| The voltage sags, one of the most common power quality disturbances, may cause the misoperation of an electric power system's sensitive loads such as computers, power electronic devices and controls, PLCs, etc.; This thesis presents the basic voltage sag analytical techniques based on circuit theory and reliability theory to estimate voltage sag levels and the number of voltages sags at a particular customer location in a distribution system. An expression for distribution feeders' critical distance is developed to identify the voltage sag sensitive areas within a distribution system. Voltage sags caused by utility primary system single line to ground faults are altered by various transformer connections and are examined in detail. In order to reveal the transient features of voltage sags, simulation case studies are conducted on an industrial power system. The simulation results reveal the voltage magnitude and voltage phase angle deviations on all buses within the industrial system. |
