Sharif Digital Repository

Recently, demand for using variant applications in distributed networks has been increased largely. Most of these applications are based on group communication.In distributed group communication, two important factors need to be considered, group construction, and Group Key Management (GKM). The group construction specifies the process of constructing a new group by cooperation between distributed users. As well, GKM ensures re-freshness of the group key after each join/leave operation. Both of these tasks must be done by collaboration between members. This leads to imposing complexity and communication overhead to the system.This thesis proposes efficient methods for group construction and... 

The purpose of the current study is developing an evaluation model for the electrical grid. Resilience is an approach toward risk management against disorders and protecting the system during critical conditions. The importance of resilience assessment, especially in crucial infrastructures, has always been at the center of attention. Nonetheless, previous studies in this field were mostly limited to micro-scales, meaning that only a limited part of the system was evaluated. Therefore, such studies rely on technical data and system details. This issue renders macro-scale assessments challenging. Some of the models, which are based on analytical-statistical methods, examine the systems at... 

Smart grids are the new generation of power grids that combine the power distribution grid with the communications network. The purpose of these networks is to create a secure, two-way infrastructure for the transmission of power and information. The complex structure of smart grids, along with the inherent vulnerabilities of physical systems, old devices and protocols on the network and the need for backward compatibility, have created serious cyber risks to critical assets and infrastructures. The difference between these types of networks and conventional computer networks has made the security mechanisms developed in conventional computer networks not very suitable for these types of... 

The purpose of this study is to investigate the resilience of the urban water supply network against earthquakes, A hydraulic analysis of the water supply network was implemented in Rtx software to study the effective parameters in the resilience of the network. Rtx software is a tool for assessing the reliability and resilience of communities and infrastructure to natural hazards by taking into account related uncertainties. The water supply network, like other networks, is affected by earthquakes. The seismic damage varies depending on the vulnerability of the network, the intensity of the earthquake, the focal depth, and the distance from the epicenter. Thus, it reduces the ability of the... 

This research develops a probabilistic framework for evaluating community resilience subject to earthquake events by modeling the water distribution system and its prevailing inter- and intra-dependencies with other infrastructure systems of the community. This framework is entitled “Rtx,” which is under continuous development at the Center for Infrastructure Sustainability and Resilience Research (INSURER) at Sharif University of Technology, Tehran, Iran. It quantifies the community resilience by integrating hazard models, risk models, and recovery models within an agent-based simulation. Comprehensive modeling of the water distribution system requires a library of probabilistic models,... 

This dissertation proposes a new platform and a new software for evaluation of urban Water Distribution Network (WDN) resilience. Resilience is considerd as the ability of an infrastructure to come back to steady state after being affected by any environmental or man-made disturbance. WDN, as an essential infrastructure, has major role on resilience and sustainability of cities and communities. Today, uninterrupted performance of WDN is a basic need of people who live in cities. This uninterrupted performance becomes bolder in face of man-made or natural disasters like earthquake. The uninterrupted performance of a system is dependent on the system’s resilience. Majority of researchers... 

Power networks are evolving dynamically, and a wide variety of control and visibility devices are being integrated into the power system, generating a significant amount of data. This thesis focuses on analyzing subscribers' electricity consumption patterns, which explores the potential insights embedded within these data. The information assessed includes active and reactive energy consumption, the current imbalance index, and the power factor. Over 6 billion records were obtained from the Hormozgan Electricity Distribution Company for the foundational dataset for this study. An extensive section of this thesis is dedicated to removing empty values and outliers from data. After this, a... 

Remote-controlled switches (RCSs) have the ability to quickly isolate the faulted area from other parts of distribution systems. On the other hand, the distributed generation resources (DGs) and tie lines can supply the interrupted loads after fault occurrence as a microgrid. In this regard, this thesis proposes a planning model for simultaneous placement of RCSs, DGs, and tie lines in distribution systems with complex topologies to improve their reliability and resiliency. Presence of renewable DGs (RDGs) including photovoltaic cells (PVs) and wind turbines (WTs), as well as the uncertainties of loads, RDGs, and outage duration of the faulted areas are also considered in the proposed... 

The Technology scaling and reduction of the size of transistors has led to an increase in the switching speed and, as a result, to an increase in the clock frequency.But in recent years, the continuation of this process of increasing the clock frequency has been almost stopped considering the considerations of power consumption. Previous research has shown that approximately 30-50% of the dynamic power consumed by the microprocessor is wasted in the clock distribution network.Therefore, the design of clock distribution networks is a big challenge for future microprocessors due to the trend of Technology scaling and process variation. In this thesis, we used the emerging technology of... 

A high percentage of power grid faults occur in the distribution sector, which causes customers to experience power outages. In order to maintain a good reputation with customers and maximize their satisfaction, improving the reliability of the services provided in the electricity distribution network and minimizing related costs have always been one of the most important challenges for electricity network managers. Therefore, managers and legislators of the power network are always looking for a way to maintain the reliability level of the power distribution network and also to improve it. So far, many researchers have focused on setting goals with the help of average performance methods... 

Recent widespread blackouts around the world have highlighted the fact that power grids must not only ensure reliability against high-probability, low-impact events (HPLI), but also against low-probability, high-impact events (HILP) such as earthquakes, hurricanes, and hurricanes and resist against unnatural events such as cyber attacks. On the other hand, transformation of traditional electricity distribution systems into smart networks that have the ability to automatically perform switching and fault locating can enable utilities to minimize operational costs in case of HILP events occurences. Although the use of distribution automation has been suggested as one of the smart grid... 

Expansion planning of distribution network assets is of importance to reliably supply the growing demand. Growing penetration of distributed energy resources (DERs) including renewable based distributed generators (DGs), conventional DGs, energy storage systems, and demand response (DR) resources in the network as well as their operational advantages make it necessary to address the investment planning of these resources in addition to the network assets. In order to effectively utilize the DERs and to solve the challenges arisen by their increasing penetration, active distribution networks (ADNs) are introduced which offer active network management capability. Passing through traditional... 

The usage of plugin hybrid electric vehicles has environmental benefits. However, the penetration of these components raises important concerns for grid planning. Thus, it is necessary to model the load change due to their charge to investigate the impact of these vehicles on distribution networks. For this reason, it is necessary to determine the specifications of these vehicles, such as battery charge and energy consumption on daily trips. In addition, the study of some behavioral patterns of these vehicles and some experts are necessary to complete the model.In this thesis, an active distribution network is planned using dynamic programming formulation. In this model, some buses are added... 

Implementation of telecommunication-based distribution automation is possible in both centralized and decentralized manners. Although centralized automation is more pervasive than decentralized automation, benefits of decentralized automation systems, like improving reliability and speeding up the fault management process, encourage distribution companies to implement these systems. However, high cost of decentralized automation can be a deterrent to most distribution companies. Therefore, economic planning and creating economic justifications for decentralized distribution automation are necessary for the development of these systems. In this dissertation, economic analysis and planning of... 

Issues related to the environmental pollution, greenhouse gas emissions, as well as the limited supply of fossil fuels and their rising prices have led to the deployment of distributed energy technologies in power systems. With the increasing penetration of distributed energy sources in distribution systems, smart grids, and in particular, microgrids have emerged as a suitable and widely accepted solution for controlling and utilizing these resources. Microgrids can enhance energy efficiency in a sustainable power grid as well as the reliability of the distribution system, through supporting high penetration of renewable energy sources and providing island performance.In view of growing... 

Nowadays, moving toward new technologies and smart grids is a successful way to prevail over distribution system challenges. In the presence of smart grids, demand-side management (DSM) is capable to affect the expansion of network resources. An effective DSM tool is demand response (DR). In this thesis, distribution system planning (DSP) considering DR is presented and the effects of DR on DSP are investigated. This thesis proposes direct load control (DLC) DR which is an incentive-based program (IBP) where a utility offers financial incentives to the customers to control their consumption through installing smart meters and switches. The utility deploys the DR program to reduce network... 

The number and severity of natural disasters have significantly increased in the recent years. Extreme weather-driven events cause catastrophic damages to power grid components. As a consequence, severe power outages occur in the affected grids. According to the published reports on natural disasters, 90 percent of such outages originate from distribution systems. In addition, the repair process of the damaged elements takes a long duration. Thus, it is necessary to improve the distribution system (DS) resilience against natural disasters. The strategies for resilience enhancement can be classified into two main groups: hardening and operation-oriented measures.Formation of microgrids has... 

During natural disasters, especially an earthquake the distribution systems operation is severely affected and interrupted by facing many failures. More than 80% of these outages are due to failures in distribution Systems. Therefore, it is crucial to enhance the resilience of the distribution systems (DSs) against these disasters. However, nowadays, due to limitation of resources for investment in these networks, only the most efficient measures should be implemented. In this work, studying the recent earthquakes in different countries, we have tried to identify the fundamental causes of failure of important network equipment, including distribution substations equipment and network... 

The worldwide increase in greenhouse gases is one of the most important human concerns today, and reducing emissions is on the agenda of politicians and the international community. Globally, the transportation fleet is one of the major sources of environmental pollutants due to the use of fossil fuels, and replacing this fleet with electric vehicles will play an important role in reducing the emission of environmental pollutants. These environmental concerns and the advancement of technologies used in electric vehicles in recent years have led to a relative increase in the presence of electric vehicles in the transportation network. The acceptance of these cars, on the one hand,... 

Due to the increasing influence of distribution generation , their effect in planning can't be ignord , especially solar panels ,which are incresing rapidly. The main purpose of this thesis is to an active distribution network that annually load bus and the amount of photovoltaic production in it increases and plan dynamically. In the planning that is done , uncertanty in the amount comsumption load and uncertanty in the pattern of sunlight and also annual innterest rates in the classical system we have planned by optimizing the network expansion costs , in addition to supplying the load bus, we can keep the voltage drop bus and line filling within the allowable . To do this , we considered...