Design of Fuzzy Logic Based Relay for Distance Protection

The safe generation and distribution of power is the most desirable factor targeted by utility companies.  Therefore, there is a serious concern for protection of the transmission line as well as the equipment involved.  Several works have been carried out on protection to protect mostly human lives while some aimed at the use of microcontrollers to optimize the performance of a relay.  Part of the conventional relay operation works was the work by IEEE Working Group I17 Incorrect Operation Reporting in which for 20 total events, for voltage above 400V, unnecessary trips during fault is 30%, unnecessary trip other than fault is 5%, and total misoperation is 35%.  These results could be improved upon.  As new technology surfaces more application areas also evolve such as the use of artificial intelligence tool like fuzzy logic to enhance the performance of a relay which is the key element in the switching operation of a power network.  This fuzzy logic based relay shows considerable improvement on false trip phenomenon usually associated with the operations of a relay in which a total of 25 events were used to form the rule base for voltage ranging from 480V to 15kV, unnecessary trip fault is 2%, and total misoperation is less than 10%. In this work, the protection scheme proposed is for transmission line's distance protections relay whose operation is adaptive and directly controlled using fuzzy logic controller which is fault tolerant, directional, and least affected by power swing.