A. A. Fouad

On-line power system security analysis

A broad overview of on-line power system security analysis is provided, with the intent of identifying areas needing additional research and development. Current approaches to state estimation are reviewed and areas needing improvement, such as external system modeling, are discussed. On-line contingency selection has become practical, particularly for static security. Additional work is necessary to identify better indices of power system stress to be used in on-line screening filters for both static and dynamic security analysis. Use of optimal power flow schemes to recommend optimal preventive and corrective strategies is presented on a conceptual level. Techniques must be further developed to provide more practical contingency action plans, which include real-world operating considerations and use a reasonably small number of control actions. Techniques must be developed for costing operating variables which are not easily quantified in dollars. Soft or flexible constraints and time variables must be included in the preventive and corrective strategy formulation. Finally, the area of on-line transient and dynamic security analysis is presented. >

The transient energy function method

Abstract The status of the transient energy function (TEF) method of direct analysis of transient stability of power systems is reviewed. The mathematical model is presented; an elementary theoretical basis of the method is introduced; the procedure for using the method in assessing power system transient stability is outlined; and the present condition of the technique and the available computer program is given. The outstanding issues, current development work and new applications are then summarized.

Direct transient stability assessment with excitation control

The authors extended the applicability of the transient energy function method by incorporating the exciter effects in the energy of a multimachine power system during the first swing transient. The generator was represented by the two-axis model and the exciter was represented by one gain, one time constant, and one limiter. In this study they compute the parameters of the extended transient energy function, which assumes a constant average internal EMF. The critical value of this transient energy is determined. A procedure for its use in transient stability assessment has been developed and successfully applied to fault disturbances in two test networks. >

Local approximation of stability boundary of a power system using the real normal form of vector fields

The objective of this work is to approximate the stability boundary of a power system without any integration using the normal form of the vector fields. This involves two steps: (1) first to test which unstable equilibrium point (UEP) lies on the stability boundary, and (2) the second step is to approximate the boundary by the second order approximated manifolds. The approximation is accomplished using the normal forms of vector fields. The stability boundary and its behavior under stressed system conditions are examined. The method is applied to an eleven-generator test system.

Conventions for Block Diagram Representations

Although the use of block diagrams to represent various systems is very widespread, there are no standard conventions for the drawing of block diagrams. This is particularly true when such diagrams are used to represent complex nonlinear systems, and most practical systems of interest are of this type. The purpose of this paper is to suggest an approach to the drawing of clearly understandable block diagrams. In the process certain conventions are suggested.