Parallel interleaved grid-connected converters in MW-level wind power generation

With the individual capacity of wind power generation system increasing, the demand for high power grid-connected converters is growing, which is usually limited by the available semiconductor technology. One solution is multiple lower power units connected in parallel. In this paper, direct parallel and interleaved parallel are analyzed and compared. Then it focuses on two parallel interleaved converters. The generating mechanism of high frequency circulating current and low frequency oscillation circulating current are both studied. Also, an interleaved SVPWM and the corresponding control strategy of circulating current are introduced. Finally, the described strategy has been implemented in a 1.5 MW grid-connected converter for wind power generation, providing a satisfactory performance.