Self-synchronization and Frequency Response Control of PMSG-Based Wind Turbine Generator

Traditional control strategy for grid-side converters (GSCs) that adopts phase-locked loop (PLL) to track grid phase is easy to lose stability under weak grid conditions. Therefore, this paper proposes a novel control method for GSC based on the dynamic of DC-link capacitance, which can realize self-synchronization and maintain the stability of DC-link voltage. Meanwhile, without adding additional frequency detection devices, the synchronous angular frequency (SAF) of the control output can be a reflection of the grid angular frequency (GAF) in real-time, and then the frequency response function can be achieved by the machine-side converter (MSC) through the auxiliary control loop. The small-signal state-space method is used to study the stability of the system. Finally, based on PSCAD/EMTDC simulation software, a simulation analysis model of the PMSG-based wind turbine generator (WTG) is established. Theoretical analysis and simulation results show the superiority and correctness of this control strategy.