A study on alternative methods of energy hub self-starting generators

Abstract

Power sources of different forms and capacities are being connected to the grid owing to the rapid increase in the use of renewable energy sources. Korea Gas Corporation is conducting a demonstration project to supply electric power to the microgrid by recycling the pressure energy consumed in the gas static pressure process and by installing a turbo expander generator (TEG) with a capacity of approximately 1.6 [MW] in the pressure reducing valve. The demonstration of the microgrid is being conducted in the southern Gyeongin region of South Korea. In this study, the TEG is replaced with a self-starting generator based on a recovery plan, which is established in the event of a power outage. The TEG is an induction generator, which requires a continuous supply of excitation current from the system to achieve independent operation. This issue is resolved through the charging current provided by the primary restorative transmission line and the TEG is replaced with a self-starting generator. The effect on the system when the TEG is replaced and when it is not replaced, is analyzed statically through the amount of power generated by the swing generator. Consequently, when the self-starting generator is replaced with the TEG, the TEG exhibits the same load level as the self-starting generator when a capacitor with a reactive power as high as 1 [Mvar] is installed in parallel to the TEG-installed busbar.