Comparative Study on the Effectiveness of UPFC and TCSC for Increasing Power Transfer Capability Applied to Non-linear Load Models

In recent years, studies have been investigated the effectiveness of UPFC and TCSC in increasing power transfer capability. However, the effectiveness of these FACTS devices in increasing power transfer capability when the load is non-linear has not been established in a comparative study yet. This paper will explore the steady-state performance of the UPFC and TCSC as impedance compensation models. The effectiveness of both FACTS devices are investigated when they are installed in multi-machine systems with different non-linear load models. Simulation results demonstrate that, upon installing UPFC, more active and reactive powers are received at the sending end bus for different types of non-linear load models. In addition, both active and reactive powers are more sensitive in changing the modulation index of the converters. Furthermore, both the active and reactive powers are less sensitive to the non-linearity of the load model type. However, active and reactive powers in case of installing TCSC are only sensitive in changing the firing angle (α) when it is between 90o to 110o. Therefore, results from this study clearly encourage the effectiveness of UPFC in comparison to TSCS in terms of increasing power transfer capability applied to non-linear load models.