Sharif Digital Repository

Isolated microgrids depend mainly on diesel generation and have polluting transportation. This is being addressed by the introduction of renewable energy resources and electric vehicles (EVs). Hence, this paper presents a novel long-term planning model for the introduction of EVs in isolated microgrids. This work studies the replacement of internal combustion vehicles with electric ones by analyzing their respective investment, maintenance and operation costs. Various case studies are discussed, considering different EV and solar photovoltaic (PV) penetration levels, and varying prices of diesel in the planning horizon. Results demonstrate that investing in EVs could significantly reduce net... 

Employing more flexibility in power systems is one of the main challenges brought about by integrating more renewable energy sources in power systems. A promising way to overcome this challenge is to have local sources of flexibility in distribution level. In this respect, a novel approach is introduced in this paper for multi-stage distribution system expansion planning which jointly considers expansion of the network assets as well as flexibility enhancement. To this end, construction and reinforcement of feeders and substations are considered as various alternatives for network expansion. Moreover, installation of conventional dispatchable distributed generation units is selected as the... 

Technical virtual power plant (TVPP) plays an important role in modern power systems by coordinating distributed energy resources (DERs) to participate in wholesale electricity market. This paper presents a framework for TVPP's energy management in an active distribution system with diverse uncertain DERs. The TVPP participates in wholesale day-ahead (DA) market and schedules DERs in order to maximize its profit, while considers actual locations of DERs in the network and takes network operational constraints into account. Many diverse DERs including DGs, renewable energy sources (RESs), and several load sectors comprising EVs, heating, ventilation, and air conditioning (HVAC) systems and... 

Purpose: Microgrids are inclined to use renewable energy resources within the availability limits. In conventional studies, energy interchange among microgrids was not considered because of one-directional power flows. Hence, this paper aims to study the optimal day-ahead energy scheduling of a centralized networked multi-carrier microgrid (NMCMG). The energy scheduling faces new challenges by inclusion of responsive loads, integration of renewable sources (wind and solar) and interaction of multi-carrier microgrids (MCMGs). Design/methodology/approach: The optimization model is formulated as a mixed integer nonlinear programing and is solved using GAMS software. Numerical simulations are... 

Stand-alone hybrid power systems are an alternative to main electricity grids, where the grid extension is costly or the trifling local consumption would not justify its expansion. However, lack of consistency and uniformity in renewable energy sources, and the restrictions of energy storage systems make system sizing a challenging task. Optimum size of a stand-alone system depends on several factors including energy demand function. In this paper, different types of demand functions are addressed for optimising a solar-hydrogen supply system. Different parameters are defined to investigate the impact of household population on the power generation cost, and also to determine the optimum... 

Stand-alone hybrid power systems are an alternative to main electricity grids, where the grid extension is costly or the trifling local consumption would not justify its expansion. However, lack of consistency and uniformity in renewable energy sources, and the restrictions of energy storage systems make system sizing a challenging task. Optimum size of a stand-alone system depends on several factors including energy demand function. In this paper, different types of demand functions are addressed for optimising a solar-hydrogen supply system. Different parameters are defined to investigate the impact of household population on the power generation cost, and also to determine the optimum... 

In recent years, there has been a rapid change in the portfolio of road vehicles. This transformation needs to be supported by reshaping fuel stations. The existing structures can be modified to supply multiple vehicle types while utilizing renewable energies. In this article, we introduce a hybrid fuel station (HFS) to supply both electric and natural gas vehicles. We incorporate an energy hub and thoroughly explain the structure and components in detail. The configuration of the proposed HFS includes renewable energy sources (RESs), a power-to-gas unit (P2G), a natural gas distributed generator (NGDG), an energy storage device, a compressor, and a gas storage device. The optimal operation... 

Installation of renewable energy sources (RESs) in power systems has been dramatically increased due to clean nature and declining investment costs in recent years. This growing trend has led to new issues in the system operational management such as intense ramps inflicted on the network called system flexibility constraints. In this regard, due to decreasing the investment in bulk flexible resources, utilities would be significantly rely on local flexible ramp resources in the system to meet the supply-demand gap in each time-period. However, development of independently operated microgrids (MGs) as a result of restructuring and privatization in the power systems has imposed limitations... 

Anaerobic fermentation of crop straw/animal dug can be the most appropriate solution for biomass conversion into applicable renewable energy-based fuels. However, due to the imperfection matching between the biogas combustion process and energy conversion system, a painstakingly design procedure is required to devise high-efficient energy system for capturing biogas efficiently. For this aim, a new trigeneration system driven by biogas is devised for electricity, refrigeration, and potable freshwater generation. The devised system encompasses a gas turbine (GT) cycle, a new cooling/electricity cogeneration system based on organic Rankine cycle (ORC) and ejector cooling cycle (ECC), and a... 

Energy harvesting systems powered by renewable energy sources employ hybrid volatile-nonvolatile memory to enhance energy efficiency and forward progress. These systems have unreliable power sources and energy buffers with limited capacity, so they complete long-running applications across multiple power outages. However, a power outage might cause data inconsistency, because the data in nonvolatile memories are persistent, while the data in volatile memories are unsteady. State of the art studies proposed various memory architectures and compiler-based techniques to tackle the data inconsistency in these systems. These approaches impose too many unnecessary check-points on the system to... 

Future of the network stability is endangered by increasing the number of Distributed Generation (DG) and Renewable Energy Source (RES) units. The idea of the Virtual Synchronous Machine (VSM) has been raised to control the power electronic-based DG/RES converters in order to have better integration with the grid. This paper introduces a new stabilizer design for VSM-based converters to guarantee the stability of the micro-grid (MG). In this regard, the Sliding Mode Control (SMC) theory, which is robust against the disturbances and uncertainties, is employed to cope with the intermittent and nonlinear nature of DGs. The mutual operation of the proposed inverter and MG stabilizer has the... 

Owing to the development of smart grids technologies, including renewable energy resources and integrated demand response, the traditional distribution network undergoes systemic improvements and has become an active system. To meet such changes in technology, the smart distribution grid is highly dependent on communication infrastructures. Although this strong reliance can make the distribution network susceptible to cyber threats, there has been inadequate attention to the distribution network cyber-security. An intruder can disrupt communication and effectively target the distribution management system core functions, leaving the distribution grid susceptible to loss of stability... 

The rapid rise in the grid integration of low-carbon technologies, e.g. renewable energy sources (RESs) and plug-in electric vehicles (PEVs), has led to several challenges in distribution networks (DNs). This is due to the intermittent generation of RESs and uncertain loads of PEVs, both of which necessitate enhancing the flexibility requirements at the distribution level so as to accommodate the high penetration of these clean technologies in the future. To address such issues, this study proposes a mixed-integer linear programming-based expansion planning model for DNs considering the impact of high RES and PEV penetration, the associated uncertainties, and providing flexibility... 

Increasing grid integration of intermittent renewable energy sources (RESs) and plug-in electric vehicles (PEVs) with uncertain behaviours have necessitated enhancing the flexibility requirements of distribution networks. Thus, in the state-of-The-Art distribution network expansion planning (DNEP) models, both flexibility requirements and high penetration of RESs and PEVs should be taken into consideration. In this respect, a novel collaborative planning model for power distribution network (PDN) and plug-in Electric Vehicle Parking Lots (EVPLs) is proposed in this paper, which leverages sizing, siting, and operation of EVPLs to enhance the distribution network flexibility. Also, to model... 

Increasing penetration of renewable energy sources with intermittent generation calls for further flexibility requirements for efficient as well as the safe operation of power systems. Considering the significant growth of distributed energy resources in distribution systems, a promising approach to fulfill such requirements is to deploy local flexibility sources at the distribution level. Nonetheless, due to the monopoly nature of electricity distribution business, effective regulations are required to direct distribution companies toward fulfilling such goals. Accordingly, this paper aims at proposing various policies to motivate distribution companies to enhance the flexibility of their... 

In this paper, the problem of frequency-constrained electricity market (FCEM) is modeled in the presence of renewable energy sources (RESs) and price-maker players by using equilibrium problem with equilibrium constraints formulation. It is worth mentioning that due to the intermittency of RESs, the FCEM problem in the presence of price-maker players becomes more imperative as stability of power system frequency is a public good and the free-rider problem arises. Moreover, as players of FCEM do not know their rivals' objective functions, the problem is modeled based on Bayesian game theory. The FCEM problem is converted into a game of complete but imperfect information under the common prior... 

The objective of the present study is the development of an optimization model for identifying the best configuration of renewable-based integrated energy systems. The system includes a combination of renewable energy systems such as wind, solar, hydropower and hydrogen production, storage facilities and conventional fossil-fuel generators. The developed tool consists of various modules where water heating assumes the utilization of waste energy as an option. Furthermore, the application, which is demonstrated for a case study in Tehran, has been considered. The power exchange with the distribution network and injection of hydrogen produced from excess renewable sources into gas network are... 

Nowadays, the high penetration of renewable energy resources, with variable and unpredictable nature, poses major challenges to operation and planning studies of power systems. Employing energy storage systems (ESSs) has been introduced as an effective solution to alleviate these challenges. Several studies have been presented in the literature to provide a framework for expansion planning studies of ESSs. However, they usually have two main drawbacks: i) ignoring the positive effect of independent-locally operated ESSs on the bulk power system preferences, ii) inability to model the charge/discharge schedule of independent-locally operated ESSs based on their investors' acceptable risk... 

The global demand for renewable energy sources has arisen significant research interests in marine hydrokinetic energy harvesting from flow induced vibrations. The current study deals with the hydrokinetic energy harvesting potentials of diamond and square oscillators at various inline configurations. Both the sharp edge sections and the wake induced vibrations in tandem arrangement can lead to galloping type of instability with high energy efficiency ratios. The present in-water towing tank experiments comprise 1DoF vibrating systems at Re ranging from 2 × 103 to 4.8 × 104. The results show that the upstream wake generally enhances the system efficiency and the mechanical work done by the... 

In this paper a strategic planning framework for selecting the best configuration and capacity of different power generating technologies including renewable energy resources in stand-alone micro-power systems is proposed. The proposed framework is composed of three decision making techniques to identify the most feasible and efficient plans according to attributes and uncertain parameters in the planning environment. The framework considers the robustness and risk analysis of different plans exposed to uncertainties in the planning environment and selects the configurations that meet the objectives with the least risk exposure. The proposed methodology is implemented as a case study of a...