Protection of Power System Using Sequential Tripping

Abstract

This paper describes a Sequential Tripping Strategy used in an electrical power system to combat situations in which protection relays have maloperated or information is missing. This is an innovative back-up protection scheme designed to prevent the occurrence of widespread blackouts. It evaluates the certainty that transmission lines are likely to be affected by the fault and uses a Sequential Tripping Strategy to isolate the fault if a firm decision is not available due to maloperated relays and/or missing information. The mode of analysis and the Sequential Tripping Strategy ensures that the fault can be cleared at minimum risk to the network. In applications like power stations and continuous process control plants, a protection system is used to trip faulty systems to prevent damages and ensure the overall safety of the personnel and machinery. But this often results in multiple or cascade tripping of a number of subunits. Looking at all the tripped units doesn't reveal the cause of failure. It is therefore very important to determine the sequence of events that have occurred in order to exactly trace out the cause of failure and revive the system with minimal loss of time.