Discussion on: "Passivity and structure preserving order reduction of linear port-Hamiltonian systems using Krylov subspaces"

The port-Hamiltonian approach to modeling and control of complex physical systems has arisen as a systematic and unifying framework during the last 20 years. The port-Hamiltonian modeling captures the physical properties of the considered system including the energy dissipation, stability and passivity properties as well as the presence of conservation laws. Another important issue the port-Hamiltonian approach deals with is the interconnection of the physical system with other physical systems creating the so-called physical network. In real applications the dimensions of such interconnected port-Hamiltonian state-space systems rapidly grow both for lumped- and (spatially discretized) distributed-parameter models. Therefore an important issue concerns (structure preserving) model reduction of these high-dimensional models for further analysis and control.