For small-scale pumped storage power plants, induction machines are more commonly used than synchronous machines in terms of initial investment cost and maintenance. Induction machines require reactive power for magnetization in motoring or generating modes. In particular, even if the output is the same, the reactive power is different in motoring or generating operation, so there is a difference in power factor. Power companies require that the power factor of induction machines connected to the grid always be maintained above a certain value. This study compared and simulated the changes in power and power factor when an induction machine with the same output was used in motoring mode and generating mode without a power factor correction device, when a compensation device such as a capacitor was used, and when an active compensation device was installed.The simulation results confirmed that compensation based on reactive power demand in generating mode effectively meets power factor requirements in both motoring and generating mode. Furthermore, the use of STATCOM maintained the power factor close to 1 regardless of operating mode or load fluctuations. This study result will contribute to improving the power factor and power quality of induction machines in small-scale pumped storage systems requiring both motoring and generating operation.
Lee et al. (Fri,) studied this question.