Lampasi, A.*; Zito, P.*; Coletti, A.*; Novello, L.*; 松川 誠; 島田 勝弘; Burini, F.*; Kuate-Fone, Y.*; Taddia, G.*; Tenconi, S.*
Fusion Engineering and Design, 98-99, p.1098 - 1102, 2015/10
In JT-60SA, the first SNU (prototype), consisting of six cubicles, was assembled in 2013. The factory tests on this system, including tests at full current and voltage, are being performed throughout 2014. The manufacturing of the remaining three SNUs will proceed after the success of such tests. The main characteristics of the developed SNU are; (1) Snchronized use of an electronic static circuit breaker (SCB) in parallel with an electromechanical bypass switch (BPS), (2) Nominal voltage of 5 kV, with a specific circuit to limit the transient voltage to 5.5 kV, (3) DC current interruption up to 20 kA, (4) Light BPS with opening and closing times shorter than 15 ms and 65 ms, respectively, (5) Breakdown resistance adaptable from 0.25 to 3.75 by four selectors, (7) Fully electronic making switch (MS) and (8) Breakdown resistors that could dissipate much more than 90 MJ.
Zito, P.*; Lampasi, A.*; Coletti, A.*; Novello, L.*; 松川 誠; 島田 勝弘; Cinarelli, D.*; Portesine, M.*; Dorronsoro, A.*; Vian, D.*
Fusion Engineering and Design, 98-99, p.1191 - 1196, 2015/10
In JT-60SA, Fast Plasma Position Control Coils Power Supplies (FPPCC PSs) control vertical position of the plasma during a plasma shot, against Vertical Displacements Event (VDE). For this task, the FPPCC PSs have to be as fast as possible and provide as much voltage as possible. Further, these will be open loop feed forward voltage controlled. The main characteristics are: 4-quadrant AC/DC converter 12-pulse with circulating current, DC load voltage 1000 V and DC load current 5 kA. The induced overvoltage in FPPC coil during a plasma disruption can reach 10 kV and it is bounded by a nonlinear resistor in parallel to the crowbar. All these technical characteristics have strongly influenced the design of the FPPC converter and of the FPPC transformers, that have been validated by simulation model of FPPCC PS. The outcomes of the simulation have allowed to finalize the performances and dynamic behavior of voltage response.
Novello, L.*; Baulaigue, O.*; Coletti, A.*; Dumas, N.*; Ferro, A.*; Gaio, E.*; Lampasi, A.*; Maistrello, A.*; 松川 誠; 島田 勝弘; et al.
Fusion Engineering and Design, 98-99, p.1122 - 1126, 2015/10
JT-60SA, the superconducting tokamak under construction in Japan, will be equipped with a mix of new and reused Power Supplies (PS). Most of the new PS are procured by European Voluntary Contributors under the framework of Broader Approach agreement between F4E and JAEA. For the toroidal circuit, the 6 pulses ac/dc converter will be procured by CEA. It is rated 25.7 kA and 80 V dc, and will work in steady state condition. For the poloidal circuits the procurement of ten ac/dc converters, rated 20 kA and about 1 kV is shared between CEA and ENEA. They are 24 pulses four quadrant converters, with back to back thyristor bridges. Plasma initiation requires a fast variation of current in the Central Solenoids, obtained with the insertion of a settable resistor in series to the coils. This is achieved with the operation of four Switching Network Units procured by ENEA, producing up to 5 kV at the nominal 20 kA. The protection of superconducting magnets, both toroidal and poloidal, is assured by 13 Quench Protection Circuits procured by Consorzio RFX, rated 20 kA and 3.8 kV for poloidal QPCs and 25.7 kA and 2.8 kV for toroidal ones. The present status of the aforementioned PS is described in the paper: their detailed design has been completed and some systems have been already manufactured and tested.
Zito, P.*; Lampasi, A.*; Novello, L.*; 松川 誠; 島田 勝弘; Portesine, M.*; Fasce, F.*; Cinarelli, D.*; Dorronsoro, A.*; Vian, D.*
Proceedings of IEEE 15th International Conference on Environment and Electrical Engineering (IEEE-EEEIC 2015), p.156 - 160, 2015/06
In JT-60SA, Fast Plasma Position Control Coils (FPPCC) PSs allow controlling the vertical position of the plasma during a plasma shot, against Vertical Displacements Event (VDE). An open loop feed forward voltage control is adopted in order to achieve a fast control of FPPCC PSs. The characteristics of the PS are: 4-quadrant AC/DC converter 12-pulse, DC load voltage 1000 V and DC load current 5 kA. The design of the FPPCC converters has been validated by a simulation model, finalizing the performances and dynamic behavior of voltage response. After the completion of the realization phase, the testing phase has been carried out in accordance to the IEC60146 Standards and this is the focus of the paper. The tests performed have pointed out a good dynamic behavior of the FPPCC converter in open loop feed forward voltage control, for a reference voltage step of 1kV, the rise time of output voltage is 2.88 ms, confirming outcomes achieved by simulations.
Burini, F.*; Kuate-Fone, Y.*; Taddia, G.*; Tenconi, S.*; Lampasi, A.*; Zito, P.*; 松川 誠; 島田 勝弘; Coletti, A.*; Novello, L.*
Proceedings of 40th Annual Conference of the IEEE Industrial Electronics Society (IECON 2014), p.5035 - 5040, 2014/10
This paper describes the design and implementation of the Switching Network Unit (SNU) for the superconducting Central Solenoid coils of the international nuclear fusion experiment JT-60SA to be built in Naka, Japan. The SNU can interrupt a current up to 20 kA in less than 1 ms to create a voltage up to 5 kV. It is realized with a hybrid switch integrating an electro-mechanical device and a solid state Static Circuit Breaker, parallel connected. SNU resistance can be pre-arranged and dynamically reduced by a solid state making switch. Preliminary test results confirmed the current balance of the multiple parallel branches constituting the solid state switch and proper behavior of the devices, confirming simulations results. Further applications could be medium voltage DC networks (either naval or land based); higher DC voltages are practicable.
山内 邦仁; 島田 勝弘; 寺門 恒久; 松川 誠; Coletti, R.*; Lampasi, A.*; Gaio, E.*; Coletti, A.*; Novello, L.*
Plasma Science and Technology, 15(2), p.148 - 151, 2013/02
One of the most essential issues for designing a power supply system of superconducting coil is to avoid any overvoltage. Here, the most concerned overvoltage can appear between turns due to the transiently concentrated voltage distribution inside the coil, which is mainly caused by parasitic capacitances and high dv/dt. For this reason, the coil power supply, especially fast high voltage generation circuit, should equip proper snubber(s) in order to suppress the dv/dt. However, it is too complicated to accurately evaluate the transient voltage in the coil because of the distributed parameters of the mutual inductance between turns and the capacitance between adjacent conductors. In this study, such a complicated system is modeled with reasonably detailed circuit network with lumped ones, and is integrated into the overall simulation model of JT-60SA PF coil circuit. Then a detailed circuit analysis is conducted in order to evaluate the possible voltage transient in the coil circuit. As a result, appropriate circuit parameters in the coil power supply including the snubbers are obtained.
山内 邦仁; Baulaigue, O.*; Coletti, A.*; Coletti, R.*; Ferro, A.*; Gaio, E.*; Lampasi, A.*; 松川 誠; Novello, L.*; 島田 勝弘; et al.
no journal, ,
The JT-60SA tokamak device consists of superconducting toroidal field (TF) and poloidal field (PF) coils, and some in-vessel coils. All of 18 TF coils are connected in series and powered by a low-voltage unidirectional DC power supply (PS), while three Quench Protection Circuits (QPCs) are inserted for every six TF coils. Meanwhile, each PF coil circuit is independent from the others, and a bidirectional DC current is driven for plasma current ramp-up and sustainment by series-connected Base PS, and Switching Network Unit or Booster PS. TF coils are energized by commercial electric power grid directly, but the rest of the coils are planned to be powered by the existing motor-generator of JT-60. This paper describes the key features and the expected performances of the main PS system for the superconducting magnets in JT-60SA.