Prevention of blackout by an effective forced islanding and restoration scheme

Blackouts in large interconnected power system can cause damage to equipment of power plants, interruption of production cycles, and great economic losses. In order to avoid blackouts from occurring in the power system, an effective forced islanding scheme with a suitable load shedding scheme can be used, for improving power system security. Further, a suitable restoration sequence is required to switch the system back to the main grid. This paper proposes an algorithm that identifies the risk during an outage and forcefully splits the system into predefined islands to prevent the propagation of cascading failures across a transmission network and thereby reducing the possibility of a large-scale blackout. The scheme makes use of DC load flow studies and sensitivity factors, such as Line Outage Distribution Factor (LODF) and Generation Shift Factors (GSF), to calculate the overloads occurring due to the outage. For each outage, the forced islands to be formed are predefined. After splitting the system into islands, the islands are analyzed for stability. If they are found to be unstable, then an under-voltage load shedding scheme is adopted to bring the system back to stability. After fault clearance, a suitable restoration sequence has been formulated. The proposed work is carried out on a sample 6 bus system using MATLAB program.