Abstract: A simple algorithm is presented to solve three-phase unbalanced Radial Distribution Network (RDN). It solves a simple algebraic recursive expression of voltage, and all the data are stored in vector form. This algorithm requires Dynamic Data Structure (DDS) to store the details of the branches. The algorithm uses basic principles of circuit theory and can be easily understood. Mutual coupling between the phases has been included in the mathematical model. The proposed algorithm has been tested with several distribution networks and the result of an unbalanced RDS is presented in the article. IEEE 8 bus and IEEE 25 bus unbalanced radial distribution system results are in agreements with the literature and show that the proposed model is valid and reliable.

Keywords: Unbalance radial distribution networks, line model, load flow, 3-phase 4-wire line.