Power Quality Enhancement of a Grid-Connected PV–WECS Hybrid Energy Storage System Using Fuzzy Logic Controller and Dynamic Voltage Restorer

Abstract

The increasing penetration of renewable energy resources into modern power systems has introduced significant challenges related to voltage regulation, harmonic distortion, renewable intermittency, and grid stability. This paper presents an intelligent grid-connected photovoltaic (PV) and wind energy conversion system (WECS) integrated with a Hybrid Energy Storage System (HESS) for enhancing power quality under varying operating conditions. The proposed system employs a Fuzzy Logic Controller (FLC) to regulate the DC-link voltage and control the Voltage Source Converter (VSC), thereby providing superior dynamic performance compared with conventional control approaches. A Dynamic Voltage Restorer (DVR) is incorporated at the Point of Common Coupling (PCC) to compensate voltage sag, voltage swell, and severe grid disturbances, ensuring continuous and reliable power delivery to sensitive loads. The coordinated operation of PV, WECS, HESS, FLC, and DVR significantly improves voltage stability, reduces Total Harmonic Distortion (THD), enhances renewable energy utilization, and strengthens fault ride-through capability. The complete system is developed and analysed in the MATLAB/Simulink environment under nonlinear loading conditions and grid disturbances. Simulation results demonstrate that the proposed intelligent control strategy effectively minimises harmonic distortion, maintains stable DC-link voltage, improves transient response, and delivers superior power quality while satisfying IEEE-519 harmonic standards for modern smart grid applications.