Self-excitation modelling in deep-bar and double-cage induction generators

Derivation of a current state-space model, in an arbitrary common frame of reference, of a self-excited saturated double-cage (deep-bar) induction machine is presented in the paper. Space vector theory is applied and the approach to saturation modelling corresponds to the one utilized for single-cage induction machines. The model is then adapted to the terminal conditions met in induction generators connected to a three-phase capacitor bank and simulation of self-excitation is performed. Constant speed operation of the induction generator under no-load conditions is analyzed. Experimental investigation is carried out in order to verify the derived model. Simulation results are confirmed by experiments and it is concluded that the derived model describes the behaviour of the machine with sufficient accuracy.