Grid-forming wind turbine architecture with time-layered hybrid storage for frequency support in converter-dominated power systems

• Unified grid-forming control integrates hybrid storage in one active-power path. • Layered SC–FW–LiB coordination improves RoCoF, nadir and frequency recovery. • Ramp-limited power channel preserves stable voltage-source behaviour. • Architecture remains robust across SCR variations without retuning. • Energy contribution of each storage tier quantified over fast and sustained windows. Converter‑dominated and low‑inertia power systems are prone to sharp frequency excursions after large disturbances, especially when grid‑forming capability is required. This work presents a wind‑turbine architecture that integrates a virtual synchronous machine with droop control and a time‑layered hybrid storage system combining a supercapacitor, a flywheel and a lithium‑ion battery. The three storage tiers are coordinated through a single ramp‑limited active‑power reference, while event‑driven gates based on RoCoF, absolute frequency deviation and a short delayed state‑of‑charge window for the lithium‑ion tier distribute injections coherently across complementary time scales. A detailed time‑domain model of a 5‑MW turbine is used to evaluate the architecture under a 10% generation‑loss event in a converter‑dominated system with an SCR of approximately 5. The results show a consistent improvement as storage layers are added: the nadir rises from 48.25 to 49.55 Hz, the maximum absolute RoCoF decreases from 1.25 to 0.30 Hz/s, and sustained re-entry into the ± 0.2 Hz compliance band occurs within 5 s. The temporal partitioning reduces lithium‑ion battery stress and yields predictable interactions among fast and slow storage devices in grid‑forming operation, supporting the applicability of the approach in multi‑device scenarios governed by droop‑based sharing.