Numerical relay algorithm for load encroachment protection

India has a very large electricity grid in the world, consist of five regional grids. The major disturbance occurred in the Northern grid at 02.33AM of 30th July 2012 leading to a blackout in nearly the entire northern region covering all the 8 States. The main cause was the mal operation of zone 3 distance relay due to load encroachment, weak inter-regional corridor and multiple outage of line. In this paper a new algorithm is proposed for numerical relay to protect grid during load encroachment and avoid the unforeseen blackout. The new algorithm is simulated for numerical relay and gives the expected result and prevents the leading of blackout in electricity grid.