فصلنامه مهندسی و مدیریت انرژی
سال چهارم شماره 1 (پیاپی 11، بهار 1393)

In this paper، Integrated Resource Planning (IRP) problem is formulated as an optimization problem in which the objective function is to minimize the total investment، operating، and outage (energy not served) costs of power system as well as the cost of DSM programs. Generation system reliability is assessed and provided by means of EENS and LOLP indices. For this sake، energy not served cost is added to the objective function، and LOLP is considered as a constraint. To solve the problem، Artificial Bee Colony (ABC) algorithm is proposed. In order to show the effectiveness and efficiency of the proposed algorithm، it is applied to a test system with 15 existing power plants and 5 types of new candidates، for two planning horizons. The Genetic Algorithm (GA)، as a mostly used method، is also applied to solve the IRP problem. Simulation results show the advantages of the proposed ABC algorithm over the GA.

DFIG based wind turbines (WTs) are very sensitive to grid voltage dips. This is because the grid voltage dips imposed at the connection point of the DFIG to the grid induce large voltages in the rotor windings، resulting in high rotor current. According to high penetration of DFIG based WTs، it is important that the WTs remain connected to the grid during the voltage dips and improve the grid stability. This paper proposes a combinational method for improving ride-through capability of DFIG-based wind turbines under unbalanced voltage dips. The method is realized through the rotor-side converter control and by using additional passive hardware، called stator damping resistor (SDR). The proposed method limits the peak values of transient response at the times of occurring and clearing the fault. It also improves damping of DFIG transient response، and eliminates or reduces undamped negative sequence oscillations with two times of grid frequency. Finally، performance of the proposed method is evaluated by time domain simulations.

During the oil and gas extraction and their refining processes at the refinery complexes، a large amount of gases are not used and then they will be sent to the Flare networks. These burnt gases cause pollution and will waste the country’s economic resources. If the Flare Gases Recovery Systems (FGRS (are employed، then we can recover the wasted energy and prevent the emission of greenhouse gases like CO2، SOX and NOX. In this paper، firstly، the FGR system process is demonstrated in order to recover burnt gases. Furthermore، the simulation of the desired system was carried out through conducting the case study in the gas processing plant. The simulation results indicate that if the flare gas recovery system is used when the refinery is in the normal operation condition، the recovery of 530 (m3. hr-1) of sweet natural gas، 12 (ton. hr-1) of gas condensates would be possible. Following environmental studies، it was found that by using the above-mentioned system، producing 300 (Kg) per day of NOx، 2142 (Kg) per day of CO and 43 (ton. hr-1) of SO2 would be prevented.

Synthesis gas is a mixture of hydrogen and carbon monoxide which is used in many chemical and metallurgy processes and is the main intermediary for some chemical compounds like methanol and ammonia، liquid fuels and solvents. Various methods of synthesis gas are available and partial oxidation of methane is one of them. One of the newest techniques is to use plasma reactors for this purpose which causes more conversion of methane to products and produces more pure hydrogen. Among these reactors gliding plasma is one with the higher efficiency rate. Plasma generator in reactor is high voltage direct current power supply. Plasma technology by using electrical energy causes motivation of molecules and provides an ideal bed for different kind of reactions to take place. In this study the reactor is modeled in a one dimensional heterogenic mode via the catalytic oxidation process of methane using Matlab software and the results shows that the model is in good agreement with experimental results.

Feed-water heating repowering is defined as using gas turbine (s) flue gasses energy for recovery by steam plant feed water heaters. Minimizing related total cost in new thermal system is the critical subject، beside of this purpose an optimal balance between capital cost investment and exergy destruction should be considered. In this research feed water heating repowering modeling of Shahid Rajae steam plant has been performed; in the next stage، optimization of mentioned system variables has been done based on thermoeconomic objective functions. Then objective functions sensitive analysis in contrast of steam turbines extraction flow rates have been performed and optimum amount of flow rate are determined by using Genetic algorithm. As a result of this optimization، some of technical and economical system properties have been upgraded. Thermal efficiency and exergy efficiency are anticipated to be 42. 2 and 40. 17 respectively and exergy destruction cost is increased about 1 to 16 percent; also it should be mentioned that 26 months has been derived for optimum period of preliminary capital return.

One of the promising sources for biodiesel production and lowering energy crisis is microalgae lipid and attracted much attention in recent years. The aim of this study was to investigate the Effect of temperature on the Lipid productivity as factors affecting biodiesel economic performance. Microalgae Nannochloropsis Oculata in Walne medium and seven different temperatures were cultured. Cell growth on a daily basis by measuring the cell density was determined by spectrophotometry. Biomass production and lipid accumulation of microalgae in the late of stationary growth phase measurements and constituents were identified by gas chromatography. By Standards، quality of oil extracted from microalgae for biodiesel production، was determined by iodine values. The results show that the maximum specific growth rate and biomass production of microalgae at 20 and 25 degrees. And the highest percentage of biomass conversion into lipid occurred at 30 degrees. Maximum lipid productivity at three temperatures 15، 20 and 25 degrees، but the analysis of fatty acids in the three temperature shows that maximum triglycerides accumulation in microalgae cells at 20 and 25 degrees. At Nannochloropsis Oculata cultivation، the optimal temperature range for maximum efficiency lipids to biodiesel production is 20 to 25 degrees Celsius.