Congestion Calculator — methodology

1. Dispatch reconstruction (C1) — the SRMC merit order is walked up to the metered national residual load to estimate which units run each 15 minutes.
2. Bus injection (C2) — generation is allocated to network buses and load to buses via postcode-consumption weights → net injection per bus.
3. DC load-flow (C3) — a pandapower DC solve yields per-line flows; each bus’s max_loading_pct is the worst |flow| / s_nom across its incident lines and transformers. ≥ 100% = a binding constraint.
4. Area rollup (CC1) — buses are mapped to areas through the gold postcodes.tennet_id → network_buses chain, and the per-bus stress is aggregated to the worst and median loading%, plus counts over the 85% and 100% thresholds.

Three grains are exposed: PC4 (postcode block — what a developer types), voedingsgebied (the capaciteitskaart unit, the natural calibration grain), and province (the coarse rollup). Each resolves to the TenneT bus(es) feeding it.

• Stressed — a bus at ≥ 85% loading (approaching its limit).
• Binding — a bus at ≥ 100% (a branch at or over its thermal rating).
• An area is flagged congested when its worst bus is binding.

Classification-grade, not metering-grade: roughly 75–85% right on “is this area stressed?”, with ±20–30% on the absolute loading%. Suitable for screening, scorecarding, research and journalism — not real-time operations, N-1 contingency, or bankable guarantees.

Three caveats inherited by every number:

• One bidding zone. The Netherlands is a single price zone, so wholesale/imbalance prices carry no locational signal. This congestion is inferred from a physics model on metered load + the merit order — not from prices.
• Line ratings (gap G1). Loadings use class-level thermal ratings per voltage tier, not per-asset nameplate values, so the absolute percentage carries error. Per-circuit ratings (TenneT IP2026) are a follow-up.
• HV ceiling (gap G6). The model stops at the HV grid feeding each area. Most MS/LV-feeder congestion a connection queue hits is below this layer and is not captured dynamically.