Hossein Nabavi, Nima Yoosef Pour, Somayeh Hajforoosh, Ali Jalali

          Vol. 4. n. 1, pp. 397-403

        

Abstract - Circulating fluidized beds (CFB) have been widely applied to many area of industry such as chemical processing, petroleum refining, catalytic cracker processing, power generation and waste treatment. The application of CFBs provides several advantages, such as improving gas-solid contact, reducing the cross-sectional area because of high superficial velocities, and having a higher solids flux trough the reactor. A cold flow circulating fluidized (CFCB) has been built at the National Energy Technology Laboratory (NETL) in Morgantown recently, a mathematical model of the CFCFB standpipe was successfully developed and tested using an extended Kalman filter EKF and an H estimator algorithm. The H estimator and EKF algorithms have been used to estimate states such as the void fraction and the bed-height of the standpipe using pressure drop measurements. Using this standpipe mathematical model requires a solid circulation rate(SCR) to be a measurable variable offered from a spiral installed in the standpipe of CFCFB the spiral device at the standpipe of the NETL CFCFB test bed is impractical when a CFB system is operating in order to estimate the solids circulation, using a least squares estimator and a subspace algorithm. In this model, the measured aeration flow rates and pressure drop are used as inputs and outputs in the from of a time series in order to build the state space dynamic model. After this model has been obtained, the Kalman filter and H algorithms is applied in order to estimate the solids circulation rate with the measured pressure drop profiles.
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Keywords:  Extended Kalman Filter, H, Cold Flow Circulation Fluidized Bed, Standpipe.

 

 

go to top   Finite-Element Simulation of Heat Generation by Laser in Welding
         by Ali Moarrefzadeh

          Vol. 4. n. 1, pp. 404-408

        

Abstract - In this paper, the laser beam welding is studied and aluminum alloy temperature field is gained in this process. Utilizing laser as a method to join plastic components is growing in popularity. The ability to create clean, strong and consistent hermetic seals is very attractive for
manufacturers. Conditions were determined for consistent coupling of a laser beam to weld aluminum alloy sheet. Full penetration butt and bead-on-plate welds on 0.8 and 1.8 mm sheets were performed. Process conditions examined included beam mode, spot size and irradiance, shielding gas flow, and edge quality and fit up. The observed weld quality variations with the different process parameters were consistent with physical phenomena and a threshold irradiance model. Optimal conditions were determined for obtaining consistent welds on 5182 alloy sheets. Formability and tensile tests were performed on the welded samples. All test failures occurred in the fusion zone. Reduction in formability and tensile strength of the welded samples are discussed with respect to weld profiles and process parameters.
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Keywords:  Aluminum, Laser Beam Welding, Finite-Element, Temperature Field.

 

 

go to top   Effects Clamped-Clamped boundary conditions for Vibration of Functionally Graded Cylindrical Shells based on T.S.D.T using Hamilton's Principle
         by M.R.Isvandzibaei

          Vol. 4. n. 1, pp. 409-416

        

Abstract - Study of the vibration of thin cylindrical shells made of a functionally gradient material (FGM) composed of stainless steel and nickel is very important. The objective is to study the natural frequencies and the effects clamped-clamped boundary conditions on the natural frequencies of the functionally graded cylindrical shell. The study is carried out using third order shear deformation shell theory (T.S.D.T). The analysis is carried out using Hamilton’s principle. The governing equations of motion of functionally graded cylindrical shells are derived based on T.S.D.T theory. Results are presented on the frequencies characteristics and the effects of clamped-clamped boundary conditions on edge end functionally graded cylindrical shell.
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Keywords:  Vibration, Cylindrical Shell, Hamilton’s Principle.

 

 

go to top   Shape and Dimension Estimation of Cracks using Neural Network in Eddy Current Testing
         by A. Babaei, S. Rafiei, A. Mrazeban, M. Saeidmanesh

          Vol. 4. n. 1, pp. 417-421

        

Abstract - This paper proposes a method for the reliable estimation of crack shape and dimensions in conductive materials using a suitable nondestructive instrument based on the eddy current testing principle and machine learning system postprocessing. The artificial neural network estimates shape and dimension of new cracks using impedance changes of eddy current probe. The experimental results and finite element method is used for training the artificial neural network and the simulation results are very promising. By increasing the numbers of experiments, finite element method is not necessary.
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Keywords:  Nondestructive Testing; Eddy Current; Artificial Neural Network; Finite Element Method; Feed Forward Backpropagation.

 

 

go to top   Estimation of Location and Magnitude of Harmonic Sources by Optimal Measurement Placement
         by S. Sajedi, F. Khlifeh, Z. Khalifeh, T. Karimi

          Vol. 4. n. 1, pp. 422-428

        

Abstract - In this research, a new method is proposed to solve the problem of optimal placement of meters for static estimation of harmonic sources in a power system. Because of limitation the number of harmonic measurements that must be installed in the network, harmonic state estimation has been considered as one of the famous methods for measuring voltage and injection current busbar, lines current and placement these measurements with algorithm based on sequential elimination method. Also, after that algorithm could find location of measurements in various busbars at harmonics, technique minimization number of sites that they¬ collect harmonic data from measurement devices, optimal placement of these measurements will be done. By use this technique, it can find optimal place of measurement for identification location and intensity of harmonic sources. This investigation have been performed on IEEE 14-bus with 69 possible location to install these measurement in Matlab software.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords:  Harmonic Measurement, Modeling, Optimal Placement, Condition Number.

 

 

go to top   Airflow Simulation of Particle Suction in Hard Disk Drives Manufacturing Process
         by N. Yimsiriwatana, T. Jearsiripongkul

          Vol. 4. n. 1, pp. 429-435

        

Abstract - In Hard Disk Drive (HDD), particles are the major problem during the operation of HDD. Thus, in the HDD manufacturing process, particles are one of the important controlled parameters. In some processes particles are removed from the HDD using suction tools. The designs of these tools affect the efficiency of particle removing process. Therefore, the prediction of the airflow induced by the suction tools becomes convenient and useful for the researchers to develop and improve each component of the tools and also the production. This project is to analyze the particle productivity and aim to improve it. In order to do so, the airflow simulation is needed to be done. The airflow is modeled and simulated using ANSYS CFX software. The suction tool is simulated at various operating height; 1 mm, 2 mm, 5 mm, and 10 mm. From the results, it is seen that the operating height of the suction tool affects the flow characteristic of the particle. The best operating height is 5 mm. This will lead the researchers and engineers to understand about the effect of each component and design of the suction tools to airflow and particle conductivity.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords:  Airflow, Hard Disk Drive, Particle, Simulation, Suction Tools.

 

 

go to top   Temporal Neuro-Fuzzy Systems in Fault Diagnosis and Prognosis
         by Mahdaoui Rafik, Mouss Leila Hayet, Mouss Med Djamel, Chouhal Ouahiba

          Vol. 4. n. 1, pp. 436-440

        

Abstract - Fault diagnosis and failure prognosis are essential techniques in improving the safety of many manufacturing systems. Therefore, on-line fault detection and isolation is one of the most important tasks in safety-critical and intelligent control systems.
Computational intelligence techniques are being investigated as extension of the traditional fault diagnosis methods. This paper discusses the properties of the TSK/Mamdani approaches and neuro-fuzzy (NF) fault diagnosis within an application study of a manufacturing system. The key issues of finding a suitable structure for detecting and isolating ten realistic actuator faults are described.
Within this framework, data-processing interactive software of simulation baptized NEFDIAG (NEuro Fuzzy DIAGnosis) version 1.0 is developed. This software devoted primarily to creation, training and test of a classification Neuro-Fuzzy system of industrial process failures. NEFDIAG can be represented like a special type of fuzzy perceptron, with three layers used to classify patterns and failures. The system selected is the workshop of SCIMAT clinker, cement factory in Algeria.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords:  Diagnosis; Artificial Neuronal Networks; Fuzzy Logic; Neuro-Fuzzy Systems; Pattern Recognition; FMEAC.

 

 

go to top   A Hybrid State Space Model for Single Stage Three-Level Resonant Rectifiers
         by Mohammed S. Agamy, Praveen K. Jain

          Vol. 4. n. 1, pp. 441-456

        

Abstract - This paper presents a state space model based on a combined averaging and multiple frequency models suitable for the prediction of the performance of a single stage three level resonant AC/DC converter operated with variable frequency asymmetrical pulse width modulation control or variable frequency phase shift modulation control to regulate the output voltage, shape the input current as well as to control the dc bus voltage. The pulse width modulation/phase shift modulation aims to regulate the input current shape as well as the level of the dc-bus voltage; whereas, the variable frequency provides a tightly regulated output voltage. This model is obtained by first deriving an average model of the switching converter, which is then analyzed to its frequency components. This results in substituting fast and slow oscillating values at steady state with variables that have a dc steady state value. This modeling approach is generally useful for variable frequency application and can be used at a detailed level that includes effect of parasitics, to a simplified linearized or a decoupled model to get steady state estimates of performance. The proposed model gives very good performance prediction under transient and steady state conditions and facilitates a better controller design.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords:  Power Factor Correction, Multiple Frequency Averaging, State Space Model.

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