ABSTRACT

Recently, global demand for power has significantly increased. However, power generation and transmission capacity has not increased proportionally with this demand. To meet the increasing demand of power the generating capacity and the power transfer through transmission lines need to be increased. However, the limited energy resources, deregulated electricity market, environmental constraints, time and capital required to build new transmission networks have led the system planners to look for the new techniques to improve the power system performance. In this Flexible Alternating Current Transmission S) FACTS) devices have achieved keen interest as a mean to improve the existing transmission network capacity. Among FACTS devices, Unified Power Flow Controller (UPFC) has been selected in this research to control power flow in transmission networks and improve the power system operation. In this thesis Fuzzy Logic Controller (FLC) is proposed to overcome the problems of the existing UPFC controllers and to provide the power flow control under different operating conditions. The UPFC shunt and series controllers based on FLC are developed as a stand-alone module in PSCAD software. The proposed FLC based UPFC is tested using IEEE-14 bus system with various test cases. The test cases are including different active and reactive power references. The results revealed that the proposed FLC has successfully improved the performance of UPFC by enhancing the active; reduce reactive power and voltage profile improvement. Moreover, the power losses of the network have been reduced. The performance of proposed FLC based UPFC has also been compared with Proportional PI) based UPFC and without UPFC for the mentioned parameters to show its effectiveness. The simulation results have shown that the proposed FLC based UPFC proved its robustness in improving all power system parameters compared to PI based UPFC.