A Framework for Robust Steady-State Voltage Stability of Distribution Systems

TL;DR

This paper introduces a fast, reliable method for approximating the long-term voltage stability regions in distribution systems, aiding in assessing system robustness amid renewable energy variability.

Contribution

The paper presents a novel approach for constructing inner approximations of voltage stability regions that outperform existing methods and cover significant portions of true stability areas.

Findings

Outperforms existing inner approximation methods

Constructed regions cover large fractions of true stability regions

Enables fast screening and loadability assessment

Abstract

Power injection uncertainties in distribution power grids, which are mostly induced by aggressive introduction of intermittent renewable sources, may drive the system away from normal operating regimes and potentially lead to the loss of long-term voltage stability (LTVS). Naturally, there is an ever increasing need for a tool for assessing the LTVS of a distribution system. This paper presents a fast and reliable tool for constructing \emph{inner approximations} of LTVS regions in multidimensional injection space such that every point in our constructed region is guaranteed to be solvable. Numerical simulations demonstrate that our approach outperforms all existing inner approximation methods in most cases. Furthermore, the constructed regions are shown to cover substantial fractions of the true voltage stability region. The paper will later discuss a number of important applications of the proposed technique, including fast screening for viable injection changes, constructing an effective solvability index and rigorously certified loadability limits.