Grid Interface of Wind Power With Large Split-Winding Alternator Using Cascaded Multilevel Inverter
In this paper, a wind energy conversion system based on a cascaded H-bridge multilevel inverter (CHBMLI) topology has been proposed to be used for the grid interface of large split-winding alternators (SWAs). A new method has been suggested for the generation of reference currents for the voltage source inverter (VSI) depending upon the available wind power. The CHBMLI has been used as a VSI and operated in a current control mode in order to achieve the objectives of real power injection and load compensation (power factor correction, load balancing, and harmonic compensation) based on the proposed reference-generation scheme. The field excitation control of SWA provides a single means to vary the dc-link voltages of all the CHBs simultaneously and proportionately. The equal distribution of switching stress and power losses among H-bridge cells, reduction in their power ratings, and high quality of inverter output makes the proposed arrangement more efficient. The closed-loop performance of the VSI has been shown to be adequate and fully achieves the control objectives, i.e., grid interface of distributed energy resource (wind) in addition to load compensation. The simulation studies on the proposed scheme have been obtained through the PSCAD/EMTDC software.