IEEJ Transactions on Power and Energy
Online ISSN : 1348-8147
Print ISSN : 0385-4213
ISSN-L : 0385-4213
Special Issue Review
Recent Technology of the Protection System
Takashi Nagasawa
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2003 Volume 123 Issue 9 Pages 1026-1029


The protection relay changed from electromechanical or analog static type to digital type using the progress of microprocessor against the growth of power network. The digital relay improved protective performance and reliability based on establishment of various protection schemes and the embedded automatic supervising function using the development of the digital technique. Additionally, the recent protection system technique enable to make the configration and operation of power system efficient. Multi-terminal transmission lines can be realized by use of PCM current differential relay. The out-of-step protection, the voltage stability control and the over load failure extension protection can increase transmission capacity.
In future, it will need to develop the protection system for the distributed power generation and decrease the cost of protection systems against the progress of deregulation.

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© 2003 by the Institute of Electrical Engineers of Japan
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