Distributed Wind Energy Conversion System Interface to the Grid Using Cascaded Multi-Level Converter

In this paper, a distributed wind energy conversion system based on the cascaded H-bridge multi-level converter topology has been proposed to be used for the medium-voltage grid interface application. This includes load compensation and injection of real power requirement of the load. The load compensation includes reactive power compensation, load harmonic mitigation, and correction for the unbalancing problem. An algorithm has been proposed for generating references for the voltage source converter in current control mode in order to inject real power together with the reactive and harmonic components of the load. Modular structure of the wind turbine-alternator sets and cascaded multi-level inverter using H-bridges suits the distributed wind energy conversion system interface to the medium-voltage grid. The factors like equal distribution of switching stress and power losses, reduced power ratings of the inverter, redundancy, and high quality of inverter output voltage make the proposed arrangement efficient for high-power applications. The cascaded topology with phase-shifted multi-carrier pulse width modulation (PWM) has the features of increasing the effective switching frequency and reducing the ripple magnitude. The proposed scheme has been verified through the simulation study using power system transient analysis tool (PSCAD/EMTDC).