Proposição de uma nova técnica para detecção de oscilações estáveis de potência em SEP

Abstract

The power system grows considerably increasing its complexity. Thus, there is a need to combine operating characteristics of protection relays, for the rapid elimination of faults and ensures selectivity in the performance of these devices. Therefore, it becomes necessary to use a distance relay (ANSI 21 function) combined with an operational logic to block its operation during a power swing due to the constant occurrence of this phenomenon in electrical systems. During such oscillation, the distance relay can act improperly since the imped-ances seen by the relay invade its operational region in the R-X plane. Based on the analysis of the main techniques for blocking the distance relay during power swings, using computational tools with low implementation complexity, this paper proposes a new technique for the detection of SPSs (stable power swings). This technique is based on analyzing the behavior of the samples of the voltage signals, arranged as ordered pairs in a Cartesian plane with its re-spective value of the first-difference function. In the study, were simulated in Matlab different situations of stable power swings for different frequency of oscillation and varied moments of oscillation incidence. Based on the obtained results, it can be said that the proposed technique is robust, quickly and accurately identifies stable power swings and this technique can be im-plemented in digital distance relays with blocking logic during stable power swings.