Study on characteristics and impacting factors of oscillation of wind farms integration via an MMC-based HVDC system

Modular multilevel converter (MMC)-based high-voltage DC (HVDC) transmission technology has become an ideal solution for large and remote wind farms integration. Oscillation or instability phenomena might occur due to the rapid control of power electronic converters in both wind farms and MMC-based HVDC system. In order to reveal oscillation characteristics of wind farms and MMC-based HVDC interconnected system, the system equivalent damping stability criterion is deduced theoretically, and a system damping analysis platform is built in this study. On this base, the impact on 1–1000 Hz oscillation characteristics from many factors including controller parameters of wind turbines and MMC-based HVDC, wind turbines power and wind turbines number is analysed, and mechanism of instability under different conditions is explained physically in terms of system damping characteristics. Time-domain simulations in RT-LAB are presented to validate the stability study.