Sharif Digital Repository

Given the high rate of energy dissipation in electric urban rail lines, methods of saving energy in these systems have become a topic of interest. The use of energy saving equipment to save the energy wasted in braking (Because of the diode rectifier, thermal energy is usually wasted and is not reversible) can play an important role in reducing the energy loss. The role of energy storage equipment, from other aspects such as voltage regulation and increasing the system reliability is also remarkable. In this thesis, the various possible methods for saving energy in the Metro system are expressed.
The various types of storage devices with increased reuse of braking energy which is the... 

Nowdays, distributed generation (DG) systems based on renewable energy sources have significantly increased around the world as an alternative solution to enhance the power quality and reliability and reduce the need for extensive transmission system as well. An evolved recent concept called microgrid is developed by grouping a cluster of loads and DG units in a common local area which increases the integaration of sustainable energy generation systems. This thesis presents control of a medium voltage (MV) microgrid considering multi-hybrid distributed generation systems (MHGS) and renewable energy resources in island mode. The first part is focused on the development a control strategy for... 

In the first part, we report a new and simple procedure for preparing reduced graphene oxide /nickel, cobalt hydroxide composite (Ni,Co-OH/rGO/NF via a fast and simple two-step electrochemical method including potentiostatic routes in the presence of Cetyl trimethyl ammonium bromide )CTAB( as a cationic surfactant. In the first step, a piece of nickel foam (NF) is sonicated in a suspension of graphene oxide (GO, 6 mg/L) after dried in an oven, reduced by electrochemically. After that, Ni, Co LDH were co-deposited on the surface of rGO/NF. The resulting modified electrode afforded extremely high specific capacitance of 2133.3 F/g at a current density of 4 A g-1. FE-SEM results showed that... 

Recently, Supercapacitors, as one of the most important energy storage devices, have attracted attensions by the scientists. Supercapcitor devices with appoporate design can store energy by two different mechanisms: i) physical (like conventional capacitors, i.e. by using polarization of the electrolyte, and ii) formation of electric double layer) and chemical mechanisms (like batteries, with reversible faradic reactions). These energy storage mechanisms allow these devices not only store high energy density but also they can provide high power density. In this project, two Co3O4/Co(OH)2 and Co3O4@Sponge-like rGO electrodes are made with chemical and electrochemical methods. To characterize... 

Supercapacitors are one of the most important energy storage devices that have been researched with respect to the development of hybrid cars. Polymer composites have received much attention due to the electrochemical properties of conductive polymers and the synergistic effects of the composite components. In the present Thesis, in order to investigate the synergistic effect of gold nanoparticles with MnO2 nanorods as a metal oxide and polyaniline as a conductive polymer and graphene as a carbon material, two groups of composites were synthesized in the presence and absence of graphene. Characterization of the electrode material is carried out by XRD, FT-IR and FE-SEM tests. The... 

Titanium carbide MXene (Ti_3 C_2 T_x) has attracted significant research interest because of its extraordinary advantages as advanced electrode material for energy storage. In this study, 4-aminodiphenylamine functionalized Ti_3 C_2 T_x/polyaniline composite synthesized by in situ growth of PANI on 4-aminodiphenylamine functionalized Ti_3 C_2 T_x nanosheets. First, Ti_3 C_2 T_x MXene nanosheets was prepared according to the minimally intensive layer delamination (MILD) method followed by sonication. Ti_3 C_2 T_x nanosheets were modified with 4-aminodiphenylamine diazonium salt. The FTIR، FE-SEM and EDS analysis were used to characterize modified Ti_3 C_2 T_x. Finally, the Ti_3 C_2 T_x... 

High-capacity electrode materials are crucial for enhancing the performance of supercapacitors. Transition metal sulfides are considered promising materials for supercapacitor applications due to their high theoretical capacity and good electrical conductivity. Additionally, cerium oxide improves the performance of supercapacitors due to stable reversible oxidation states and greatly supported the faradaic redox reaction. In this study, ceria nanosheets incorporated with MCoS (M=Mn, Zn, Cu) were synthesized successfully through a facile hydrothermal method by sulfidation of MCo LDH/CeO2. The structural and morphological characteristics were analyzed using X-ray diffraction, scanning electron...