Hedge-Algebra Speed Controller – Experimental Implementation in a Sensorless Stand-Alone WECS

This paper considers a stand-alone wind energy conversion system (WECS) designed for dc load supply and battery charging. An indirect rotor-field-oriented (IRFO) control scheme is applied for the wind turbine (WT) driven induction generator (IG). High level of agreement between the actual IG and the IRFO controller is ensured by including the IG stray load and iron losses as well as the magnetic saturation in the control algorithm. Within the considered IRFO controller, the reference flux is adjusted to achieve minimum IG losses. Similarly, the WT speed is controlled to ensure maximum WT power at different wind speeds. To achieve this, it is essential that the actual WT speed closely tracks the reference and that it is robust to disturbances in the system. The proposed hedge algebra (HA) speed controller is here for the first time experimentally implemented within a WECS. Its performance is evaluated over a wide range of wind speeds by using a 1.5 kW experimental setup with the DS1103 controller board (dSPACE). To avoid speed sensor, the rotor speed is estimated by means of the model-reference-adaptive system. The obtained results show superior performance of the HA controller in terms of overshoot, settling time, and disturbance rejection in comparison with a conventional PI controller.