نشریه انرژی ایران
سال پانزدهم شماره 4 (پیاپی 57، زمستان 1391)

In recent years optimal placement of distributed generators system has been designed considering the reliability and loss reduction. In this paper a powerfull algorithm used to optimization the objective function variables. The objective function consist of maximum power loss reduction، reliability improvement، voltage profile، DG size and cost of the DG installation proper sizing and position of hybrid photovoltaic/Wind distributed generators are ardently necessary. So the constriction of optimization problem is reliable load supplying and minimum cost. According to this difinition، 20-bus network located in Meshkinshahr has been investigated. The result of optimization shows that loss reduction in the network with DG installation is more than the netwok without DG installation.

Power stations use a series of batteries in case of losing their ac current for any reason. These batteries provide the required power of relays، meters، counters، etc for a short or long period of time according to the energy stored in them. However، blackout can take longer time to recover so batteries may run out of power and lead to more problems. As it can be said، if dc current of the station is lost، relays، meters، etc will switch off and breakers will automatically open after a very short time. This paper investigates the dc load of a power station in Khuzestan province in order to design a photovoltaic system for supplying the dc current by solar cells during the day and by batteries during the night، in case that the station loses ac current. This improves reliability in power stations and reduces long term blackouts.

The purpose of this paper is to investigate and determine optimal efficiency and optimal generated power of thermoelectric generator systems. First، the maximum efficiency and the maximum generated power for multi-stage thermoelectric generator systems connected in both parallel and series are calculated. Then، the performances of these systems are compared and the priority of utilizing each system in its work temperature is determined. The average temperature of work temperatures in each stage is employed in this paper; however، some researchers have used the properties of thermoelectric substances in the average temperature of cold and hot surface. Eventually، Particle Swarm Optimization (PSO) is used as an efficient optimization method in the aspect of optimizing continuous problem to optimize this challenging issue.

Energy loss reduction in power system is one of the most important issues in generation، transmission and distribution systems. The harmonic distortion which is generally injected by the non-linear loads to power system، is a significant factor increasing losses in power system. In order to eliminate these harmonics، active power filter is implemented. The appropriate generation of reference current is a main part of shunt active power filter control algorithm. In this article، the most common used theories for control and extraction of reference current in three-phase power system with non-linear load was simulated. Then the effect of selected method on active filter performance was analyzed and evaluated. A comprehensive comparison between control methods was performed in terms of harmonic cancellation and loss reduction capabilities، reactive power compensation، transient response speed and design requirement. The numerical results showed that “BPF” method has the best performance to improve total harmonic distortion (THD). In addition، voltage disturbances had no effect on its operation. However، this method did not represent good performance for unbalanced compensation. For this purpose، the using of reactive power theory (P-Q) was the most useful. The results showed that the selection of reference current generation method should be based on compensation purposes and design Limitations.

Development of power plant could be inevitable part of those function established fitted areas under optimal parameters for logical evaluation. Consequently Tehran shall be optimal candidate due to sharing most proportion of urban and population development with contribution of more choice simulation process. The present paper puts forward MCDM and priorities through GIS as a comprehensive tool to storage، synchronization، retrieval and data processing plus graphic and digital schematic production in convenient scale in order to produce effective information required by resource optimized management. Consequently map with scale of 1/250000 of fuzzy logic used for suggested areas and factorial maps as validation in means to truncate the regions with less values which caused less areas suggested، finally with FTOPSIS the suggested choices shall be prioritized under optimal locus to lay out power plants introduced.

In order to improve the performance and increase of Micro Gas Turbine (MGT) efficiency، it can be combined with Solid Oxide Fuel Cell (SOFC) which is has high operating temperature. In this paper، the model of solid oxide fuel cell -micro gas turbine hybrid power system is presented. SOFC capacity has significant influence on the electrical efficiency of hybrid power system. Therefore، the effect of SOFC cell number (capacity) on the hybrid system performance is investigated. Also، this paper studies the effect of other key parameters in SOFC-MGT hybrid system. The investigation rules of main parameters of SOFC-MGT hybrid system with considering the turbine inlet temperature (TIT) of MGT as a constraint condition، are presented. The results show firstly، with increase of SOFC capacity، hybrid system efficiency increases. While، by the more increase of SOFC capacity، the efficiency increase rate is decreasing. Also، by increase of SOFC capacity، temperature of exhaust gases from SOFC increases that cause to increase of turbine inlet temperature (TIT). At the end، the effect of using exhausts gases from MGT for preheating entrance fuel and air to SOFC is surveyed. Results show the application of system heat management and heat recovery can increase the electrical hybrid system efficiency to 17. 8%. The achievements earned from this paper can supply the valuable information for further study on SOFC-MGT hybrid system.

Reconfiguration of distribution systems is a subject related to operation especially in the presence of automation systems. The reconfiguration can be done with different goals. Ever، various reconfiguration methods presented for unbalanced distribution networks. In this paper، reconfiguration of the unbalanced distribution system in the scheme of multi-objective model proposed to reduce the losses، power imbalances، switching operations and improvement the voltage profile. Bees algorithm has been implemented in MATLAB software to solve the multi-objective reconfiguration problem، as well as Graph theory is used to check the radial structure and being all loads in service. The results of applying the new technique on a sample distribution system are presented and prove the efficiency of the proposed method.