Discrete control of unified power flow controller for stability improvement

The emerging flexible ac transmission system (FACTS) controllers are considered to be suitable for transient stability control due to their speed and flexibility. In this paper, a control strategy is developed to achieve maximal improvement in transient stability and damp the rotor oscillations using unified power flow controller (UPFC). The control strategy involves maximization and minimization of power flowin a line. In general, this involves the solution of a constraine doptimization problem at each step to determine the voltage and current injected by the UPFC. For the special case of a lossless symmetrical line, when the UPFC is located at the midpoint of the line, analytical solution can be derived. The control strategy can be extended to multimachine system and maximizing and minimizing power flow on a critical line can improve transient stability. The control strategy is evaluated by simulation studies.

[1]  R. J. Nelson,et al.  A study of equipment sizes and constraints for a unified power flow controller , 1996, Proceedings of 1996 Transmission and Distribution Conference and Exposition.

[2]  K. R. Padiyar,et al.  Control design and simulation of unified power flow controller , 1998 .

[3]  D. N. Kosterev,et al.  Bang-bang series capacitor transient stability control , 1995 .

[4]  Rafael Mihalic,et al.  Improvement of transient stability using unified power flow controller , 1996 .

[5]  Laszlo Gyugyi,et al.  Unified power-flow control concept for flexible AC transmission systems , 1992 .

[6]  M.L. Shelton,et al.  Bonneville power administration 1400-MW braking resistor , 1975, IEEE Transactions on Power Apparatus and Systems.

[7]  K. R. Padiyar,et al.  Power system dynamics : stability and control , 1996 .

[8]  Jaewon Chang,et al.  Time-optimal control of power systems requiring multiple switchings of series capacitors , 1998 .

[9]  K. Uma Rao,et al.  Discrete control of series compensation for stability improvement in power systems , 1997 .

[10]  Laszlo Gyugyi,et al.  Understanding FACTS: Concepts and Technology of Flexible AC Transmission Systems , 1999 .

[11]  O. Smith.  Power System Transient Control by Capacitor Switching , 1969 .

[12]  K. R. Padiyar,et al.  On-line detection of loss of synchronism using locally measurable quantities , 2001, 2001 IEEE/PES Transmission and Distribution Conference and Exposition. Developing New Perspectives (Cat. No.01CH37294).