Active power delivery capability improvement of self-excited induction generator for remote and rural area applications

The induction machine used as self-excited induction generator in an isolated stand-alone system has inherently a problem of delivering reasonable output power within voltage regulation band without using sophisticated and costly converters. The use of passive elements can be a good solution to provide self-regulation of such generators to be implemented in the rural area where system overall cost and maintenance issues are prerequisite. In this paper, the magnetic saturation zone of the given machine has been explored in optimizing the excitation and series capacitors needed in order to improve the active power delivery capability and voltage profile. An induction machine of 7.5 kW, 380 V (220 V phase voltage) is used as generator and a vector controlled induction machine is used as a prime mover. Two operating points, those corresponding to the maximum permissible voltage band of +6% and +10% above the rated voltage has been taken as focal points to evaluate and compare the active power delivery capability in permissible minimum voltage regulation band. Both the experimental and simulation results are suggesting that a machine which operates in more saturated region of the magnetization curve provides improved result in terms of active power delivery capability and voltage profile without use of a control system.