Modeling and simulation of Interline Power Flow Controllers: Application to enhance system damping

In this paper, an investigation into the use of Flexible ac Transmission Systems (FACTS) devices to aid damping of low-frequency inter-area oscillations in longitudinal power systems is presented. A linear model of VSC-based FACTS devices that takes into account the dynamics of dc links is developed and incorporated into a production-grade software for small signal analysis of large power systems. Based on this representation, a unified framework for modal power oscillation flow studies is then developed to analyze the sensitivity of modal behavior to FACTS control action. With this method, the transmission corridors and system parameters having a large contribution to critical system oscillations modes are determined. The method is particularly well suited for investigating inter-system oscillations in large-scale power systems with embedded FACTS controllers The utilized methodology is tested on a practical 45-machine Mexican system that includes several major static VAR compensators. Control mode implementations are discussed and tested and comparisons with existing technologies are presented.