Real Time Measurement and Control at JET Overview & Status

October 2005 ICALEPCS 2005 / RTMC at JET / R.Felton 1

Real Time Measurement and Control at JETOverview & Status

Robert Felton1, and JET EFDA Contributors1 Euratom / UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon, OX14 3DB, UK

This work this work has been performed under the European Fusion Development Agreement. It is funded in part by the United Kingdom Engineering and Physical Sciences Research Council and by EURATOM


JET = Joint European Tokamak• Fusion plasmas in reactor-relevant conditions

• Theory - Deuterium and Tritium easiest to access– D + D = T 1MeV + p 3MeV– D + T = 4He 3.5 MeV + n 14 MeV

– temperature 100 M oC, – density 2-3 x 1020 m-3 (1 mg m-3) – confinement > 1s

• improved confinement modes

– complex interplay of magnetic and kinetic forces • internal and edge instabilities with pressure gradients

• short and long range forces: not “classical ideal gas”

• Practical - Toroidal Magnetic Confinement– magnetic confinement, shape and current– power loads on vessel components– particle fuelling and exhaust– impurities from plasma-wall interaction


JET = Joint European Tokamak• Machine Engineering - many and varied issues

– vessel toroidal R 3m, r 2m, 200 m3, Inconel – wall CFC tiles (Beryllium and Tungsten coming)– vacuum base 10-8 mBar (cryo), plasma 10-5 mBar– magnets 32 Toroidal, 9 Poloidal, ~ kV, ~ kA– heating NB, 20MW, RF 30MHz 8MW, 3.7GHz 10MW – fuelling 12 gas injectors + pellet; ~500 mBarl per pulse– radiological Biological shield, Tritium compatibility – remote-handling radioactive and toxic (Be) components– diagnostics magnetic, thermal, optical x-ray .. visible,

neutronic ...

Pulsed ~ 10s 300MJ


JET = Joint European Tokamak• Systems Engineering - many and varied

– machine control • hierarchical, distributed, pulsed

• home-grown

– real-time communications• analogue, digital signals

• data packet networks

– operations data• 15000 points, 35000 pulses and growing

– data acquisition • 1ns … 1s, nV .. kV,

• VME, PCI, CAMAC, PLC

– data analysis• traditionally post pulse,

• increasingly real-time

– remote participation• VRVS


Tokamak Measurement & Control

Hierarchical machine controlSystems (vessel, magnets, gas, auxiliary heat & fuel, diagnostics)

Independent, with common, distributed time-base (fibre-optic + local decode)

Controlled by specific Operators

Connected by ethernet (TCP/UDP/IP; > 100 systems, miles of copper/fibre)

Operations (experiments)Parameter sets designed by Session Leader in pulse schedule

Distributed to the Systems by Level1 Supervisor infrastructure

Checked and loaded to machine by Engineer-in-Charge, and System Operators

Distributed real-time controlSystems

Real-time, calibrated outputs (avoid device dependence)

Real-time data sent to/from a Central Controller over ATM AAL5 (~ 40 systems)

Central Controller has its own Operator (PDO)

OperationsControl algorithm - conceptualised by Scientists, realised by PDO

Event driven (step NB on n=2 mode) and feed-back (3He conc, q-profile)

High level language in pulse schedule


Hierarchical Machine Control

L1 Machine Supervisorsuser interface

component data

parameter data

results data

user & system logs

L2 Machine Systemscontrol & status

start & stop

set-up & readout

r-t signal processing

r-t physics

L3 Device Driversspecific functions

Pulse

RF

laser

Magnets Heat Diagnostics

NB oct4 ECELIDAR ...

recorder ...

Level 1

Gas

parameters resultsLevel 2

Level 3

gas valve

control status

Heat DiagnosticsGasMagnets

...

psu


Machine Operations

Pulse Schedule

Edit

Pulse Schedule

SL

Run Pulse

EIC

Check & Load

Pulse Schedule

EIC, Operators

Pulse Schedule

log

JET

machine

JET

plant state

Pulse Schedulesreference to other pulse schedules or JET

pulsesconvert physics parameters to control

parameters. validate parameters for consistency and

safety.non-experts use expert scenarios for

otherwise tricky situations (shape)

The EIC and Operators validate the parameters (JET Operating Instructions) and load the plant.

Other users (e.g. Heating, Diagnostics) set-up their equipment.

The Plasma Duty Officer prepares and loads Real-Time Control Algorithms.


The JET Real-Time Control Facility - Basic

Magnetics

plasma

Shape & Current Control

NBI

ICRH

LHCD

GAS + Pellets

PF Coils

Comms network analogue

TAE

Interferom Density


The JET Real-Time Control Facility - 2005

Magnetics

R-T Signal Server

R-T Controller

plasma

CXS Ti (R)

MSE pitch (R)

Flux surfaces EQX

Confinement

VUV impurities

Shape & Current Control (PPCC)

ECE Te (R)

q profile

Neutron X-ray etc.

Interferom/Polarim

NBI

ICRH

LHCD

GAS + Pellets

PF Coils

Vis H/D/T

Vis Da, Brem, ELM

Comms network ATM, some analogue

X-ray Ti (0)

LIDAR Ne&Te(R)

Simulink codeEQX kinetic map

Pale blue = Diagnostic, Sky blue = Analysis, Red = Heating / Fuelling / Magnets & Power, Yellow = PPCC (XSC), Green = RTMC

TAE / EFCC

Wall Load

Coil Protection


Distributed Process Control (Real-Time)• Data

– physics device independent – standard data sets – sizes : 4 to 400 float pt nos.– rates : 1 to 250 ms

• Connections – fast, low latency < 0.15 ms– one-to-many– changes : local impact– isolation : fibre-optic– range : 1 .. 100 m

• Technologies– analogue messy– ATM AAL5 configurable, reliable, available– Industry standard, multi-platform, multi-vendor

• Time - a seperate network

NB

RTControlMagnetics

...

Level 2

Interferom

LH

...

q-profile


Diagnostics & Analysis

Wide range of processing techniques, and space / time resolution

Filtering and down-samplingBlack Body Bolometer 48 chan, 2ms out

Cross-calibration factorsElectron Cyclotron Emission 96 chan. 2ms

Phase tracking of modulated signals Far InfraRed Interferometry 15 chan. 2ms

Lock-in amplifiers (in software)Motional Stark Effect 25 chan. 2ms

Levenberg Marquadt spectral fittingCharge Exchange Spectr. 14 spectra, 50ms

Thomson Scattering

LIDAR laser 250ms, analysis 25 ms

Plasma magnetic boundary by Taylor expansion

“XLOC” 65 coeffs, 2ms

Finite element MHD equilibrium Grad-Shafranov

“Equinox” 500 pt mesh 25ms

Interpolation Te, Ne, q, etc on flux surfaces

“Equinox map” r/a = 0; 0.1; 1.0

Earl Ferrers:“My Lords, what kind of thermometer reads a temperature of 140 million degrees centigrade without melting?”

Viscount Davidson:“My Lords, I should think a rather large one.”from a debate on JET in the House of Lords (1987)

The JET LIDAR

Thomson scattering

system


Magnets, Heating & Fuelling

Physics Inputs Outputs Rate

Ion Cyclotron RF Preq[4], Freq[4] Pact[4], Fact[4] 10 ms25..50 MHz 4MW

Lower Hybrid RF Preq[3] Pact[3] 10 ms12 GHz 4MW

Neutral Beam Preq[8] Pact[8] 10 ms120kV 60A 20 MW

Alfven Eigenmode Freq Fact 10 ms

Gas & Pellets GIM[3] GIM[3] 10 msDensity Control Dens[3] Dens[3] 10 ms

[n] refer to Groups == flexible selection of different NB PINIs, RF oscillators, antennae, gasses, etc.

Shape & Current Magnetics PF currents [9] 2 msVertical Stability Fast Radial Field 0.2 ms


The Real-Time Controller

Preparation Level1

• User (PDO) designs and loads the algorithm• High level process block / data flow language

Operation Level2

• RTCC receives measurement data• RTCC evaluates the user algorithm• RTCC sends heat /fuel requests Algorithm RTCC

evaluator

Diag. Inputs

Heat/FuelOutputs

Real-time

10 ms cycle

Features

• flexible, general purpose (not low-level code)

• easy (for PDO) :Event-triggered e.g. disruption avoidance, MHD

Feedback SISO e.g. with NBI

• difficult (even for PDO) :MIMO control e.g. profiles

Vector, matrix calculations, state-space

Modular sub-routines


The Real-Time Controller - Matlab/Simulink extension

Preparation Matlab/Simulink & Level1

• User designs Matlab / Simulink models• User generates C function, data and DLL files• User transfers the code and parameter files to RTMX

Operation Level2

• RTMX receives Diagnostic data, etc.• RTMX sends control requests to RTCC• RTCC relays the Heat/Fuel requests

Simulink model

RTCCevaluator

Diag. Inputs

Heat/FuelOutputs

RTMX processor

Real-time

10 ms cycle

Features• Flexible• EFDA users work on control problem at home lab• Use Matlab / Simulink function libraries (discrete time)• Responsibilities

– PDO still loads and runs RTMX and RTCC

– Protection stays with Local Managers


Control Design

System Identification

To obtain signals Actuator : u(t) e.g. PNB and Sensor y(t) e.g. N use theoretical models TRANSP, JETTO, ASTRA, CRONOS, GS2, …or use experimental data.

Model the process P as a differential equation for y(t) resulting from u(t). use State-Space or Laplace transforms : Y(z) = GP(z) . U(z)

Control Design

Design a controller C which achieves a desired reference signal r(t) by driving the actuator u(t) using feedback of the measured signal y(t) within constraints (e.g. error, settling time)Check the controller C by simulation, using the process model P

U(z) = GC(z) . E(z) E(z) = R(z) - Y(z)

C

P

r(t) or R(z)

reference

E(z)

error

Ufb(z)

feedback

y(t) or Y(z)sensor

u(t) or U(z) actuator

uff(t) or Uff(z)

operating point


RT System Engineering

• RT systems have been developed to satisfy JET Scientific Programme– they work in parallel with existing measurement and control systems– they integrate with existing system infrastructures

• Even so, diversity and sustainability not always balanced– Common Application Frameworks - HTTP protocol

• 1 VxWorks, 2 Windows - healthy competition - should have prize-giving !

– Common Platforms • VME + PowerPC + VxWorks & PCI + PC + Windows - future ?

– Association-supplied Diagnostics “In-kind procurement”• Windows + Linux diverse interfaces, long-term support of internals ?

• RT systems will evolve further– Need to improve functional partitioning, and data distribution– Model-based system engineering not yet established at JET way to go!

Diagnostic Analysis Control ActuatorDiagnostic Analysis Control Actuator


Work In Progress (JET’s EP programme)• Magnets / Shape and Current Control

eXtreme Shape Control Plasma Ops, CREATE, ENEA, CEA

Coil Protection System Power Supplies

• Heating and FuellingxxLM upgrade to PowerPC and ATM CODAS

RF frequency control, LH position control CODAS

• DiagnosticsBolometer, MSE, X-ray Expts, CODAS

visible cameras, video distribution, hot spots Expts, CODAS

• AnalysisMatlab / Simulink Plasma Ops

Equinox and Polarimetry, MSE Plasma Ops, CEA, U.Nice

Disruption Prediction Plasma Ops, U.Naples, ENEA

L-mode / H-mode Plasma Ops, & Murari

• Databases & Communications extend ATM network, Plasma Ops, CODAS


Long term To Do (JET’s EP2 programme)• Magnets / Shape and Current Control

– Vertical Stabilsation upgrade project ~ many Associations, ~ MEu !– Error Field Correction Coils control ?

• Heating and Fuelling– ELM info for ITER-like antenna ?– Pellet synch

• Diagnostics & Analysis– EP2: Be / W Diagnostics, Neutron and Gamma Cameras– Alven Eigenmodes ? – RT magnetics analysis to speed up PostPulse Analysis– “Integrated” Analysis ancient (map onto flux) and modern (pattern recog.)

• Databases & Communications & Computers– try EPICS, MDSplus – evaluate new network technology Is there an Integrated Services Data

Network (control, status, events, audio, video, time)?– evaluate new computer technology PCIexpress, CELL


Summary• Real-time Diagnostics

– simplified operation and analysis :: reliable quick-look– real-time processing will be “designed in” to many new Diagnostics– limited by lines of sight, field of view, calibration dependencies

• Real-time Magnets, Heating & Fuelling– improving modelling and control algorithms for shape and stability – improving power output and control

• Real-time Experiment Control– SISO and MIMO demonstrated; more sophisticated tools needed

• Real-time Communications – ATM ok - fast enough for most applications, flexible, reliable

• Science Requirements (JET programme in support of ITER) can best be satisified by Real-Time Measurement and Control

– Scientific Task Forces explore Plasma and Fusion Physics, and physics-based control concepts - either simple or complex

– Real-time systems are the means to practically demonstrate the concepts.

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Real Time Measurement and Control at JET Overview & Status