A Composite Converter Architecture for Wind Energy Systems Connected to AC Grid

A composite converter architecture consisting of a multi-port generator and a set of power electronic converters is proposed for a wind energy system tied to an ac grid. The generated power is delivered to the grid by way of two paths: one via a passive rectifier and line-frequency inverter, and the other through an active rectifier and an inverter operating at switching frequencies higher than their respective fundamental frequencies, with the maximum power processed only <tex-math notation="LaTeX">$10%$</tex-math> of the rated power. The remaining power is processed using the line-frequency path, employing reliable, efficient, and inexpensive diodes and switches. An analytical design framework shows that the high-frequency switch volt-ampere rating can be reduced by <tex-math notation="LaTeX">$67.9%$</tex-math>. This results in an overall loss reduction ranging between <tex-math notation="LaTeX">$46.8%$</tex-math> and <tex-math notation="LaTeX">$53%$</tex-math> depending on the extracted power. Control and modulation strategies and a maximum power point tracking algorithm are presented. Experimental results obtained from a laboratory prototype validate the performance and the effectiveness of the proposed converter architecture, and its control and modulation strategies. This approach opens up opportunities for integrating ac-collection networks through an efficient, reliable, and cost-effective energy conversion system.