Development of a low - voltage hybrid AC/DC distribution microgrid system.

Abstract

Micro grids are small-scale power grids that can operate independently or collaboratively with other small power grids. Hybrid microgrids integrate two or more independent ac and dc microgrids. In Uganda, the power systems face a lot of power quality issues like voltage sag or swell, voltage unbalance, power factor, harmonics and voltage fluctuations. The harmonics are caused by electric equipment with non-linear loads drawing in current in abrupt short pulses like PCs, copies, fluorescent lights, transformers, elevators among others. This project therefore proposes a hybrid AC / DC micro-grid consisting of an AC grid and a DC grid. The proposed micro grid consists of DC and AC buses that have different types of loads distributed over the voltage levels of AC (415V and 240V) and DC. The DC grid is being supplied by a solar PV system, a Battery Energy Saving System and AC power from the ac grid converted to dc to supplement the dc supply. A complete model of a hybrid grid is simulated using MATLAB/Simulink to study the effect of harmonics on the hybrid and how much of them are reduced and how power losses are also reduced. Simulation of measurements related to power quality variables such as current and voltage total harmonic distortion were calculated including capability to compute power line losses.