Sharif Digital Repository

In this paper, a multi-agent framework is proposed to address the expansion planning problem in a restructured active distribution network. In this framework, the objective and techno-economic constraints of participating agents are addressed in the expansion planning of power network and DER assets as well as the network and DERs optimal operation management. The agents include distributed generator owners and load aggregators which participate along with the distribution network operator (DNO) in the active distribution network planning. The proposed framework is formulated as a bi-level optimization problem with multi-lower levels in which the DNO optimizes the network expansion planning... 

The introduction of cryptocurrencies as a new form of money has attracted a tremendous amount of attention in recent years. This new financial paradigm relies on miners to validate transactions by running their cryptocurrency mining devices (CMDs). Nowadays, the significant profitability of the mining business has tempted a large number of private players in the electrical industry to employ their renewable energy resources to mine digital currency. Here, microgrid (MG) owners may use their excessive generated power to mine digital money instead of exporting it to the main grid. This paper is devoted to investigate the influential potentials of this trending business on distribution networks... 

This paper presents a novel stochastic planning framework for the integration of renewable distributed energy resources (DERs) into existing power systems without relying on new investments in the transmission networks. The upper-level problem of the proposed model aims at minimizing the total expected social cost of supplying demand that includes the expected cost of getting energy from conventional generating units and DERs, the congestion cost of transmission networks, and the greenhouse gas (GHG) emission cost, while each of the privately invested DER satisfies a specified rate of return. The lower-level problem clears the electricity market to find locational marginal prices (LMPs) and... 

This paper presents a new framework for multistage expansion planning in active power distribution networks, in which the distribution system operator (DSO) considers active network management by clearing the local energy market at the distribution level. The proposed model is formulated as a bi-level optimization problem, where the upper level minimizes the net present value of the total costs imposed to DSO associated with the investment and maintenance of the network assets as well as the network operation, while the lower level on clearing the local energy market captures the participation of distributed energy resource (DER) owners and demand aggregators to maximize the social welfare.... 

Hydrogen as an energy carrier can play a significant role in reducing environmental emissions if it is produced from renewable energy resources. This research aims to assess hydrogen production from wind energy considering environmental, economic, and technical aspect for the East Azerbaijan province of Iran. The economic assessment is performed by calculation of payback period, levelized cost of hydrogen, and levelized cost of electricity. Since uncertainty in the power output of wind turbines may affect the payback period, all calculations are performed for four different turbine degradation rates. While it is common in the literature to choose the wind turbine based on a single criterion,... 

This paper presents a new model to maximize the utilization of existing transmission system infrastructure by optimally sizing and siting the future developments of variable renewable energy sources (VRES). The model tries to maximize the integration of VRES in power systems with minimum expected energy curtailment without relying on new investments in the transmission systems. The proposed model is formulated as a linear stochastic programming optimization problem where VRES output scenarios are generated such that their spatio-temporal correlations are maintained. The Progressive Hedging Algorithm (PHA) with bundled scenarios is utilized to solve the proposed model for large-scale cases.... 

The concept of flexibility is defined as the power systems’ ability to effectively respond to changes in power generation and demand profiles to maintain the supply–demand balance. However, the inherent flexibility margins required for successful operation have been recently challenged by the unprecedented arrival of uncertainties, driven by constantly changing demand, failure of conventional units, and the intermittent outputs of renewable energy sources (RES). Tackling these challenges, energy storage systems (ESS) as one important player of the new power grids can enhance the system flexibility. It, therefore, calls for an efficient planning procedure to ensure flexibility margins by... 

Algorithmic trading based on machine learning is a developing and promising field of research. Financial markets have a complex, uncertain, and dynamic nature, making them challenging for trading. Some financial theories, such as the fractal market hypothesis, believe that the markets behave based on the collective psychology of investors who trade with different investment horizons and interpretations of information. Accordingly, a multi-agent deep reinforcement learning framework is proposed in this paper to trade on the collective intelligence of multiple agents, each of which is an expert trader on a specific timeframe. The proposed framework works in a hierarchical structure in which... 

The deployment of flexible ac transmission system (FACTS) devices, despite miscellaneous benefits and applications, has been restricted mainly due to their large investment costs. Accordingly, the notion of distributed FACTS (D-FACTS) was recently proposed. Distributed static series compensators (DSSCs), as a new member of D-FACTS, are directly clamped to conductors of transmission lines. The possibility of controlling the compensation rate of DSSCs from the control center affords the active control of network power flow. This paper presents a comprehensive reliability model for the DSSC. The model is then reduced and a state-space representation is extracted for a transmission line with a... 

The deployment of flexible ac transmission system (FACTS) devices, despite miscellaneous benefits and applications, has been restricted mainly due to their large investment costs. Accordingly, the notion of distributed FACTS (D-FACTS) was recently proposed. Distributed static series compensators (DSSCs), as a new member of D-FACTS, are directly clamped to conductors of transmission lines. The possibility of controlling the compensation rate of DSSCs from the control center affords the active control of network power flow. This paper presents a comprehensive reliability model for the DSSC. The model is then reduced and a state-space representation is extracted for a transmission line with a... 

This paper presents a long-term dynamic multi-objective planning model for distribution network expansion along with distributed energy options. The proposed model optimizes two objectives, namely costs and emissions and determines the optimal schemes of sizing, placement and specially the dynamics (i.e., timing) of investments on distributed generation units and network reinforcements over the planning period. An efficient two-stage heuristic method is proposed to solve the formulated planning problem. The effectiveness of the proposed model is demonstrated by applying it to a distribution network and comparing the simulation results with other methods and models  

Friction stir welding (FSW) parameters, such as tool material, tool geometry, tilt angle, tool rotational speed, welding speed, and axial force play a major role in the weld quality of titanium alloys. Because of excessive erosion, tool material and geometry play the main roles in FSW of titanium alloys. Therefore, in the present work for the first time, tool material and geometry, tool tilt angle, cooling system and shielding gas effects on macrostructure, microstructure, and mechanical properties of pure titanium weld joint were investigated. Result of this research shows that Ti can be joined by the FSW, using a tool with a shoulder made of tungsten (W) and simple pin made of tungsten... 

Direct steam generation (DSG) in parabolic trough collectors causes an increase to competitiveness of solar thermal power plants (STPP) by substitution of oil with direct steam generation that results in lower investment and operating costs. In this study the integrated solar combined cycle system with DSG technology is introduced and techno-economic assessment of this plant is reported compared with two conventional cases. Three considered cases are: an integrated solar combined cycle system with DSG technology (ISCCS-DSG), a solar electric generating system (SEGS), and an integrated solar combined cycle system with HTF (heat transfer fluid) technology (ISCCS-HTF).This study shows that... 

This paper presents a dynamic multi-objective model for distribution network expansion, considering the distributed generations as non-wire solutions. The proposed model simultaneously optimizes two objectives namely, total costs and technical constraint satisfaction by finding the optimal schemes of sizing, placement and specially the dynamics (i.e., timing) of investments on DG units and/or network reinforcements over the planning period. An efficient heuristic search method is proposed to find non-dominated solutions of the formulated problem and a fuzzy satisfying method is used to choose the final solution. The effectiveness of the proposed model and search method are assessed and... 

This paper studies the optimization of micro turbine application to meet the electrical, heating and cooling loads of a building by energy, economics and environmental analysis. In this study following three cases are considered: 1: A simple micro gas turbine to meet the electrical power of the building. 2: A simple micro gas turbine to meet the electrical power of the building as well as the power required by heat pump and mechanical refrigerator needed for heating, cooling and domestic hot water (DHW) systems. 3: A CHP micro gas turbine to meet the electrical power of the building as well as part of the power required by heat pump and mechanical refrigerator needed for heating, cooling and... 

After a brief review of the global gas flaring and venting in oil industries including the emission of air pollutants and greenhouse gases and the amount of energy resources wasted, the focus is on Iran as a major oil producing and the world's third largest gas flaring country. Gas flaring is also practiced in natural gas industries, petroleum refining and petrochemical plants, although the level of emission is very low compared with emissions from oil production. The historical emission of these gases globally and Iran specifically, geographic location of emission sources, composition of gases, environmental impacts of gas flaring and the current and future projects to mitigate emissions... 

Aquifers are underground porous formations containing water. Confined aquifers are surrounded by impermeable layers on top and bottom, called cap rocks and bed rocks. A confined aquifer with a very low groundwater flow velocity was considered to meet the annual cooling and heating energy requirements of a residential building complex in Tehran, Iran. Three different alternatives of Aquifer Thermal Energy Storage (ATES) were employed to meet the heating/cooling demands of the buildings. These alternatives were using ATES for: Cooling alone, heating alone by coupling with at-plate solar collectors, and cooling and heating by coupling with a heat pump. For the economic evaluation of the... 

One of the efficient solar energy harvesting technics is the parabolic trough concentrated solar power plant. However, if the concentrated solar power plant were not equipped with a storage system, the power plant capacity factor would be deficient. Latent thermal energy storage system using phase change material (PCM) is a high energy density storage system to provide durable energy with a constant temperature. In this study, first, a dynamic analysis is performed implementing TRNSYS software on the parabolic trough concentrated solar power plant located in Shiraz, Iran. Consequently, this system is assisted by the latent thermal energy storage system to improve its performance and capacity... 

Ground-coupled ejector cooling (GCEC) systems have been introduced to solve the air-coupled ejector cooling (ACEC) systems problems. To date, no research study is dedicated to compare the GCEC and the ACEC systems and determine the relative payback period of the GCEC system vs. the ACEC system. Furthermore, almost all the previous studies simulated the GCEC systems by elementary models. Therefore, a comprehensive simulation is conducted to assess the techno-economic performance of a GCEC system. The model consists of the ejector and the borehole heat exchanger submodels. The first section of the results compares the ACEC system and the GCEC system during a cooling season. The seasonal... 

In this paper, a systematic investigation and modeling of all available technologies (such as NGL, injection in pipelines, LNG, GTL, NGH, and CNG plants, EOR, electricity production by thermal power plants, and water generation by MED technologies) for flare gas recovery has been developed. An optimal combination of the technologies has been proposed for flare gas recovery of five oil wells in the south of Iran with different specifications as case studies. The optimal combinations of all the technologies have been investigated with minimizing the payback period of capital costs (economical) and maximizing CO2 pollutant reduction (environmental) objective functions by using the genetic...