Sharif Digital Repository

The problem of this paper deals with the multi-mode project scheduling problem under uncertainty of activity duration where only the renewable resources are taken into account and a given deadline has to be met at the cost of recruiting additional resources. A heuristic algorithm is employed to solve this problem, and to maintain the robustness of the baseline schedule, the concept of critical chain project management (CCPM) is applied in which a new definition to resource buffer is considered. A simulation methodology is used to determine the size and location of resource buffers in the schedules in which three different buffer sizes and three different uncertainty levels are considered.... 

This paper formulates flow of energy from primary resources and import routes to different socio-economic sectors by making use of Long-Range Energy Alternatives Planning (LEAP) model. It presents a baseline of how Iran’s future production and consumption patterns evolve. It also seeks plausible scenario for renewable energies utilization and evaluates its mitigation potential and economic aspects. Model results indicate that exploitation of a "not-too-strict" package of renewable sources featuring 10 GW of wind and 19 GW of hydro by the end of 2035 will lead to CO2 emissions to be reduced up to an amount of 190.7 million tons in the study period. By accounting for the opportunity costs... 

In this paper, a new approach to formulate a class of scheduling problems is introduced, which can be applied to many other discrete problems with complicated structures. The concept of graph circular coloring is applied to develop a model for the special case of an open shop scheduling problem. In this problem, there are some independent jobs to be processed in a shop with dedicated renewable resources. Each job consists of several tasks with no precedence restriction. Each task is processed without preemption. The processing time of the tasks is given. Processing each task requires using some multiple specified types of resource, while no more than one task can use each resource,... 

Observing the growing energy demand of modern societies, many countries have rec-ognized energy security as a looming problem and renewable energies as a solution to this issue. Renewable hydrogen production is an excellent method for the storage and transfer of energy generated by intermittent renewable sources such as wind and solar so that they can be used at a place and time of our choosing. In this study, the suitability of 15 cities in Fars province, Iran, for renewable hydrogen production was investigated and compared by the use of multiple multi-criteria decision-making methods including ARAS, SAW, CODAS, and TOPSIS. The obtained rankings were aggregated by rank averaging, Borda... 

With high growth rate of demand for energy in different societies, the need for energy resources has been increased significantly. This has resulted in introduction of new energy resources, i. e. renewable energy resources in generation sector of energy systems. However, the intrinsic features of these energy resources call for higher flexibility in different sectors of energy systems. Flexibility in a comprehensive sense tries to cover the amount of imbalance between production and demand in energy systems. This paper has attempted to introduce the concept of operational flexibility in microgrids and it also has presented a step-by-step algorithm to assess this operational index based on a... 

The reliable design, planning, and operation of power systems are of paramount importance for providing reliable services to customers. This article reviews the different aspects of power system reliability, ranging from planning to operation. Standard benchmarks employed for power system studies are reviewed according to nearly 2,500 IEEE journal papers from 1986 to early 2019. Our overview provides the pros and cons of existing test systems, implying the lack of appropriate benchmarks for future power system studies, including renewable resources and modern technologies. Furthermore, this article presents requirements for updating and modifying the benchmarks for modern power systems... 

Voltage source converter based multi - terminal DC grids (VSC - MTDC) are widely used for integration of renewable resources. Control of these grids requires vector control method, which includes inner and outer current controllers, tuning of these controllers is very important. Conventionally used tuning methods consider approximated linear model to tune the proportional - integral (PI) parameters of voltage source converter (VSC) which fails to produce optimum disturbance rejection results. In this research an Ant Colony Optimization (ACO) technique is used to get the optimum parameters of inner and outer power control layers for multi - terminal DC system. ACO is applied simultaneously on... 

Voltage source converter based multi - terminal DC grids (VSC - MTDC) are widely used for integration of renewable resources. Control of these grids requires vector control method, which includes inner and outer current controllers, tuning of these controllers is very important. Conventionally used tuning methods consider approximated linear model to tune the proportional - integral (PI) parameters of voltage source converter (VSC) which fails to produce optimum disturbance rejection results. In this research an Ant Colony Optimization (ACO) technique is used to get the optimum parameters of inner and outer power control layers for multi - terminal DC system. ACO is applied simultaneously on... 

Proliferation of renewable energy resources in distribution networks has captured distribution companies' attention towards more active management tools. Thanks to the smart grid paradigm, hourly network reconfiguration, which is still among immature ideas, can bring the activeness required to handle fluctuating output of renewable resources. The aim of this study is to analyze the worthiness of the hourly reconfiguration in the presence of renewable energy resources. For doing so, a mathematical model is devised to minimize daily network losses via applying hourly reconfigurations. The model is a mixed integer second-order cone programming problem and is solved via MOSEK solver. The... 

The present work investigated the outdoor performance of a basin type multi-stage solar still as well as the effect of collector over basin area (CBA) ratio on the distillate production. The effect of CBA was studied in outdoor experiments for the first time. The system consisted of a still coupled with one, two or three flat-plate solar collectors. In order to study the effect of CBA more accurately, the experiments were conducted in both winter and summer. In these experiments, the distilled water production of the multi-stage still was measured during the whole 24. h of a day on an hourly basis. The results revealed that in the winter, the basin coupled to one solar collector (CBA. =... 

In this paper, a reduced order model for the nonlinear dynamic analysis of the wind turbine blade under operational loading is presented. The accuracy and efficiency of the proposed model are investigated through various static and dynamic analyses. A comprehensive straightforward formulation for the nonlinear beam model is developed based on different large deformation strain theories. Also, the fluid-structure coupling effects due to quasi-steady aerodynamics and gravitational forces are included. The new matrix expressions are introduced for direct conversion of the developed formulation into the reduced order model (ROM). Thereafter, the ROM based on the Galerkin method is developed... 

In this paper, special focus is paid to the long-term adoption of renewable electricity technologies and their implications for emissions reductions in Iran. MESSAGE, as a bottom-up energy supply optimization model, is used to assess the lowest-cost technology options. The potential impacts of transitioning to a renewable electricity supply are quantified, and the investment requirement to achieve a low-carbon generation mix is estimated. Alternative scenarios are defined to evaluate the impact of fossil fuel prices, the carbon tax and government incentives on the utilization of renewable resources, national renewable targets, and emissions reductions. The prioritization of non-hydro... 

Pulsating heat pipes (PHPs) are compact cooling equipment used for various applications. This type of heat pipes can be used in renewable energy systems, cooling electronic devices, heat recovery systems and many other applications. Since PHPs have superior thermal performance, by applying them in energy systems enhance their efficiency. In addition, PHPs are a reliable medium for cooling various devices which have high heat flux. In this study, various works conducted on the applications of PHPs are reviewed and analyzed. It is concluded that PHPs are efficient and reliable devices for utilization in various energy systems. Moreover, at very low temperatures, such as cryogenic applications,... 

Scheduling under nonrenewable resources is one of the challenging issues in project scheduling problems. There are many cases where the projects are subject to some nonrenewable resources. In most of the literature, nonrenewable resources are assumed to be available in full amount at the beginning of the project. However, in practice, it is prevalent that these resources are procured along the project horizon. This paper studies the generalized resource-constrained project scheduling problem (RCPSP) where, in addition to renewable resources, nonrenewable resources are considered, such as budget or consuming materials by the project activities. As the problem is NP-hard, some sub-algorithm... 

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... 

A lot of projects in real life are subject to some kinds of nonrenewable resources that are not exactly similar to the type defined in the project scheduling literature. The difference stems from the fact that, in those projects, contrary to the common assumption in the project scheduling literature, nonrenewable resources are not available in full amount at the beginning of the project, but they are procured along the project horizon. In this paper, we study this different type of nonrenewable resources. To that end, we extend the resource constrained project scheduling problem (RCPSP) by this resource type (RCPSP-NR) and customize four basic branch and bound algorithms of RCPSP for it,... 

Recent advancements in photovoltaic (PV) system technologies have decreased their investment cost and enabled the construction of large PV farms for bulk power generations. The output power of PV farms is affected by both failure of composed components and solar radiation variability. These two factors cause the output power of PV farms be random and different from that of conventional units. Therefore, suitable models and methods should be developed to assess different aspects of PV farms integration into power systems, particularly from the system reliability viewpoint. In this context a reliability model has been developed for PV farms with considering both the uncertainties associated... 

The application of the solar energy in thermal desalination devices is one of the most beneficial applications of the renewable energies. In this study, a novel solar desalination system is introduced, which is benefited from the undeniable advantages of pulsating heat pipe (PHP) as a fast responding, flexible and high performance thermal conducting device. Results show a remarkable increase in the rate of desalinated water production and the maximum production reaches up to 875mL/(m2.h). However, the optimum water depth in basin and the filling ratio of the PHP are measured 1cm and 40%, respectively  

Introduction of large amounts of new wind generation can affect the small signal stability of power systems with three mechanisms: displacing synchronous generators (SGs); reducing SGs power generation; and the dynamics of wind farms (WFs) interacting with the electromechanical mode of SGs. In this paper a novel approach is developed to investigate the impact of the latter mechanism on existing power systems oscillations. In this approach, the dynamic behavior of grid connected WFs is studied independent of the dynamic behavior of system SGs. This approach helps to identify the conditions in which the dynamics of WFs may interact with the electromechanical mode of SGs. Also it helps to... 

The promotion of the adoption of renewable energies in deprived and remote areas can be considered as an important step towards reduction of threats to the loss of biodiversity through community mobilization. One important outcome is mitigation of the deforestation processes through firewood collection. The aim is achievement of sustainable development of the forest biodiversity, awareness raising and the capacity building for execution of similar projects. The social and economical aspects and the obstacles for execution of such project were investigated and guidelines were prepared to facilitate the promotion of renewable energy in similar small communities