Coordinated energy management in autonomous hybrid AC/DC microgrids

In most recent years, there is an increasing interest of promoting the proportion of power supply from the renewable energy sources through integrating various forms of small-scale Distributed Generators (DGs) and energy storage units with the capacity ranging from a number of kilowatts to a number of Megawatts, e.g. Fuel cells (FC), Photovoltaic cells (PV), Batteries, micro turbines, to the medium voltage power distribution networks. This is mainly driven by advances in renewable energy technology and the ambition of meeting the target of C02 emissions reduction and the demand of enhancing energy security and quality of supply. Currently the microgrid becomes a new energy provision paradigm to enhance the power supply reliability which has a collection of power loads, micro sources and energy storage systems (ESSs). In addition, the hybrid AC/DC microgrid becomes prevalent which is capable of direct interfacing different forms of renewable sources and loads, and hence eliminates the conventional multiple energy conversions in AC and DC energy systems. Such hybrid microgrid provides a cost-effective energy supply paradigm with significantly reduced operation and maintenance cost. In this paper, we present the modeling and implementation of a simulation test-bed of AC/DC hybrid microgrid system considering the most available distributed generators (e.g. PV, micro turbines), typical storage facilities (e.g. battery) and different forms of power loads (linear and non-linear loads), based on the MATLAB/Simulink tool and investigate the coordinated energy management approach for improving the DG utilization efficiency as well as the power quality under different microgrid operational conditions. The effectiveness and performance of the suggested coordinated energy management approach in the autonomous hybrid AC/DC microgrid is well assessed through carrying out a set of simulation experiments for typical microgrid operational scenarios.