Effect of Induction Machines „Efficiency Class‟ in Their Application as Self-Excited Induction Generator (SEIG)

In this new millennium, the induction generator, with its lower maintenance demands and simplified controls, appears to be a good solution as isolated power supply schemes for rural electrification. Recent emphasis on the utilization of clean and renewable energy sources to reduce dependency on fossil fuels makes the use of SEIG even more attractive because vast amount of energy sources, such as wind and mini-hydro are available in remote areas where utility power is well out reach. In this paper, an attempt has been made to investigate the application of standard efficiency (IE1) class motor and premium efficiency (IE3) class motor as self-excited Induction Generator (SEIG) for stand-alone system. The study has been undertaken in two 3-phase induction motors with rated output power of 5.5 kW and class efficiency of IE1 and IE3 respectively. Both experimental and modeling analysis has been carried out in both machines to evaluate and compare their magnetization curve, selfexcitation process, voltage delivery capability in permissible range and power load capability under resistive load condition. The obtained results are suggesting that machines operating in relatively high magnetic saturation region are more appropriate and economical in applying them as self-excited induction generator for stand-alone system. The study has also given valuable insight in method of determination of appropriate excitation capacitance to maximize the active power delivery of induction generator and to maintain the voltage in permissible region by taking in to account the magnetic saturation level of the given machine. Keywords-SEIG, Premium efficiency, Standard efficiency, rural electrification, power load capability.