An improved damping adaptive grid-forming control for black start of permanent magnet synchronous generator wind turbines supported with battery energy storage system

Abstract

Permanent magnet synchronous generators (PMSGs) equipped with back-to-back grid-forming converters have the ability to form a 100% renewable energy power grid. Black-start is the key capability of grid-forming converters when restoring the system from a blackout. It is necessary for a grid-forming converter of the PMSG to operate in black-start and grid-connected active support modes. This paper investigates an improved damping adaptive grid-forming (DA-GFM) control method for PMSG wind turbines to suppress system frequency fluctuations and achieve a smooth black start. The proposed DA-GFM control introduces the frequency variations and natural constant function to adaptively adjust its damping coefficient in the dynamic operating progress. The implementations and effects of the proposed DA-GFM control method on the grid-forming converter are theoretically evaluated. Additionally, the detailed black-start operation process is completely studied through a microgrid system with two PMSG wind turbines and energy storages. Compared with the conventional grid-forming control, the proposed control scheme can not only suppress frequency fluctuations better, but also achieve a smooth forming power grid process. Finally, experiment tests on a controller-level hardware-in-the-loop simulation platform are carried out to validate the proposed control strategy for achieving a smooth black start.