An improved MRAS based sensorless vector control method for wind power generator

Abstract

This paper describes an improved sensorless vector control strategy for a squirrel cage induction generator used in variable speed wind energy conversion systems (WECS). The main goal is to design a robust control algorithm immune to generator parameter variations. In order to estimate the rotational speed of the induction generator, a model reference adaptive system (MRAS observer) is used. It is shown that a generator parameter mismatch has a great influence on the rotor speed estimation. In order to estimate the speed accurately, the generator stator resistance must be identified at the same time to correct the mismatched resistance value used in the observer. The proposed rotor speed estimator with parallel stator resistance identification is first verified by computer simulation. Finally, the experiment is conducted in order to verify the obtained simulation results. It is proved that this control scheme can enhance the efficiency of a variable speed WECS.