A separately scoped technical program for subsynchronous control interaction and related oscillatory behavior, with explicit data requirements, analysis methods, and report boundaries.
The protocol is designed around evidence supplied for a defined facility or corridor. Analysis may include frequency identification, damping assessment, mode comparison, signal-quality review, and event-window comparison where the required data support those methods.
Analysis is report-only by default. Plant writes or control-setting changes are excluded unless a separate signed change order identifies the existing setpoint and authorizes the specific work.
Review a defined event dataset and produce a technical report on identified oscillatory behavior, subject to data sufficiency and agreed scope.
Target delivery: 15 business days after usable PMU data is receivedA time-bounded corridor evaluation with agreed success criteria, report-only outputs, and a defined review point. The agreement states the metric and termination conditions.
90-day pilot · Agreed metric and kill clauseOngoing corridor watch following a paid pilot that is reviewed and formally qualified against its agreed metric.
Requires qualifying pilot and written reviewFor a usable oscillatory record, a modal component can be represented conceptually as x(t) = A eσt cos(2πft + φ). The real part σ describes exponential growth or decay while f describes the oscillation frequency. The protocol compares independent estimates rather than treating a single numerical fit as self-validating.
x(t) = A eσt cos(2πft + φ)Conceptual modal representation; not a compliance criterion.Illustrative only. Actual event plots use the supplied PMU record and the accepted analysis window.
Scope A can compare Prony and ESPRIT estimates and require agreement within 0.1 Hz for the stated modal frequency before the result is treated as a corroborated identification. Disagreement is reported rather than hidden.
A damping estimate can be expressed from the exponential term as ζ = −σ / √(σ² + ω²), where ω = 2πf. For this protocol, a damping value below 3% is a screening flag when the stated frequency, signal-quality, and window requirements are satisfied. It is not a universal stability threshold.
ζ = −σ / √(σ² + ω²), ω = 2πfScreening relationship used with the accepted method and data conditions.The stated screening conditions include a 5–55 Hz analysis band, SNR ≥ 6 dB, and persistence across two analysis windows. If those conditions are not met, the report identifies the result as data-limited or inconclusive rather than manufacturing certainty.
Conceptual comparison only; it does not represent a measured facility event.
Where multi-channel data permit it, the analysis can compare normalized channel participation and relative phase behavior. A mode-shape review is descriptive: it helps identify which measured channels move together or oppose one another and does not by itself establish causation.
Illustrative normalized participation. Actual mode characteristics depend on the supplied channels and method.
One-time event analysis establishes a documented baseline; the 90-day pilot evaluates an agreed corridor-specific measurement objective; annual corridor watch provides recurring analytical review after the pilot qualifies. A watch agreement defines observation cadence, data custody, alert criteria, periodic reporting, and escalation contacts. The annual service does not promise uninterrupted real-time monitoring unless the executed scope specifically provides it.
Establish measurement channels, time synchronization, data gaps, normal operating bands, network topology assumptions, and prior oscillation signatures.
Apply version-controlled event windows and quality gates; compare identified modes, damping estimates, and channel coherence against a documented baseline. Investigate recurring or materially changed modes.
Issue dated technical findings with data limitations, review disposition, and recommended follow-up study. Any mitigation recommendation remains advisory unless separately authorized.
The DEOCI protocol focuses on measured subsynchronous oscillation and controller-interaction evidence. Where the engineering question requires a broader study, DEOB may scope additional examinations with qualified third-party specialists under a separate written agreement. The catalog identifies established study families, not a claim that every method is currently performed internally or automatically included in SSCI pricing.
SSCI, subsynchronous resonance (SSR), and subsynchronous torsional interaction (SSTI) screening; frequency scanning; modal and eigenvalue analysis; impedance-based interaction studies; and time-domain electromagnetic transient (EMT) simulation. Torsional torque assessment requires appropriate shaft-train data and a specifically authorized model.
Transient and rotor-angle stability, small-signal stability, voltage stability, frequency-response studies, controller interaction, power-oscillation damping, and inverter-based resource model review. Methods and simulation platforms are chosen to match the validated study model and scope.
Steady-state power flow, short-circuit and contingency analysis, AC/DC and HVDC interaction, interconnection impact, protection coordination, power quality and harmonics, switching transient and insulation coordination, black-start and restoration feasibility, and model validation. Field tests, hardware-in-the-loop work, and commissioning require separately confirmed specialist resources.
Synchrophasor/PMU event reconstruction, spectral screening, Prony and ESPRIT modal estimation, damping trends, phase/coherence comparisons, channel-quality assessment, and repeatable corridor trend reporting. Findings are conditioned on usable measurements and documented uncertainty.
Each examination begins with a study question, asset and network boundary, data inventory, model provenance where simulation is involved, acceptance criteria, and a quality-control plan. Frequency-domain, eigenvalue, impedance-based, or time-domain methods are selected based on the physical mechanism and evidence available; they are not interchangeable substitutes.
Technical deliverables distinguish measured results from simulated outcomes, identify sensitivity to operating condition and model uncertainty, record software and model versions when relevant, and separate observed correlation from demonstrated causal mechanism. Mitigation options may include control tuning, network configuration, protection review, or additional instrumentation, subject to engineering validation and separate approval.
Original schematic showing study stages, not measured test results.
Study terminology is informed by established industry practice, including Siemens PTI system dynamics and transients studies and PTI Consulting study categories. DEOB is not Siemens PTI, does not claim affiliation or endorsement, and does not represent unverified vendor arrangements as executed partnerships. Applicable NERC, IEEE, IEC, utility, or ISO requirements are identified for each engagement rather than claimed universally.
No. A flag identifies behavior that meets the stated analytical screening conditions. Causation requires additional evidence and is limited by the accepted scope.
Independent methods provide a corroboration check. A disagreement is itself relevant evidence and should be documented rather than averaged away.
No. The standard program is report-only. Any plant write requires a separately signed change order naming the existing setpoint and authorizing the specific work.
No. It is a DEOB protocol screening flag when the stated data conditions are satisfied. It is not presented as a NERC or FERC requirement.
Analytical output is not, by itself, a determination of NERC or FERC compliance, certification, or permission to modify plant controls. Results depend on data quality, scope, and the stated method.
Review specialized testing and engineering studies available for quotation through DEOB and qualified external providers.
DEOCI focuses on defined disturbance and oscillation examinations. When findings call for additional apparatus testing, engineering review, or field measurement, DEOB can coordinate those separate scopes through its technical services framework.