PERFORMANCE OF THE DPFC BEFORE AND DURING SERIES CONVERTER FAILURE

Distributed Power Flow Controller (DPFC) is one of the devices within the FACTS family. DPFC is resulting from the UPFC. The DPFC having much control capability like UPFC, however at much reduced cost and an improved reliability. The DPFC comprises the adjustment of the transmission line parameters i.e. impedance of the line, the transmission angle, and the bus voltage. The DPFC can be designed with multiple single phase series converters and one three phase shunt converter. Before the series converter failure, the DPFC control the active power exchange between the shunt and series converter that are through the transmission line at the 3rd harmonic frequency. During the series converter failure, the DPFC continue to control the active and reactive power exchange between the converters with the adapted control schemes. This paper presents performance of the DPFC before and during the failure of single series converter. The failure of single series converter can cause flow of negative and zero sequence currents at fundamental frequency. Adapted control schemes are employed to each series converters, which can automatically suppress the negative and zero sequence currents and keeps the DPFC system stable during the series converter failure. The reliability of the DPFC system is further improved by the use of multiple single phase series converters with the adapted control schemes.