A power system protection system consists, at least, of an instrument trans-
former, a protective device (relay), and a circuit breaker. Conventional instrument
transformers bring currents and voltages from power network levels to much lower
scaled-down replicas that serve as input signals to protective relays. The relay's function is to measure input signals (or a relationship among them in some cases) and
compare them to defined operating characteristic thresholds (relay settings) to quickly
decide whether to operate associated circuit breaker(s). Existing protection systems
within a substation are based on a hardwired interface between instrument transformers and protective relays. Recent development of electronic instrument transformers
and the spread of digital relays allow the development of an all-digital protection
system, in which the traditional analog interface has been replaced with a digital
signal connected to digital relays through a digital communication link (process bus).
Due to their design, conventional instrument transformers introduce distortions to
the current and voltage signal replicas. These distortions may cause protective relays
to misoperate. On the other hand, non-conventional instrument transformers promise
distortion-free replicas, which, in turn, should translate into better relay performance.
Replacing hardwired signals with a communication bus also reduces the significant
cost associated with copper wiring. An all-digital system should provide compatibility
and interoperability so that different electronic instrument transformers can be connected to different digital relays (under a multi-vendor connection) Since the novel all-digital system has never been implemented and/or tested in practice so far, its
superior performance needs to be evaluated. This thesis proposes a methodology for
performance and compatibility evaluation of an all-digital protection system through
application testing. The approach defines the performance indices and compatibility
indices as well as the evaluation methodology.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4941 |
| Date | 25 April 2007 |
| Creators | Portillo Urdaneta, Levi |
| Contributors | Kezunovic, Mladen |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 903585 bytes, electronic, application/pdf, born digital |
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