A Resilient FLL Control for Solar-Hydro Generation Based Utility Interactive Microgrid With Enhanced Power Quality

Abstract

This article focuses on the control based on an extended second-order generalized integrator with a frequency locked loop (Ext-SOGI-FLL) to provide satisfactory performance for synchronization of microgrid (MG). In the existing phase-locked loop (PLL) based control, the loop filter used is not capable to entirely remove harmonics. Hence, the harmonics in voltage considerably affect the frequency as well as phase extraction, both in the dynamics and steady-state situations. To deal with this problem in this system, the voltage source converter is controlled using Ext-SOGI-FLL. This control algorithm extracts the fundamental voltage and current for assessment of phase angle and reference source current (maintaining the required IEEE power quality standard-519 & 1547). This FLL-based control is also capable of estimating the exact frequency and phase magnitude, which suffer from phase offset due to frequency change. The comparative results validate that the response of Ext-SOGI-FLL control in comparison to the existing control algorithms is faster at loads and generation perturbations. Simulated and test results for MG system combining a solar photovoltaic, pico-hydropower generation, and battery validate its performance while feeding local loads uninterruptedly.