The latest generation FACTS controller named the convertible static compensator (CSC) was recently installed at the New York Power Authority (NYPA) Marcy substation as part of a project that will increase power transfer capability and maximize the use of the existing transmission network. Within the general framework of the CSC, two innovative FACTS controllers are used. The static synchronous series compensator (SSSC) coupled with a transformer is connected in series with a transmission line. The interline power flow controller (IPFC) combining at least two converters, can be configured. Mathematical models of the SSSC and the IPFC and their implementation in Newton power flow are reported. Numerical results based on the IEEE 30-bus are presented to demonstrate the performance of the Newton power flow algorithm with incorporation of the SSSC and IPFC.