Stable coordination of multiple PMSGs in an islanded DC microgrid: A distributed model predictive control approach

For permanent magnet synchronous generators (PMSGs)-based dc microgrids operating in islanded mode, coordinated load sharing among multiple PMSGs is necessary when the available wind power exceeds the load demand. During the load sharing process, PMSG may prone to instability due to possible over deceleration. In order to address this issue, this paper presents a new distributed control scheme, which achieves stable load sharing among multiple PMSGs in a dc microgrid. Based on the distributed model predictive control (DMPC) approach, the proposed scheme coordinates the operation of parallel connected grid-side converters, thus optimizing the load sharing ratio for each PMSG. The salient feature of this scheme is that, by incorporating the rotor kinetic energy and generation margin into the controller design, it ensures stable operation of all PMSGs. Simulation results verify the effectiveness of the proposed scheme.