Does a DC screen find the N-1 outages an AC power flow flags?

research/infra-n1screen

DC against AC N-1 screening on IEEE 14-, 30-, 39-, 57- and 118-bus cases (every line and transformer outage, modelled, ratings swept): at 25 % rating headroom the DC screen misses 13 to 40 % of the outages an AC power flow calls insecure; flagging at 0.8 of rating misses none, at the cost of 102 false alarms on case118 (186 outages).

7 tests

What it found

Operators screen N-1 security with a linear DC power flow. On pandapower's MATPOWER cases 14, 30, 39, 57 and 118, every line and transformer outage is solved as an AC power flow (truth: any other branch over its rating, a bus newly out of the 0.94–1.06 band, or non-convergence) and as a DC flow (screen). Ratings are a swept headroom over base-case flow, not taken from the cases. At 25 % headroom the DC screen misses 25, 17, 13, 40 and 14 % of insecure outages with almost no false alarms; flagging at 0.8 of rating misses none on any case but flags all 186 outages on case118 (84 truly insecure). Judging AC on MW alone cuts the miss rate (e.g. 14 to 12 % on case118, 40 to 20 % on case57), so reactive flow and voltage explain part. Checks: a closed-form 3-bus LODF case. Limits: base dispatch only (no redispatch), single outages, swept ratings (assumed), non-converged AC solves count as insecure, 20–186 outages per case. Modelled benchmark cases, not measured systems.

Paper, code and results

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Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.