Grid-Interactive Smooth Transition Control of Wind-Solar-DG Based Microgrid at Unpredictable Weather Conditions

This paper presents the grid interactive wind-solar-diesel generator (DG) based microgrid (MG) at unpredictable weather conditions with improved reliability of power. With enhanced reliability, loads are powered continuously during both on-grid and off-grid modes. In view of sensitive loads, DG is used in the system on grounds of its dispatchability, which is lacking in the wind-solar power generation. However, DG is controlled to consume minimum fuel during its operation. The wind power is captured by using a doubly fed induction generator (DFIG). Moreover, a battery bank is connected in the system for energy storage and to deliver when its need arises. Modified controls are presented for converter on rotor side (CRS) and converter on load side of DFIG to make MG flexible for on/off-grid operations and for smooth connection/disconnection of DG. An adaptive step change incremental conductance based maximum power point tracking (MPPT) technique is utilized for acquiring peak power from solar photovoltaic (PV) array. Moreover, a modified adaptive step change based perturb and observe wind MPPT strategy is incorporated in control of CRS for improved power capturing as compared to conventional fixed step methods. Simulated results are presented to evidence MG performance along with a comparison of wind turbine efficiency. Moreover, an experimental test bench is built to evidence dynamic and steady state performance of MG at various operating scenarios i.e., at varying winds and varying solar irradiances, during on/off-grid modes and smooth connection/disconnection of DG, and at change in loads.