18. Real-time, distribution and dynamic estimation

The estimation estate beyond the static transmission WLS of ch. 6 - the layered build-out toward a real-time state estimator for renewable grids. Everything here is governed by UnderstandingRestrictions.md: state estimation is a filter (it resolves the present/past from observations), never forward inference; the 169 h horizon guard (ch. 8) stands at every dated ingester; and any fusion of Dynamics/ into Estimation/ passes the review gate (RestrictionReview, mirrored by restriction-review-log.md).

Detailed design specifications live under docs/technical/design/. This chapter is the map.

18.1 Real-time engineering

• Simulation/RealtimeEstimatorEngine / RealtimeDseEngine - resident streaming estimators over guard-permitted-age or replayed windows; warm-started, resilient, deterministic.
• Per-state covariance diag(G^-1) -> per-bus 1-sigma bounds on EstimationResult.
• Host surfaces: CLI serve, Web RealtimeEstimatorHostedService + ReplayDirectoryWindowFeed.

18.2 Dynamic State Estimation (Estimation/Dse/)

EKF / UKF / EnKF network-state trackers and a frequency/RoCoF Kalman filter, behind an IProcessModel seam (random-walk persistence by default). Each is gate-registered; RoCoF-as-a-state is the Blue-Cut-relevant capability. See [design/three-phase-dsse.md] context and the review log.

18.3 Robust estimation & bad data

EstimationMethod.SchweppeGm (leverage-adjusted Huber), ProjectionStatistics (masking-immune leverage), HypothesisTestingBadData (HTI for interacting errors). See design/robust-gm-leverage.md.

18.4 Numerics

EstimationMethod.Qr / QrWlsStep (orthogonal, avoids the normal equations, Numerics/HouseholderQr); correlated 2x2 block-R in the linear PMU estimator; the new IMagPu / IAngDeg measurement kinds.

18.5 Distribution / unbalanced three-phase (Distribution/)

Per-phase MultiPhaseModel, ThreePhaseSweep power flow, SymmetricalComponents, the node-voltage ThreePhaseWlsEstimator (with robust WLAV) and the BranchCurrentDsse, SequenceFaultStudy (3-phase/SLG/LL/LLG), TransformerConnectionModel, and pseudo-measurements. See design/three-phase-dsse.md.

18.6 Synchrophasor / PMU (Synchrophasor/)

IEEE C37.118.2 decoder + CONFIG-2 parser, PhasorDataConcentrator, PmuMeasurementSetMapper, the LinearPmuStateEstimator, and the hybrid multi-rate scheduler. See design/c37118-synchrophasor.md.

18.7 Security & assurance

Estimation/Security/FdiaScreen (physics audit as an FDIA detector), Diagnostics/AuditLog (hash-chained) + EstimationAuditTrail. Assurance docs: caf-mapping, nis-oes-gap-assessment, rbac-sbom-secrets-notes.

18.8 Standards & interop

IO/Cim/ - CIM/CGMES import/export + CimGridModelBridge (ohm->pu via BaseVoltage); see design/cim-cgmes-mapping.md. IO/Telemetry/ - frame codecs for IEC 60870-5-104, DNP3 and IEC 61850 GOOSE, and (IEC-104/Modbus) their object-model decoders. The live ingest path built on these - the interpose verb, correction pipeline, crosswalk and quarantine sink - is ch. 20 (The RTU/SCADA interposer).

18.9 Solver breadth

Analysis/ContinuationPowerFlow (loadability margin) and Analysis/AcOptimalPowerFlow (loss-aware AC-OPF).

See the 0.19.0 entry in CHANGELOG.md for the full itemised list.