Direct Transfer Trip (DTT) leveraging redundant cellular communication channels

The increased penetration of distributed energy resources requires new protection and control algorithms to maintain stability and reliability of the distribution grid. These algorithms heavily rely on live data from the field devices to make fast operational decisions during the fault events. When a line fault occurs, the protection scheme is expected to interrupt the fault current and quickly disconnect other power sources to protect the Distributed Generation (DG) site from any damages, ensuring that it will not feed into a faulted circuit while line repairs are made by field crews. This is achieved via Direct Transfer Trip (DTT) signals, traditionally sent between substations and remote DG sites using leased telephone lines. Due to the highly specialized and critical nature of DTT systems, the equipment, including the communication infrastructure, must be extremely reliable and conform to highest substation standards. The use of traditional leased lines is becoming more and more problematic as telecommunication companies are moving away from this technology or even not providing this as a service. Fiber utilization is not always feasible due to the installation cost for long distances. A cost-effective alternative is wireless communication, including cellular systems provided by the major carriers nationwide. The cellular communication infrastructure supports tunneling of the Layer II traffic, therefore DTT applications can employ IEC61850 protocol with GOOSE messaging to perform peer-to-peer data exchange between Intelligent Controllers in the DTT/Protection system.