Whole-System First-Swing Stability of Inverter-Based Inertia-Free Power Systems

TL;DR

This paper demonstrates that inverter-based, inertia-free power systems can achieve extended first-swing stability through fast primary control, challenging traditional reliance on inertia for grid stability.

Contribution

It introduces a decentralized approach to extend first-swing stability in inertia-free systems, supported by mathematical proof and IEEE 68-bus system simulations.

Findings

Extended stability region surpasses classic inertia-based criteria

Decentralized control ensures stability across all modes and timescales

Impacts on frequency stability can be effectively mitigated

Abstract

The emphasis on inertia for system stability has been a long-held tradition in conventional grids. The fast and flexible controllability of inverters opens up new possibilities. This paper investigates the {first-swing stability} of inverter-based inertia-free power systems. We illustrate that by replacing inertia with fast primary control (i.e. inertia-free), the first-swing stability region is greatly extended compared to the classic equal area criterion of inertia-rich systems. The extended stability region is fully decentralised and ensures whole-system stability for all swing modes across all timescales and interaction boundaries in a complex grid. The removal of inertia has impacts on frequency stability but these impacts can be well mitigated. The findings of the paper are proved mathematically and verified by simulation on the IEEE 68-bus system.