The Direct-drive Permanent Magnet Synchronous Generator Based on an Improved VSG-controlled High Voltage Ride-through Strategy

In this paper, an expression of the relationship between the voltage of the grid-connected point of the direct drive permanent magnet synchronous generator and the reactive power demand of the DC transmission system is established for the scenario of direct-drive permanent magnet synchronous generator (PMSG) being transmitted through UHVDC. In order to improve the transient response characteristics of active and reactive loops controlled by conventional virtual synchronizers, a virtual synchronous machine control strategy based on transient current compensation is proposed, and the active and reactive loops controlled by the conventional virtual synchronous machine are improved. The improved control strategy is verified by PSCAD simulation to provide some active support to the transient voltage and power of the delivery system while effectively avoiding the large-scale off-grid of wind turbines in case of commutation failure faults in the DC system.