Investigation on Resonating Behaviour of a Self Excited Induction Generator

A self excited induction generator (SEIG) may be operated in various configurations such as shunt, short shunt and long shunt. In each case SEIG winding constitutes RLC parameters and, therefore, when supplying variable power factor loads it experiences resonance. This paper presents a detailed analysis on resonating behaviour of a SEIG operating under short shunt configuration. The steady state SEIG model used for the analysis is based on double field revolving theory while the performance equations are developed through branch impedance method. The different SEIG characteristics are obtained using developed model to assess its performance under two different modes; the shunt connection and short shunt connection. In order to make a realistic performance analysis it is necessary to identify the optimum shunt and series capacitances for the model. Therefore, affects of the variation of shunt capacitance only on various output parameters of SEIG are evaluated to obtain optimum shunt capacitance. The developed shunt model is also verified experimentally and simulated results show reasonable convergence with the experimental data. Consequently, the model is re-evaluated by including a compensation (series) capacitance. The results show considerable improvement in the steady state performance of the SEIG after inclusion of series capacitance. The optimum short shunt model is analysed with variable power factor loads to study the effects of resonance on SEIG performance. An elaborate analysis of different characteristics reveals that there exists a power factor range within which affects of resonance are negligible. Thus, it is imperative that this operating power factor range is defined along with optimum shunt and series capacitances for stable SEIG performance.