EFDA “Feedback control group”: general information and foreseen activities

1. EFDA “Feedback control group”: general information and foreseen activities D. Mazon (Group Leader) CEA Cadarache France A. Pironti (Deputy Leader) CREATE, Napoli ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

2. Outline • Presentation of the “EFDA Feedback Control Group” • Possible overlapping between the Control Group and the ITM task force ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

3. General information about the Feedback Control Group • EFDA ‘Feedback control group’ created this year • Group members list is under preparation (already 20 members, new candidates welcome) • Group is under the auspice of the EFDA ‘Diagnostic Topical Group’ • Strong interaction with: • The other EFDA Topical Group • JET Task Force D • The European Task Forces (FT, PWI, …) • The ITM task Force • The ITPA • The “data validation” group also created this year • ITER and DEMO ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

4. Main objectives of the Group • Assessment of the present status in the field of integrated plasma control in current and future fusion devices, identify weak areas and urgent development needs • Assessment of relevant control techniques used in industry or different fields of science and not yet considered in the fusion area • Proposal of tasks (through the Diagnostic Topical group) in the field of integrated control to be launched in the near future (call for participation, up to 40% paid by EFDA for hardware and software, 20% for salary) • Follow the selected Tasks up to their conclusion ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

5. How do we plan to proceed? • To Assess of the present status in the field of integrated plasma control- Organize a kick off meeting (July, 29th at JET) with the real-time specialists of the European associations- Visit and/or contact the different real time specialist in the associations to complete the missing information: This will constitute a good reference for identifying the weaknesses areas.This brainstorming will cover both present machines and future devices. ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

6. How do we plan to proceed? 2. To Assess the relevant control techniques used in industry or different fields of scienceand not yet considered in the fusion areaLink needs to be strengthened between physics and control engineer community. For this we propose to meet industrial and people specialists of control from different field of science during general meetings or conferences related to feedback control. Some people are already identified and could be contacted in priority because many efforts have been done in the past to start either working with them or introduce them to the fusion community and its challenges. ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

7. How do we plan to proceed? • Which kind of relevant techniques?One key point is the identification of the plasma model either from the simulation or the experimental data side. In any case, whatever the control should be, plasma identification and modelisation is already identified as one of the main priority and control specialist could help a lot in that area.This will give inputs to the requirements on measurements accuracy.Then nonlinear control is also something that might be used under some conditions (like extremum seeking optimization which might be very useful for the control of the q profile during the current ramp up, the adaptive controllers,…) and finally model predictive control could be also investigated. ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

8. How do we plan to proceed? 3. Tasks to be launched?The main guidelines inside which we would like to propose tasks are the following and can be split into 3 parts: A/ Machine protection B/ Operation C/ Advanced Physics ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

9. A/ Machine Protection All this suppose of course high quality measurement are performed off or on line. • Infrared thermography in real time, treatment and algorithms for machine protection, automatic real time in situ calibration of the measurement (reference point could be used as black body inside the view of the camera and correction of the windows matrix transmission could be performed to get an accurate measurement), development of real time techniques for the image treatment that could be inspired from the medical algorithms. • Disruption avoidance which supposes detection of the precursors and treatment in order to avoid disruption (Measurements and reaction strategies), robust diagnostics during the disruption phase • Erosion/deposition monitoring (ITER input?) • ….. ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

10. B/ Operation • Equilibrium reconstruction in real time with external and internal constraints including some pressure measurement (not yet available for the moment in the present tokamaks). The reconstruction can be performed either with standard Grad-Shafranov solver or more original techniques like the Bayesian approach. This will need to tackle the problem of the confidence interval of the output. • Feedback control strategy for current density profile control during ramp up and flat top of the discharges • Density reconstruction from interferometry and fringe jump correction techniques applied in real time • Development of a new Soft X-Ray camera pixels based having the capability to include some toroidal view (could provide some internal constraints to the equilibrium codes when used as classical tomography technique) feasibility studies • Impurity profile reconstruction in real time using for example SXR measurements. This will be important for the monitoring of the impurity level due to the new walls that will be used (beryllium, tungsten …??) as well as edge Zeff profile. • ….. ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

11. C/ Advanced Physics • Plasma model identification from measurements in a burning plasma. Identify which diagnostics are essentials, which quantity could be added with a great impact, which minimum interval confidence do we need?... • Simulation of profile control during burning plasma • Simulation of integrated profile control (JETTO, ASTRA, CRONOS…) • ….. ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

12. Deliverables • R1: Report on current status and weak areas on integrated control in existing fusion devices • R2: Report on relevant control techniques • R3: Assessment of the project and proposal of new tasks Milestones • End December 2009: First draft of R1 and R2 • End of March 2010: Final releases of R1, R2, and R3 ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

13. CG / ITM TF overlapping interest • Predictive tokamak simulation codes can be useful in the following area: • Generation of input/output data for identification purposes; • Derivation of simplified models for controller design (e.g. by linearization procedures) • Validation of controller performance by means of closed loop simulation; • Integrated control systems • Of particular interest are the areas of “Burning plasma” and “advanced diagnostic” simulations ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

14. Example: Plasma Shape Control • CREATE-L code to obtain linearized models for controller design • Initial validation of the controller performance on the linearized model taking into account actuator and diagnostic limitations • Power supply voltage and current limits • Plasma shape identification errors • Final validation on nonlinear code (e.g. MAXFEA, DYNA, …) ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

15. Integrated control Several real-world complex systems can be viewed as interconnections of subsystems which are more or less coupled each other. Although the system is made up of several subsystems, usually the objective of the control is to maintain some desirable global system behavior in the presence of disturbances. ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

16. Integrated Control In a centralized control system, a centralized controller determines the control inputs for all the subsytems, taking into account the coupling among them The design procedures requires the availability of a full MIMO dynamic model of the overall controlled system, including the dynamic interactions among the subsystems. This approach, in principle, can guarantee the best performance of the overall control system. ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

17. Integrated control • Plasma shape and kinetic parameters to be controlled together • Many uncertainties in the modeling part of the problem => there does not exist simplified model allowing controller design (attempt has been made by using approaches based on identification both from experimental data or simulation) • Controllers can be much more complex: they can have event driven behaviors represented by state-charts, sequential function charts, or finite state machines => Closed loop simulation on tokamak simulation codes could be much more difficult ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache

18. The EFDA Feedback Control Group is open to your contribution, please contact us if you want to be part of this new adventureThanks for your attention ! ITM Meeting on Control Issues – 22-23 June 2009 - Cadarache