Fast-decoupled power flow method for integrated analysis of transmission and distribution systems

Abstract The growing participation of distributed generation in the electricity supply along with the advances in smart grid technologies have emphasized the active role of distribution systems and their more complex interaction with the transmission system. As a consequence, the operation of the power grid requires closer coordination between transmission and distribution systems. This paper proposes an integrated analysis that allows a unique power flow method to be effectively applied to any voltage level of the power system, from the high-voltage bulk transmission network to the low-voltage distribution feeders. The proposed methodology combines the decoupled power flow approach and complex per unit normalization technique to efficiently deal with the high dimension of unified network analysis and the different characteristics of transmission and distribution networks, regarding line parameters and topological arrangements. Simulations are conducted in an integrated T&D network, and in a large primary-secondary distribution system as well. The results demonstrate the effectiveness of the proposed approach and attest the relevance of integrated power flow analyzes to adequately determine the interrelationships between the different operating levels of the electrical network.