Dynamic model based complex checking of out-of-step protections

In the recent period, with power systems operating closer to stability limit due to market liberalization and cross-border trade increase, and at the increasing ldquodemandrdquo related to blackout lessons, more and more protection manufacturer firms include functions of protection against ldquoasynchronous operation ldquo (out-of-step functions) in the protection numerical terminals for transmission lines. This paper presents a possible variant for the complex checking of the settings, logic and selectivity of pole-slip/out- of-step protection functions implemented at two transmission system levels, that is at generator terminals (24 kV) and on the transmission lines (400 kV) connected to the bus bars receiving the generators output.