Power Quality Improvement in PMSG Based Hydro-BES System Operating in Isolated Remote Areas Using CF-FLL Control

In this work, a hydro based autonomous energy conversion system supported by the battery energy storage (BES) is presented. A permanent magnet synchronous machine is used as a generator for hydro energy conversion. A 4-leg voltage source converter (VSC) connected to the point of common coupling (PCC) of this system, is used to control voltage, frequency and to improve power quality of this system. The overall control strategy compensates the neutral current and alleviates the effect of unbalance in three-phase 4-wire load using a 4-leg insulated gate bipolar transistor (IGBT) based VSC. The harmonic rejection capability of combined filter-frequency locked loop (CF-FLL) control technique is demonstrated through experimental results. The system achieves active power balance through charging and discharging of BES, which is coupled to a DC-link through a bidirectional DC/DC converter (BDC). Performance of presented system using the CF-FLL control strategy suppresses the effect of unbalanced nonlinear loading.