A Nonlinear H-Infinity Control Approach to Stabilization of Distributed Synchronous Generators

Abstract

This paper proposes a new nonlinear H-infinity control method for stabilization and synchronization of distributed interconnected synchronous generators. At first stage, local linearization of the distributed generators’ model is performed round its present operating point. The approximation error that is introduced to the linearized model is due to truncation of higher-order terms in the performed Taylor series expansion and is represented as a disturbance. The control problem is now formulated as a min–max differential game in which the control input tries to minimize the state vector's tracking error while the disturbances affecting the model try to maximize it. Using the linearized description of the distributed generators’ dynamics, an H-infinity feedback controller is designed through the solution of a Riccati equation at each step of the control algorithm. The inherent robustness properties of H-infinity control assure that the disturbance effects will be eliminated and the state variables of the individual power generators will converge to the desirable setpoints. The proposed method, stands for a reliable solution to the problem of nonlinear control and stabilization for interconnected synchronous generators. It is also a novel approach, comparing to control of synchronous generators based on global linearization methods. Its efficiency is further confirmed through simulation experiments.