A Backward Method for Solving PV Nodes in Weakly Meshed Distribution Networks

In this paper, a new iterative backward/forward methodology for the load flow solution of weakly meshed systems with fixed voltage nodes is presented. Such technique models the loads at each iteration by means of impedances, and the PV nodes by means of reactances. Each iteration is organised in two steps. In the first, the radial network attained from the meshed system through cuts and composed of shunt and series impedances is solved. In the second step, based on a reduced Thévenin impedance matrix, the compensation currents to be injected in the cut nodes are deduced. Modelling the PV nodes by means of reactances allows the attainment, for the reactive power of these nodes, of the same precision that it is possible to get solving the network with the methods usually adopted for transmission networks. After the presentation of the different implementations of the backward/forward method proposed in the literature, the new technique and the relevant implementation are presented in detail. The methodology allows the solution of systems with meshes and PV nodes; test results show precision, speed and good convergence properties.