Local Performance Indices Research Articles

Locally optimal-digital redesign of continuous-time systems

The authors present a novel optimal digital redesign technique for finding a dynamic digital control law from the given continuous-time counterpart by minimizing a local quadratic performance index. The quadratic performance index is chosen as the integral of the weighted squared difference between the states of the original closed-loop system and those of the digitally controlled open-loop system at any instant between each sampling period. The developed optimal digital redesign control law enables the states of the digitally controlled open-loop system to match closely those of the original closed-loop system at any instant between each sampling period, and it can easily be implemented using microcomputers with a relatively large sampling period. An illustrative example is presented to demonstrated the effectiveness of the proposed method. >

Evaluation of a local DC load flow screening method for branch contingency selection of overloads

The author presents a novel screening method, involving a local DC solution, for branch flow limit violations (overloads) which, when incorporated with a performance index (PI) method, can greatly enhance the selection capabilities for online as well as study purposes. The local DC screening method and PI method are compared to results obtained from a full-system DC load flow assessment of two cases: a 24-bus system and a 584-bus representation of the Mid-Continent Area Power Pool system. The results indicate that, when these two methods are combined, excellent contingency selection capabilities are produced. The philosophy for this implementation and the details needed to implement the local DC screening method are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Computer Aided Design of Multi-Level Systems with Prescribed Structure and Control Constraints

In this paper two hierarchical control algorithms (P and PI) for linear discrete-time interconnected systems are presented. At the first level minimization of local performance indexes is done and at the level 2 - coordination, based on a gradient procedure. The algorithms presented satisfy constraints impased on the control components. They are convinient for two level microprocesors based control systems. Computer programs are developed for computer aided design of subcontrolers parameters and coordination.

Coordination and Sensitivity Analysis of a Large Scale System with Performance Interaction

A large scale system structure is considered for the case where the performance functional is not a simple sum of local performance indices. A decomposition method of the large scale problem consists of modifying the local performance functionals according to the global performance requirements.The large scale problem and its decomposition are formulated in Hilbert space; a formulation as a control problem is also presented as an example of possible detailed formulations. The properties of the decomposed problem are investigated. A new method of coordination based on an alternative approach to the variable operator method in Hilbert space is described; the basic properties of the method are analysed. A special feature of the variable operator method is stressed, which makes it possible to apply the method to large scale problems.The variable operator method is also useful in evaluating the sensitivity of the large scale structure to the coordination variables. A general discussion of sensitivity properties of large scale systems is also included. The large scale system structure and the method of evaluating its sensitivity can be of particular interest when applied to environmental control.