Power swings are disturbances in a power system, and are caused by caused by load changes, line switching, loss of generation, and other power faults. These can result in potentially dangerous spikes in current. Electrical power engineers need tools and methods to analyze power swings. This assists them in devising preventative measures that eliminate the potential for costly whole system failures.

In this application, the transient state defined by swing equation of Two machine system, and the impedance behavior are analyzed to obtain the required information in order to determine the appropriate settings for Out-Of-Step protection.