Dynamic capture method for out-of-step center of power grid based on measurement information

This paper dynamically captures the out-of-step center for a bulk power system based on measurement information. First, the position characteristics of the out-of-step center are discussed from the perspective of triangular geometry under different potential and uniform impedance distributions based on a two-machine system. The correlation between the out-of-step center and the oscillation center is analyzed. Second, combined with analytical geometry, it is inferred that the distribution characteristics of the out-of-step center voltage vector ends are a circle or a straight line, and the position of the out-of-step center corresponds to the intersection between the voltage drop of the line and the distribution characteristics; then, the accurate location of the out-of-step center and the determination of the appearance moment is realized. Finally, a dynamic equivalence method for a power grid is proposed based on the electrical parameters of the transmission line, and an alternative iterative correction of equivalent parameters is carried out by trajectory sensitivity, which provides a new way for capturing the out-of-step center dynamically in a multimachine system. The proposed method is validated using a three-machine system, the IEEE-39 system and the Northwest China Power Grid, and shows potential for online applications.