The Operation Results and Study of KSTAR Pulsed Electric Power Network for Superconducting Magnet Power Supply

To achieve 2 MA plasma current with 300 s pulse length in the Korea Superconducting Tokamak Advanced Research (KSTAR), its pulsed electric power network (PEPN) was designed. The PEPN system, which was installed in 2012, consists of an exciter, a synchronous machine (SM), and a large power variable voltage and variable frequency (VVVF) inverter. Several commissioning activities were performed on the mechanical parts of SM, and the PEPN has been used to supply AC power to the KSTAR superconducting magnet power supplies (MPSs) since entering into service in 2015. However, due to electrical faults in the VVVF inverter during certain types of plasma operations, the operation window of KSTAR has decreased, especially during high plasma current and long-pulse operations. The operation results of the KSTAR PEPN are reviewed in this paper. In addition, a comprehensive study of faults in the VVVF inverter system is performed from the viewpoint of active power variation using real plasma operational scenario results and model-based simulations. This paper also describes the design upgrade of the PEPN system for extended KSTAR operations in the future.