POWER FLOW CONTROL USING GENERALIZED UPFC

Abstract

Flexible AC Transmission Systems (FACTS) are becoming very popular power flow control devices, mainly due to two reasons. First reason is that high power semiconductor devices along with new control features are available at reasonable costs. Secondly, due to the restructuring of electric power utilities, economic and environmental issues, transmission corridors are operating close to their limits. Shunt FACTS controllers are useful in reactive power compensation and for improvement in dynamic performance of the system whereas series controllers are used for improving both static (power flow control etc.) and dynamic performance (damping oscillation etc.). Unified Power Flow Controller (UPFC) is a device, which is combination of series, and shunt controller and uses two converters. It is more versatile controller. Multi-converter (more than two converters) is termed as generalized UPFC and has 5 or more than 5 control parameters. It is important to ascertain the location for placement of these devices because of their considerable costs. Modeling of generalized unified power flow controller (GUPFC), based on the static consideration, and has been presented in this thesis used for power flow control. A sensitivity based approach has been presented to optimally locate GUPFC in the system based on the reduction of system real power loss and reduction in the system overloading. A Newton-Raphson load flow program has been developed which includes comprehensive control facilities and yet exhibits very strong convergence characteristics. The GUPFC injection model is incorporated into Newton-Raphson load flow algorithm in polar coordinate. The modified Jacobian matrix and power mismatch equations are deduced based on the injection model of GUPFC to control active and reactive powers and voltage magnitude in any combination or to control one of them. Test results are presented on IEEE 30-bus system, which demonstrates the effectiveness of the used method.