Optimal power flow in radial distribution systems

Radial distribution systems (RDS) have lines with high R/X ratios and hence Newton based methods were not reliable to solve their set of bus power balance equations. Historically, a recursive solution method using a set of voltage equations and its variants are very popular to determine a voltage solution of a RDS. Consequently, use of classical optimization was not possible. Recent developments in the last decade have created a system of equations that can be reliably solved using first order Newton Raphson method to determine a voltage solution of a RDS. This opens up the possibility of using classical optimization method for optimizing these systems. This paper uses this new load flow method to determine optimal setting of controllers in a RDS such that its real power losses are minimized and voltage magnitudes are acceptable. This method is completely described along with its theory. It is tested on popular RDS examples found in literature.