Damping torque analysis of a UPFC installed in a real Chinese power grid

A real Chinese power grid where a vector controlled unified power flow controller (UPFC) has just been installed is researched in this paper. Firstly, the principle of vector control strategy is presented. Then the linearized model of the power grid is established. Based on the model, damping torque analysis (DTA) method is described. By using the DTA method, the best channel to install the damping controller on the vector controlled UPFC has been picked out. Finally, both the modal analysis method and nonlinear simulation have been used to validate this result of channel choice to install the damping controller in the real power grid. Furtherly, this paper presents a comparison of the different damping characteristics of UPFC with phase angle and vector control strategy respectively. Finally, it is found that the damping controller installed on vector controlled UPFC is less effective to provide damping than the phase angle controlled one.