ABSTRACT

The power system has four stages generation, transmission, distribution and utilization. Whenever fault occurs at any stage of power system voltage profile will change in magnitude with change in phase angle. In distribution system very sensitive loadsare connected with system due to fault conditions, unbalancing in voltage occur so equipment may be burnt or damage. Fault in distribution system may leads to voltage sag in system, it is big issue of power quality, to analysis of voltage sag on different fault type and transformer winding connections is very.
essential to ensure the power quality.
This research how the analysis of voltage sags when different fault occur in distribution y tern, there are two types of faults symmetrical and unsymmetrical so voltage ag has al o two types symmetrical and unsymmetrical. In distribution system transformer is one of the important machine to raise or down the voltage, in distribution transformer has different winding connections so voltage sag due to faults can propagate from primary of transformer to secondary of transformer depends upon the fault type and winding connections of transformer.
In this thesis after analysis of voltage sags it has found that when zero sequence
components are not involved then same voltage sag will propagation takes place at primary of transformer to secondary of transformer. In this thesis it is also analysis that voltage sage propagation depends on fault types and winding connection of transformer .This research results are helpful for design of adaptive protection and
voltage controller for power system.