Operating constraints of FACTS devices

The operation of the first commercial unit of UPFC in the American Electric Power (AEP) system marks the beginning of a new era in the history of FACTS and shows the future direction in power engineering. The successful incorporation of FACTS controllers in the power systems requires a clear understanding of all possible approaches and their operating limits. In this paper, first, a systematic study of the operating constraints of 1-converter FACTS devices based on series voltage and shunt current injection is conducted. Then, the power ratings of the series voltage and shunt current injection devices performing the same job of reactive power compensation or power flow control are compared and the conditions under which each approach becomes more economical are derived. The results can be generalized to FACTS devices with more than one converter such as UPFC