In recent years, the Flexible AC Transmission System (FACTS) controllers have been widely used to
enhance the controllability, security and flexibility in power transmission networks. Interline power flow
controller (IPFC) is a versatile member of FACTS devices that can be used to control the power flow in
multiple lines in network. Modeling of IPFC with handling its operating constraints is an important issue
to determine the practical capabilities of this device. This paper presents a simple modeling with strategies
for handling all operating constrains of IPFC in Newton–Raphson (NR) load flow algorithm. The various
operating constraints such as; the injected series voltages, injected line currents passing through the
converters and exchanged powers among the series converters are investigated. The developed IPFC
model with these constraints is validated using standard IEEE 30-bus and IEEE 118-bus test systems.