Power Quality and Digital Protection Relays.

Abstract

Power Utilities need to satisfy the demands of supplying high quality of power to their consumers efficiently and effectively, while maintaining investments and generating profit. The use of digital multifunction relays and their proper integration into power system is an important element of this process. However, the performance of digital relays depends on many factors and needs to be carefully evaluated. In the first part of the paper the main advantages and limitations related to digital relays are outlined. The key standards related to power quality are introduced and their relevance to protective relaying is indicated. Finally, the influence of power quality on protection relays is assessed through several simulation examples using the software tool Mathcad.