Control of hybrid energy systems micro-grid

Abstract

This paper presents the control and performance of a DC micro-grid, which consists of 60kW wind energy conversion system (WECS), 40kW photovoltaic (PV) panels, 65Ah battery and 40kW fuel cell (FC) with hybrid DC and AC buses. The WECS is controlled by the indirect field orientation control (FOC) which generates the available maximum power from the wind. The PV module generates the available maximum power using P&O MPPT control method considering environmental conditions. The FC delivers its power when there is a shortage of power generated from the PV and WECS generators. A decoupled i <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> -i <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</sub> current-controlled bidirectional converter connects the DC micro-grid to the 200V AC bus of the main grid. The bidirectional converter controls the DC bus voltage, power and reactive power to/from the grid according to the available power from the hybrid sources and load demand with the help of a phase-locked-loop (PLL). The battery subsystem helps smoothing and regulating the DC bus voltage by charging/discharging the battery using a bidirectional DC/DC converter particularly at transient conditions. The adopted control strategies show secure operation of the micro-grid during transient and steady state operations for both grid-connected and autonomous case studies.