Anti-windup filtered second-order generalized integrator-based spontaneous control for single-phase grid-tied solar PV-H2/Br2 redox flow battery storage microgrid system

Photovoltaic (PV) sources are increasingly deployed as distributed generators in remote single-phase utility grids. Meanwhile, variable power demand and fluctuating PV power output pose a challenge to utility grid stability and consistent power supply. This article introduces a hydrogen/bromine (H-2/Br-2) redox flow battery (RFB) for a single-phase grid-integrated PV system. A unique spontaneous control scheme for a single-phase two-stage gridconnected PV-H-2/Br-2 RFB system is proposed using an orthogonal signal generator-anti-windup filtered secondorder generalized integrator (OSG-AWFSOGI) and tilt integral derivative (TID) controller. The OSG-AWFSOGI extracts the fundamental component from the grid voltage, even when the grid voltage is characterized by under-voltage, over-voltage, severe harmonics distortion, and other uncertain conditions. The TID controller is also used to regulate the DC-link voltage and current of the H-2/Br-2 RFB under various disturbances and dynamic conditions to deal with system fluctuation and prevent further degradation of the voltage quality. The control architecture also incorporates a feed-forward component to provide a quick dynamic response. Furthermore, a new sparrow search optimization algorithm is used to fine-tune the controller parameters for optimum TID control action. A battery control scheme is developed to control the H-2/Br-2 RFB to smooth the PV output and boost system operation planning, resiliency, and efficiency by providing short response time, rapid regulation, and voltage support. An incremental conductance-voltage current control (INC-VCC) maximum power point tracking (MPPT) system is proposed, with VCC based on a TID controller for rapid PV MPPT under solar irradiation changes and unexpected grid disturbance conditions. The proposed control is modelled and simulated in Matlab and verified using the OPAL-RT real-time simulator test bench. During simulation and testing, irradiance and temperature variations on PV array, load perturbation, over voltage, under voltage in grid voltage, and different complex disturbances and dynamic conditions are considered. Also, in comparison results, the proposed strategy outperformed compared to state-of-the-art approaches.

Automated summary

This article introduces a hydrogen/bromine redox flow battery for a single-phase grid-integrated PV system and proposes a unique spontaneous control scheme to deal with uncertain grid voltage conditions. Furthermore, a new optimization algorithm is used to fine-tune the controller parameters for optimum control action. The proposed control scheme enhances the stability and efficiency of the system by smoothing the PV output and providing voltage support.