Multisurface Super-twisting Sliding Mode Control for DFIG systems: Robust and Low-complexity Solution for Time-varying Disturbance

Wind energy has emerged as a key contributor to global decarbonization, with megawatt-class doubly fed induction generators(DFIGs) playing a central role in modern wind turbine systems owing to their high efficiency and controllability. However, conventional sliding mode control (SMC) strategies, including the super-twisting SMC (STSMC), often exhibit limited adaptability and high chattering when exposed to rapidly changing environmental and grid disturbances. In this study, we developed a novel multisurface super-twisting sliding mode control (MSSTSMC) approach that enhances system robustness without increasing structural complexity. By overlapping multiple sliding surfaces, the controller dynamically adjusts its response to disturbance intensity in real time. Comprehensive simulations were conducted for a 2-MW grid-connected DFIG system under step and turbulent wind profiles, severe parameter variations (up to 180%), and time-varying grid frequency fluctuations. The MSSTSMC outperformed the conventional SMC, STSMC, and disturbance-observer-based STSMC. Further, it achieved up to 37% lower active power tracking error and faster convergence times (< 0.75 s), while maintaining a low computational footprint. These results demonstrate that the MSSTSMC offers a practical, scalable, and computationally efficient solution for high-performance wind energy systems operating under dynamic conditions, thereby contributing to a more stable and reliable renewable power generation.