This chapter discusses the recent developments in modeling of multi-functional multi-converter FACTS-devices in power flow analysis. The objectives of this chapter are:
1. to model not only the well-recognized two-converter shunt-series FACTS-device - UPFC, but also the latest multi-line FACTS-devices such as IPFC, GUPFC, VSC-HVDC and M-VSC-HVDC in power flow analysis,
2. to establish multi-control functional models of these multi-converter FACTS-devices to compare the control performance of these FACTS-devices.
3. to handle the small impedances of coupling transformers of FACTS-devices in power flow analysis.