Stator Flux Producing Current-Based Promoted Rotor Angle Estimator of Doubly-Fed Induction Generator for Encoderless Operations

In the context of position or speed sensorless control scheme, an improved rotor position estimation process for doubly-fed induction generator (DFIG) is presented in this paper. Model reference adaptive system (MRAS) is considered for the computation of rotor position. The stator flux producing current is taken as main working variable for the estimator. The estimator has various desirable features such as free from integrator-differentiator based computation, no information needed about initial rotor position (catch on fly operation), capability to work at very low slip condition (near synchronous speed operation), non-involvement of flux calculation, negligibly sensitive to mismatch in machine parameters. The major advantage of the proposed scheme is that it is insensitive to magnetizing inductance and rotor resistance of the electrical machine. Also, the novelty of the estimator lies in the fact that the suggested estimator works stably and accurately from very light load to full load operating conditions. The robust operation of proposed estimator is verified through real-time experimental set up.