Determination of optimal system configuration in Japanese secondary power systems

In Japan, when a secondary radial power system (66 kV, 77 kV) has a number of connected feeders whose circuit breakers (CBs) can be opened or closed, the combinatorial number of possible system structures created by switching CBs becomes very large. In order to determine the optimal configuration of secondary radial power systems in both the normal state and fault state, a new computation algorithm is proposed. The proposed algorithm is based on enumeration and reduced ordered binary decision diagram (ROBDD). In order to verify the availability of the proposed approach, the authors obtain optimal configurations for normal and fault states on the IEE of Japan secondary power system model (IEEJ model) by using the proposed method. The IEEJ model has the distinctive characteristics of practical Japanese power systems, the total number of configuration candidates is the 76th power of 2 (=75 000 000 000 000 billion approximately). The optimality of the system configuration obtained by the proposed method is mathematically guaranteed.