Graph‐theoretic‐based approach for solving load flow problem of AC–DC radial distribution network with distributed generations

Abstract

Owing to the rising power demand, depleting conventional energy sources and recent advancement in incorporating deeper injections of renewable energy resources into the grid, the existing distribution system will have to take into account DC injections/withdrawals, thus giving rise to AC-DC distribution system. The load-flow in the aforementioned systems is an exigent task because of the presence of power converters. This work presents a novel and computationally efficient load-flow algorithm for AC–DC radial distribution network utilizing the notion of graph-theory with matrix-algebra. The remarkable trait of the proposed methodology lies in the formulation of path impedance matrix, loads beyond branch matrix, path drop matrix, slack bus to other buses drop matrix and load flow matrix which will remain unaffected for the entire load-flow operation. The per-unit equivalent model of power converters has been developed for solving load-flow equations in per-unit. Various models of distributed generations are also incorporated in the proposed load-flow study. The developed method is capable of addressing the aforementioned modeling challenges. The proposed technique has been tested on several AC–DC test networks that include different operating modes of power converters and various models of DGs, which proves feasibility and legitimacy of the proposed technique.