Modeling of Single Machine Infinite Bus (SMIB) System with UPFC

Abstract

The increasing complexity of modern power systems, characterized by large-scale interconnections and dynamic operating conditions, necessitates advanced control strategies to ensure stability and efficient power flow. The Single Machine Infinite Bus (SMIB) system serves as a fundamental model for analyzing the dynamic behavior of synchronous generators connected to large power grids. However, conventional SMIB systems are highly susceptible to disturbances such as faults, load variations, and oscillations, which may lead to instability. The integration of Flexible AC Transmission System (FACTS) devices, particularly the Unified Power Flow Controller (UPFC), has emerged as a promising solution to enhance system performance. The UPFC is capable of simultaneously controlling voltage magnitude, line impedance, and phase angle, thereby enabling independent regulation of real and reactive power flow.

This study focuses on the comprehensive modeling of a SMIB system integrated with a UPFC, emphasizing both steady-state and dynamic characteristics. Mathematical modeling is developed using nonlinear differential equations representing generator dynamics, excitation systems, and UPFC control mechanisms. The interaction between the shunt and series converters of the UPFC is analyzed to understand its impact on system stability. Furthermore, the model is suitable for simulation in MATLAB/Simulink environments to evaluate transient and small-signal stability. The results demonstrate that the inclusion of UPFC significantly improves damping of low-frequency oscillations, enhances voltage stability, and increases power transfer capability. The proposed modeling framework provides a robust foundation for further research in advanced control strategies and optimization of FACTS devices in power systems.