Nodal-Price Dependent, Dual-Mode Transmission Line Protection Strategy

It is argued that the Independent Sgstem Operator (ISO) should be able to adjust the securitg and dependability of the protection sgstem in response to the system and market conditions. However, the existing protection philosophy’s multiple, overlapping schemes tend to favor individual elements over the secun”t~ of the wide-area. We revisit the rare-probability, hidden failures embedded within the indiw“dualrelay8 but this time include the failure to trip when a fault needs to be cleared along with the unnecessary tn”pping of a transmission line. We devise a relaging 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 bg changing to a secure mode over the dependable region of operation.