Bus protection application challenges

Bus protection is one of most challenging applications because it requires highest degree of security and dependability. Unforeseen during engineering and not detected during commissioning potential problems can cause a blackout in the large geographical area. This paper will discuss several common problems and solutions for the low impedance bus differential protection to increase security and dependability for this protection. Specifically, paper will focus on the following: •Increasing security by using supervising elements, such as external check zone or undervoltage. •Detection of open CT at any feeder, connected to the bus-possible solutions will be presented. •Monitoring isolators positions to ensure including/excluding in the zone without causing any potential misoperation. •Ability to detect external fault and prevent bus differential misoperation when fault occurs on the feeder with a low CT ratio and feeder CT will saturate extremely fast. •Experience with engineering of the bus protection for the configurable buses with several zones. •End Fault protection to cover blind spots. Paper will be illustrated with real life examples of the application challenges and how these challenges can be addressed.