Research On Control Of ITER Coil Power Supply System And Reactive Power Compensation Device

The ITER(International Thermonuclear Experimental Reactor)plan is going to build and operate a sustainable Tokamak-type fusion experimental reactor with an output of 500 MW fusion energy to verify the engineering and technical feasibility of the fusion reactor.It is one of the ways to explore the ultimate energy source for human beings.The ITER Coil Power Supply(CPS)system,which is currently the largest pulse power source in the world,provides the guarantees for plasma breakdown,heating and control.The CPS system based on phasecontrolled converter technology has complex operating modes and huge power impact,which brings the issues of compatibility and stability among the power grid,power supply and load.The main problems are as follows:Firstly,the real-time control of the plasma of the Tokamak device requires the CPS system to maintain a certain responsiveness and output reliable and accurate parameters(such as voltage and current),while the power response among the strong coupling magnet coil circuits interferes with each other.Secondly,the voltage stability of the power supply network depends on the good coordination between the ITER power supply system and the Reactive Power Compensation(RPC)device SVC.As the traditional open-loop control method cannot avoid the inherent delay defects,the model parameter perturbation of the device and other factors,it is difficult to meet the requirements of reactive power control in the working condition with special loads of the fusion device.Therefore,the optimization control problem of SVC becomes urgent under the background of high-power impulsive load.Thirdly,because of the control interaction problem of the joint operation of SVG pre-added in the second stage of the ITER project and SVC,the search for a reasonable and feasible means of the coordination of reactive power has been put on the agenda.In view of the above three problems,the main work of this paper is as follows:(1)Facing the power response accuracy requirements of the plasma real-time control of the fusion load,based on the control parameter design that guarantees the ITER grid reactive power optimization,a hybrid control scheme combining state feedback and static decoupling was proposed to reduce the coupling effect between the CPS response.By combining the test of the estimated parameters in the plasma operating simulation program(DINA)environment,the PF/CS coil power circuit simulation model was established on the MATLAB platform to verified the effectiveness of the proposed scheme.(2)The parameter setting of the control strategy was determined by the system identification theory.Then aiming at the shortcomings of the existing control scheme of the SVC,the Lyapunov function control scheme under the high-impact load condition of the highpower power supply was proposed.Based on the MATLAB platform,a joint operation system of ITER CPS system and SVC was established,and the advantages and disadvantages of reactive power control of different schemes were compared through simulation.The results showed that the proposed strategy could effectively improve the compensation accuracy of the ITER RPC system and improve its comprehensive compensation performance,thereby enhancing the stability of the bus voltage.(3)Facing the plan II of the ITER project,which the reactive power of the load increasing greatly under the demand of fusion load control,the existing RPC control system is unsustainable.The necessity of installing advanced dynamic RPC device SVG was explained,the general rules for the capacity allocation of SVC and SVG cooperative operation were given,the interaction between the control loops during the joint operation of SVC and SVG was analyzed in detail,and the reactive power coordination measures based on filter distribution was proposed.Then the equivalent model simulation on MATLAB platform verified the effectiveness of the program.In summary,this paper studies the control problem of the coordination between CPS and the RPC device for the compatibility and stability of the ITER grid under the background of fusion load.The analysis of the above problems and the research on countermeasures could provide references for the future design and operation of the device to a certain extent.