per Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452013-121135765articleN. BiabaniBiabani_naser@yahoo.com1M. Ramezanimramezani@birjand.ac.ir2H. Falaghifalaghi@birjand.ac.ir3دانشگاه بیرجندIn addition to the great benefits of distributed generation (DG) resources to power systems, there are some disadvantages. In spite of some benefits like decrease of received power from transmission grid, increment of DGs penetration can lead to voltage increase in distribution networks during off peak. Hence the recent efforts have been made to handle problems to increase the penetration of these resources. The use of energy storage systems (ESSs) is one of the ways to prevent defects may arise from use of DGs in power systems and can help to increase penetration of DGs in power systems. ESSs can save energy during off peak and deliver it to the network in peak hours; hence, these equipment can reduce power losses and prevent voltage deviation during off peak by increasing load due to ESS charging. In this paper, first DG allocation and ESS placement are introduced then simultaneous placement of DG and ESS to reduce power losses in the distribution network are described. The proposed models are solved using genetic algorithm as optimization tool. The obtained results show that simultaneous placement could increase DG penetration compared to the separate allocation of these devices and prohttp://ijece.org/Article/28059Increment of distributed generation penetration genetic algorithm simultaneous placement energy storage systemsper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452013-121136674articleM. Samadimahdi.samadi@stu-mail.um.ac.ir1M. H. Javidih-javidi@um.ac.ir2M. S. Ghazizadehghazizadeh@pwut.ac.ir3Ferdosi UniversityFerdosi UniversityDemand response is becoming a promising subject in operation of restructured power systems. As a result, recently more attention is paid to demand response programs. Customers can contribute in operation of power systems by deployment demand response. The growth of customers’ participation in such programs may affect planning of power systems. Therefore, it seems necessary to consider the effects of demand response in planning approaches. In this paper, the impact of demand responsiveness on decision making in generation expansion planning is modeled. Then, avoidance or deferment in installation of new generating units is comprehensively investigated and evaluated by introducing a new simple index. In addition, changes in investment cost and total cost paid by customers are investigated. The effects of demand responsiveness are studied from both the customers’ and generation companies (Gencos) points of view. The proposed model has been applied to modified IEEE 30-bus system and the results are discussed.http://ijece.org/Article/28060Demand response generation expansion planning responsive demandper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452013-121137582articleS. M. Abediabedism@gmail.com1 HAGHIFAM@modares.ac.ir2Tarbiat Modares UniversityTarbiat Modares UniversitySeveral regulation schemes such as Rate of Return (ROR) and Price Cap (PC) lack incentives for efficient investment. ROR lead to overinvestment and PC on the other hand lead to underinvestment. Regulator employs various forms of reward/penalty schemes (RPS) to cover inherent weaknesses in PC. Adding RPS allow utilities to make cost effective reliability improvements in response to changes in technology and costs but since this schemes result in consumers purchasing reliability and delivery as a single, optimal level of investment can’t be insured. To solve this problem, in the recent year, the Reliability Insurance Scheme (RIS) has been introduced which through it the reliability and delivery services are unbundled and so the efficient investment is insured. In this paper, firstly, the investment structure under RIS is compared to that of traditional regulatory schemes and, according to this comparison; the advantages of RIS are illustrated. In the second step, under RIS, the effects of free-riding and investment delay on the investment dynamics are evaluated and finally the centralized method for alleviating these effects is proposed.http://ijece.org/Article/28061Asset management free riding investment structure reliability insuranceper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452013-121138390articleB. Noshadbahramnoshad@yahoo.com1M. Razazrazaz_m@scu.ac.ir2S. Gh. Seifossadatseifossadat@yahoo.com3One of the mal-operation of the power transformer differential protection that may occur during the energization of a loaded power transformer is the ultra-saturation phenomenon. In this paper, a new model to study the ultra-saturation phenomenon during the energizaton of a loaded three-phase power transformer is presented and its effect on the differential protection of the power transformer is considered. For modeling of the ultra-saturation phenomenon, the nonlinear characteristic of the transformer core and the saturation effect of current transformers are considered. It is assumed that the load of the power transformer is a resistive and an inductive load. The mal-operation of the differential protection depends on a variety of factors the most important parameters of which are inception angle and residual flux. In this paper the parameters mentioned will study in different cases. In this paper, simulation is done by MATLAB program.http://ijece.org/Article/28062Three-phase power transformer differential protection ultra-saturation phenomenon inrush current mal-operationper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452013-121139197articleM. Hosseinpourhoseinpour.majid@gmail.com1M. Mohamadianmohamadian@modares.ac.ir2A. Yazdian Varjaniyazdian@modares.ac.ir3Tarbiat Modares UniversityTarbiat Modares UniversityTarbiat Modares UniversityThis paper investigates the performance of four-leg parallel inverters sharing unbalanced and nonlinear loads. An inner current and external voltage control loops are considered to control the parallel four-leg inverters. In this paper, a proportional controller for the current internal loop as well as a proportional-resonant one for the voltage external loop are considered to support the proper performance of the system. The proposed system is able to feed balanced, unbalanced, and nonlinear loads and provides an appropriate sinusoidal voltage waveform for loads by accurately sharing power between the parallel inverters. Simulation results verify the accurate and proper performance of the proposed system.http://ijece.org/Article/28063Four-leg inverter parallel inverters operation current sharing circular chain controlper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452013-1211398104articleD. Aziziazizi@iust.ac.ir1M. R. Alizadeh Pahlavanimr_alizadehp@iust.ac.ir2Ahmad Gholamigholami@iust.ac.ir3University of Science and TechnologyIn this paper, a dynamic arc model based on MHD (Magneto Hydro Dynamic) equations for a high voltage (HV) SF6 interrupter has been investigated and analyzed. Moreover, for simulating the insulating performance and interrupting characteristics of the SF6 interrupter, dynamic variation of the arc, such as arc moving in the presence of Lorentz force have been established, and the compressibility and viscosity of SF6 gas in the whole interrupting course has been taken into consideration. The mass-fraction equation is introduced to the model on the basis of traditional mass, momentum, and energy-balance equations. The distributions of temperature field, pressure field, and mass fraction in the arc chamber are calculated.http://ijece.org/Article/28064Circuit breaker electric arc electric current voltageper Iranian Research Institute for Electrical Engineeringفصلنامه مهندسی برق و مهندسی کامپيوتر ايران16823745168237452013-12113105111articleR. Fathipourrasoulfathipour@yahoo.com1A. Saberkaria_saberkari@guilan.ac.ir2In this paper, a CMOS output-capacitor-free low-dropout regulator (LDO) is presented in which a capacitor multiplier based on a current-mode amplifier is embedded into the error amplifier to enhance the dynamic specifications to load variations, pole splitting, and simultaneously power saving. The proposed LDO topology is designed and simulated in HSPICE in a 0.35 µm CMOS process to provide a 1.8 V output voltage with a 200 mV dropout for a wide range output current between 0-100 mA while its quiescent current is 22 µA. In order to have a fair conclusion, the article reveals a FOM-based comparison with other reported designs.http://ijece.org/Article/28065Multiplier error amplifier fast path low-dropout regulator