Zhiquan Song

Quench protection of the poloidal field superconducting coil system for the EAST tokamak

This paper gives a description of the poloidal field coil quench protection (QP) and control of the EAST poloidal field power supplies. A configuration of the QP hardware and an operating scenario are presented; the QP design principle in the EAST tokamak is also introduced.

Power supply system of EAST superconducting tokamak

the paper gives a description and key design features for the EAST power supply system consisting of superconducting coil power supply, inner vessel coil power supply, and additional heating power supply including microwave power supplies and neutral beam injection power supply. These power supplies are all realized by AC/DC converter, H Bridge and IGBT chopper.

Design and Test Results for the PF Power Supply System of EAST

Abstract The EAST superconducting tokamak is an advanced steady-state experimental device built at the Institute of Plasma Physics, Chinese Academy of Sciences between 2000 and 2006. This paper describes the poloidal field EAST power supply. The configuration and design of the power supply and its operation scenario are presented. A unit test and whole power supply test results are also discussed in detail.

Poloidal Field Power Supply Systems for the HT-7U Steady-State Superconducting Tokamak

The paper gives a description of the poloidal field power supplies and the control system of the HT-7U superconducting tokamak required to energize the magnetic field coils for plasma excitation and confinement. An original configuration of alternating-current/direct-current (dc) converter, thyristor dc circuit breaker, and power supply control system are introduced in detail.

On the Sequential Control of ITER Poloidal Field Converters for Reactive Power Reduction

Sequential control applied to the International Thermonuclear Experimental Re- actor (ITER) poloidal fleld converter system for the purpose of reactive power reduction is the subject of this investigation. Due to the inherent characteristics of thyristor-based phase-controlled converter, the poloidal fleld converter system consumes a huge amount of reactive power from the grid, which subsequently results in a voltage drop at the 66 kV busbar if no measure is taken. The installation of a static var compensator rated for 750 MVar at the 66 kV busbar is an essential way to compensate reactive power to the grid, which is the most efiective measure to solve the problem. However, sequential control of the multi-series converters provides an additional method to improve the natural power factor and thus alleviate the pressure of reactive power demand of the converter system without any additional cost. In the present paper, by comparing with the symmetrical control technique, the advantage of sequential control in reactive power consumption is highlighted. Simulation results based on SIMULINK are found in agreement with the theoretical analysis.

Prototype Design and Test of ITER PF Converter Unit

This paper presents the design and testing of the full scale prototype of the international thermonuclear experimental reactor (ITER) poloidial field converter unit (PFCU), which is mainly composed of converter transformer, converter module, external bypass, and dc reactors with a rated capacity of 82 MVA and a rated dc current of 55 kA. Considering the space limitation, the high safety and reliability requirements, the nonsame-phase antiparallel connection structure, and the fault suppression capability criterion are applied in the prototype design. After the completion of the preliminary design of the PFCU in summer 2012, the detailed prototype structure design and the manufacturing of the PFCU were launched and completed at the end of 2013, then the following main type tests, including short circuit current test and temperature rise test on the main components of the PFCU, have been done on the ITER power supply test platform at ASIPP site. In addition, the PFCU integration test has also been done to verify the system operation performance. The prototype test results are well in compliance with the design requirements of the ITER PF converter system. It indicates that the full scale prototype research and development of PFCU has been accomplished successfully.

Prototype Design of External Bypass for ITER Poloidal Field Converter

This paper describes the prototype design of an external bypass that provides protection for the ITER poloidal field converter and magnets in fault conditions. The maximum peak pulse current of the bypass will reach to about 350 kA in the worst case. Three kinds of arm structures are compared according to the design requirement and the specific circumstances of branches. The structure, whose current flows in and out on the same side, is selected and combined with the installation and location. The external bypass structure model is analyzed and compared through analytical and numerical methods. Then a 3-D numerical model of an electromagnetic field is established based on Maxwell. Now a full prototype has been manufactured by China, and the dynamic stability test of the prototype has also been accomplished successfully. It shows that the prototype design can fully satisfy the design requirement and the reliability has been improved.

Full scale prototype research and development of the ITER PF converter unit

This paper presents the design, manufacturing and testing of the full scale prototype of the ITER Polodial Field Converter Unit (PFCU) for the coil power supply system of the ITER superconducting Tokamak. The PFCU is mainly composed of converter transformer, converter module, external bypass and dc reactors with a rated capacity of 82 MVA and a rated dc current of 55 kA, which is also required for the Fault Suppression Capability (FSC) criterion. After the completion of the preliminary design of the PF converter package in summer 2012, the detailed prototype structure design, manufacture of the PFCU were launched and completed at the end of 2013. Then the following main type tests, including short circuit current test and temperature rise test on the main components of the PFCU, have been done on the ITER power supply test platform at ASIPP site and are described in this paper. And the PFCU integration test has also been done to verify the system operation performance. The prototype test results are well in compliance with the design. It indicates that the full scale prototype of PFCU can fully meet the design requirements of ITER PF converter system.

R&D of High Current Balance Reactors

The design of high current balance reactors used in the ITER DC testing platform is presented, which is verified by simulations with finite element method software, and the reactors are fabricated and tested according to the design output. These reactors are chosen as multilayer multi-turn structure and cooled by water. The multilayer multi-turn structure is usually selected by some high voltage reactors, but is seldom used in high current situations. The analysis and testing results indicate that the multilayer multi-turn structure is also feasible for high current reactors with many advantages, and is of considerable significance to similar applications.

Research on Commutating Over-Voltage Protection for High Power Converter

Abstract In the course of converter normal operation, large transient surges called commutating over-voltage may be generated internally during the commutating process of thyristor. The commutating voltage can effectively be reduced by the RC snubber circuit parallel to thyristor. In the RC snubber circuit design of high power thyristor, the reverse recovery process of thyristor must be considered in detail. Based on the analysis about reverse recovery transient of thyristor, the mathematical model of the converter thyristor reverse recovery current is created. Through the equivalent transformation of converter circuit during thyristor reverse recovery period, the analytical expressions about the relationship between commutating over-voltage and RC value are derived based on the Kirchhoff’s equation. Utilizing the analysis results, the optimal resistance and capacitance value can be selected by considering the reduction of peak over-voltage value and snubber power loss. It turns out that the proposed approach is available through the commutating over-voltage simulation and experiment results of high power converter.