Determination of equivalent impedances of UPFC voltage-source model from the dynamic responses of UPFC switching-level model

This paper presents the equivalent impedances of unified power flow controller (UPFC) voltage-source model from the dynamic responses of UPFC switching-level model. UPFC switching-level model is constructed using pulse width modulation method (PWM) and detailed UPFC simulation is performed using electro-magnetic transient program (EMTP). The dynamic responses of UPFC switching-level model are shown and the dynamic characteristics are analyzed. UPFC voltage-source model is constructed with equivalent voltage-sources and impedances using MATLAB(R). Based on the EMTP simulation results, the appropriate equivalent impedances of UPFC voltage-source model, which represents similar dynamic responses with UPFC switching-level model are determined by optimization routine. This routine can be used to determine the equivalent impedances of the UPFC installed in real systems. The impedances through this routine can be applied to the UPFC studies in large power systems. (C) 2003 Elsevier Science Ltd. All rights reserved.