Increasing demand coupled with limitations on new construction indicate that existing power transmission must be better controlled in order to continue reliable operation. Recent advances in FACTS devices provide a mechanism to better control power flow on the transmission network. One particular device, the unified power flow controller (UPFC), holds the most promise for maintaining operation even when the system has suffered partial failure (either naturally occurring, due to human error, or a malicious attack). In addition to the capital cost, the primary obstacles to widespread UPFC use are the combined problems of selecting the most cost effective locations for installation and maintaining proper control of them once installed. In this paper we list evidence that gradient descent search based on load-flow computation is more realistic and accurate than many of the optimization techniques currently in use. We then demonstrate that gradient descent search can be used to select control points that improve system fault tolerance more than those found by the max-flow technique. In addition, we demonstrate that the size of the system being computed and the number of computations is bounded and is practical for real time control.

Meeting Name

37th Annual North American Power Symposium (2005: Oct. 23-25, Iowa State University, Ames, IA)


Electrical and Computer Engineering

Second Department

Computer Science

Keywords and Phrases

FACTS Devices; UPFC Control; Fault Tolerance; Flexible AC Transmission Systems; Gradient Descent Search; Gradient Methods; Load Flow Control; Max-Flow Technique; Operation Reliability; Optimization Techniques; Partial Failure; Power Transmission; Power Transmission Control; Real Time Control; Unified Power Flow Controller

International Standard Book Number (ISBN)


Document Type

Article - Conference proceedings

Document Version

Final Version

File Type





© 2005 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Oct 2005