Passivity-Based Pressure Control for Grid-Forming Compressors in Gas Networks.

An increase in local renewable gas production will necessitate gas outflows to higher pressure networks to achieve balancing in the future gas networks. We expand on traditional valve-based pressure regulation by introducing a grid-forming compressor unit. This unit incorporates a centrifugal compressor based on the Greitzer model and enables pressure regulation with bi-directional gas flows. Nonlinear controllers are proposed for the valves of the compressor unit, whereas a proportional-integral controller with damping injection is used for the centrifugal compressor. We provide scalar design inequalities for controller which ensure the controlled compressor unit is equilibrium-independent passive (EIP). By showing that the gas pipelines also EIP, we demonstrate the modular and topology-independent stability of the gas network equilibrium in which so-called prosumers may inject or extract gas at any node in the network. The controller and stability results are verified via simulations.