Information Structures in AC/DC Grids

TL;DR

This paper explores the topological and information structure properties of AC/DC grids, revealing how control inputs couple states across boundaries and enabling tractable decentralized control solutions.

Contribution

It demonstrates that AC/DC grids inherently possess poset-causal information structures, facilitating decentralized control design, and characterizes special cases like multi-terminal DC grids.

Findings

States on either side of converters are coupled only by control inputs.

AC/DC grids have poset-causal information structures.

Multi-terminal DC grids exhibit coordinated and leader-follower structures.

Abstract

The converters in an AC/DC grid form actuated boundaries between the AC and DC subgrids. We show how in both simple linear and balanced dq-frame models, the states on either side of these boundaries are coupled only by control inputs. This topological property imparts all AC/DC grids with poset-causal information structures. A practical benefit is that certain decentralized control problems that are hard in general are tractable for poset-causal systems. We also show that special cases like multi-terminal DC grids can have coordinated and leader-follower information structures.