PID-type Terminal Sliding Mode Control for Permanent Magnet Synchronous Generator-based Enhanced Wind Energy Conversion Systems

The provision of wind farm (WF) grid codes (GCs) has become imperative for sustained grid operations, especially for WFs with permanent-magnet synchronous generator (PMSG) wind energy conversion system. Numerous techniques have been developed for executing GC requirements in the event of grid faults. Among the methods, an intriguing strategy is to enhance the performance of back-to-back (BTB) converter controllers. In this research, the PID-type terminal sliding mode control (PID-TSMC) scheme is implemented for both machine-side and grid-side converter-modified controllers of BTB-converter, to reinforce the nonlinear relationship among the state-variable and the control input. The application of this control scheme decreases the response time and improves the robustness of the BTB-converter controllers regarding uncertainty of parameters and external disturbances. The grid-side converter tracks the maximum power point, contributing to the rapid decrease of generator active power output during faults. This frees up converter capacity for injecting GC-compliant reactive current into the grid. Besides, the machine-side converter regulates DC-link voltage, in which its variations during external disturbances decrease substantially with the PID-TSMC. The discussions on the simulations contemplate on the robustness and efficiency of the implemented PID-TSMC strategy in comparison to other BTB-converter control strategies.