A Comparative Study Between Two MPPT Algorithms for Photovoltaic Energy Conversion System Based on Modular Multilevel Converter

This paper compares two Maximum Power Point Tracking (MPPT) strategies for a medium-scale multi-string photovoltaic energy conversion system based on modular multilevel converter (MMC). The Perturb and Observe (P&O) and Incremental Conductance (INC) techniques are considered as the MPPT controller and their power point tracking performances are compared together. A model predictive control (MPC) is used to control the currents at the micro-grid side and also upper and lower capacitors voltage balancing is controlled by a closed-loop controller according to the energy equations. The main challenges involve the voltage regulation and also ensuring the source-end pure sinusoidal three-phase currents. A typical PV energy conversion system composed of a 10-level MMC and PV as the string cells is evaluated through simulation in MATLAB/Simulink. The P&O and INC strategies are applied on the PV system and the performance of each one is evaluated. The results demonstrate that the INC method has better behavior in terms of PV output power and three phase load power oscillations and also extracting the maximum power point from the PV panel.