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Farhadkhani M.,Niroo Research Institute
30th Power System Conference, PSC 2015 | Year: 2015

Since the emergence of power market, the target of power generating utilities has mainly switched from cost minimization to revenue maximization. They dispatch their power energy generation units in the uncertain environment of power market. As a result, multi-stage stochastic programming has been applied widely by many power generating agents as a suitable tool for dealing with self-scheduling strategies under uncertainty. However, dependence structure between stochastic variables has been almost ignored in the literature. Copula function is a new concept in the probability and statistics field which has the capability to represent the dependence structure among stochastic variables. However, Copula function has recently taken into account in power system studies by some articles. In this article, self-scheduling strategy of a generation utility owning thermal units is investigated while the dependence structure among stochastic load and market price variables is taking into account. We assume that the generation utility is a price-taker agent in a power market, and it also has to meet the load of a specific region as a retailer. The results indicates that as the stochastic dependence structure among load and price variables is considered in modeling load and price scenarios, the output of unit commitment problem changes so that the revenue of generation utility increases. © 2015 IEEE.

Hosseini Hashemi B.,International Institute of Earthquake Engineering and Seismology | Jafari M.A.,Niroo Research Institute
Journal of Constructional Steel Research | Year: 2012

This research was performed to evaluate two analytical methods for predicting the compressive strength of batten columns. Batten columns were subjected to pure axial compression, and the compressive strength was measured. The analytical methods used included the well-known Ayrton-Perry and ultimate strength curve methods to calculate the compressive strength of imperfect solid web columns, but their validity has not yet been studied experimentally on built-up columns. The geometrical parameters considered included the batten plate spacing and dimensions and the distance between the two longitudinal chords. The results show that the analytical methods were generally valid for the prediction of the compressive strength in batten columns and solid web columns. Using the average results of the Ayrton-Perry and ultimate strength curve methods leads to the best prediction of the column compressive strength. It was also shown that the initial imperfections in the batten columns could have a more important effect than the geometrical specifications on the value of compressive strength. © 2011 Elsevier Ltd.

Hasani-Marzooni M.,Niroo Research Institute | Hosseini S.H.,Sharif University of Technology
Energy Policy | Year: 2013

This paper develops a system dynamics model to analyze the impacts of different kinds of capacity payment as investment incentive mechanisms in Iranian electricity market. Since it is aimed that the incurred capital and operating costs of generation technologies be recovered in Iranian electricity pool, the noncompetitive capacity payment mechanism has been introduced for this purpose in order to encourage new investments in electric power generation system. In the current mechanism, the capacity payments are designated to the generating units in the whole country electricity market. An annual base value of capacity payment is proposed based on recovering the capital cost of a benchmark generation technology. This value is altered according to the operational reserve in the day-ahead electricity market. This supporting policy is simulated and analyzed in the proposed dynamic framework in order to track the trend of new investments in the Iranian electricity market. The feasibility study of implementing the regional capacity assignment is the main focus of this paper. Different possible regulating policies such as floating rates for capacity payment and electricity price cap, the multiple capacity payments to various technologies, and the regional electricity market with territorial capacity allocation are examined in order to investigate the consequences and performances of different decisions and policies in the capacity investment of Iranian electricity market. © 2012 Elsevier Ltd.

Akbari-Garakani M.,University of Tehran | Mehdizadeh M.,Niroo Research Institute
Materials and Design | Year: 2011

The present work was carried out to investigate the effect of long-term service exposure on microstructure and mechanical properties of a gas turbine hot gas path component, made of Alloy 617. The results showed significant service-induced microstructural changes, such as excessive grain boundary Cr-rich M23C6 carbides formation and some oxidation features in the exposed material in compare with the solution-annealed material. Also it was found that the yield strength and hardness of the alloy have increased while the ductility of the alloy has decreased. In the similar test conditions, the stress-rupture life of the exposed alloy decreased considerably compared to the solution-annealed sample, which could be attributed to the microstructural degradation, especially formation of continuous M23C6 carbides on grain boundaries. © 2011 Elsevier Ltd.

Hasani-Marzooni M.,Niroo Research Institute | Hosseini S.H.,Sharif University of Technology
IEEE Transactions on Power Systems | Year: 2013

This paper proposes a dynamic time simulation model for long-term generation capacity investment decisions in the presence of either perfect or imperfect electricity market. The model is based on system dynamics concept in which the dynamics of capacity construction is traced using the forecast of electricity price cleared in the short-term electricity market. Both the perfect and oligopolistic competitions are considered and a market power index is defined to evaluate the competition level of the electricity market. The short-term and long-term dynamic analysis are used to represent the generation firms' behavior in bidding strategy and capacity investment, respectively. Both possibilities of using forward bilateral contracts and application of wind power generation have been assessed individually in the proposed model in order to mitigate the market power. The time simulation results derived from a case study demonstrate the effectiveness of the model in illustrating the oligopoly in electricity marketplace and also the alternative decisions to attenuate it. Such a decision tool enables both the generation firms and the regulators to gain perfect insight into the oligopoly and its consequences in the long-term capacity investment in the electricity market. © 2012 IEEE.

Tajik Mansouri M.,Niroo Research Institute | Ahmadi P.,Energy Optimization Research and Development Group EORDG | Ganjeh Kaviri A.,University of Technology Malaysia | Jaafar M.N.M.,University of Technology Malaysia
Energy Conversion and Management | Year: 2012

In the present research study, the effect of HRSG pressure levels on exergy efficiency of combined cycle power plants is investigated. Hence, three types of gas turbine combined cycles, with the same gas turbine as a topping cycle are evaluated. A double pressure, and two triple pressure HRSGs (with and without reheat) are modeled. The results show how an increase in the number of pressure levels of the HRSG affect the exergy losses due to heat transfer in the HRSG and the exhaust of flue gas to the stack. Moreover, the results show that an increase in the number of pressure levels affects the exergy destruction rate in HRSG, and as a result, it causes a tangible increase in exergy efficiency of the whole cycle. The results from thermodynamic analysis show that the losses due to heat transfer in the HRSG and the exhaust of flue gas to the stack in a triple pressure reheat combined cycle are less than the other cases. From the economic analysis, it is found that increasing the number of pressure levels of steam generation leads to an increase for the total and specific investment cost of the plant for about 6% and 4% respectively. The net present value (NPV) of the plant increases for about 7% for triple pressure reheat compared to with the double pressure CCPP. Therefore, the results of economic analysis show that it is economically justifiable to increase the number of pressure levels of steam generation in HRSG. © 2012 Elsevier Ltd. All rights reserved.

Adl M.,Zhejiang University | Adl M.,Niroo Research Institute | Sheng K.,Zhejiang University | Gharibi A.,University of Shanghai for Science and Technology
Applied Energy | Year: 2012

Methane yields from cotton stalks have been reported in the range of 0.022-0.150Nm3/kg-VS in the preceding studies. In this study, hydrothermal pre-treatment of cotton stalks was performed under atmospheric conditions prior to anaerobic digestion process through which, three agents were examined; hot water, dilute ammonia solution containing 2% NH3 (dry matter basis), and recycled liquid from anaerobic process. All three options increased methane yield but the highest results (over 0.200Nm3/kg-VS) were obtained by utilization of recycled process liquid (PL) under an adjusted ammonia content and C:N ratio, which was achieved by dilution of PL with water as well as application of stabilized swine sludge as a nitrogen rich inoculum. The energy balance evaluation of the overall process revealed that bioenergy recovery from pre-treated cotton stalks by anaerobic digestion is feasible and viable only at feed streams with above 10% solids content, methane yield above 0.175Nm3/kg-VS and with heat recovery from hydrothermal pre-treatment tank. A methane yield of 0.184Nm3/kg-VS was observed under semi-continuous feeding of PL treated stalks to a hybrid plug-flow pilot reactor. © 2011 Elsevier Ltd.

Abdollahi A.,Niroo Research Institute | Matinfar F.,Niroo Research Institute
IEEE Transactions on Power Delivery | Year: 2011

A new algorithm based on the least-squares method is proposed for online power system frequency estimation. The algorithm is based on a formula which holds for every three consecutive samples. Several of these formulae are written for some consecutive triples of samples and the least-squares method is applied to estimate the frequency. A revised version of the approach with less computation burden at the cost of little decline in estimation accuracy is presented. Response time and processing time of the algorithm are discussed. The effect of data window size, sampling frequency, noise, harmonic, interharmonic, exponentially decaying dc, and filtering on the performance of the approach is discussed. The approach is compared with that of a recent similar paper and a demodulation approach. © 2010 IEEE.

Jahangiri M.R.,Niroo Research Institute | Abedini M.,Niroo Research Institute
Materials and Design | Year: 2014

In the present study, the effects of long-term service exposure have been investigated on microstructure and mechanical properties of gas turbine vanes made of IN939 superalloy. The major microstructural changes for the investigated service-exposed vanes include the formation of continuous grain boundary carbides and the transformation (degeneration) of MC carbides located at the grain boundaries. The brittle σ phase, which is predicted to be stable on the basis of thermodynamic calculations, is not observed in the microstructure of service-exposed vanes. The microstructural changes during service lead to a loss in room temperature ductility as well as in creep properties of the alloy. © 2014 Elsevier Ltd.

Asnaghi A.,Niroo Research Institute | Ladjevardi S.M.,Niroo Research Institute
Renewable and Sustainable Energy Reviews | Year: 2012

A solar chimney power plant (SCPP) is proposed to be built as the first national SCPP in central regions of Iran. Studies of DLR MED-CSP project show that Iran can be a part of the Mediterranean solar power generation chain in 2050 to provide electrical power demand of Europe. High direct solar radiation and available desert lands in Iran are factors to encourage the full development of solar power plants like solar chimney power plants for the thermal and electrical productions of energy for various uses. The interested region is the central region of Iran where solar radiation and global insolation are much better than other areas. However, to evaluate SCPP performance and power generation throughout Iran, 12 different areas across the country are considered. The obtained results clear that solar chimney power plants can produce from 10 to 28 MWh/month of electrical power. This power production is sufficient for the needs of the isolated areas and can even used to feed the grid. © 2012 Elsevier Ltd. All rights reserved.

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