Single-phase seven-level grid-connected photovoltaic system with ripple correlation control maximum power point tracking

Abstract

This paper puts forward a control scheme for single-phase photovoltaic (PV) fed grid connected with cascade Hbridge (CHB) inverter. A unique control strategy based on the voltage ratio is proposed and is embedded with ripple correlation control (RCC) based maximum power point tracking (MPPT) to ensure the efficient energy conversion. The control scheme employed enables the independent operation and control of individual DC link voltage, ensuring the extraction of maximum power available from each PV panel. In addition, low harmonic grid currents are generated with an arbitrary power factor. Independent control of active and reactive power is exercised by decoupled component method. Numerical simulation was performed using the MATLAB/SIMULINK platform and results for three H-bridge cells connected in series are presented to support the theoretical concepts and control scheme proposed.