Coordinated adaptive controllers for single and multimachine power systems

The speed governor and excitation control functions are rarely incorporated into existing power plant computer control structures. However, current research trends indicate a growing interest in the integration of these functions into the computer control hierarchy. To this end, several control schemes have been proposed for replacing the main governor and excitation control functions as well as the conventional Power System Stabilizer (PSS) with on-line controllers at the generating unit level. This dissertation presents some digital PSS design techniques for single and multimachine power systems suitable for easy integration into the power system control hierarchy at the generating plant level. Two adaptive PSS design algorithms are presented; algorithm #1 is formulated in continuous-time and based on the Decentralized Model Reference Adaptive Control concept using Lyapunov function methods. Algorithm #2 is based on a discrete-time Adaptive Model-Following Control (AMFC) scheme using the hyperstability conditions. A scheme for implementing the proposed controllers in typical power system control hierarchies is also described.; The effectiveness of the proposed techniques is demonstrated on single-machine and multimachine power systems using computer simulation studies. Results obtained show that an improvement in the overall system damping characteristics is obtained using the proposed adaptive controllers in comparison to those of other digital controllers.