A New Fast Decoupled-Like Algorithm for Radial Distribution Power Flow Problem by Using Rectangular Coordinates

The classical fast decoupled power flow method is an efficient, important, and commonly used method for solving load flow problems in power systems. Unfortunately, this method encounters convergence problems when used to obtain power flow solutions in radial distribution systems with high r/x ratio feeders. An efficient tool for calculating the complex voltages at all nodes is a prerequisite for reliable operation of radial distribution automation. To this end, research on a reliable fast decoupled power flow method for radial distribution systems remains an outstanding issue. This study presents an effective approach for implementing a fast decoupled-like algorithm to solve the power flow problem in a radial distribution system. The mathematical formulation of the problem was developed by utilizing node injection into a branch current matrix (NIBC). The nodal voltages and system parameters are described using rectangular coordinates. The mathematical model was described using a system of nonlinear algebraic real equations. These equations were numerically linearized by applying the Newton-Raphson iterative scheme. The elements of the Jacobian matrix were simplified and approximated to yield a decoupled constant Jacobian submatrix. These constant submatrices are inverted prior to the iterative process. The proposed algorithm was tested on several small- and large-scale radial distribution systems. The results revealed that the proposed method exhibits remarkable convergence characteristics for a wide range of system parameters. The proposed mathematical model can be used in other basic studies on radial distribution networks.