An Advanced Modular Multilevel Inverters for Grid-connected PV Optimization by Maximum Power Point Tracking

Modular multilevel inverters (MMLIs), acknowledged not only for its modular structure, scalability and low harmonic distortion but also offers an efficient solution<sub>,</sub> for managing high-power renewable-energy applications. However, these often depends on conventional centralized control methods<sub>,</sub> which are insufficient in addressing critical challenges like scalability and hardware delays in distributed control systems. This paper emphases on the design and implementation<sub> </sub>of an advanced 3-Ph. MMLI for a 400-kW solar plant connected to a 25 kV grid. The study examines the system's performance, control strategies and operational challenges encountered during the integration with grid. To optimize energy extraction from the PV array, incorporate a DC/DC<sub>,</sub> converter featuring MPPT<sub>,</sub> through ‘Perturb and Observe’ (P & D) technique. The extracted energy is then stepped up and converted into 3-Ph. AC voltage through MMLI. The output from these, feed into a common 500V DC bus, enabling the overall system integration. Unlike earlier methods which are used open-loop control to address power imbalances among legs, this study employs closed-loop control using to correct mismatched DC loop currents. This allows, dynamic adjustment the voltage across PV array to optimize output efficiency. The efficacy of the proposed control-strategy has been validated through Mat lab/Simulink simulations, demonstrating its potential.