The influence of GUPFC FACTS device on small signal stability of the electrical power systems

In this paper a power injection model is presented for the Generalized Unified Power Flow Controller (GUPFC), which facilitates its representation in the electric power system (EPS). This model of the GUPFC device becomes an attractive option to be implemented in power flow and optimal power flow programs. An efficient structure for the GUPFC control system is also presented in the article. This can be used to represent the dynamics in both stability analysis of small perturbations, which is the focus of this work, and in transient stability analysis (large disturbances) of the EPS. Considering the most basic GUPFC configuration, the proposed structure can control four active and reactive power flows in two lines, the voltage at the common installation bus; addition to these characteristics inherent in the GUPFC, this device can provide damping for the electromechanical oscillations of the EPS, as a POD (Power Oscillation Damping) controller is coupled to the control loop. Simulations are performed on one multimachine test system, whose results are analyzed and discussed in this paper, in order to analyze the performance of the power injection model and its proposed control structure in the damping of oscillations.