New Approach to Hierarchical Decomposition of Large-Scale Systems

摘要

Several techniques have been proposed for control of large-scale systems (LSSs) by decomposing them into a hierarchy of coordinators and subsystems. A disadvantage common to those methods is that they require iterative solution of the coordinator and subsystem controller equations. The technique presented in this paper results in a noniterative scheme for near-optimal control of both linear and nonlinear large-scale systems. In this approach, the role of the coordinator module is that of a supervisory controller whose task is to establish the strategy for distributing the overall system demands among each of the subsystems according to their performance and plant status. Each subsystem's controller relies on optimal control algorithms based on uncertain dynamics methods. The solution to each subsystem's optimal control problem is based on Pontryagin's Maximum Principle and the time reversal paradigm for free terminal-time problems. This approach transforms the two-point boundary value problem into an initial value problem, which permits integration of both the state and adjoint equations forward in time. Results obtained on the application of the technique to the power system originally discussed shows good agreement between the decomposed controller and the corresponding centralized optimal controller. In addition, each of the two subsystems' controllers synthesized correctly the dynamics of the two coupling state variables whose contribution to the subsystem model equations was replaced with unknown terms. 5 refs., 6 figs. (ERA citation 14:004443)