PMSG based multi-generator architecture for wind generation application

The direct-drive wind turbine has received much attention compared to the geared turbine in terms of reliability and cost. However, dimension of the direct-drive turbine will be too large to transport and assembly with the increase of power-scale. This paper proposes a multi-generator architecture to address potential challenges: dimension, cost and reliability. Two permanent magnet synchronous generators (PMSG) are desired to share one shaft driven by turbine. The outputs of two PMSGs are rectified to connect in series and supply the intermediate DC chopper and back-end inverter. Due to the serial connection, a high DC-link voltage inspires to eliminate the DC chopper during strong wind period, and thereby the rated power of the DC chopper is only required to be a fraction of the system rating. Meanwhile, the control scheme for the DC chopper and the grid-side inverter is presented as well as the reconfiguration strategy of the proposed system in case of generator faults. The performances and practicalities of the proposed architecture are verified in simulation using one MW-level wind turbine.