Detection and properties of voltage impasse regions in the presence of nonlinear static loads

Abstract

This paper introduces a generic method for detection of Voltage Impasse Region(s) (V IR) that may appear when power system dynamics are represented by a set of differential algebraic equations. The recently introduced V IR denotes a singular area where voltage causality is lost due to the nonlinear modelling of static loads. Yet, the existing analytical study can predict V IR when only one load is of nonlinear type. To detect V IR for multiple nonlinear static (or ZIP) loads in a more general sense, this paper proposes an idea of a quasi-dynamic approach that maps the state-space. The newly introduced method assigns a discrete index V IR flag to each inspected state-space location and estimates V IR based on V IR flag values. By deploying the developed approach, this study structurally analyses the impact that various load nonlinearities have on V IR. As such, the paper is primarily of educational character and it thoroughly examines (and visualizes) the features of V IR by using IEEE-9 bus test system. The new method retains the accuracy of the analytical approach while becoming fairly general. Moreover, the performed study demonstrates that the cumulative amount of nonlinear load appears to be the most influential contributor to V IR existence and size.