A robust decoupled power flow for distribution systems

This paper presents a robust decoupled power flow technique based on line current flows in rectangular coordinates for radial distribution systems. The functions of line current flows and their equivalent values, which are computed from the specified load powers, are linearised around a known operating point and transformed through a constant matrix with a view to eliminate the off-diagonal blocks of the Jacobian. The transformation enables perfect decoupling of the power flow problem into two sub-problems without making any assumptions on voltage magnitudes, angles and r/x ratios. The approach is simple and uses a sparse constant sub-Jacobian matrix that needs to be factorised only once for both real and reactive sub-problems; and is solved iteratively similar to FDPF technique. Test results of 15, 29 and 69 node systems indicate that the proposed method is efficient, robust, accurate and exhibits potential for on-line applications.