Control System for Low-Voltage Ride-Through of Grid-Tied Wind and Photovoltaic Energy Conversion Systems

In this paper, the operation of renewable (wind or photovoltaic) energy conversion systems with low-voltage ride-through capability is presented. Control systems, for balanced and unbalanced grid voltages, are presented for the generator and grid sides. In normal grid condition, the dc-dc converter is controlled in order to achieve maximum power extraction, and the inverter is controlled to maintain a constant dc-link voltage and power transfer at a unity factor. In grid fault condition, the dc-link voltage regulation is achieved by the dc-dc converter and the required active and reactive powers injection is achieved by the inverter to meet the grid code requirements. Experimental renewable energy conversion system, configured as wind or photovoltaic, is used to implement and test the control systems under different conditions.