Observer-Based High-Order Sliding Mode Control of DFIG-Based Wind Energy Conversion Systems Subjected to Sensor Faults

Recent advances in technology have paved the way for the increased penetration of wind energy conversion systems (WECSs) into the grid, worldwide. However, the existence of model uncertainties and intermittency of wind power can lead to malfunction of the stabilizing controllers and degrade the WECSs' power production performance. In this work, a compound control scheme comprising active fault-tolerant fractional-order nonsingular terminal sliding mode controllers (AFTSMCs) and a sliding mode observer (SMO) is developed to enhance the robustness of doubly-fed induction generator (DFIG)-based WECSs against uncertainties and maintain their desired performance. The developed AFTSMCs alleviate the chattering problem and overcome the compromise between fast response and the undesirable chattering problem. At the same time, it performs the speed trajectory tracking and rotor current regulation tasks. Moreover, under inevitable false fault detections due to unavoidable gradual performance degradations in the current sensors, a tolerance boundary is circumscribed for actual faults occurrence, allowing the developed robust SMO to estimate and reconstruct the rotor current during sensor faults with a high level of reliability. Evaluations of comparative performance are provided and validate the cooperative fault-tolerant method's superior control performance over other advanced approaches.