Operation modes and Protection of VS(Vertical Stabilization) Converter for International Thermonuclear Experimental Reactor

This study describes the structure and operation modes of vertical stabilization (VS) converter for international thermonuclear experimental reactor (ITER) and proposes a protection method. ITER VS converter supplies voltage (±1000 V)/current (±22.5 kA) to superconducting magnets for plasma current vertical stabilization. A four-quadrant operation must be achieved without zero-current discontinuous section. The operation mode of the VS converter is separated in 12-pulse mode, 6-pulse mode and circulation current mode according to the magnitude of the load current. Protection measures, such as bypass and discharge, are proposed for abnormal conditions, such as over current, over voltage, short circuit, and voltage sag. VS converter output voltage is controlled to satisfy voltage response time within 20 msec. Bypass operation is completed within 60 msec and discharge operation is performed successfully. The feasibility of the proposed control algorithm and protection measure is verified by assembling a real controller and implementing a power system including the VS converter in RTDS for a hardware-in-loop (HIL) facility.