impedance-based out-of-step protection of generator in the presence of statcom

This paper presents a novel impedancebased approach for outofstep (oos) protection of a synchronous generator. the most popular and commonly used approaches for detecting oos conditions are based on the measurement of positive sequence impedance at relay location. however, facts devices change the measured impedance value and thus disrupt the performance of impedancebased relay function. in this paper, the performance of synchronous generator oos protection function connected to the transmission line in the presence of a static synchronous compensator (statcom) is investigated. moreover, an analytical adaptive approach is used to eliminate the effect of statcom. this approach requires only the remote bus voltage and current phasors to be sent to the relay location via a communication channel. simulation results show that statcom changes impedance trajectory and causes the incorrect operation of oos relay. furthermore, the proposed approach corrects the relay maloperation and improves the accuracy of oos impedancebased function when the statcom is used in the system.​