On Power Quality and Protection by

This project combines knowledge from the power quality field and the protection field. The concept of power quality is extended to the terminals of the protective relay. Disturbances in voltage and/or current, not due to a fault in the zone-to-be-protected, may lead to an incorrect trip of the relay. This phenomenon has been known for a long time, and has its consequences in both the threshold setting of relays and the testing of relays. Future generations of protection relays are expected to be faster, and thus more sensitive to disturbances. This project aims at using power quality data and knowledge for the testing of future relays and protection algorithms. A study was made on the different disturbances that occur in the power system and the way in which they affect protection equipment. Information was obtained from: power quality monitoring surveys, power quality and power system literature; measurements performed in our laboratory. Potential impact was assessed from the transients and non-fundamental frequency component