Robust Bayesian Regression Model of Centrality and Voltage Stability Index for Power Networks under Nodal Attack

Electrical node centrality for the power networks is an essential parameter to identify the critical nodes under attack. Topological analysis is vital for evaluating the network robustness while electrical characteristics have to be considered to make the analysis consistent for realistic power networks. However, the capacity limit of the power network changes under various nodal attacks. It is essential to find the relationship between the loading margin limit of the power network with the node centrality features, so that appropriate measures can be considered to improve the robustness of the power networks. Thus, voltage stability index (VSI) is defined for every node, and its centrality features are modelled. Robust Bayesian regression is used to model the nodes responsible for a change in loading margin and causing grid blackout. The method has been validated on benchmark complex power networks like reduced Great Britain network, IEEE 57-bus and IEEE 118-bus systems.

I. Introduction

Power grids are critical infrastructure in modern society. Extreme events or component failure can cause a widespread blackout or a massive service interruption in a large area causing severe socio-economic consequences [1]. In order to prevent power blackouts, it is essential to identify critical nodes and branches in the power network where network centrality measures with electrical and topological features are mainly used. Voltage instability of the power grid can cause a major blackout. As defined in [2], voltage stability is the ability of the power system to maintain its voltage such that, with the increase in load, both power and voltage are controllable. It is the ability to maintain steady-state voltage after subjected to a disturbance. As given in [3], in order to avoid voltage instability, weak buses or lines are needed to be improved by distributed generations or voltage supporting equipments. The Voltage stability index (VSI) helps in finding the weak nodes/links in the power networks [4], [5].