A nonlinear control for coordinating TCSC and generator excitation to enhance the transient stability of long transmission systems

Abstract The transient stability of a long transmission system can be significantly influenced by the action of excitation systems and any TCSC controls installed. This paper presents a coordinated control scheme for excitation systems and TCSC controls for improving the stability of a transmission system, where a power plant is connected with a power grid through long transmission lines. Based on the TCSC equivalent reactance and the modulated active power, a control law for the TCSC is deduced associated with the control law of the excitation system on nonlinear basis. The proposed control scheme is developed upon nonlinear optimal-variable-aim strategies (OVAS). With two pre-selected aims to be achieved during first swings following a fault and in sequent dynamic ranges, coordinated actions of the TCSC and excitation system can be an effective means of enhancing transient stability and damping subsequent oscillations. The effectiveness and robustness of OVAS-based controls are demonstrated with a one-machine system, where the simulations are carried out by the NETOMAC program system. In comparison with a conventional control scheme, significant improvements in dynamic performance of the test system are achieved by the proposed control strategy.

[1]  S. G. Jalali,et al.  A stability model for the advanced series compensator (ASC) , 1996 .

[2]  L. Xu,et al.  Advanced SVC control for damping power system oscillations , 1991 .

[3]  Takashi Hiyama,et al.  Coordinated fuzzy logic control for series capacitor modules and PSS to enhance stability of power system , 1995 .

[4]  Mehrdad Ghandhari,et al.  Improving power system dynamics by series-connected FACTS devices , 1997 .

[5]  E. W. Kimbark,et al.  Improvement of System Stability by Switched Series Capacitors , 1966 .

[6]  H. F. Duan,et al.  Nonlinear optimal-variable-aim excitation control strategy for voltage stability improvement , 1997 .

[7]  X. Zhou,et al.  Overview of control schemes for TCSC to enhance the stability of power systems , 1999 .

[8]  R. R. Mohler,et al.  Variable-structure facts controllers for power system transient stability , 1992 .

[9]  Zhe Zhang,et al.  Analysis and control of Yimin–Fengtun 500 kV TCSC system , 1998 .

[10]  C. Gama,et al.  Brazilian North-South Interconnection control-application and operating experience with a TCSC , 1999, 1999 IEEE Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.99CH36364).

[11]  R. Barnard.  An optimal-aim control strategy for nonlinear regulation systems , 1975 .

[12]  Einar Vaughn Larsen,et al.  Thyristor controlled series compensation prototype installation at the Slatt 500 kV substation , 1993 .

[13]  D. Maratukulam,et al.  Advanced static compensator for flexible AC transmission , 1993 .

[14]  P. S. Dolan,et al.  A study of TCSC optimal damping control parameters for different operating conditions , 1995 .

[15]  W. Rugh.  Linear System Theory , 1992 .

[16]  M. Pai.  Energy function analysis for power system stability , 1989 .

[17]  Edwin Lerch,et al.  A large integrated power system software package-NETOMAC , 1998, POWERCON '98. 1998 International Conference on Power System Technology. Proceedings (Cat. No.98EX151).

[18]  Xiaohua Liu,et al.  Nonlinear optimal-variable-aim strategy for improving multimachine power system transient stability , 1996 .

[19]  Luis Rouco,et al.  An eigenvalue sensitivity approach to location and controller design of controllable series capacito , 1997 .

[20]  R. R. Mohler,et al.  Nonlinear self-tuning control of a flexible AC transmission system , 1993, Proceedings of 32nd IEEE Conference on Decision and Control.

[21]  H. F. Wang,et al.  A unified model for the analysis of FACTS devices in damping power system oscillations. I. Single-machine infinite-bus power systems , 1997 .