A backward sweep method for power flow solution in distribution networks

Abstract

A methodology for the analysis of radial or weakly meshed distribution systems supplying voltage dependent loads is here developed. The solution process is iterative and, at each step, loads are simulated by means of impedances. Therefore, at each iteration, it is necessary to solve a network made up only of impedances; for this kind of network, all the voltages and currents can be expressed as linear functions of a single unknown current (in radial systems) or of two unknown currents for each independent mesh (for meshed systems). The methodology has been called ‘‘backward” since the unique equation, in case of radial network, and the linear system of equations, in case of meshed network, in which such unknown currents appear can be determined by starting from the ending nodes of the radial system, or of the radialized network (obtained by means of cuts in meshed networks). After a brief presentation of the b/f method, which is currently the most commonly used technique for solving distribution networks, the solution methodology is detailed both for radial and for meshed systems. Then, the way in which PV nodes can be considered is also described. Finally, the results obtained in the solution of some networks already studied in the literature are presented with other methods, in order to compare their performances. The applications show the efficiency of the proposed methodology in solving distribution networks with many meshes and PV nodes.