FLL Unified AVF and NAAP Filter for Performance Investigation of Renewable Based AC Microgrid Under Grid to Standalone Transition Mode

In this work, grid synchronization control, islanded microgrid operation and power surety to the residential/critical loads are ensured for each microgrid operating stage i.e., off-grid, grid associated and seamless transfer. The microgrid under study consists of photovoltaic power generation unit and wind power generation unit that power the consumer loads under on-grid and grid-outage conditions. The variability of the resources is comprehended by the battery energy storage unit, which allows easy power flow between the microgrid and loads. The mode of operation is executed by the power electronic based static transfer switches, which obtain their control signals from the developed control algorithm comprising of two major control algorithms fulfilling two tasks. The first task is to detect the grid outage and that is continuously monitored using frequency locked loop unified adaptive vectorial filter (FLL-AVF), which effectively estimates the grid and load angle under all the adverse conditions. The second task is to extract the load fundamental current, which is successfully estimated the normalized adaptive all pass (NAAP) filter. It allows the sensitive load operation. The control and microgrid operation are verified by the Matlab/Simulation result. For real world validation of the concept and control, the experimental results obtained from the laboratory developed prototype (mimicking the microgrid) are highly convincing. The grid current quality is improved and the microgrid successfully operates under all the conditions.