Hybrid Grid-Forming and Grid Following PMSG-SMES Architecture With Enhanced FRT Capability

To improve the voltage and frequency support capability of conventional grid-following (GFL) type permanent magnet synchronous generator (PMSG) during normal operation and fault ride-through (FRT) capability under both symmetric and asymmetric grid faults, this paper proposes a novel hybrid reconfigurable GFL and grid-forming (GFM) architecture for the PMSG, which integrates a superconducting magnetic energy storage (SMES) system. The SMES is connected to the DC bus of the PMSG through a DC/DC converter, and an additional energy side converter (ESC) is parallel connected with the grid-side converter (GSC). During normal operation, the ESC adopts GFM control thus the PMSG can work in weak AC grids. When a grid fault occurs, the connection of the ESC is reconfigured to a series connection between the GSC and the grid, in which case voltage compensation control is adopted for the ESC to maintain the terminal AC voltage of the PMSG to be the pre-fault value. Simulation results in PSCAD/EMTDC verify that the proposed scheme can increase the grid-forming capability of conventional GFL PMSG and show excellent FRT performance under various symmetric and asymmetric grid faults.