Sharif Digital Repository

An analog circuit for maximum power point tracking of a PV battery charger with minimum number of elements is proposed which works in a full range condition with a fixed switching frequency. In conventional MPPT algorithms which provide PV current or voltage reference value as output, fast climate changes may cause system instability. Here, a new variable is defined to eliminate the problem and improve the stability of the system. In order to compare the presented circuit with a conventional system, perturb and observe (P&O) MPPT algorithm which is well-known in PV systems is implemented on the same system. Simulation results (Conventional P&O algorithm and proposed structure) are presented... 

This paper proposes a new methodology to find the most economic system configuration and energy management strategy for Li-ion battery based off-grid renewable energy systems. A system level macroscopic model and a microscopic battery lifetime prediction model are incorporated into the optimization framework to simulate hourly performance of the system. Due to the computational efficiency of the model, optimization is carried out using enumerative method (evaluating all the possible combinations of components and control strategies) to ensure finding the global optimum solution of the problem. To investigate the effectiveness of the proposed methodology, the optimization results are compared... 

The current paper reports the deposition of sulfur micro-particles using sulfur vapor deposition (SVD). Sulfur particles in size of 5 to 45 μm were deposited on a stainless steel substrate to be used as the cathode with porous structure in lithium sulfur (Li-S) batteries. Mass loading of about 0.5 mg cm-2 was obtained from this pure sulfur cathode. The structure of this binder-free cathode was characterized by field emission scanning electron microscopy (FESEM), x-ray spectroscopy (EDS), and x-ray diffraction (XRD). The electrochemical performance of the battery with two different organic liquid ether- and carbonate-based electrolytes was investigated and the results demonstrated that the... 

Energy infrastructures are perceived continuously vulnerable to a range of high-impact low-probability (HILP) incidents - e.g., earthquakes, tsunamis, floods, windstorms, etc. - the resilience to which is highly on demand. Specifically suited to battery energy storage system (BESS) solutions, this paper presents a new resilience-driven framework for hardening power distribution systems against earthquakes. The concept of fragility curve is applied to characterize an earthquake hazard, assess its impact on power distribution systems, and estimate the unavailability of the network elements when exposed to extreme earthquakes. A new metric is defined to quantify the network resilience taking... 

In Li-ion batteries the interface between the nano-size spherical core graphite and its surrounding solid electrolyte interphase (SEI) layer, just inside SEI is susceptible to damage. Thus, accurate determination of the associated elastic fields is one of the challenges in optimizing the lifetime and capacity of Li-ion batteries. The required precision is achieved by considering the core graphite which belongs to the crystal class D6h as homogeneous spherically isotropic and SEI layer as functionally graded (FG) isotropic material. Moreover, to account for the surface/interface effects appropriately the core-shell nano-structure subjected to the diffusion-induced time-dependent nonuniform... 

Nickel-zinc batteries as safe and economic energy storage devices suffer from lack of high electrochemical performance of cathode materials. Herein, a new cathode material for rechargeable Ni/Zn batteries is introduced based on various compositions of mixed metal oxide (MMO) through a calcination process of nickel-vanadium layered double hydroxide at different temperatures. The results demonstrated that the prepared sample at 500 °C presents the best electrochemical properties such as a good electrochemical discharge capacity (278.4 mAh g-1 at 0.5 A g-1), good cycle life (capacity retention of 74% after 1000 cycles at 5 A g-1), and excellent rate capability (177 mAh g-1 at 5 A g-1). These... 

Designing transactive energy (TE) markets in distribution systems has been a hot topic due to the increased presence of residential prosumers. In the literature, several residential market platforms have been proposed; however, they usually have two main drawbacks: 1) ignoring the effect of single-phase distributed energy resources on the voltage unbalance (VU) in active distribution networks to develop a transactive coordination model that will effectively mitigate the VU and 2) inability in providing a user-friendly strategy for home occupants to adjust the willingness to pay/accept of responsive assets according to their comfort and economic purposes. This article amends the shortcomings... 

Choosing the appropriate ion exchange membrane in vanadium redox flow batteries plays an important role in achieving optimal system performance. In this article, the implementation of commercial cation exchange membranes (Nafion 115, Nafion 117, and Nafion 212), anion exchange membranes (FAP 450 and QA-PFE), and the combination of them are investigated. In this regard, the effects of membrane type, thickness, electrical conductivity, and the transfer of vanadium species at different current densities are examined carefully. In addition, the influences of the flow rate and the concentration of electrolytes are investigated using a comprehensive developed model. The model predictions are... 

This study has investigated the effect of carbon coating on the electrochemical performance of SnO2 Nanowires (NWs) as an electrode along with a bis (trifluoromethane) sulfonimide lithium (LiTFSI)-based electrolyte in a lithium-ion battery (LIB). The vapor-liquid-solid approach has been used to grow SnO2 NWs on the stainless steel mesh current collector. The obtained results have demonstrated that the utilization of the LiTFSI-based electrolyte improved the battery performance with the SnO2 NWs electrode over the LiPF6-based electrolyte. This may be due to the formation of a stable and thin solid electrolyte interphase layer. Since bare SnO2 NWs exhibit inferior cycling stability due to... 

Massive amounts of spent lead-acid battery separators with 50 wt % silica nanoparticles (SiNPs) can be recycled for further use. One compelling application is form-stable phase change materials (FSPCMs). This study proposes a novel tertiary eutectic mixture of green and non-toxic lauric acid, palmitic acid, and paraffin, and recycled SiNPs to find a sustainable approach to deal with industrial wastes and energy consumption. Fatty acids and paraffin are promising for thermal energy storage in buildings. However, they lack sufficient thermal conductivity, mechanical strength, and suffer from leakage. To give mechanical strength, high-density polyethylene (HDPE) was added and sintered.... 

In a wirelessly-powered communication network (WPCN), an energy access point (E-AP) supplies the energy needs of the network nodes through radio frequency wave transmission, and the nodes store their received energy in their batteries for possible data transmission. In this paper, we propose an online control policy for energy transfer from the E-AP to the wireless nodes and for data transfer among the nodes. With our proposed control policy, all data queues of the nodes are stable, while the average energy consumption of the network is shown to be within a bounded gap of the minimum energy required for stabilizing the network. Our proposed policy is designed using a quadratic Lyapunov... 

This manuscript describes the implementation of plasma-enhanced chemical vapor deposition (DC-PECVD) and vapor-liquid-solid (VLS) techniques to fabricate a yolk-shell SnO2@Void@C nanowire (NW) structure. SnO2 nanowires have been synthesized on the stainless steel mesh substrate through the VLS method. The PECVD-assisted growth of carbon nanolayer on the SnO2 and SiO2 coated SnO2 NWs has been performed to fabricate SnO2@C core-shell and SnO2@SiO2@C yolk-shell structures, respectively. A consequent silica etching process converted the SnO2@SiO2@C into SnO2@Void@C structure. The electrochemical performance of bare SnO2 NWs, SnO2 NWs @ C, and SnO2 @Void @ C coaxial NWs structures have been... 

This paper proposes a new energy management model for residential buildings to handle the uncertainties of demand and on-site PV generation. For this purpose, the building energy management system (BEMS) organizes a transactive energy (TE) market among plug-in electric vehicles (PEVs) to determine their charge/discharge scheduling. According to the proposed TE framework, the PEV owners get reimbursed by the BEMS for the flexibility they offer. In this regard, the PEV owners submit their response curves for reimbursement upon arrival. Then, the BEMS solves an optimization problem to maximize its own profit and determine the real-time TE market-clearing price. Afterward, based on the clearing...