Online parameter identification methods for doubly fed induction generators

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Abstract
Two different online parameter identification methods for doubly fed induction generators (DFIG) are investigated in this paper. A model reference adaptive system (MRAS) and a new approach for estimation of the inductances are introduced. Lyapunov stability theory is applied to the adaptive law of the MRAS method. This method requires a test signal which excites all systems eigenvalues. Therefore stator and rotor have to be excited by a test signal. However, not all eigenvalues are excited if the stator of the DFIG is directly connected to the grid. In contrast to common methods the new approach presented here needs no excitation signal. This method estimates the inductances by a set of equations which are based on the description of the DFIG neglecting the stator and rotor resistances. It yields to good results for the mutual inductance and the stator leakage inductance also for the grid connected stator. Both methods are analysed by simulations. The new approach for estimation of the inductances is also tested by measurements at a laboratory setup and yields to good results of the stator leakage and the mutual inductances.