Cyber-Security Constrained Placement of FACTS Devices in Power Networks From a Novel Topological Perspective

Hossein Parastvand,Airlie Chapman,Octavian Bass,Mohammad A S Masoum,Stefan Lachowicz

doi:10.1109/access.2020.3001308

Abstract

Optimal placement of flexible AC transmission systems (FACTS) devices and the cyber-security of associated data exchange are crucial for the controllability of wide area power networks. The placement of FACTS devices is studied in this paper from a novel graph theoretic perspective, which unlike the existing approaches, purely relies on topological characteristics of the underlying physical graphs of power networks. To this end, the maximum matching principle (MMP) is used to find the set of required FACTS devices for the grid controllability. In addition, the cyber-security of the most critical data related to the FACTS controllers is guaranteed by introducing the concept of moderated- $k$ -security where $k$ is a measure of data obscurity from the adversary perspective. The idea of moderated- $k$ -symmetry is proposed to facilitate the arrangement of the published cyber graph based on a permutation of nodes within the symmetry group of the grid, called generator of automorphism. It is then verified that the published cyber-graph can significantly obscure the data exchange over the cyber graph for adversaries. Finally, a similarity is observed and demonstrated between the set of critical nodes attained from the symmetry analysis and the solution of the FACTS devices placement that further highlights the importance of symmetry for the analysis and design of complex power networks. Detailed simulations are applied to three power networks and analyzed to demonstrate the performance and eligibility of the proposed methods and results.

Highlights

The imbalance between reactive power at the generating side and the network demand causes voltage instability
A TOPOLOGICAL APPROACH TO THE PLACEMENT AND CONTROL OF flexible AC transmission systems (FACTS) DEVICES IN POWER NETWORKS we look at the placement of FACTS devices from a controllability perspective
As the network size increases, the proposed approach is more effective since the typical network symmetry group is bigger and the nodes with maximum multiplicities in generators of automorphisms are more effective in determining the number of required FACTS devices

Summary

INTRODUCTION

The imbalance between reactive power at the generating side and the network demand causes voltage instability. An analytical approach for the placement of FACTS controllers is proposed based on the topological characteristics of the network which does not suffer from the computational issues To this end, the maximum matching principle is implemented which is a mechanism to find the set of unmatched nodes that are considered as the set of driver nodes which are able to drive the states of system from any initial state to any desired state in reasonable time (network controllability). This study proposes an approach to secure the critical elements of power networks via obscuring the published graph of the grid and, in turn, reducing the chance of distinguishing and manipulating the critical data of FACTS devices by adversaries. The cyber-security of the critical data of the network including the data exchange between FACTS controllers is addressed in section III using the concept of symmetry groups. The symmetry elements, including Aut(G) and Gen(G), are computed in Sage (System for Algebra and Geometry Experimentation)

CN CONTROLLABILITY IMPLICATIONS FOR PLACEMENT OF FACTS DEVICES

DEFINITIONS AND PROPOSED THEOREMS

PROPOSED ALGORITHM FOR LOCATING AND SECURING CRITICAL FACTS DEVICES

CONCLUSION