Self-Synchronizing Control Enabling Disruption-Free Operation and Seamless Mode Transitions in Wind–Solar Based Hybrid AC/DC Microgrid

Abstract

This paper introduces a novel self-synchronizing control architecture for the power converters in a hybrid AC/DC microgrid (HMG), wherein, the doubly fed induction generator (DFIG) and the solar photovoltaic (SPV) array are utilized for wind and solar generation, respectively. The self-synchronizing control enables the HMG to remain functional and provides a disruption-free power at all the four identified operation modes. Different operation modes are enforced due to grid islanding or DFIG wind generator disconnection scenarios. Meanwhile, the shifting among these four operation modes culminate into eight possible transition phases. The HMG's self-synchronizing control is devised to achieve seamless operation at all possible transition phases, and avoids any voltage spikes or transient overcurrents. Such a seamless transition functionality becomes increasingly vital in case of the DFIG-SPV based HMG. This is due to the direct interconnection of DFIG stator with the utility grid that renders the system largely vulnerable to any un-synchronized transition. Therefore, major research emphasis of this work is on the development of a novel methodology for ensuring a disruption-free operation and seamless mode transitions in a DFIG-SPV based HMG. The HMG control is based on a new affine projection sign algorithm (APSA), which supplements the HMG with unity power factor operation and load unbalance/harmonics mitigation. The viability of the HMG and its self-synchronizing control at various mode transition phases and system dynamics are extensively tested on an experimental rig developed in the laboratory. Test results endorse the feasibility of the self synchronizing control, while, a comparative analysis demonstrates the superiority of the APSA scheme over other state-of-art approaches.