With increasing of distributed generation (DG) and smart grid applications, power protection system (PPS) have been passing for several challenges. Traditional relay coordination presents a relevant difficult to operate with DG plants. Modifications on short-circuits levels and current directionality may include miscoordinations on PPS. An alternative of traditional relay system is adaptive protective system (APS). APS provides an automatic update of relay setting ever when power grid have a modification. A large number of method may be used to identify these modification. In this paper a frequency estimation method was used to identify grid modification and flag to APS methods. To evaluate proposed method, a real Brazilian distribution system was used considering that only instantaneous overcurrent relay compose PPS. Obtainer results shown a efficacy on grid topology identification and same modification among obtained relay settings using APS architecture.