Smooth Synchronization Capability of Distributed Generation Based AC Microgrid

Abstract

This paper deals with an effective control strategy that enables the seamless changeover in operating modes of the microgrid that consist of distributed generation and battery storage. An operational criterion is developed for the microgrid to incorporate selective mode transfer in different scenarios. The grid isolation from the microgrid leads to shift in operating control scheme i.e. from current to voltage control for switching the grid connected converter. The isolation/reconnection of the utility to the microgrid takes place with the help of static transfer switches (STS) that operate on the detection/clearance of faults. The high quality power is ensured by utilizing normalized least mean square-sign error (NLMS-SE) algorithm to evaluate the total current active component of loads. All pass filter based frequency locked loop (APF-FLL) effectively estimates the phase angle of grid under phase and frequency oscillations prevailing in the system under synchronization. The proportional resonant (PR) controller regulate the load voltages during voltage control operating mode. The microgrid allows sensitive load operation, uninterrupted residential load supply and improved power quality and these are confirmed from MATLAB simulated results.