Smooth Operation Changeover Scheme for Dual Stage BES-SPVA Grid Coupled System

This paper deals with a two-stage hybrid configuration of a solar photovoltaic array (SPVA) and battery energy storage (BES) distributed generation source (DGs) connected to the three-phase utility grid and critical non-linear load via a DC-AC voltage source converter (VSC). To improve the effectiveness of this system, the perturb and observe (P&O) technique is employed to extract the maximum power from the SPVA. A DC-DC boost converter is used to boost up the generated SPVA voltage for MPPT. BES is directly connected before VSC to support the critical load during the outage of the grid and SPVA. Unbalanced load, unbalanced grid voltage (voltage sag and swell), DC offset, and environmental effect, i.e., change in solar insolation are considered when evaluating the system's effectiveness. To obtain reference grid currents extended state lowpass second order generalized integrator (ESLSOGI) is employed for voltage source converter control, which converges quickly and exhibits fewer steady-state fluctuations. With this control, grid current harmonics adhere to IEEE-519 standards, performance is acceptable under a variety of load and environmental conditions, and smooth operation changeover is done between grid-connected mode (GCM) and standalone mode (SAM).