Dynamic Analysis of Three-phase Photovoltaic Inverters with a High Order Grid Filter

The aim of this paper is to analyze the control loops stability of three-phase photovoltaic inverters for distributed power generation. The main issues regarding the design of the control stage are outlined, including a small signal model of the photovoltaic cells for control purposes and the influence of high order grid filters on the system stability. Experimental results carried out on a 100 kW inverter are presented to validate the analytical results. The experimental inverter generates a balanced set of currents with a distortion lower than 3%.