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

The integration of a solar photovoltaic array (SPVA) system with local non-linear loads into utility grid presents a complex undertaking. This complexity arises from additional strain placed on the grid by both SPVA system and the non-linear loads, potentially resulting in challenges related to power quality, power management, and synchronization. Moreover, widespread utilization of power electronic devices contributes to grid voltage contamination with many harmonics. Because of nonlinear loads and grid pollution, it is crucial to implement a novel and robust pre-filter and in-loop filter with VSC to provide filtered voltages and currents at the point of common coupling (PCC) and mitigate power quality problems. Thus, this paper presents a two-stage hybrid configuration of an SPVA and battery energy storage (BES) distributed generation source connected to three-phase utility grid and critical nonlinear load via a DC-AC voltage source converter (VSC). To obtain reference grid currents and filtered grid voltages, an extended state lowpass second order generalized integrator (ESLSOGI) is employed as a pre-filter and in-loop filter, resulting in quick convergence and low steady-state fluctuations. Employing the ESLSOGI methodology guarantees that grid current and filtered voltage THD remain under 5% and adhere to the stringent criteria outlined in the IEEE-519 standard. The system's operational integrity is consistently upheld across a spectrum of load variations and environmental conditions, encompassing irregular loads, fluctuations in grid voltage, DC offset, and fluctuations in solar irradiation. Furthermore, the inherent resilience and adaptability of the ESLSOGI framework facilitate a seamless transition between grid-connected mode (GCM) and standalone mode (SAM), ensuring continuous and reliable operation under varying grid conditions. Presented system with proposed control is tested on MATLAB and verified through a hardware prototype made in a laboratory.