Consideration of DC capacitor and line inductance in the design of UPFC to improve transient stability

Practical application of the unified power flow controller requires proper design of each component of the UPFC device in order to satisfy both economic requirements and technical specifications. Economic and performance indices are always conflicting factors in the design of the practical devices and an acceptable design of practical device must be based on a reasonable compromise between these two factors. Although an overwhelming number of studies have been conducted on the UPFC and its application, the study at the components level is limited, especially regarding the selection of parameters of UPFC devices. Using the analysis of transient characteristics of UPFC installed in a power system, this paper attempts to identify the effects of the size of DC capacitor and equivalent line inductance. The relationship between the transient stability of the power system and these parameters is studied at the components-level simulation. The findings of this study can be useful in the determination of UPFC parameters for the purpose of improving transient stability, and highlight some of the practical considerations in UPFC implementation.