DECOMPOSITION APPROACH FOR THE OPTIMAL COORDINATION OF DIRECTIONAL OVERCURRENT RELAYS OF LARGE ELECTRICAL-POWER SYSTEMS

This paper presents an efficient decomposition technique for the optim al coordination of directional overcurrent relays of large electrical power systems. The large power network is decomposed into number of su b-networks called blocks by identifying boundary buses, branches and r elays. The blocks are analysed sequentially and the boundary data tabl e is updated during the solution process. The method reported is disti nctly superior to the complete optimal coordination method from the po int of view of speed and memory requirements. The results are discusse d for the SPC 26-bus and the IEEE 57-bus power systems. The results ar e also discussed for the 64-bus system of North West India.