Reduction of Reactive Power Compensation Efforts for Fusion Magnet Power Supplies Using Variable Series Capacitors

This work investigates the feasibility of the series compensation of thyristor converters using variable series capacitors to reduce the reactive power for the excitation of fusion magnets. The variable series capacitor can control the DC voltage with a leading power factor seen in the AC system. As a case study, the authors conducted the reactive power calculation of the JT-60SA EF coil Booster PS. From the results, the series compensation of the thyristor converter using a gate-controlled series capacitor (GCSC) significantly becomes a feasible solution to the peak reactive power reduction in a high current range compared to the symmetric control and the asymmetric control of the conventional thyristor converters. However, there remains an increase in the required capacity for reactive power compensation in a lower current range due to the limitations of the GCSC operation area.