Adaptive Sensorless SM-DPC of DFIG-Based WECS Under Disturbed Grid: Study and Experimental Results

Abstract

This paper focuses on the enhanced control and improved fault-ride-through capability of a doubly fed induction generator (DFIG)-based wind energy conversion system (WECS) under disturbed grid conditions. An adaptive sliding-mode control of stator powers, with sensorless rotor current and constant switching frequency, is introduced. The proposed control method is derived directly from the nonlinear DFIG state model, and the control law is computed based on nominal stator flux. Therefore, the flux estimation or measure, which is cumbersome in some methods, is no longer required. Furthermore, an adaptive term is added to sliding-mode control in order to attenuate the chattering effect. The proposed control law is validated via simulations in the case of 1.5 MW DFIG-based WECS, and experimental results on a 7.5 kW hardware prototype. The control system robustness and performance is assessed in the presence of modeling errors, parameter variations, and grid side disturbances, such as voltage dip, swell, imbalance, distortion, and flicker (according to IEEE Standard 1159).