| The Unified Power Flow Controller (UPFC) is one of the modern power electronics devices that can be used for the control of real and reactive power in a transmission line. The UPFC uses voltage sourced converter (VSC) technology to inject a series voltage with the sending end ac source to achieve its control objective with high speed, making it suitable for maintaining the voltage and mechanical stability of a network.; Using circuit theory, this thesis first develops the operating regimes of the UPFC and identifies how the injected voltage affects the flow of real and reactive power. Based on this analysis, various control schemes are designed and analyzed. It is possible to develop an open-loop control scheme, which works well in the steady state, but shows undesirable transients in the control of say, reactive power when the real power is changed. It is also not accurate if the system data on which it is based is approximate. (Abstract shortened by UMI.)... |
