Longitudinal differential protection
US4855861A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 26, 1988 |
| Grant date | Aug 8, 1989 |
| Priority date | — |
| Expiry date | Oct 26, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H7/26
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The present invention comprises a longitudinal differential protective relay for protection and supervision of power line zones in a distribution system. The protective relays are located at each end of the zones that are desired to be monitored. One of the protective relays operates as a master for the other slave protective relays. A TRIP function indicating a line fault in any protected zone is performed by transmitting locally processed measured signals to the central protective relay which determines if and when any measure is to be taken. Each local protective relay comprises a measuring device, a filter and an A/D converter for phase currents and voltages. The digital signals are used to generate a truncated Fourier model of the measured signals in a parameter estimator which cooperates with a frequency estimator and a sampling regulator which, via a synchronization unit, ensures that sampling is performed simultaneously in all protective relays included in the protective system. In the parameter estimator the residuals of the phase quantities are also generated. Fourier components and residuals are supplied to a logic unit where local loss functions, based on the residuals,…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.