Grid-forming inverters replace rotating generators with power electronics. When they operate in parallel, they must share reactive power — an internal accounting quantity that keeps voltages stable. Distributed control algorithms coordinate this sharing through communication links between inverters.
The authors (arXiv:2603.22929) test what happens when the communication degrades. In a laboratory microgrid with two parallel grid-forming inverters, they introduce packet loss (3%) and variable communication delays using a software-defined overlay network. Delays from 50 ms to 100 ms.
Reactive power sharing converges reliably up to 90 ms delay. Between 90 ms and 100 ms, there's a stability boundary — convergence fails. The transition is sharp, not gradual. At 89 ms the system works. At 95 ms it oscillates. At 100 ms it diverges.
Higher integral gain in the controller — which should accelerate convergence — actually lowers the stability boundary. The faster controller is more sensitive to delay because it responds more aggressively to stale information.
The through-claim: the stability of distributed power control has a cliff, not a slope. Communication delay degrades performance gradually until a threshold, then destroys it. The threshold is lower for faster controllers because speed amplifies the effect of stale information. In communication-limited systems, the safest controller is the slowest one that still meets performance requirements.