An Experimental Validation of Nonlinear Extended State Observer Controlled Small Hydro-PV Array and Battery Storage-Based Microgrid for Remote Areas

This paper presents a hybrid microgrid system designed for rural areas, integrating small hydro and photovoltaic (PV) arrays with battery storage to ensure uninterrupted power supply to local loads in isolated regions. A self-excited induction generator (SEIG) is employed for small hydro power generation, while power quality issues caused by nonlinear loads are addressed using the Volterra Filtered-X Least Mean Square (VFXLMS) technique. This method effectively suppresses dominant harmonic components in load currents and accurately estimates the fundamental frequency of load currents. The PV array is interconnected at the DC link of a voltage source converter (VSC) through a boost converter, while a bidirectional converter manages battery operations, facilitating efficient power management. The bidirectional converter supports the export and import of power from/to the battery, optimizing energy utilization within the microgrid. Conventional proportional-integral (PI) control has limitations in DC voltage tracking and mitigating overshoot and undershoot. To address this, a nonlinear extended state observer (NESO) is employed to mitigate disturbances. The NESO, combined with a disturbance observer, enhances the operational reliability of the microgrid. An experimental setup has been developed to validate the system’s performance under conditions of unbalanced loads and varying PV insolation levels.