Modeling series compensation effect on the bus impedance matrix for online applications

Abstract

This paper derives new expressions for updating Bus Impedance Matrix (Zbus) elements to account for the modification of the series impedance of a line connected between two existing buses. Such kind of modification is not accounted for in Brown's method and requires building Zbus all over again which is time-consuming, and redundant. Afterwards, we show that a modified form of Sherman–Morisson identity is the generalization of our work. We test our modeling approach with seven systems of different sizes. Results show very minor errors between the predictions of our techniques and Brown's method. Further, speed comparison shows that our method substantially improves calculation speed from a few minutes with Brown and Bus Admittance Matrix (Ybus) inversion methods to seconds (1.35s and 2.9s for 2383 and 3120 bus systems, respectively) making it more suitable for online applications.