Three-phase power flow calculations using direct ZBUS method for large-scale unbalanced distribution networks

Abstract

In this study, a three-phase power flow solution method using graph theory, injection current, and sparse matrix techniques for large-scale unbalanced distribution networks is proposed. In the bus frame of reference, a direct iterative method is adopted. To integrate the electric characteristics of transformers and step voltage regulators into the proposed method, the existing component models are modified by equivalent injected currents. To validate the performance and effectiveness of the proposed method, four three-phase IEEE test systems and random test systems are used for comparison purposes. As the size of the network increases, the proposed direct ZBUS method drastically shows its superiority over the other methods. The results reveal that the proposed method has good potential for improving the computational efficiency of optimal planning and design as well as real-time power dispatch applications in large-scale distribution systems.