Model of a three-phase autonomous power generator using solar batteries, a supercapacitor, a step inverter and a transformer

Abstract

The global deployment of renewable energy technologies is accelerating due to finite fossil fuel reserves and the imperative toreduce harmful emissions from combustion. This study concentrates on photovoltaic (PV) solar generation as a practical option forresidential power supply and examines the less-explored combination of PV arrays with supercapacitor energy storage. Acomprehensive literature review shows that electrochemical batteries have been the dominant storage solution for solar systems sincethe inception of PV technology, while supercapacitors have only recently been investigated, typically as auxiliary units supportingbatteries. Research specifically addressing the direct interaction between PV arrays and dedicated supercapacitor banks remainslimited. Most existing works employ pulse width modulated (PWM) inverters with output filters to meet power quality requirements,which motivates the evaluation of whether a simple stepped inverter with an output transformer can still deliver acceptable gridindependent power quality when paired with supercapacitors.A detailed MATLAB Simulink model of a standalone power source was developed from standard blocks to address thesequestions. The modeled system includes a PV array, a supercapacitor bank, a DC-DC boost converter, a stepped three-phase inverter,and an output voltage transformer. Time-domain simulations under varied operating conditions show that the PV array consistentlysupplies energy to both the boost converter and the supercapacitor bank. Under conditions of deep supercapacitor dischargeaccompanied by marked DC-link voltage sag, the PV array inherently limits its output current to a maximum safe level for the PVmodules, preventing damage and preserving stability. When surge power is required, the supercapacitor bank supplies high peakcurrent without disrupting normal system operation.Because output voltage amplitude is strongly load-dependent, an automatic voltage stabilization loop based on a PI controllergoverning the boost converter was implemented. Analysis of voltage and current waveforms under the stabilization schemedemonstrates power quality that meets the criteria of IEEE 519-2022. Acceptable voltage quality is maintained until thesupercapacitor state of charge falls to approximately 40 percent, corresponding to a voltage drop from roughly 30 V to roughly 10 V.