Harmonic Analysis of a Stand-Alone Photovoltaic-Battery-Supercapacitor Hybrid System

This paper presents a harmonic distortion analysis of a stand-alone photovoltaic (PV)-batterysupercapacitor hybrid energy system modeled in MATLAB/Simulink. The system integrates a PV array, boost converter, bidirectional DC-DC converters, a lithium-ion battery, supercapacitor, inverter, LC filter, and load. The study addresses the power quality challenge in standalone PV systems, focusing on Total Harmonic Distortion (THD) under varying environmental conditions. Simulation results show that the integration of a supercapacitor reduces voltage fluctuations and marginally lowers THD levels, improving stability and inverter performance. The THD under Standard Test Conditions (STC) was 14.82%, while under Nominal Operating Cell Temperature (NOCT), it increased to 15.45%. This work highlights the role of hybrid energy storage systems (HESS) in mitigating harmonics and enhancing power quality for off-grid renewable applications.