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 at unpredictable weather conditions with improved reliability of power supply. With the enhanced reliability, the loads are powered continuously during both on-grid and off-grid modes. In view of sensitive loads, the DG is used in the system on the grounds of its dispatchability, which is lacking in the wind-solar power generation. However, the DG is controlled to consume minimum fuel during its operation. The wind power is captured by using a doubly fed induction generator (DFIG), which is coupled to the wind turbine. 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 (CLS) of DFIG to make the microgrid flexible for on-grid and off-grid operations. An adaptive step change incremental conductance based maximum power point tracking (MPPT) technique is utilized for acquiring the peak power from the solar photovoltaic (PV) array. Moreover, a modified adaptive step change based perturb and observe (P&O) wind MPPT strategy is incorporated in the control of CRS for improved power capturing as compared to the conventional fixed step methods. Results are presented to evidence the microgrid performance during on-grid and off-grid modes, at fluctuating wind speeds and solar irradiances. Moreover, the comparison of wind turbine efficiency is presented between the modified and conventional wind MPPT techniques.