The Impact of Power Swing to the Operation of Distance Relay

The presence of Distributed Generation (DG) System with the impact to the power swing during the instability was revealed. Some of the scenario which affect to the Zone Protection of Distance Relay has been observed. The result shows that the apparent impedance was passes through both the Zone 1 and Zone 2 of protection of distance relay during installing the DG system to the network. In this study, the distance relay is chosen to be a protective system into the system network in order to protect the transmission lines. The distance relay will have the instantaneous directional Zone 1 protection and one or more time delayed zones. The tripping signal produced by Zone 1 is instantaneous that is should not reach as far as the busbar at the end of the first line so it is to cover only 80-85% of the protected line of transmission lines. The remaining 15-20% provides a factor of safety in order to mitigate against errors introduced by the current and voltage transformer, and line impedance calculations. The 15-20% at the end of the line is protected by Zone 2. All of the circumstances during protective of transmission line with and without DG system have been captured and discussed in the end of this paper.