Justifying pilot protection on transmission lines
Bibliographic record
Abstract
Pilot protection schemes use communication channels to send information from the local relay terminal to the remote relay terminal, thereby allowing high-speed tripping for faults occurring within 100% of the protected line. This document is intended as a tool for protection engineers to assist in determining when pilot protection should be installed for transmission line protection, in addition to a communications independent system. The emphasis is not on which pilot scheme to use, but rather if pilot protection is necessary. (Note: The document does not purport to provide a comprehensive list of all considerations that may be used in making this determination or in determining redundancy requirements.) It is evident that it would be less expensive to only install non-pilot step-distance protection since no communication equipment would be necessary (estimates as high as $150K per terminal for the addition of pilot protection). It is prudent to provide engineering considerations that would aid in justifying the installation and future maintenance costs. This report explores this issue by providing the following: (i) Considerations to determine the need for, and benefits of, pilot protection such as high-speed reclosing, improved system stability and power quality, easier coordination, better resistive coverage, and regulatory issues. (ii) Alternatives to pilot protection and fall back strategies when the channel is lost or degraded, or when temporary configurations are entered. Options include stepped distance, ground inverse time overcurrent, Zone 1 extension, and taking the line out of service. (iii) Considerations to determine pilot system redundancy for a given application depending on the voltage level, regulatory issues and economics, role of voting schemes and redundant channels, dependability vs. security, etc.
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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 | 0.007 | 0.037 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.002 | 0.003 |
| Scholarly communication | 0.003 | 0.004 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.004 | 0.003 |
| Insufficient payload (model declined to judge) | 0.009 | 0.002 |
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".