Stability Analysis of Low-Inertia Power Systems with Grid-Forming Battery Energy Storage

Grid-forming (GFM) battery energy storage systems (BESS) are expected to stabilize power systems in which inverter-based resources (IBRs) displace synchronous generators, but their effect on frequency, small-signal and transient stability is rarely examined together. This paper maps these three aspects over the plane of IBR share λ and GFM fraction γ on a Kron-reduced two-area model, complemented by a current-limited single-machine study. With grid-following IBRs only, the local 100 ms RoCoF rose from 0.60 to 3.73 Hz/s as λ increased to 90 %, while the 500 ms RoCoF and the nadir hardly changed. Keeping it below 1 Hz/s required γ ≥ 50 % for λ = 50–70 % and γ ≥ 62.5 % for λ = 80–90 %. GFM units add a 2.5 Hz mode whose frequency and damping are independent of λ and γ and follow closed-form expressions (errors ≤ 2.1 % and ≤ 0.9 %); reaching ζ = 0.1 requires a virtual damping above 25.8 p.u. A 1.2 p.u. current limit reduced the critical clearing time from 518 to 209 ms, below that of an equivalent synchronous generator, while a saturation-triggered power-reference adaptation restored stability for faults of up to 2 s in all but the least-damped case.

Hali tarjima qilinmagan