Electricity: electrical systems and devices – Safety and protection of systems and devices – Feeder protection in distribution networks
Patent
1988-10-26
1989-08-08
Deboer, Todd E.
Electricity: electrical systems and devices
Safety and protection of systems and devices
Feeder protection in distribution networks
361 79, 361 81, 324512, 324522, 364483, H02H 726
Patent
active
048558613
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, are compared with set threshold values for evaluation of whether an abrupt event in the network has occurred.
REFERENCES:
patent: 4148087 (1979-04-01), Phadke
patent: 4261038 (1981-04-01), Johns et al.
patent: 4719580 (1988-01-01), Nimmersjo 324512
J. Esztergalyos, D. C. Erickson and J. N. Andres, Proceedings of the American Power Conference; Apr. 24-26, 1984; Chicago; the Application of Synchronous Clocks for Power System Fault Location, Control and Protection; pp. 437-447.
W. S. Kwong et al., IEE Power System Protection Conference; Apr. 1985; London; A Microprocessor-Based Current Differential Relay for Use with Digital Communication Systems; pp. 65-69.
Yamaura et al., IEE Power System Protection Conference, Mar. 1980; London; FM Current-Differential Carrier Relaying; pp. 156-160.
Aggarwal et al., IEE Power Protection Meeting; Apr. 1985; London; High Speed Differential Protection of Teed Circuits using Wideband Communication Techniques; pp. 60-64.
Bergman Sten
Ljung Stefan
Asea Brown Boveri AB
Deboer Todd E.
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