New control strategy for multifunctional grid-connected photovoltaic systems

Abstract

The main aim of this work consists of proposing a new control strategy for multifunctional grid-connected photovoltaic systems (GCPVSs) to enhance the power quality at the point of common coupling (PCC) while considering the inverter-rated capacity. In addition, an Adaptive neuro-fuzzy inference system (ANFIS) based maximum power point tracking (MPPT) controller for a two-phase interleaved boost converter is proposed to improve the dc-link voltage oscillation of the GCPVS. The control strategy takes into account the inverter's rated capacity in terms of power, which is defined by its maximal current modulus. It limits the inverter current to prevent overrating operations, and it also manages the GCPVS's functions: active power injection, reactive power compensation, and current harmonic filtering. The Active power injection into the grid takes precedence over power quality enhancement. Then, The reactive power compensation takes priority over the filtering of nonlinear load current harmonics. The proposed strategy is applied to a grid-connected PV system through an interleaved boost converter and a three-level neutral point clamped (NPC) inverter. Various scenarios with different solar irradiation levels are investigated using MATLAB/Simulink environment. Compared with another existing control strategy in terms of grid current total harmonic distortion (THD) enhancement, the simulations results indicate the superiority of the proposed method. Furthermore, the simulation results also show that the multifunctional GCPVS can perfectly perform all its functions simultaneously with up to 16.95% reduction in grid current THD.