Implementation of Two-Level Control Coordinate for Seamless Transfer in Standalone Microgrid

This paper investigates two-level control coordinate and enhanced phase locked loop (EPLL) for a seamless transition between modes of operation under presence of nonlinear loads in standalone Microgrid (SMG). Two-level coordinating control approach for voltage, frequency regulation and power quality improvement at the point of common coupling (PCC), are proposed. Furthermore, the saturation issue, and mitigation of the 5
^th
and 7th order-harmonics, are taken on considered in design of the proportional resonant and proportional integral controllers. To ensure soft and fast transition between mode of operation in SMG, enhanced phased looked loop (PLL), is employed. The proposed concept for standalone microgrid is validated by simulation using MATLAB/ Simulink and in the laboratory using a small ratings prototype of 2 kW.