Evaluation of Power System Response to Network Perturbations

Abstract

When a power system is subject to large network perturbations, the most fundamental questions in steady state analysis are (i) whether a solution for the perturbed load-flow problem exists and (ii) if so. what the system response to the perturbations is. Conventional load-flow based methods seek the solution of the power system nodal equation and hence represent a general approach to the problem. As an expected result, (i) the tests for existence of solution are impractical and conservative and (ii) the load-flow solution has to be obtained by iterative means. On the contrary, network-based methods, as presented here, are useful only for the study of the power system response to network perturbations. Their basis is a selected form of Tellegen's equation, rather than the system nodal equation. As a result, (i) the tests for existence of solution are simple and expeditious and (ii) the response is evaluated noniteratively.In this paper this alternative modelling of power systems subject to network perturbations is presented. This includes background review, formulation of the problem in the context of linear systems theory, testing for existence of load-flow solution, development of noniterative formulas, analysis of multiple solution regions, and presentation of illustrative numerical results.