Paradigm and Paradox in Topology Control of Power Grids

TL;DR

This paper investigates topology control in power grids using line switching to improve reliability and reduce costs, comparing heuristic methods and highlighting the effectiveness of locally optimal strategies.

Contribution

It provides a comparative analysis of heuristic algorithms for topology reconfiguration, emphasizing the potential of locally optimal switches to approximate global solutions.

Findings

Globally greedy heuristic reduces costs but is computationally intensive.

Locally optimal switches better approximate global solutions.

Heuristics vary in performance depending on grid topology.

Abstract

Corrective Transmission Switching can be used by the grid operator to relieve line overloading and voltage violations, improve system reliability, and reduce system losses. Power grid optimization by means of line switching is typically formulated as a mixed integer programming problem (MIP). Such problems are known to be computationally intractable, and accordingly, a number of heuristic approaches to grid topology reconfiguration have been proposed in the power systems literature. By means of some low order examples (3-bus systems), it is shown that within a reasonably large class of greedy heuristics, none can be found that perform better than the others across all grid topologies. Despite this cautionary tale, statistical evidence based on a large number of simulations using using IEEE 118- bus systems indicates that among three heuristics, a globally greedy heuristic is the most computationally intensive, but has the best chance of reducing generation costs while enforcing N-1 connectivity. It is argued that, among all iterative methods, the locally optimal switches at each stage have a better chance in not only approximating a global optimal solution but also greatly limiting the number of lines that are switched.