The Effect of Various UPFC Operating Points on Transient Stability

In this paper, it is shown that using the power injection model for a UPFC, there exists a set of operating points for which the same amount of AC bus voltage and active/reactive series power injections can be evaluated. These various operating points are designated by different dc bus voltages (V_dc) and modulation amplitudes (k₁,k₂) and phases (alpha₁,alpha₂). Simulations show that the dynamic behavior of a UPFC could be related to its pre-fault operating situations. The question to be answered is to verify which operating point would be the best candidate from a network stability point of view. A linear approach based on the eigenvalue problem has been used to answer the question and satisfactory results have been outlined.approach based on the eigenvalue problem has been used to answer the question and satisfactory results have been outlined.