Advanced control of Grid-Connected PV with Supercapacitor Storage for Grid Stability

This paper presents a dynamic performance assessment of a grid-connected photovoltaic system integrated with a supercapacitor energy storage system for DC-link stabilization and power smoothing under realistic partially cloudy conditions. A one-hour irradiance profile representative of coastal tropical weather at NIT Goa is synthesized to impose fast irradiance ramps. The system is implemented in a Simulink environment using average-value converter models to preserve transient accuracy. Simulation results indicate that PV generation varies between approximately 90 kW and 260 kW, creating instantaneous DC-link power imbalances approaching ±150 kW in the absence of storage. Without SCESS, DC bus power fluctuates widely between 150 kW and 550 kW, and the DC-link voltage undergoes severe excursions from nearly 400 V to 1250 V around the 550 V reference during high ramp-rate events. With SCESS integration, the supercapacitor voltage varies smoothly within 540-590 V, absorbing excess energy during high-generation intervals and supplying power during deficits. Consequently, DC bus power is confined to 280-320 kW and grid power injection is regulated within 285-305 kW around the scheduled 300 kW level. The DC-link voltage remains tightly maintained within 540-580 V with significantly reduced ripple. The results quantitatively demonstrate that supercapacitor-based buffering enhances DC-domain inertia, mitigates fast renewable intermittency, and improves grid power quality.