الفهرس 
introductionOnly 14 pages are availabe for public view
 |  | from | 126 |  |  |
| | | from | 126 | | |
Abstract
power transformer are particularly important in the network power system. they are alsoo one of the most common nonlinear elements in power system. one of the most important problems caused by magnetizing inrush current (M.I.C.) of the transformer is mal-operation of protective equipment. main factors to determine the magnitude of the inrush currents depends on the residual flux ɸr of the transformer, and the phase angle (a) of voltage source. many articles about magnetizing nirush current phenomenon (M.I.C) have been reviewed. some of the discussed different method of calculating MIC, some discussed discrimination between fault current and inrush current and some which presenting solutions and discussed technique to reduce this phenomenon. presents the suggestion to mitigate the magnetizing inrush current, mitigation techniques can be divided into four groups and sub-sections techniques to reduce MIC, power transformer, a detail the different methods to reduce or mitigation the M.I.C, illustration the advantages and disadvantage of each method. simulation was performed using MATLAB program.in this thesis a general purpose to investigate minimization inrush current in power transformers, by using combination of two methods are control the switch and the pre-insertion of series resistor. the pre-insertion series scheme provides a solution for inrush current mitigation in transformers with un-grounded primaries. it has been prepared experimental model for the study of the magnetizing inrush current phenomena.