Sharif Digital Repository

Nowadays, the increasing integration of variable renewable energies (VREs) in power systems have resulted in operational transformations of energy systems. Respectively, the high-amount of integrated VREs could cause severe-ramping in the net-load of energy systems due to abrupt changes in their power production. Accordingly, based on the limited flexibility capacity in transmission systems, severe ramping-up/down (RU/RD) in distribution systems should be addressed by employing local flexible resources (LFRs). Nevertheless, evolution of multi-agent structured distribution systems has limited the direct access of distribution system operators (DSOs) in scheduling of LFRs. Consequently, this... 

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... 

The energy system is one of the major sub-sectors of the economy in every society in which both supply with high reliability and compatibility of the energy sector with the environment is a necessity in the process of economic reconstruction and sustainable development. The energy system has been more susceptible to various disruptive events in recent years. Thus, designing a resilient energy system capable of resisting and recovering rapidly from high-impact low-probability (HILP) disruptive events is essential. This paper focuses on developing a two-stage long-term optimization framework for evaluating the energy system resilience as a crucial Critical Infrastructure (CI) system against... 

The hybrid power system is a combination of renewable energy power plants and conventional energy power plants. This integration causes power quality issues including poor settling times and higher transient contents. The main issue of such interconnection is the frequency variations caused in the hybrid power system. Load Frequency Controller (LFC) design ensures the reliable and efficient operation of the power system. The main function of LFC is to maintain the system frequency within safe limits, hence keeping power at a specific range. An LFC should be supported with modern and intelligent control structures for providing the adequate power to the system. This paper presents a... 

The optimal energy consumption and production is one of main aims in the many countries to improve technical, economic and environmental issues by smart energy systems. This paper proposes a bi-stage multi-objectives optimization of the smart multi energy system with optimal coordination of active consumers than electrical and thermal prices in the day-ahead market. The optimization is implemented under uncertainty of demand and price for electrical and thermal energies. In the first stage, original electrical and thermal demand curves are optimized using demand shifting strategy based on energy prices. Then, optimized electrical and thermal demand curves are applied in the second stage for... 

Optimal planning of residential complex energy systems requires thorough mathematical modelling to address the interconnections between all the energy installations from the largest ones, shared by all the residents, to the smallest ones in each distinct unit. Besides, conflicting desires of investors and residents in various aspects such as reliability index make this problem more challenging. In response, this paper presents a thorough framework to obtain the optimum design and operation of a residential complex energy system from scratch. To address the appropriate interconnection between various components of such an energy system, a multi-layer energy hub structure is proposed. Besides,... 

The use of hybrid renewable energy has increased in recent years due to the growing environmental concerns caused by the consumption of fossil fuels. The purpose of this study was the economic-environmental feasibility of using hybrid energy systems in one of the most polluted and populated provinces in Iran, Isfahan province. Various components of the hybrid energy system such as wind turbine (WT), photovoltaic panel (PV), diesel generator (DG), converter (CV) along with two scenarios of energy storage including battery (BT) and hydrogen storage have been considered in modeling the energy system. Six scenarios were considered based on the combination of different components for supplying... 

Renewable energy (RE) as a new player in the generation sector of power systems imposes new challenges to the system operators. The intermittent nature of REs for systems where are autonomous calls for new operational and planning strategies to reach more efficient power management. An autonomous hybrid green power system (HGPS) should be able to meet the load while keeping the cost of the HGPS as low as possible. Many studies have presented different un-optimal and optimal operational strategies, a few of which were optimally sized. In this regard, this paper develops a new thorough framework for designing and optimizing an autonomous HGPS. To reach this goal, the proposed model (a)... 

This study aims to investigate the hydrogen production process using an integrated system based on solar energy. This system includes an evacuated tube collector to absorb solar energy as input energy of the system. A parametric analysis was conducted to determine the most important design parameters and evaluate these parameters' impact on the system's objective functions. For identifying the optimum system conditions, multi-objective optimization was performed using particle swarm optimization (PSO) algorithm. The results obtained from the parametric analysis show that an increment in the collector mass flow rate and the turbine inlet temperature, as well as a decrement in the collector... 

A cost-effective, durable, and easy-to-produce improvement in bifunctional electrocatalysts for water splitting is crucial for future renewable energy systems. In this present study, shape-controlled one-dimensional (1D) phosphorized cobalt (CoP) on 3D porous nickel foam (NiF) was synthesized through successive treatment of commercial NiF with acetone and ethanol, followed by hydrothermal growth of Co and final process of phosphorization by thermochemical reactions. The evaluations of products proved reduced overpotential (270 mV at 10 mA. cm−2 for hydrogen evolution reaction (HER) process and a low overpotential of 320 mV to reach a high current density of 20 mA. cm−2), low Tafel slope... 

In recent years, increased integration of renewable energy sources (RES) calls for extensive and costly investments in transmission networks. In response, power system decision-makers try to apply alternative solutions aimed to decrease the imposed investment costs. In this context, the presence of large-scale energy storage systems (ESSs) in transmission network can be a practical option for deferring investment in expansion plans of transmission lines, alleviating system congestions, and attaining higher flexibility. In this paper, an efficient model is proposed for co-planning expansion studies of compressed air energy storage (CAES) units and transmission networks. The associated... 

Utilization of heat storage units in solar energy systems can resolve the challenge of fluctuation and uncertainty of the solar energy. Phase change materials (PCMs) are used as the storage media for solar energy storage systems. In this research, a system including of a solar collector and a PCM-based cascaded energy storage unit was numerically investigated. Air was used as the heat transfer fluid (HTF) and three paraffin-based materials (RT50, RT65, and RT80) were used as PCM for the energy storage unit. The investigated system mainly operates between 15 °C and 90 °C and considering different PCMs, the selected PCMs were appropriate. Paraffin-based PCMs also present acceptable thermal... 

Thermal power generation needs great volumes of water for cooling purposes. A multi-period Low Water Generation Expansion Planning (LW-GEP) model is proposed to plan the future generation mix including type, capacity, time of installation, and proper cooling system of generation technologies to supply the future electric peak loads under the water resource limitations. Different types of generation technologies with conventional and modern cooling systems are considered as expansion candidates in the proposed LW-GEP model. The access of candidate and existing power plants to the water resources are considered. Renewable resources as water smart solutions are integrated in the proposed energy... 

Presence of microgrids (MGs) and renewable energy sources (RESs) in distribution power systems could result in dramatic changes in operation and planning of these systems. In this regard, operational procedures employed by utilities should take into account the intermittent nature of RESs, while coping with the independent operation of MGs. In this perspective, this paper develops a distributed power management framework based on alternating direction method of multipliers (ADMM) for distribution networks with multi-MG (MMG) structures. The proposed approach develops a transactive signal in the context of ADMM to coordinate operation of MGs in a distributed manner. In this context, the... 

An integrated view of energy markets has led to the introduction of new market participants named energy retailers (ERs). Competition among ERs in an integrated market greatly improves market performance in areas such as sustainability, supply security, and environmental awareness. ER performance is evaluated in an integrated market with emission penalty reduction in the objective function. Bi-level programming is used to model an ER game, and the equilibria of different configurations are compared. In the game's first level, ERs offer various energy carrier selling prices to optimise profits. In the second level, consumers respond by switching from the retail market to minimise their energy... 

Energy is one of the most important social and economic infrastructures and human life is strongly depends on it. In recent years, the occurrence of natural disasters such as drought as a high-impact low-probability event is undeniable. So, energy planning in the disruption situation is necessary in order to anticipate and maintain the performance of the energy system in optimal condition. This paper focuses on developing a hybrid long-term framework for evaluating the energy system resilience based on sustainability concept against drought. The model bridges the gap between long-term energy system planning in macro level and short-term switching operations or micro level modeling approach... 

The rise of the damage to energy systems caused by both natural and man-made disruptive events and the connection between energy systems and socio-economic systems have motivated the study of energy system resilience. This paper conceptualizes and comprehensively presents a systematic review of the recent literature focused on the analytical, technical, and mathematical points from the standpoint of the energy systems facing disruptive events. To this end, five phases are developed. Firstly, the concept of the energy system resilience is presented, and then the energy resilience characters and the resilience states are introduced and connected. Thirdly, the formulation and indicators of the... 

In recent years, the need to reduce environmental impacts and increase flexibility in the energy sector has led to increased penetration of renewable energy sources and the shift from concentrated to decentralized generation. A fuel cell is an instrument that produces electricity by chemical reaction. Fuel cells are a promising technology for ultimate energy conversion and energy generation. We see that this system is integrated, where we find that the wind and photovoltaic energy system is complementary between them, because not all days are sunny, windy, or night, so we see that this system has higher reliability to provide continuous generation. At low load hours, PV and electrolysis... 

Energy is one of the most important social and economic infrastructures and human life is strongly depends on it. In recent years, the occurrence of natural disasters such as drought as a high-impact low-probability event is undeniable. So, energy planning in the disruption situation is necessary in order to anticipate and maintain the performance of the energy system in optimal condition. This paper focuses on developing a hybrid long-term framework for evaluating the energy system resilience based on sustainability concept against drought. The model bridges the gap between long-term energy system planning in macro level and short-term switching operations or micro level modeling approach... 

The rise of the damage to energy systems caused by both natural and man-made disruptive events and the connection between energy systems and socio-economic systems have motivated the study of energy system resilience. This paper conceptualizes and comprehensively presents a systematic review of the recent literature focused on the analytical, technical, and mathematical points from the standpoint of the energy systems facing disruptive events. To this end, five phases are developed. Firstly, the concept of the energy system resilience is presented, and then the energy resilience characters and the resilience states are introduced and connected. Thirdly, the formulation and indicators of the...