Nodal-price dependent, dual-mode transmission line protection strategy

It is argued that the Independent System Operator (ISO) should be able to adjust the security and dependability of the power protection system in response to system and market conditions. However the existing protection philosophy´s multiple, overlapping schemes tend to favor individual elements over the security of the wide-area. We revisit the rare-probability, hidden failures embedded within the individual relays but this time include the failure to trip when a fault needs to be cleared along with the unnecessary tripping of a transmission line. We devise a relaying concept to reduce the probability of cascading outages by decreasing incorrect relay operations through a dual-mode or the security-dependability mode (S-D Mode) scheme. It is our contention that during periods of high nodal prices which may even predict a cascading event, we can reduce the probability of a blackout by changing to a secure mode over the dependable region of operation.