per Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452017-03144247261articleM. Heydariheydari@qut.ac.ir1A. Yazdian Varjaniyazdian@modares.ac.ir2Tarbiat Modares UniversityReducing the number of semiconductor switches in power electronic converters has been a continuing effort in recent years as a measure to enhance the system reliability and to decrease its size, weight, and component cost. For these reasons, a new reduced switch count three-phase ac/ac converter is being proposed. Being realized by only six active switches and anti-parallel diodes, the proposed converter topology employs the minimum number of semiconductor devices amongst the converters of its kind. It also features unity power factor, regenerative operation, pulse width modulated output voltage, and sinusoidal input current. The reduced number of switches results in a simplified associated gate drive circuit as well as cooling system which, in turn, may cut the overall manufacture cost, especially in low voltage and low power applications. The modulation scheme of the new converter is developed, and a control algorithm is proposed for the converter’s rectifier side. Moreover, an analysis is performed on the dc link capacitor sizing for the purposes of reducing dc link voltage ripple, balancing the input current, and lowering its THD. The simulation and experimental results corroborate the transient and steady state performance of the proposed converter topology.http://ijece.org/Article/28205Three-phase ac/ac converter reduced switch count converter dc-link capacitor sizing dc-link voltage ripple reduction back to back ac-ac converterper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452017-03144262270articleJ. Modarresij.modarresi@eng.ui.ac.ir1E. Gholipoure.gholipour@eng.ui.ac.ir2A. Khodabakhshianaminkh@eng.ui.ac.ir3Load shedding is the last line of defense for controlling and stabilizing of the power system in the occurrence of a disturbance. Determining the amount and location of the load shedding are issues that the power system operators always have faced In this paper, a new method is proposed for determining the location of under voltage load shedding (UVLS). The proposed method, unlike the previous UVLS methods, uses two different factors to determine the effective location of UVLS. Considering the load reactive power in the process of determination of the UVLS location leads to disconnecting more reactive power during the initial steps of UVLS. Therefore, less active power sheds by the UVLS. To verify the accuracy of the proposed method, the proposed UVLS method accompanied with the method which uses the sensitivity of voltage with respect to the active power are implemented in IEEE 118-bus test system and New England 39 bus system. The obtained results show the superiority of the proposed method.http://ijece.org/Article/28206Under voltage load shedding effective bus reactive power voltage sensitivity voltage stabilityper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452017-03144271280articleF. Faghihifaramarz_faghihi@hotmail.com1soodabeh Soleymanis.soleymani@srbiau.ac.ir2M. Mollazadeh Shahroudimh.mollazadeh@srbiau.ac.ir3In this paper a control technique for renewable energy resources–grid interface is proposed based on extended multi output-recursive least square (EMO-RLS) algorithm considering active power management and harmonic, unbalanced and reactive current components elimination. The proposed method is evaluated via MATLAB/SIMULINK software. Firstly, an artificial three-phase unbalanced harmonic signal is generated. It will be transmitted to different estimators for their outputs comparison. The results indicate proper performance of the suggested structure for active harmonic symmetrical components analysis in comparison with the other traditional methods. Also, its dynamic operation in tracking of load current variations is evaluated employing EMO–RLS algorithm for control system of a DG source interface. It illustrates the active power injection to the grid is managed, as well as the harmonic, unbalance and reactive current components, are decreased simultaneously.http://ijece.org/Article/28207EMO-RLS method injected active power control power quality harmonic symmetrical components renewable energy resources interfaceper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452017-03144281288articleS. Daniars.daniar@mail.ilam.ac.ir1S. Daniare.norouzi1992@yahoo.com2Directional protection is a crucial function in advanced transmission network relays. In this paper, a novel directional algorithm for transmission line protection is presented. Proposed algorithm responds to all kind of faults accurately without any dead zone. In this scheme, discrimination between internal and external faults will be done precisely even for close relay faults. The proposed algorithm utilizes a close form equation achieved by least squares optimization. Directional protection function is carried out based on proposed algorithm under various conditions such as current transformer saturation, power swing and source capacity changes. Moreover, variation on some parameters such as fault inception and fault resistance has only negligible effects on algorithm performance. Due to employing of low sampling frequency, hardware implementation of the proposed algorithm is not complicated. Algorithm performance is evaluated by applying the field data from Manesht 230kV substation located at Ilam province as well as extracted data form EMTP-RV simulations. Simulation results verify the speed and reliability of the proposed algorithm.http://ijece.org/Article/28208CT saturation digital protection directional relay positive sequence component dead zoneper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452017-03144110articlehttp://ijece.org/Article/28209per Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452017-03144110articleThis paper proposes to design, optimization and finite element simulation of an axial-flux, super-high speed, permanent magnet motor. The target motor with 0.5 hp rated power at speed of 60,000 rpm is used in a special industrial application. Based on nominal specifications of the motor and using analytical relations of motor design, the design calculations, sizing and motor dimensions are investigated. Due to special application of the target motor that needs to the demanded torque with minimum current and copper losses, the dimensions and design specifications of motor is optimized via genetic algorithm based on a torque per ampere cost function. Optimization algorithm determines the optimum value of airgap, permanent magnet flux density, current density and turns number of stator windings. To demonstrate of analytical design and optimization results, using 3-D model of motor in Maxwell software, finite element analysis are carried out in Magneto-static and Transient modes. The FEM simulation results confirm the analytical design results. Moreover, they show the significant reduction in RMS current and copper loss at rated torque. There is a good agreement between the values of torque, motor efficiency, and flux density resulted from both methods.http://ijece.org/Article/28210Permanent magnet synchronous motor high speed disk-type motor analytical design 3-D finite element analysis genetic algorithm optimizationper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452017-03144289297articleS. A. Seyedi Seadatis_ali_seyedi@yahoo.com1A. Halvaei Niasarhalvaei@kashanu.ac.ir2Department of Electrical and Computer Engineering, University of KashanThis paper proposes to design, optimization and finite element simulation of an axial-flux, super-high speed, permanent magnet motor. The target motor with 0.5 hp rated power at speed of 60,000 rpm is used in a special industrial application. Based on nominal specifications of the motor and using analytical relations of motor design, the design calculations, sizing and motor dimensions are investigated. Due to special application of the target motor that needs to the demanded torque with minimum current and copper losses, the dimensions and design specifications of motor is optimized via genetic algorithm based on a torque per ampere cost function. Optimization algorithm determines the optimum value of airgap, permanent magnet flux density, current density and turns number of stator windings. To demonstrate of analytical design and optimization results, using 3-D model of motor in Maxwell software, finite element analysis are carried out in Magneto-static and Transient modes. The FEM simulation results confirm the analytical design results. Moreover, they show the significant reduction in RMS current and copper loss at rated torque. There is a good agreement between the values of torque, motor efficiency, and flux density resulted from both methods.http://ijece.org/Article/28211Permanent magnet synchronous motor high speed disk-type motor analytical design 3-D finite element analysis genetic algorithm optimizationper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452017-03144298304articleM. R. Alizadeh Pahlavanimr_alizadehp@iust.ac.ir1Y. Shahbazi Ayatyusef.shahbazi@gmail.com2A. Vahediavahedi@iust.ac.ir3University of Science and Technologypaper present an improved design of Axial Flux Permanent Magnet (AFPM) synchronous machines using PSO algorithm that consider practical limits. At first sizing equations is provided and 20 kW AFPM machine is designed, and then output power density is improved using PSO algorithm. A comparison between improved designed AFPM machine and a prototype constructed machine is performed. Improved machine has more output power density than constructed machine. Then magnetic flux density is calculated based on Maxwell equations analytically. Analytical results have good agreement with finite element method (FEM) results. Use of analytical method takes much less computational time than FEM dose.http://ijece.org/Article/28212Improved design permanent magnet machine TORUS-NS axial flux machineper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452017-03144305310articleM. R. Alizadeh Pahlavanimr_alizadehp@iust.ac.ir1Y. Shahbazi Ayatyusef.shahbazi@gmail.com2A. Vahediavahedi@iust.ac.ir3University of Science and TechnologyThis paper presents a semi-3D analytical method for calculation of the no-load magnetic flux density in an axial flux permanent-magnet machine. This method is based on a 2-D analytical solution of magnetic field and using modulation function for considering machine’s radial effect on magnetic field distribution. Modulation function is obtained analytical and by use of airgap and leakage permeances. This analytical method takes much less computational time than 3-D finite element method (FEM) does, and is, thus, useful for designing and optimization purposes. Finally, the accuracy of the presented analytical model is validated by comparing its results to corresponding finite-element analysis.http://ijece.org/Article/28213Axial flux machines magnetic field permanent magnet analytical modelper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452017-03144110articleM. Takim.taki@qom.ac.ir1R. Mahin Zaeemreza.zaeem@gmail.com2In this paper, a new scheme for completely reliable transmission of the information (with an error probability tends to zero) in a wireless communication link will be proposed in which to compensate the effects of fading and multipath, adaptive modulation and coding is used. Obviously, by the practical forward error correction it is impossible to achieve error free communication. Removing the residual error is by an auto-forwarding system. Of course, if error correction coding capability is weak, number of retransmissions will be increased to the much needed and it severely undermines the system throughput. On the other hands, strong error correction capability needs high block length codes and high transmission power which are limited in practice. In this paper, a method for optimum combination of error correction and auto forwarding is provided. In this paper, link adaptation is based on imperfect channel state information. Numerical results demonstrate efficiency of designed method.http://ijece.org/Article/28214Discrete link adaptation adaptive modulation and coding automatic repeat request reliable transmissionper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452017-03144311317articleM. Takim.taki@qom.ac.ir1R. Mahin Zaeemreza.zaeem@gmail.com2In this paper, a new scheme for completely reliable transmission of the information (with an error probability tends to zero) in a wireless communication link will be proposed in which to compensate the effects of fading and multipath, adaptive modulation and coding is used. Obviously, by the practical forward error correction it is impossible to achieve error free communication. Removing the residual error is by an auto-forwarding system. Of course, if error correction coding capability is weak, number of retransmissions will be increased to the much needed and it severely undermines the system throughput. On the other hands, strong error correction capability needs high block length codes and high transmission power which are limited in practice. In this paper, a method for optimum combination of error correction and auto forwarding is provided. In this paper, link adaptation is based on imperfect channel state information. Numerical results demonstrate efficiency of designed method.http://ijece.org/Article/28215Discrete link adaptation adaptive modulation and coding automatic repeat request reliable transmission