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substation-automation

Energy, industry and public infrastructure | substation-automation — protection and control in substations: protective relays (distance, differential), IEC 61850 GOOSE and sampled values, PTP time sync, bay controllers, station gateways to SCADA, secure engineering tools

SEL, Siemens SIPROTEC, Hitachi Energy, GE Vernova

SystemTechniques · 25Primitives · 93 substation-automation Clock synchronizationdistributed · medium: Estimate a clock's offset from four timestamps, filter out queueing noise, and steer the clock smoothly; NTP gets about a millisecond, PTP with hardware timestamps under a microsecond.›Deterministic simulation testingdistributed · medium: Run the whole system in one thread under a seeded scheduler with simulated network, disk and clock, so every failure replays from its seed.›Primary-backup replicationdistributed · medium: One node orders all writes and ships them to standbys; the acknowledgement rule (none, one, all) sets what a crash loses, and an external arbiter decides who takes over.›A/B partition updatesembedded · medium: Two bootable slots and a small atomic metadata block: write the new image to the idle slot, try it once, and fall back by itself unless it reports healthy.›Alarm managementembedded · medium: Turn raw process limits into a few actionable operator alarms with delay, deadband, acknowledge and shelving states, plus flood measurement.›Fault detection isolation recoveryembedded · medium: Monitor/response tables, fault isolation and safe-mode recovery hierarchies for autonomous systemsIndustrial network segmentationembedded · medium: Zones and conduits (IEC 62443/Purdue) with firewalls and protocol allow-lists for OTSecure boot chainsecurity · low: Each boot stage verifies the signature of the next before running it, anchored in an immutable ROM key hash, with version counters against downgrade and a TPM log of what ran.›Fixed-rate control loopembedded · low: Run a controller at an exact period using absolute deadlines and a fixed dt, so jitter never accumulates and the math stays valid.›X509 certificatessecurity · low: Certificate chains, path validation, SANs, revocation and short-lived issuanceAEAD (AES-GCM, ChaCha20-Poly1305)security · low: Authenticated encryption that encrypts and detects tampering in one call; the only kind of symmetric encryption you should use.›Hdr histogramdata-structures · low: Log-linear bucketed histograms with bounded relative error for latency percentilesDifferential protection restraintembedded · low: Differential relay with percentage restraint, harmonic blocking and CT saturation detection for trip decisionsDistance protection impedanceembedded · low: Distance relay: measure fault impedance from phasors and compare against mho or quadrilateral zones with timersDnp3 protocolembedded · low: DNP3 outstation/master protocol: event buffers, unsolicited reporting, time-stamped dataIec 61850 goose sampled valuesembedded · low: Ethernet publish/subscribe of trip signals and sampled analog values with retransmission and stNum/sqNumOpc uaembedded · low: OPC UA industrial protocol: address space, subscriptions and monitored items, security modesSynchrophasor estimationembedded · low: GPS-timed DFT phasor, frequency and ROCOF estimation in PMUsProcess supervisionhardware-os · low: A parent process starts services, reaps their exits and restarts them under a delay and burst-limit policy, then stops them with SIGTERM before SIGKILL.›Spline interpolationnumerics · low: Linear, bilinear/trilinear and cubic spline interpolation on grids and tablesMutual TLSsecurity · low: TLS where the client also proves a certificate key, so every connection carries a verified, rotatable machine identity.›Replay protection windowsecurity · low: A highest-seen counter plus a bitmap of the last W numbers rejects duplicates and stale messages in O(1) with a few hundred bytes of state.›IIR and FIR filterssignal-processing · low: Two ways to shape a sampled signal's spectrum: FIR (finite taps, always stable, exact linear phase) or IIR (feedback, a few coefficients, cheap but phase-distorting).›+ 18 more techniques+ 77 more primitives

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