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Novello, L.*; Cara, P.*; Coletti, A.*; Gaio, E.*; Maistrello, A.*; 松川 誠; Philipps, G.*; Tomarchio, V.*; 山内 邦仁
IEEE Transactions on Applied Superconductivity, 26(2), p.4700507_1 - 4700507_7, 2016/03
被引用回数:7 パーセンタイル:39.28(Engineering, Electrical & Electronic)The voltage transient appearing across and inside the toroidal field (TF) coils of JT-60SA in case of fast voltage variation, such as a safety discharge operated by the quench protection circuit (QPC), can be significantly high. In fact, the voltage distribution between coils and inside the winding can be not uniform during fast transient, being influenced by the presence of parasitic capacitances. A simplified electrical model of the TF coils has been developed to investigate this aspect. The obtained model has been used in conjunction with an electrical model of the TF circuit elements, including a simplified model of the QPC. The worst case in terms of transient voltage applied to the winding has been identified, corresponding to a fault to ground occurring just after QPC operation. It has been verified that the resulting voltage is largely inside the coil insulation capability defined by performed insulation voltage tests.
Maistrello, A.*; Gaio, E.*; Novello, L.*; 松川 誠; 山内 邦仁
Fusion Engineering and Design, 98-99, p.1109 - 1112, 2015/10
被引用回数:8 パーセンタイル:55.62(Nuclear Science & Technology)The interruption of high direct currents, required in fusion experiments, is a challenging task. Depending on the technology of the circuit breakers the resulting current derivative may be high, leading to dangerous transient overvoltages. This aspect has been analyzed for JT-60SA Quench Protection Circuits (QPC) devoted to the protection of superconducting coils. The QPC adopts edge technology solutions: a Hybrid mechanical-static Circuit Breaker (HCB) as main circuit breaker in series with a PyroBreaker (PB) as backup protection. Snubbers or clamp networks can be provided in parallel to the breakers to smooth the voltage waveform. Dedicated clamp networks for the HCB have been designed and tested during the qualification of the QPC prototypes. On the contrary, it was preferred not to apply any component in parallel to the PB, the ultimate protection, to avoid reducing its reliability. For PB a different approach has been worked out, based on the optimization of the layout of the QPC connections. Analyses have been performed to highlight the impact of different busbar routes on the transient voltage across the toroidal field coils at the PB intervention. The results indeed showed a variation of the peak voltage in between 30% of the maximum allowed value. The paper will present the analyses and will discuss the results.
Ferro, A.*; Gaio, E.*; Novello, L.*; 松川 誠; 島田 勝弘; 川俣 陽一; 武智 学
Fusion Engineering and Design, 98-99, p.1053 - 1057, 2015/10
被引用回数:3 パーセンタイル:25.54(Nuclear Science & Technology)JT-60SA is the satellite tokamak under construction in Naka, Japan, in the framework of the EU - JA "Broader Approach" Agreement. In JT-60SA, to attain steady-state high-beta plasmas, suppression of Resistive Wall Modes (RWM) is necessary. At this purpose, a passive stabilizing plate (SP) and an active control system based on 18 in-vessel sector coils (SC) are foreseen. This paper firstly reports the main requirements for the RWM control system. Then, the reference design of the RWM-PS is described. It includes an ac/dc conversion system, dc-link capacitor banks and a set of 18 fast inverters. The advantages of the proposed scheme are discussed and the main electrical parameters are shown in detail. The main requirements of the control section are given, with details on possible implementation and interfaces with JT-60SA central control.
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
被引用回数:16 パーセンタイル:78.98(Nuclear Science & Technology)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.
Maistrello, A.*; Gaio, E.*; Ferro, A.*; Perna, M.*; Panizza, C.*; Soso, F.*; Novello, L.*; 松川 誠; 山内 邦仁
IEEE Transactions on Applied Superconductivity, 24(3), p.3801505_1 - 3801505_5, 2014/06
被引用回数:14 パーセンタイル:58.32(Engineering, Electrical & Electronic)This paper deals with the qualification process of the full scale prototypes of the Hybrid mechanical-static dc Circuit Breaker (HCB) for the Quench Protection Circuits (QPC) of the Toroidal Field (TF) and Poloidal Field (PF) superconducting coils of the Satellite Tokamak JT-60SA. The HCB developed for JT-60SA QPC is the first dc circuit breaker based on hybrid mechanical-static design at this level of power (25.7 kA - 1.93 kV, 20 kA - 3.8 kV). Special type tests have been designed to verify the performance of the device up to the nominal ratings and beyond, thus proving the suitability of the technology, the design margins and the reliability; the results of the most significant tests are presented and discussed. The qualification program also includes the validation of the electrical models developed during the design phase, which are described in the paper too.
Gaio, E.*; Maistrello, A.*; Barp, M.*; Perna, M.*; Coffetti, A.*; Soso, F.*; Novello, L.*; 松川 誠; 山内 邦仁
Fusion Engineering and Design, 88(6-8), p.563 - 567, 2013/10
被引用回数:15 パーセンタイル:74.05(Nuclear Science & Technology)This paper deals with the development, manufacturing and testing of the full scale prototype of the Quench Protection Circuit (QPC) for the superconducting magnets of the JT-60SA Satellite Tokamak, which will operate in Naka, Japan. After the completion of the system detailed design in summer 2011, the manufacture of the poloidal and toroidal prototypes was launched and completed at the beginning of 2012. Several factory type tests on the main components have been done at the manufacturers' premises and are described in this paper. Then, two main campaigns have been performed to test the operation of the overall poloidal and toroidal QPC prototypes; the main results are reported in the paper too.
Toigo, V.*; Zanotto, L.*; Bigi, M.*; Decamps, H.*; Ferro, A.*; Gaio, E.*; Gutirrez, D.*; 土田 一輝; 渡邊 和弘
Fusion Engineering and Design, 88(6-8), p.956 - 959, 2013/10
被引用回数:18 パーセンタイル:79.49(Nuclear Science & Technology)ITER NBIの加速電源の設計進捗を報告する。この電源は1MVで55MW、準定常の大パワー電源であり、挑戦的なシステムである。EU国内機関と日本国内機関とで分担して製作することから、特に共通のインターフェースとするために設計が複雑である。この二つのシステムの間での重要なインターフェースについての改訂について報告する。さらに、異なるパラメータの許容値を考慮した運転状態において要求を満足することを確認したことを報告する。
松川 誠; 島田 勝弘; 山内 邦仁; Gaio, E.*; Ferro, A.*; Novello, L.*
Plasma Science and Technology, 15(3), p.257 - 260, 2013/03
被引用回数:7 パーセンタイル:29.97(Physics, Fluids & Plasmas)トカマク装置において高性能プラズマを実現するためには、誤差磁場補正が重要な課題の一つである。実際、国際熱核融合実験炉ITERにおいては、誤差磁場補正用の超伝導コイルが計画されており、JT-60SA装置では常伝導コイルが使用される予定である。同様のコイルは、他の世界中の多くの装置で据え付けられており、また運転中でもある。JT-60SA装置の場合、誤差磁場補正コイルは12個(あるいは18個)のセクターコイルが真空容器内に設置される予定である。本論文は、このような誤差磁場補正コイル用電源の回路構成と制御方式にかかわる概念設計について述べるものである。結論としては、電流フィーダや半導体電力素子の数を最小化することのできる多相インバータが、コスト面のみならず、軸対称成分による誘導電圧を相殺できる点などから、最も有望であることを示す。
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
被引用回数:6 パーセンタイル:25.86(Physics, Fluids & Plasmas)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.
Gaio, E.*; Maistrello, A.*; Coffetti, A.*; Gargano, T.*; Perna, M.*; Novello, L.*; Coletti, A.*; 松川 誠; 山内 邦仁
IEEE Transactions on Plasma Science, 40(3), p.557 - 563, 2012/03
被引用回数:29 パーセンタイル:76.38(Physics, Fluids & Plasmas)This paper describes the detailed design of the quench protection circuits (QPC) for the superconducting toroidal field (TF) and poloidal field (PF) magnets of the Satellite Tokamak JT-60SA, which will be installed in Naka, Japan. The nominal currents to be interrupted and the maximum reapplied voltages are 25.7 kA and 2.8 kV for the TF QPCs and 20 kA and 5 kV for PF QPCs. The innovative solution proposed in the QPC design is based on a hybrid circuit breaker (CB) composed of a mechanical Bypass Switch for conducting the continuous current, in parallel to a static CB for current interruption. The main choices of the final design are presented and discussed, either to confirm or to update and complete the study performed at the conceptual design level.
Ferro, A.*; Gaio, E.*; 武智 学; 松川 誠
Fusion Engineering and Design, 86(6-8), p.1527 - 1530, 2011/10
被引用回数:2 パーセンタイル:18.18(Nuclear Science & Technology)JT-60SAにおいて定常高ベータ運転を行うには抵抗性壁モード(RWM)の安定化が必須である。そのため、JT-60SAには真空容器内に安定化板とRWM制御コイルが設置される予定である。この論文ではこのRWM制御コイルの電磁気解析を行うことにより、コイルの生成する磁場の強さや分布を調べ、必要な電圧や電流値等の評価を行う。また、ディスラプションやVDE時の誘起電流を示す。これらの結果はRWM制御コイルとその電源の設計の進展の指針となる。
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
被引用回数:21 パーセンタイル:82.40(Nuclear Science & Technology)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.
Novello, L.*; Gaio, E.*; Piovan, R.*; 武智 学; 井手 俊介; 松川 誠
Fusion Engineering and Design, 86(1), p.33 - 40, 2011/01
被引用回数:10 パーセンタイル:60.56(Nuclear Science & Technology)The identification of the maximum amplitude of the currents circulating in the circuits is a useful indication for the design both of magnet and power supply components in fusion experiments. This paper evaluates the maximum level of coil overcurrents in the poloidal superconducting magnets of JT-60SA. To derive these information, a complete model capable to take into account all the mutually coupled elements was worked out, including the poloidal superconducting coils, the plasma position control in-vessel coils, the vacuum vessel, the stabilizing plates and the plasma. The model was utilized to analyze plasma disruption and quench protection circuit intervention in a large variety of different conditions to identify the possible overcurrent levels. The paper describes the model and the analyses performed, and presents and discusses the results.
松川 誠; 寺門 恒久; 山内 邦仁; 島田 勝弘; Cara, P.*; Gaio, E.*; Novello, L.*; Ferro, A.*; Coletti, R.*; Santinelli, M.*; et al.
Journal of Plasma and Fusion Research SERIES, Vol.9, p.264 - 269, 2010/08
Reliable plasma initiation is very important in the nuclear fusion devices especially in superconducting tokamaks. Applicable breakdown electric field would be limited up to level of 0.5 V/m to suppress large AC losses in the superconducting magnet. Furthermore, induced current in the passive structure such as vacuum vessel and stabilizing plate would increased easily to the comparable level of plasma current with several hundred kA even in the case of ECH assist breakdown. Therefore, optimization of the applied voltage to the poloidal field coil is necessary for stable plasma initiation. In this paper, the rationalized plasma initiation scenario using cost effectively designed power supply system will be provided.
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.
島田 勝弘; 寺門 恒久; 松川 誠; Cara, P.*; Baulaigue, O.*; Gaio, E.*; Coletti, R.*; Candela, G.*; Coletti, A.*
Journal of Plasma and Fusion Research SERIES, Vol.9, p.163 - 168, 2010/08
This paper describes the stable coil current control method of back-to-back thyristor converters as a design study. The back-to-back thyristor converter is applied to "Base PS" which is low-voltage power supply for PF coil in JT-60SA. This converter has six arms of anti-parallel connected thyristor devices to enable to operate with 4 quadrant operation. The dead beat control method is applied on the current feedback control algorithm. In addition, the non-interacting control method is adopted between coil current and circulating current among converters, which is necessary for smooth reversing of the coil current polarity. The rate limiter for control angles of thyristor converter is introduced to suppress the excessive current unbalance between converters. To estimate the proposed coil current control method, the real "Base PS" models are simulated by "PSCAD/EMTDC" code. From the simulation results, the stable control capability was obtained.
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
被引用回数:19 パーセンタイル:75.92(Nuclear Science & Technology)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。
松川 誠; 菊池 満; 藤井 常幸; 藤田 隆明; 林 孝夫; 東島 智; 細金 延幸; 池田 佳隆; 井手 俊介; 石田 真一; et al.
Fusion Engineering and Design, 83(7-9), p.795 - 803, 2008/12
被引用回数:17 パーセンタイル:72.53(Nuclear Science & Technology)JT-60SAは、日欧の幅広いアプローチの下で建設する完全超伝導トカマク装置で、ITERや原型炉への貢献を目指している。2007年の両極の国会批准後、実質的には既に建設段階に移行している。JT-60SAは、既存の建屋,電源,プラズマ加熱装置,計測装置などの、JT-60U設備の最大限の有効利用が前提であり、完全に新作する主たる機器は本体装置のみである。最大プラズマは電流5.5MAで、プラズマ主半径3.06m,アスペクト比2.65,非円形度1.76,三確度0.36である。最大プラズマ加熱入力41MW,プラズマ電流のフラットトップ時間は100秒間である。本論文では、トカマク装置本体だけでなく、プラズマ加熱装置や遠隔保守装置の設計などについても言及するとともに、EUとの技術的な議論を踏まえて行った超伝導導体に関する最近の設計変更案などを紹介し、装置の全体像を明らかにする。
松永 剛; 武智 学; 櫻井 真治; 井手 俊介; 松川 誠; 大山 直幸; 相羽 信行; 栗田 源一; Ferro, A.*; Gaio, E.*; et al.
no journal, ,
JT-60SA is designed and under construction as fully superconducting tokamak under a combined project of the ITER satellite tokamak program of EU-JA (Broader Approach Activities) and the Japanese national program. One of the main purposes of JT-60SA is the steady-state high-beta operation above the ideal no-wall beta-limit with suppressing resistive wall modes (RWMs). In order to control the RWMs, the RWM control coils and error field correction coils (EFCCs) are to be installed. The current design of these coils composes of 18 sector coils (6 coils in toroidally and 3 coils in poloidally) so as to suppress n=1-3 RWMs and to compensate various error fields. The EFCCs can also be utilized to apply the resonant magnetic perturbation to ergodize the peripheral magnetic field structure to mitigate and avoid the large edge localized modes. The design and analysis of these in-vessel tools for high-beta plasmas on JT-60SA will be presented.
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.
武智 学; 松永 剛; 栗田 源一; 櫻井 真治; 藤枝 浩文*; 井手 俊介; 相羽 信行; Bolzonella, T.*; Ferro, A.*; Novello, L.*; et al.
no journal, ,
JT-60SAの最も重要な目的の一つは、ITERからDEMOへの補完のために定常高ベータ運転の実証と開発を行うことである。高ベータプラズマにおいて問題となる抵抗性壁モードの安定化に用いる制御コイル及び電源の仕様をフィードバックシミュレーション及びFEM解析を用いて行った。プラズマ着火時,ロックトモード回避,抵抗性壁モード安定化に重要な誤差磁場の補正コイルの仕様をNBIの打消しコイルの磁場評価及びトロイダルコイルとポロイダルコイルの公差から決定した。また、高速位置制御コイルの仕様を位置制御のフィードバックシミュレーションから決定した。これらの制御システムを用いてMAにおいての非誘導定常プラズマが可能となる。さらに、ディスラプションシミュレーションを機器の電磁力の評価のために行った。