English title

In the recent years use of Special Protection Schemes due to impact of notable these schemes in improving the performance of power systems  has found increasing usage. The purpose of this paper is design a suitable and fast special protection schemes to deal with extreme contingency that will led to collapse of power network if they occurred. So at the first, for a clear form of power transmission paths a graph model of Fars region was found. Then using propose algorithm in this paper extreme contingency in power transmission network by DigSILENT program analysis and identified. Finally after identifying these events, generation rejection and load rejection schemes as the most popular and most common schemes in power networks around the world with transmission switching as new special protection scheme proposed in this paper to deal with these contingencies is presented. The results of implementation these schemes show acceptable performance of them to deal with events and contingencies identified.