SSO Supplementary Damping Control Method for DFIG based on Model-free Adaptive Control

Doubly-fed wind power integrated systems could suffer from sub-synchronous oscillation (SSO). Due to the accuracy of modeling and the fixity of parameters and structure, the conventional sub-synchronous damping controller (SSDC) may has the problem of poor adaptability. In this paper, a sub-synchronous damping controller based on model-free adaptive control (MFAC-SSDC) was designed, using the dynamic linearization technology to extract dynamic characteristics from the input and output data of the system. By this way, the control method can get rid of the dependence on the accuracy of modeling and improve the adaptability of the controller. First, the control structure was designed based on MFAC, and a one-step-ahead weighted predictive control algorithm suitable for damping control was proposed. Furthermore, it is theoretically proved that the tracking error of the closed-loop system is uniformly ultimately bounded (UUB) and bounded input-bounded output stable under the improved control algorithm. The optimization method of the controller parameters was also proposed. Finally, comprehensively considering the influences of wind speed, active/reactive power regulation of wind farm, the number of wind turbine generators and series compensation level, the damping effects of MFAC-SSDC proposed in this paper were verified. Results show that this method achieves strong adaptability and can effectively mitigate SSO under various operating conditions. © 2022 Chin. Soc. for Elec. Eng.