Delay-Dependent Stability for Load Frequency Control With Constant and Time-Varying Delays

Load frequency control (LFC) requires transmitting measurements from remote RTUs to control center and control signals from the control center to plant side. Constant delays exist in the conventional dedicated communication channels, while the future usage of open communication networks will introduce time-varying delays. Those delays would degrade the dynamic performance of LFC and in the worst case, cause instability. The maximal delay time which allows an LFC scheme embedded with controllers to retain stable is defined as the delay margin. This paper investigates the delay-dependent stability of the LFC scheme by using Lyaponuv-theory based delay-dependent criterion and linear matrix inequalities (LMIs) techniques. Case studies are carried out based on one-area and multi-area LFC schemes installed with proportional-integral (PI) controllers, respectively. Relationship between the gains of PI controller and the delay margin of the LFC scheme are investigated and results obtained can be used to tune the PI controllers to achieve a compromise between the dynamic performance and the delay margin. Both constant and time-varying delays are considered. The effectiveness of the criterion used is verified by simulation studies.

[1]  Yu Xiaodan,et al.  A simple method for power system stability analysis with multiple time delays , 2008, 2008 IEEE Power and Energy Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century.

[2]  Yong He,et al.  Delay-dependent stability criteria for linear systems with multiple time delays , 2006 .

[3]  Ibraheem,et al.  Recent philosophies of automatic generation control strategies in power systems , 2005, IEEE Transactions on Power Systems.

[4]  Wen Tan,et al.  Unified Tuning of PID Load Frequency Controller for Power Systems via IMC , 2010, IEEE Transactions on Power Systems.

[5]  Nejat Olgaç,et al.  Complete stability robustness of third-order LTI multiple time-delay systems , 2005, Autom..

[6]  Ali Feliachi,et al.  Robust load frequency control using genetic algorithms and linear matrix inequalities , 2003 .

[7]  Takashi Hiyama,et al.  Robust decentralized PI based LFC design for time-delay power systems , 2008 .

[8]  Kevin Tomsovic,et al.  Designing the Next Generation of Real-Time Control, Communication, and Computations for Large Power Systems , 2005, Proceedings of the IEEE.

[9]  Shengyuan Xu,et al.  On Equivalence and Efficiency of Certain Stability Criteria for Time-Delay Systems , 2007, IEEE Transactions on Automatic Control.

[10]  H. Shayeghi,et al.  Multi-stage fuzzy PID power system automatic generation controller in deregulated environments , 2006 .

[11]  Rifat Sipahi,et al.  An exact method for the stability analysis of time-delayed linear time-invariant (LTI) systems , 2002, IEEE Trans. Autom. Control..

[12]  Nedjeljko Perić,et al.  Sliding mode based load-frequency control in power systems , 2010 .

[13]  Hassan Bevrani,et al.  Robust Power System Frequency Control , 2009 .

[14]  Dexin Wang,et al.  A preliminary study of AGC structure for a regional system considering communication delays , 2005, IEEE Power Engineering Society General Meeting, 2005.

[15]  Khosrow Moslehi,et al.  Power System Control Centers: Past, Present, and Future , 2005, Proceedings of the IEEE.

[16]  A. Bose,et al.  Communication models for third party load frequency control , 2004, IEEE Transactions on Power Systems.

[17]  Yong He,et al.  Delay-dependent criteria for robust stability of time-varying delay systems , 2004, Autom..

[18]  P. Kundur,et al.  Power system stability and control , 1994 .

[19]  I. Hiskens,et al.  Simulation and optimization in an AGC system after deregulation , 2001, PICA 2001. Innovative Computing for Power - Electric Energy Meets the Market. 22nd IEEE Power Engineering Society. International Conference on Power Industry Computer Applications (Cat. No.01CH37195).

[20]  J. Wen,et al.  Delay-Dependent Stability Analysis of the Power System With a Wide-Area Damping Controller Embedded , 2011, IEEE Transactions on Power Systems.

[21]  K. Tomsovic,et al.  Application of linear matrix inequalities for load frequency control with communication delays , 2004, IEEE Transactions on Power Systems.

[22]  Quanyuan Jiang,et al.  Stability analysis of time delayed power system based on Cluster Treatment of Characteristic Roots method , 2008, 2008 IEEE Power and Energy Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century.

[23]  N. Peric,et al.  Discrete-Time Sliding Mode Control of Load Frequency in Power Systems with Input Delay , 2006, 2006 12th International Power Electronics and Motion Control Conference.

[24]  H. Bevrani,et al.  A control strategy for LFC design with communication delays , 2005, 2005 International Power Engineering Conference.

[25]  Lihua Xie,et al.  Further Improvement of Free-Weighting Matrices Technique for Systems With Time-Varying Delay , 2007, IEEE Transactions on Automatic Control.

[26]  H. Bevrani,et al.  On Load–Frequency Regulation With Time Delays: Design and Real-Time Implementation , 2009, IEEE Transactions on Energy Conversion.

[27]  Zhan Xu,et al.  Robust analysis and design of load frequency controller for power systems , 2008, 2008 IEEE International Conference on Control Applications.