Predictive control of grid connected PV system

Abstract

In this work, a predictive current control for a photovoltaic conversion chain connected to a grid, based on the finite states space model of the converter is investigated.The elaborated control algorithm selects the switching state of the inverter by generating a current identical to a reference current generated by the MPPT algorithm, then minimizes the error between the predicted and the reference current to their computed values for all different voltage vectors. The ideal voltage vector that minimizes the cost function is then applied to the output of the power converter. The investigated predictive control technique uses only one sample time prediction and it is exceptionally intuitive since it is very straightforward and gives encouraging performances. The whole system consists of a PV array that generates the DC power and a Two-levelVoltage Source Inverter (VSI) which is controlled using Model Predictive Control (MPC) approach to inject a controlled current into the grid. A phase-locked loop (PLL) is used to lock grid frequency and phase while an L filter is employed at the inverter output to remove the high-frequency ripples. The main result of the project is that power has been injected into the grid while the current's total harmonic distortion (THD) has been kept below the level required by international standards.