Review of control strategies in three phase grid connected renewable energy systems with practical case study

• Reviews inverter control strategies (2020–2025) for 3-phase grid-connected renewable systems. • Covers PI/PR, MPC, SMC, AI, and grid-forming control techniques. • Includes experimental validation using PR controllers on Imperix hardware. • Demonstrates stable operation under dynamic load and energy scenarios. • Bridges recent control theory with practical lab-tested implementation. This paper combines a review of control methods for three-phase grid-connected renewable power systems with experimental validation of the methods. The review evaluates recent inverter control strategies from 2020 to 2025 by analyzing PI/ Proportional-Resonant (PR)methods and fractional-order controllers, intelligent techniques, tuning methodologies and implementation barriers and application patterns. The practical case study involved building a low-voltage laboratory prototype that used a house-side inverter with PV and battery storage functions, and a stationary-frame PR controller optimized using classical optimum magnitude and symmetrical optimum criteria. The system underwent testing under balanced and unbalanced load conditions while operating in different energy flow scenarios that included PV-only supply and battery discharge and simultaneous charging. The experimental results showed that the inverter maintained voltage regulation within ±2% of the nominal value, achieved power-sharing accuracy above 95% between the PV and battery sources, and maintained stable DC-link operation during dynamic transitions, with response times below 10 ms. The research links theoretical developments to practical execution by providing both an updated review of current technology and a verified reference model for upcoming inverter-based renewable systems.