JT-60SAクエンチ保護回路の欧州による現地据付・調整試験と作業安全管理

山内 邦仁; 岡野 潤; 島田 勝弘; 大森 栄和; 寺門 恒久; 松川 誠; 小出 芳彦; 小林 和容; 池田 佳隆; 福本 雅弘; et al.

JAEA-Technology 2015-053, 36 Pages, 2016/03

JAEA-Technology-2015-053.pdf:8.33MB

JT-60SA計画は、日本の実施機関である原子力機構と欧州の実施機関であるFusion for Energy(F4E)が物納貢献により共同で進める国際事業である。欧州側では超伝導トロイダル磁場コイルの他、磁場コイル用電源の主要機器や極低温システム等を分担するが、F4Eの総括のもとで各国の指定研究機関が欧州のメーカーと契約し、その欧州のメーカーが那珂研での現地据付・調整試験までを行う。このため、原子力機構にとっては直接の契約がないにも係らず、欧州の作業員に対する作業管理や安全管理を行わなければならないという非常に難しい課題があった。本報告は、JT-60SA計画において、欧州の作業員による最初の那珂研での現地作業であるクエンチ保護回路の据付・調整試験を遂行するにあたって、欧州側との事前の密な交渉の結果として合意し、構築・実施した作業管理や安全管理の取組み、およびそれらをもとに完遂した欧州作業についてまとめたものである。これらの取組みの結果、欧州作業員によるクエンチ保護回路の現地据付調整作業を無事故で完遂させることができ、日欧双方にとって非常に大きな成果となった。

First switching network unit for the JT-60SA superconducting central solenoid

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

https://doi.org/10.1016/j.fusengdes.2015.06.177

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.

Overview of the new magnet power supply systems of JT-60SA procured by EU

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

https://doi.org/10.1016/j.fusengdes.2015.06.014

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.

Design and implementation of four 20 kA, 5 kV hybrid switching networks for plasma ignition in the international tokamak JT-60SA

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

https://doi.org/10.1109/IECON.2014.7049265

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.

Minimization of reactive power fluctuation in JT-60SA magnet power supply

島田 勝弘; 寺門 恒久; 山内 邦仁; 松川 誠; Baulaigue, O.*; Coletti, R.*; Coletti, A.*; Novello, L.*

Plasma Science and Technology, 15(2), p.184 - 187, 2013/02

https://doi.org/10.1088/1009-0630/15/2/22

In JT-60SA, the four thyristor converters in poloidal field coil (PFC) power supplies are used for plasma initiation. In this case, the large reactive power fluctuation induced by the "Booster PS" is the cause of large voltage fluctuation across the terminals of the motor-generator. To minimize the reactive power fluctuation during plasma initiation, an asymmetric control method and a sequential timing control to start/stop each "Booster PS" are foreseen. To evaluate the effectiveness of above control methods for the "Booster PS", the reactive power has been simulated by using "PSCAD/EMTDC" code. From the simulation it results that the reactive power induced by the four units of the "Booster PS" can be dramatically reduced. In addition, the voltage fluctuation of the motor-generator connected to the "Booster PS" is expected to be suppressed to less than 10%, which ensures the stable control of JT-60SA magnet power supplies.

Resonance characteristics and maximum turn voltage of JT-60SA EF coil

村上 陽之; 木津 要; 土屋 勝彦; 吉田 清; 山内 邦仁; 島田 勝弘; 寺門 恒久; 松川 誠; 長谷川 満*; 湊 恒明*; et al.

IEEE Transactions on Applied Superconductivity, 22(3), p.9501405_1 - 9501405_5, 2012/06

https://doi.org/10.1109/TASC.2011.2178010

超伝導コイルの開発において、ターン間絶縁の耐電圧特性は重要な設計パラメータである。しかし実機コイルのターン間電圧は、電源の電圧変動やコイル内の共振現象により、理想的に電圧が分布した場合に比べ局所的にターン間電圧が高くなる危険性が指摘されている。そこで電源の電圧変動を評価するためJT-60SAと同等の大型電源であるJT-60Uの電源電圧測定を実施した。また、コイル内の共振現象を把握するため、EF4ダミーパンケーキを用いた共振特性試験及び数値解析によりEFコイルの共振特性を評価した。これらの結果、実際のターン間電圧は理想的な電圧分布から大きく外れないことが確認できた。

JT-60SA power supply system

Coletti, A.*; Baulaigue, O.*; Cara, P.*; Coletti, R.*; Ferro, A.*; Gaio, E.*; 松川 誠; Novello, L.*; Santinelli, M.*; 島田 勝弘; et al.

Fusion Engineering and Design, 86(6-8), p.1373 - 1376, 2011/10

https://doi.org/10.1016/j.fusengdes.2011.02.042

JT-60SA is a joint international research and development project involving Japan and Europe, in the frame of the "Broader Approach Agreement", for the construction and operation of a new tokamak intended to prepare and support ITER operation. JT-60SA is to be built in Naka, Japan, using existing infrastructures and subsystems of the former JT-60U experiment, as much as possible. SA, as "super advanced", refers to the use of Superconducting Coils Magnets (SCM) and to the study of advanced modes in plasma operation. The SCM system includes Toroidal and Poloidal Field Coils (TFC and PFC respectively). In addition the machine features a number of normal conducting coils: Fast Plasma Control Coils (FPCC), a Resistive Wall Mode Control Coils and the Error Field Correction Coils. The paper describes the main features of the JT-60SA SCM Power Supply System (SCMPS) with special regard to coil current regulation mode and SCM protection.

Electric circuit analysis for plasma breakdown in JT-60SA

山内 邦仁; 島田 勝弘; 寺門 恒久; 松川 誠; Cara, P.*; Gaio, E.*; Santinelli, M.*; Coletti, R.*; Coletti, A.*

Journal of Plasma and Fusion Research SERIES, Vol.9, p.220 - 225, 2010/08

High current of about 500 kA will be induced in the passive structures such as vacuum vessel and stabilizing plate at plasma initiation in JT-60SA, because the total resistance of the passive structure is approximately 16 and the breakdown electric field of 0.5 V/m is expected for stable plasma initiation from the experiments of JT-60U. Therefore, a precise evaluation of the magnetic field performance using the accurate circuit analysis model has to be conducted to obtain stable plasma breakdown and for designing the detail of power supply system. In this paper, the preparation procedure of the analysis model will be presented. Then, some circuit analysis results of plasma breakdown will be given using ideal power supply and actual thyristor converter model for comparison. The delay effect of converter voltage control and the discrepancy of current control would be summarized as the first achievement. The voltage fluctuation of generator (H-MG, 400 MVA) at plasma initiation will be also described, because large reactive power fluctuation may cause large voltage fluctuation and sudden phase shift of the AC source voltage of thyristor converter.

Conceptual design of the quench protection circuits for the JT-60SA superconducting magnets

Gaio, E.*; Novello, L.*; Piovan, R.*; 島田 勝弘; 寺門 恒久; 栗原 研一; 松川 誠

Fusion Engineering and Design, 84(2-6), p.804 - 809, 2009/06

https://doi.org/10.1016/j.fusengdes.2008.12.100

コイルクエンチ時に超電導コイルの蓄積エネルギーを高速に取り除かなければならないJT-60SAのクエンチ保護回路の概念設計について発表を行う。クエンチ保護回路の主要部は、高速にコイル消磁を行うためにコイル電流を抵抗に転流させる直流電流スイッチで構成される。本発表では、機械スイッチと半導体スイッチの一つであるIGCT(Integrated Gate Commutated Thyristor)の並列接続で構成されたハイブリッド型電流スイッチを提案し、検討した結果について述べる。また、クエンチ保護回路の主要部のほかに、電流スイッチで電流遮断失敗した場合のバックアップ回路として直列にパイロブレーカーを接続する。提案するハイブリッド型クエンチ保護回路は、半導体スイッチの特徴である高速遮断性能とメンテナンスフリーの利点と機械スイッチの特徴である低損失の利点の両方を併せ持つ回路構成となる。

JT-60SAにおける直流電源系の初期設計検討

島田 勝弘; 大森 栄和; 岡野 潤; 松川 達哉; 寺門 恒久; 栗原 研一

JAEA-Technology 2008-031, 38 Pages, 2008/03

JAEA-Technology-2008-031.pdf:10.84MB

臨界プラズマ試験装置JT-60の次期装置としてJT-60SA(Super Advanced)の設計検討が進められている。JT-60SAでは、トロイダル磁場コイル(TFコイル),ポロイダル磁場コイル(PFコイル)が超伝導化され、100s以上のフラットトップを持つ長時間プラズマ運転が可能となる。このようなプラズマ運転,コイルの超伝導化に対応するために新しい直流系電源システムの構築を行う必要がある。これらの超伝導コイルに直流電力を供給する電源は、既存のJT-60電源を有効に再利用した電源機器と新規製作による電源機器を組合せた構成とし、コストの低減を図った。また、超伝導コイルを用いるため、コイルクエンチ時にコイル蓄積エネルギーを急速に消費させるクエンチ保護回路を新規に導入した。本報告書では、JT-60SAの直流系電源(TFコイル電源,PFコイル電源)の回路構成やそれらの制御手法の検討結果及びPSCAD/EMTDCを用いた設計した電源システムでの初期電源制御シミュレーション結果について報告する。