Component level cascade control of UPFC

A complete three-phase UPFC model has been developed using EMTDC. A method to regulate the UPFC to improve the dynamic performance of the power system is proposed in the paper. It consists of three different control levels that have been implemented by means of a well-established digital simulation software package PSCAD/EMTDC. Cascade control of the UPFC and the design of controllers for different level control of UPFC are discussed. In each level, basic structure and control method are elaborated, and the design considerations for the booster transformer are outlined. The main function of UPFC to enhance transient stability and damp oscillation is demonstrated for a test system. Simple and effective controller has been designed to demonstrate the effect of UPFC on the improvement of power system dynamic performance under a 3-phase fault condition. Simulation results are presented to show that the proposed controller is a simple but powerful technique to control UPFC for the purpose of improving dynamic performance of power system