Dong-Keun Lee

Development of In-Vessel Vertical Coil Power Supply in KSTAR

The Korea Superconducting Tokamak Advanced Research (KSTAR) device is an advanced superconducting tokamak to establish scientific and technological bases for an attractive fusion reactor [1]. In-vessel vertical coil (IVC) power supply (PS) is developed for vertical stability and shape control of KSTAR plasma. IVC PS in KSTAR is based on a single-phase full-bridge inverter. The output voltage and current are dc ±1 kV and ±10 kA, respectively. Insulated gate bipolar transistor is used as switching power device in IVC PS and maximal 5 kHz of switching frequency is adopted to meet the requirement of fast control by plasma control system. This paper describes the configuration and engineering of the IVC PS system and analyzes both the IVC coil commissioning and the major performances that D-shape plasma achieved in experiments.

Stabilization of the KSTAR Power System for the First Plasma Operation

After more than ten years of construction, the Korea Superconducting Tokamak Advanced Research (KSTAR) device finally completed its assembly in June 2007. We conducted the first plasma operation from April 2008 to July 2008 and succeeded in the plasma generation in July 2008. The electric power system for the first plasma operation is made up of various electric devices, including 154-kV circuit-breaker systems, a 154/22.9-kV 50-MVA transformer, 22.9-kV circuit-breaker systems, and reactive power compensator (RPC) and harmonic filter (HF) systems. When the poloidal-field magnet power supplies were operated, the reactive power and harmonic currents (12n ± 1) were generated instantaneously in the KSTAR electric power system for the first plasma generation due to the characteristics of the KSTAR superconducting coils. The measured voltage drop and harmonics seriously affected the other experimental equipment as well. Therefore, it is important to compensate the reactive power and remove the harmonics with the RPC and HF system for the superconducting tokamak device. In this paper, we discuss the stability of the electric power system and the operational results of the RPC and HF systems during the KSTAR first plasma operation. Furthermore, the upgrade plan of the electric power system based on the KSTAR operation plan will be discussed.

Stabilization of the KSTAR power system for the first plasma operation

The KSTAR(Korea Superconducting Tokamak Advanced Research) facility is composed of thirty superconducting magnets for plasma experiment. The electric power system for the first plasma operation is made up of various electric devices including 170 kV GIS, 154 kV 50 MVA transformer, 22.9 kV circuit breaker systems and RPC & HF systems. When PF MPS was operated, reactive power and harmonic currents of 1±12ns occurred instantaneously in the KSTAR electric power system due to the characteristics of the KSTAR superconducting coil for the first plasma generation. However, the measured voltage drop and harmonics seriously affect other experiment equipments as well. Therefore, the RPC & HF system for the superconducting tokamak device is important to compensate the reactive power and remove harmonics. In this paper, we discuss the stability of the electric power system and the operation results of the RPC & HF systems during the KSTAR first plasma operation. Also, the upgrade plan of the electric power system based on the KSTAR operation plan will be discussed.

Superconducting Magnet Power Supply System for the KSTAR 2 nd Plasma Experiment and Operation

The Korea Superconducting Tokamak Advanced Research (KSTAR) device is an advanced superconducting tokamak to establish scientific and technological bases for attractive fusion reactor. This device requires 3.5 Tesla of toroidal field (TF) for plasma confinement, and requires a strong poloidal flux swing to generate an inductive voltage to produce and sustain the tokamak plasma. KSTAR was originally designed to have 16 serially connected TF magnets for which the nominal current rating is 35.2 kA. KSTAR also has 7 pairs of poloidal field (PF) coils that are driven to 1 MA/sec for generation of the tokamak plasma according to the operation scenarios. The KSTAR Magnet Power Supply (MPS) was dedicated to the superconducting (SC) coil commissioning and 2 nd plasma experiment as a part of the system commissioning. This paper will describe key features of KSTAR MPS for the 2 nd plasma experiment, and will also report the engineering and commissioning results of the magnet power supplies.

Quench Protection System for the KSTAR Toroidal Field Superconducting Coil

The design of the integrated quench protection (QP) system for the high current superconducting magnet (SCM) has been fabricated and tested for the toroidal field (TF) coil system of the Korea Superconducting Tokamak Advanced Research (KSTAR) device. The QP system is capable of protecting the TF SCM, which consists of 16 identical coils serially connected with a stored energy of 495 MJ at the design operation level at 35.2 kA per turn. Given that the power supply for the TF coils can only ramp up and maintain the coil current, the design of the QP system includes two features. The first is a basic fast discharge function to protect the TF SCM by a dump resistor circuit with a 7 s time constant in case of coil quench event. The second is a slow discharge function with a time constant of 360 s for a daily TF discharge or for a stop demand from the tokamak control system. The QP system has been successfully tested up to 40 kA with a short circuit and up to 34 kA with TF SCM in the second campaign of KSTAR. This paper describes the characteristics of the TF QP systems and test results of the plasma experiment of KSTAR in 2009.

Superconducting magnet power supply system for the KSTAR 1 st plasma experiment and engineering

The Korea Superconducting Tokamak Advanced Research (KSTAR) device is an advanced superconducting tokamak to establish scientific and technological bases for an attractive fusion reactor. This device requires 3.5 Tesla of toroidal field (TF) for plasma confinement, and requires a strong poloidal flux swing to generate an inductive voltage to produce and sustain the tokamak plasma. KSTAR was originally designed to have 16 serially connected TF magnets for which the nominal current rating is 35.2 kA. KSTAR also has 7 pairs of poloidal field (PF) coils that are driven to 1 MA/sec for generation of the tokamak plasma according to the operation scenarios. The KSTAR Magnet Power Supply (MPS) was dedicated to the superconducting (SC) coil commissioning and 1st plasma experiment as a part of the system commissioning. This paper will describe key features of KSTAR MPS for the 1st plasma experiment, and will also report the engineering and commissioning results of the magnet power supplies.

Development of In-vessel Vertical Coil (IVC) power supply in KSTAR

The Korea Superconducting Tokamak Advanced Research (KSTAR) device is an advanced superconducting tokamak to establish scientific and technological bases for an attractive fusion reactor [1]. In-vessel Vertical Coil (IVC) power supply has been developed for vertical stability and shape control of KSTAR plasma. IVC power supply in KSTAR is based on a single-phase full-bridge inverter. The output voltage is DC ±1kV and output current is ±10kA. IGBT is used as switching power device in IVC power supply and maximal 5kHz of switching frequency is adopted to meet the requirement of fast control by PCS. This paper describes the configuration and engineering of the IVC power supply system and analyzes both the IVC coil commissioning and the D-shape plasma major performances achieved by experiments.

A reactive power compensation and harmonics removal of superconducting nuclear fusion device through tsc base massive RPC & HF systems

The KSTAR(Korea Superconducting Tokamak Advanced Research) device needs a large pulse power to supply to a superconducting magnet power supply(MPS) and a heating device to generate plasma and restrict plasma.

Quench protection system for the KSTAR superconducting toroidal field coil

A compact and unique design of the integrated quench protection (QP) system for the high-current superconducting magnet coils has been fabricated and tested for the toroidal field (TF) coil system of the Korea Superconducting Tokamak Advanced Research (KSTAR) device. The QP system is capable of protecting the TF superconducting magnet coils, which consist of 16 identical coils serially connected with a stored energy of 495 MJ at the design operation level, 35.2 kA per turn.