Flexible DG interface using repetitive control

Distributed generation (DG) units are widely spread in most electrical power systems. Such large extensive presence attracted many researchers to optimally exploit the available DG units in order to enhance the overall performance of the main power system grid. In this work a repetitive control-based technique is applied to operate the DG unit as an active power supplier and power quality enhancer. The enhancement provided to power quality is summarized in filtering load current harmonics and supporting reactive power sharing as well. The main advantage of the repetitive control is simplicity. Current filtering, and active and reactive powers sharing control are done directly in the abc frame. There is no need for the dq, and its inverse, transformation. However, the applied technique shows a high quality performance under normal conditions and fast, robust performance under sudden load changing.