Unified power flow controller on the AEP system: commissioning and operation

The unified power flow controller (UPFC) on the American Electric Power System employs two GTO-based inverters, each rated ±160 MVA, connected via a common DC link. One inverter is connected in shunt configuration with the transmission line and the other is in series. The two inverters can be de-coupled and operated separately, one as a static VAr compensator (STATCOM), the other as a synchronous static series compensator (SSSC), each with inverter ratings of ±160 MVA. Normally, they will be operated as a UPFC, with a total inverter rating of ±320 MVA, to regulate terminal bus voltage and simultaneously control power flow. In 1997, the shunt inverter was installed and commissioned as a STATCOM. The series inverter was also installed in 1997, and it was successfully commissioned as part of the UPFC in 1998. Since the dedication in June 1998. The UPFC has successfully been in full operation.