In this paper, a decoupled active and reactive power control strategy based on finite set model predictive control is proposed to control grid connected six-level NPC inverters for photovoltaic application. The purposes of this strategy are: injection control of the active power produced by photovoltaic system as well as the reactive power requested by the grid operator, also the assurance of high grid current quality and dc link capacitors voltages balance. Using the discrete time model of six level NPC inverter tied to the network, the proposed strategy is based on prediction of the future behavior of active and reactive grid power values and dc link capacitor voltages for 216 possible switching states and compare them with using a cost function for obtaining the optimal vector and applying it during the next sampling time. The global system is simulated using Matlab/Simulink and Simpower system packages. The performance of the proposed strategy is evaluated under the step change in the solar irradiation and the reactive power reference. The obtained results proves that the proposed strategy provide high performance control.

Keywords: Solar energy, Six-level neutral point clamping (NPC) inverter, Decoupled active and reactive power control, Finite set model predictive control