Sharif Digital Repository

One of the shortcomings of differential logic in power transformers is its inability to detect small percentage faults at the end of the winding. The occurrence of a phase-to-ground short circuit in the last few percent of the winding near the neutral causes a very large fault current to pass through the neutral and the faulted coils, while the changes in the current observed at the transformer terminal will be very small. To improve the performance of the power transformer protection system, a restricted earth fault (REF) protection is normally used in parallel with the differential protection. To implement REF protection, several solutions have been proposed in scientific and industrial... 

In this thesis titled "Enhancing Energy Efficiency in Ideal Binary Distillation tower with a Dynamic Process Intensification," operational methods in distillation units are explored and improved. Given the high cost of energy, limited energy resources, and environmental considerations, increasing energy efficiency in process industries has become significantly important. In this context, this research attempts to enhance the performance of the distillation unit by utilizing dynamic process intensification with two operational points corresponding to the production of products with purities both higher and lower than the desired product purity, and switching between these two points. The... 

This thesis examines the impact of daylight saving time policy on electricity consumption in Iran. After World War I, many countries gradually implemented annual time change laws to extend daylight availability. This involved moving a specific amount of time (usually one hour) forward in early spring and back in early autumn. Historically, the majority of the electricity load on power grids was due to lighting, so this decision made sense. However, with technological advances and diversification of electricity usage, this decision is now being questioned, particularly in light of air conditioning loads, which make up a large part of electricity usage in Iran. These loads have the potential... 

In order to control accesses in semantic environments, a semantic-based access control and policy specification language should be choosen. Upon to them, some security mechanisms should be designed and implemented. Several access control models and policy specification languages have been arisen, but seldom have focused on designing mechanisms to satisfy their models in any environment. In this thesis, we focus on implementation aspects of access control in semantic environments. We chose semantic web as our studying environment and an extension of the SBAC model named MA(DL)2 as our access control model. To control accesses in the selected environment, we divide semantic web into some... 

In order to reduce damage caused by power outages on rare events that lead to long-term disconnection of microgrid from utility grid, isolated mode performance of microgrids including wind and hudro turbines with energy storage systems is considered in this study. Using wind energy as a renewable resource is considered as an appropriate choice for power production in microgrids. However, the uncertainty in wind turbines power generation is something challenging. The existence of water resources near the wind farms causes a special opportunity for operation of these resources along with wind turbines. This thesis aimed at balancing energy supply and demand in island mode of microgrid,... 

The analysis of electrical energy consumption parameters such as rate and amount of consumption, plays an important role in the planning of power systems. Because the dynamic analysis and evaluation of these parameters provides a detailed forecast of consumption and power system load. these forecasts is given to planners and engineers as the input of power system planning .Given that the electrical energy consumption system can be thought as a dynamic system, System Dynamics (SD) method would be very appropriate for modeling and analyzing its behavior. In this thesis, based on the SD and by means of dynamic loops, a comprehensive dynamic system for electrical energy is introduced. So the... 

Cogeneration or combined heat and power (CHP) which simultaneously produces electricity and heat energy from sequential use of single fuel source, has been introduced increasingly for industrial, commercial and residential applications due to its high energy efficiency. While the capital costs of CHP systems are comparatively higher than the conventional systems, their proper selection and optimal sizing and also optimal operation could result in shorter capital recovery period and lower cost of energy supply. Essentially the technical, economic and environmental performances of CHP system are closely dependent on its design and operation strategy. This project presents an optimization... 

In Endurance Time method structures are subjected a set of predesigned intensifying excitations. These excitations are produced in a way that their response spectrum, while complying with a specified spectrum, intensifies with time. So they can be used approximately to simulate the average effects of several ground motions scaled to different intensities. In this study applicability of Endurance Time method for evaluating collapse potential of buildings is investigated. A set of steel moment frames is used for collapse assessment. The process of using Endurance Time method in collapse evaluation is explained with consideration of uncertainty effects. collapse fragility curves and collapse... 

One of the topics that has been given great consideration after restructuring and smart grid emergence, is loss management. This subject is specifically important in distribution systems, which have been reported to have 70% of the total loss in power systems. In this thesis, distribution loss is studied and its affecting factors are analyzed. Then loss optimization and loss cost allocation to distribution consumers are studeid. In order to acheive these two goals, it is neccessary for the distribution system to have the capabilities of a smart grid. The subjectof distribution reconfiguration is duiscussed as one of the loss reduction methods. Traditional reconfiguration problem trend... 

As electric energy loss in Iran is around 31 percent and 01 percent of this loss is related to the distribution of electric energy, management and operation of distribution network is of high importance. There are different ways for operating the distribution network while decreasing the loss, such as using capacitors, tap changers, energy storing devices, distributed generations, etc. One of the most common ways is to use Network Reconfiguration. In this thesis, daily reconfiguration of a 03-kV 22-bus distribution network is investigated. The objective function consists of cost of energy loss and improvement of voltage profile. Wind turbines are used as the sources of distributed generation... 

In a centralized power system, the system operator, derives a maintenance scheduling plan that maximizing reliability of system and minimizing operating cost. But in a restructured power system the goals of GENCOs and independent system operator (ISO) are separate and each of them optimize its own goal. The goal of each GENCO is to maximize its annual benefits and the goal of ISO is to maximize the reliability of system throughout the year. Therefore there are two objective functions for finding an optimum maintenance schedule in restructured power system. This thesis proposes a new method for maintenance scheduling of generation units in a restructured power system. Firstly each GENCO... 

This thesis presents a new method for scheduling wind generation companies to participate in day-ahead market. The assumed market structure of this thesis, considers day-ahead energy market and balancing market, simultaneously. The stochastic model of this, implements a robust function to face the uncertainties of these markets. The risk of participation in these market are controlled with Information Gap Decision Theory (IGDT). Finally the allowable percent of each uncertain parameters are introduced to met an specific level of profit for the company