Control Strategy for Two-Stage Photovoltaic Power Converter During Simultaneous Grid Faults and Irradiance Change

The development of the distributed power energy sources has resulted in the increase of the number of the power converters in the distribution network. The control strategies of these converters have to be improved in order to maximize the power production and satisfy the grid code requirements, especially in abnormal grid conditions. In this paper control algorithm for a photovoltaic (PV) system connected to the grid through two-stage power converter is analyzed considering normal grid conditions and grid faults, as well as sudden change of the illumination intensity on the PV side. The proposed solution features several key improvements comparing to the existing solutions, such as smooth transition between the modes of operation, fast response to the grid disturbances, provision of several grid support strategies and instantaneous limitation of the phase currents. The control algorithm is tested in the hardware-in-the-Ioop testing environment and the results that verify the proposed control strategy are given.