Loss minimum configuration of distribution system considering N-1 security of dispersed generators

Dispersed generators (DGs), such as fuel cells and solar ceils, etc., are going to be installed in the demand side of power systems. The dispersed facilities can reduce distribution system loss by the appropriate allocation. However, when a DG that has a large capacity is disconnected from a distribution network by fault, violation of operational constraints, such as line current capacity and voltage drop, may occur. From a viewpoint of system reliability, robust system configuration for suddenly disconnecting DG from the distribution network must be determined, since system operators cannot control DG connection to the distribution network online. In this paper, the authors propose an algorithm to determine loss minimum configuration of a distribution system with DGs while maintaining system reliability. Namely, in the proposed algorithm, N-1 contingencies for DGs are considered as an operational constraint, when the loss minimum configuration is determined under the constraints for line current capacity and voltage drop. In order to determine the loss minimum configuration effectively, an algorithm based on tabu search with strategic oscillation is proposed. Numerical simulations are carried out for a distribution system model with 118 sectionalizing switches in order to examine the validity of the proposed algorithm in comparison with the conventional approach. Index Terms--Combinatorial optimization problem, dispersed generators, distribution system, loss minimum configuration, N-1 security, optimization method, strategic oscillation, tabu search.