On-Line Setting of Digital Distance Protections in a Distribution Power Network Using an Expert System

J.M. Beir?o Andrês, Zita A. Vale, and J.A. Dias Pinto (Portugal)


Distribution Network, Digital Distance Protections, Expert System


Traditionally electromechanical and static relays have been applied successfully to the protection of electric power networks. In the last years digital relays based on microprocessor technology and in the new developments in high-speed communication links have been progressively used since they can easily make adjustments to various protection functions in order to make them more attuned to prevailing power system conditions. The effective parameterisation of these numerical relays, which ensures the best possible exploration of their advantages, requires depth knowledge of the power system configuration as well as the actual power system state operation. In this paper it is presented a new methodology for on-line setting of the adaptive distance relays in a distribution power network using an expert system developed by the authors. The study was carried out in a 60 kV Portuguese distribution power network. Different load levels were considered. For each one the optimal configuration was obtained and the adaptive distance relays were set accordingly. If a line outage occurs then the expert system automatically adjusts the parameters of the relays taking into account the new network topology. Finally, some conclusions that provide a better understanding of the on-line application of the digital distance relays are pointed out.

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