Impact of Variable Fault Impedances during Symmetrical Fault in Active Distribution Network

Symmetrical fault is the most severe fault in the power network. This occurs rarely however with equal amount of severe currents in the three phases. Now, in an active distribution network (ADN) shunt faults such as load fault or line tripping faults are observed to occur frequently due to uncertain penetration of distributed generated (DG) power from the distributed energy resources (DERs). The impact of different fault parameters such as phase voltages, phase angles and current flows due to symmetrical fault with variable fault impedance in ADN is noticeable. Hence, the analysis of symmetrical fault for different fault impedances are required to study in the ADN. In this work, the impact symmetrical fault with three fault impedances is taken into consideration including bolted fault in an ADN utilizing Power World Simulator. Moreover, the symmetrical fault is analyzed individually at different buses such as generator bus, load bus, and DG connected buses as available in the network to compare the severity of the fault and variation of the fault impedances at the different buses while measuring the fault parameters. The result analysis shows that the bolted fault has the highest severity on the ADN particularly at the DG connected load bus. It is also observed that when the fault impedance is increasing the severity of the symmetrical fault reduces in the network.