PCPDIPM-based optimal reactive power flow model using augmented rectangular coordinates

Abstract

A novel optimal reactive power flow (ORPF) model using augmented rectangular coordinates is established. The load tap changing (LTC) transformer is represented by an ideal transformer and its series impedance with a fictitious node located between them. The ideal transformer is replaced by the current injections at the two end nodes, and the constraint equations relating the current injections and voltages between two sides are formed. Meanwhile, the nodal voltages, injection currents, reactive power injections, and transformers turn ratio are considered as optimization variables. By the procedure, the ORPF model turns into quadratic and can be expressed in the blocked-matrix form. The predictor-corrector primal-dual interior point method is used to implement the optimization. The quadratic model results in the constant Hessians that all have elements of 1 or −1,and mostly being zero, and multiplication is not required to form the full Hessian, thereby accelerating the entire optimal process significantly. Column Approximate Minimum Degree algorithm is used to order the coefficient matrix, resulting in great reduction of the number of the fill-in elements. The proposed and the conventional methods are programmed in MATLAB for comparison. Extensive numerical simulations on test systems ranging from IEEE 14 to 300 buses have shown the validity and higher efficiency of the proposed model than the conventional one. Copyright © 2013 John Wiley & Sons, Ltd.