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ESIC Seminar: Resetting Protection Complexity by Krishnanjan Gubba Ravikumar, SEL

Engineering Teaching Research Laboratory, Pullman, WA
ETRL 101
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About the event

Resetting Protection Complexity to be presented by Krishnanjan Gubba Ravikumar, SEL Engineering Services, Inc.


   In 1962, A. R. van C. Warrington wrote in his seminal book, Protective Relays – Their Theory and Practice: “Whereas the main requirement of instrumentation is sustained accuracy, the most important requisite of protective relays is reliability since they may supervise a circuit for years before a fault occurs; if a fault then happens, the relay must respond instantly and correctly. For this reason, the designers should always attempt to use simple constructions and simple connections of relays. In spite of good intentions in this respect, there is a tendency to extend the operation of relay schemes by adding additional features until complexity results and then it becomes necessary to re-design. In other words, a graph of the progress of relay engineering as regards complexity tends to follow a saw-tooth shape.

   In 1984, the world’s first microprocessor-based relay reset our industry with simpler construction methods, self-tests, better fault-detection sensitivity, and simple human-machine interfaces consisting of serial ports, a modest set of commands, and less than a page of settings. The new technology was solidly embraced; however, the desire for the inclusion of more features began to drive up complexity that included capabilities such as integration, automation, metering, SCADA protocols, synchrophasors, and sampled values.

   Today, the amount of code performing automation and communications in a protective relay is nine times larger and more complicated than the code performing the protection algorithms. As Warrington predicted, the saw-tooth shape of protection complexity has continued to increase, so it is fair to ask:

a) Is today’s power system protection too complex?  

b) Is complexity a natural and unavoidable consequence of advancing power system protection? 

c)  Is protection, automation, and communication in single devices advantageous, or should these functions be separated into dedicated devices? 


   Krishnanjan Gubba Ravikumar received his Ph.D. degree from Washington State University, M.S.E.E. degree from Mississippi State University and his B.S.E.E. degree from Anna University, India. He is presently working as a principal engineer at SEL Engineering Services, Inc., a subsidiary of Schweitzer Engineering Laboratories, Inc., in Pullman, Washington, focusing on the design, development, and testing of protection systems. His areas of expertise include protection systems, real-time modeling and simulation, synchrophasor applications, remedial action schemes, power management systems, and power electronic applications. He has extensive knowledge of power system controls and renewable distributed generation. He is a senior member of the IEEE and a member of the Eta Kappa Nu Honor Society.