Enhanced Third-Order Sinusoidal Signal Integrator-Based Seamless Control for Single-Phase Grid-Tied PV-Battery System

This article presents a smart control strategy for a single-phase, grid-interfaced, solar energy conversion-battery energy storage system for critical load applications. The presented control scheme ensures uninterrupted power supply to critical loads even in the absence of utility mains. The system is compatible with operating in grid-connected and islanded modes, respectively. A self-reliant control scheme ensures a seamless switchover between grid-connected and islanded modes of operation. A modified exponential hyperbolic sine adaptive filter is proposed for the computation of the active weight component of load current. Such a filter also ensures an accelerated weight convergence rate, minimizes steady-state error and improves dynamic response. The presented adaptive filter-based constant switching frequency model predictive control regulates grid current and allows an active power exchange from the ac mains. Such a strategy also improves the power quality parameters on the utility side. A constant switching frequency model predictive voltage control is designed to regulate instantaneous load voltage and maintain optimum power quality in islanded mode. An enhanced third-order sinusoidal signal integrator-based frequency-locked loop is proposed to synchronize the grid, mitigate dc offset and harmonics under adverse grid circumstances. The experimental results demonstrate the system performance under various operating conditions using OPAL-RT 5600.