Current harmonic generation of a modeled and simulated single phase grid connected PWM current controlled photovoltaic inverter

There has been a significant increase in the number of renewable distributed generation sources in the power distribution network. In particular the levels of penetration of grid connected Photovoltaic, (PV), systems have shown a continuous growth. These grid connected PV systems through the use of a DC/AC inverter are required to inject current of unity power factor into the grid´s supply. One of the key technical aspects of these grid connected PV inverters when operated in a current control mode is the generation of current harmonics at its output. In this paper, a single phase grid connected PV inverter employing current control is modeled and simulated in Matlab/Simulink and the interaction between its operation and the operating conditions of the grid is investigated by considering the response of its output current injected into the grid in terms of its harmonic content and profile under three different cases. In case 1, the simulated model is run when connected to an ideal grid model and compared when connected to a polluted grid model. In case 2, the simulated model is run at varying levels of rated power. Case 3 considers the response when the grid´s inductance experiences a change of ±5% of its nominal value. It has been shown that the current harmonic generation is affected by three main parameters; (1) the distortion of the grid´s voltage, (2) the operating or generation point of the PV inverter and (3) the impedance of the grid´s network.