Communication-based permissive protection scheme for power distribution networks

A communication-based permissive protection method for protecting an electrical power distribution network from an electrical fault in the network, the method comprising:

• providing a power source that provides a power signal;
• providing a plurality of fault interrupters on one or more electrical lines in the network each receiving the power signal;
• detecting the fault on one of the electrical lines by each fault interrupter that is between the fault and the power source;
• sending a drop of voltage message from each fault interrupter that detects a drop of voltage without indication of a fault further downstream as a result of the fault to its immediate upstream fault interrupter towards the power source;
• sending a fault detection message from each fault interrupter that detects the fault to an immediate upstream fault interrupter, wherein receiving the fault detection message causes the fault interrupter to change its TCC curve from an initial TCC curve to a shifted TCC curve so that a fault interrupter that detects the fault but does not receive a fault detecting message will open based on its initial TCC curve and a fault interrupter that detects the fault and does receive a fault detecting message will open based on its shifted TCC curve;
• and
• opening the fault interrupter that both detects the fault downstream and receives a drop of voltage message from all of the fault interrupters immediately downstream of that fault interrupter.