This paper explains the decoupled control of the power flow through a transmission line using a PWM based Unified Power Flow Controler (UPFC). The dynamic model of the UPFC has been developed using the space-vector representation of the instantaneous three-phase variables. The Park´s transformation and the reference frame selected reduce the control of the real and reactive-power flows to the control of the d- and q-axis currents, respectively. The proposed control scheme produces fast and decoupled response of the real and the reactive-power flow through a transmission line. It also achieves tight control of the d.c.-link capacitor voltage, thanks to the careful coordination between the control of the series and shunt compensators of the UPFX. A 15 kVA prototype with 750 Hz switching frequency has been built to illustrate the main contributions. Experiemental results agree closely with the theoretical analysis.
Keywords: PWM invertors; compensation; load flow control; power transmission control; power transmission lines; reactive power control
IEE Proceedings-Generation Transmission and Distribution. Volume: 150 Issue: 2 Pages: 147-154
JCR Impact Factor and Scopus quartile: 0.341 (2003); 0.868 (2008).
DOI reference: 10.1049/ip-gtd:20030026
Published on paper: March 2003.