الفهرس 
Introduction and Literature SurveyOnly 14 pages are availabe for public view
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Abstract
Among the main Objectives of Electrical power systems are to provide continuous supply of electrical power with high reliability and improved quality along with maintaining power balance. These objectives must be operated in an optimal level which means best performance with minimum costs. Transformers are basically the most important components in the power system where transformers step up voltage for transmission system in order to reduce power losses, also they used for power transfer and control along with supplying different subsystems, hence reliability of the transformers affects the reliability of the power system directly. Failures of the transformers can lead to the inability of the transformers to perform their duties which results in the dissatisfaction of the customers and the interruptions will impact on costs and lifespan of the transformers as transformers outages can be caused by failures of one or more of the components or subassemblies of the transformers.
This thesis studies two main subjects regarding the transformers of different voltage subpopulations: 500 kV, 220 kV, 132 kV and 66-33 kV of the Egyptian power grid, the first subject is the impact of the failures on customer interruption costs (CIC) and the second is determining the remaining lifetime of the transformers.
CIC is estimated through customer damage functions (CDFs) in which establishing Composite Customer Damage Function (CCDF) model is made by combing sector customer damage functions (SCDFs) of various load sectors into one damage function by weighing percentage factors of different interruption power and interruption energy of diversified load sectors with interruption durations. The model is constructed to an equation through curve fitting using Microsoft excel and then it is applied to the transformers in different voltage populations as well as their subassemblies.
Before estimating remaining lifetime of transformers in different voltage subpopulations, time between failures (TBFs) must be calculated, then determining the best fit probability distribution to be used among different probability distributions from which calculations are made using MATLAB program in order to determine failure rate, reliability and remaining lifetime at different reliability levels for the transformers and their subassemblies. Afterwards, deterministic calculations are performed for both CIC and repair time.
The results obtained from the thesis can be used in the manufacturing of the transformers for better quality and in improving the operation process along with enhancing the maintenance schedules for the transformers by taking into consideration the impact on failures on both CIC and lifetime of the transformers in order to deliver a balanced, continues power supply to the customers.