Produces a simplified 0-100 Stability Index for a proposed islanded microgrid, combining three factors commonly cited as first-order drivers of islanded stability: how much generation headroom exists above the load, how much rotational/synthetic inertia the system has, and the planned operating reserve margin. This is a first-pass screening indicator to flag obviously under-resourced designs early — it is explicitly not a substitute for a real dynamic (small-signal or transient) stability study.
Standards followed
Simplified composite screening heuristic: Index = 40×min(1,(supportRatio−1)/0.5) + 30×min(1,inertiaFactor) + 30×min(1,marginPct/20) — a screening model, not a literal power-system dynamics calculation
What it can do
- Source support ratio (dispatchable generation capacity ÷ load) and headroom score.
- Inertia score from a normalized 0-1 system inertia factor.
- Reserve margin score from planned operating reserve percentage.
- Composite Stability Index with an UNSTABLE→ROBUST classification.
Example problem
1200kW dispatchable generation capacity, 800kW load, inertia factor 0.6, 15% reserve margin.
- Support ratio = 1200/800 = 1.5 → headroom score = 40×min(1,0.5/0.5) = 40
- Inertia score = 30×0.6 = 18
- Margin score = 30×min(1,15/20) = 22.5
- Index = 40+18+22.5 = 80.5
Stability Index ≈80.5 — STABLE band.
This is a deliberately simple composite heuristic for early-stage screening, not a substitute for real islanded-microgrid dynamic studies (frequency/voltage transient response, protection coordination, grid-forming vs grid-following inverter control interactions, and black-start sequencing). A design that scores well here can still fail a detailed dynamic study, and vice versa — use this only to flag obviously under-resourced concepts before committing to detailed engineering.