Harmonic content of the synchronous generator stator current in the case of unit transformer saturation due to geomagnetically induced currents
Bibliographic record
Abstract
The study investigates the features of the operation of off-the-grid power systems. Such power systems are commonly used for supplying power to consumers spread throughout the Arctic zone of the Russian Federation, and their unique operating conditions are due to the effect of geomagnetically induced currents (GICs) resulting from geomagnetic disturbances. We argue that the cause of stator current deviations from the pure sine wave are unit transformers. Their low-voltage windings are directly connected to stator windings of synchronous generators, and GICs run through grounded high-voltage windings. To support our claim, we simulated the effect of a test GIC event. Its amplitude in each of high-voltage phase windings of the unit transformer was 100 A, and the duration was 20 seconds (power transformers of the Hydro-Québec power grid were exposed to geomagnetically induced currents of a similar intensity during the geomagnetic storm on March 13-14, 1989). The spike targeted the "generator (TVF-100-2) - transformer (TDTs-125000/220/10.5)" unit that fed a major consumer node (Рnom = 83.125 MW, Qnom = 29.75 Mvar, cosφ=0.95) through a 160 km long double-circuit overhead line. Our study demonstrated that the effect of GICs on the operation of synchronous generators started from the moment of saturation of the unit transformer's core due to the inverse transformation of magnetizing current harmonics in the stator winding circuit. The harmonics introduced significant deviations from the pure sine wave into the curve of instantaneous stator currents. We calculated the nonlinear distortion factor of the stator current, which reached an unacceptably high value of THD=55.59%, 10 seconds into the test GIC event. The study showed that the 2nd and 4th harmonics of the unit transformer magnetizing current were responsible for the great bulk of deviations from the pure sine wave of the stator current.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".