M. Mesić, S. Tenjak, and S. Skok (Croatia)
Auxiliary DC installation, failure, reliability and security
Due to failures of auxiliary DC installations outages of power plants and substations and degradation of reliability and security of power system in the past occurred. The auxiliary DC installation in switchyard has been calculated based simplified stationary model. New standard 61660-1 had been published 1997 and it was significant improvement of conditions related to dimensioning and analyzing auxiliary DC installation. That standard related to calculation of short circuit current took into account not only resistances, but inductances and capacities of all auxiliary DC installation components as well as the active alternative current network in front of the rectifier. In the past it was recorded numerous failures of auxiliary DC installation and it was reason for reconstruction of the most jeopardized DC subsystems. After reconstructions old and nonselective existing auxiliary DC installations and construction of DC subsystems in new switchyards respected of new criteria and IEC 61660-1 reliability and security of these switchyards and whole power system had been improved. However standard IEC 61660-1 should be changed from the reasons of new technology of components and new input data relevant for correct dimensioning and analyzing of auxiliary DC installation.
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