Abstract
An Optimal Power Flow (OPF) for transmission power system whith presence of photovoltaic based DG (PV-DG) is proposed by this study. We have minimized power losses using Biogeography-Based Optimization method (BBO) by the objective function. This method has determined the optimal PV-DG size and location in a transmission power system. The BBO method has been examined and tested by the modified IEEE 30_bus, and validated by reduced Algerian power system (114_bus) using MATLAB software.