Anders Wallander

ITER CODAC status and implementation plan

CODAC (Control, Data Access and Communication) is the central control system responsible for operating the ITER device. CODAC interfaces to more than 160 plant systems containing actuators, sensors and local control. CODAC is responsible for coordinating and orchestrating the operation of these plant systems including plasma feedback control. CODAC is developed by ITER Organization, while plant systems are developed by the seven ITER parties (China, Europe, India, Japan, Korea, Russia and United States). This procurement model poses enormous challenges, has a big impact on architecture design and requires a strong standardization for better integration and future maintenance. In this paper we briefly describe the CODAC conceptual design, elaborate on the actions taken by the CODAC team to move from conceptual to engineering design during the last year and outline the plans ahead.

Engineering design of ITER prototype Fast Plant System Controller

The ITER control, data access and communication (CODAC) design team identified the need for two types of plant systems. A slow control plant system is based on industrial automation technology with maximum sampling rates below 100 Hz, and a fast control plant system is based on embedded technology with higher sampling rates and more stringent real-time requirements than that required for slow controllers. The latter is applicable to diagnostics and plant systems in closed-control loops whose cycle times are below 1 ms. Fast controllers will be dedicated industrial controllers with the ability to supervise other fast and/or slow controllers, interface to actuators and sensors and, if necessary, high performance networks. Two prototypes of a fast plant system controller specialized for data acquisition and constrained by ITER technological choices are being built using two different form factors. This prototyping activity contributes to the Plant Control Design Handbook effort of standardization, specifically regarding fast controller characteristics. Envisaging a general purpose fast controller design, diagnostic use cases with specific requirements were analyzed and will be presented along with the interface with CODAC and sensors. The requirements and constraints that real-time plasma control imposes on the design were also taken into consideration. Functional specifications and technology neutral architecture, together with its implications on the engineering design, were considered. The detailed engineering design compliant with ITER standards was performed and will be discussed in detail. Emphasis will be given to the integration of the controller in the standard CODAC environment. Requirements for the EPICS IOC providing the interface to the outside world, the prototype decisions on form factor, real-time operating system, and high-performance networks will also be discussed, as well as the requirements for data streaming to CODAC for visualization and archiving.

Present status of the ITER real-time Plasma Control System development

ITER will be the worlds largest magnetic confinement tokamak fusion device and is currently under construction in southern France. The ITER Plasma Control System (PCS) is a fundamental component of the ITER Control, Data Access and Communication system (CODAC). It will control the evolution of all plasma parameters that are necessary to operate ITER throughout all phases of the discharge. The design and implementation of the PCS poses a number of unique challenges. The timescales of phenomena to be controlled spans three orders of magnitude, ranging from a few milliseconds to seconds. Novel control schemes, which have not been implemented at present-day machines need to be developed, and control schemes that are only done as demonstration experiments today will have to become routine. In addition, advances in computing technology and available physics models make the implementation of real-time or faster-than-real-time calculations to forecast and subsequently to avoid disruptions or undesired plasma regimes feasible. A further novel feature is a sophisticated event handling system, which provides a means to deal with plasma related events (such as MIlD instabilities or LH transitions) or component failure. Finally, the schedule for design and implementation poses another unique challenge. The beginning of ITER operation will be in late 2020, but the conceptual design activity has already commenced as required by the on-going development of diagnostics and actuators in the domestic agencies and the need for integration and testing. In this paper, an overview about the functional requirements for the plasma control system will be given. The main focus will be on the requirements and possible options for a real-time framework for ITER and its interfaces to other ITER CODAC systems (networks, other applications, etc.). The limited amount of commissioning time foreseen for plasma control will make extensive testing and validation necessary. This should be done in an environment that is as close to the PCS version running the machine as possible. Furthermore, the integration with an Integrated Modeling Framework will lead to a versatile tool that can also be employed for pulse validation, control system development and testing as well as the development and validation of physics models. An overview of the requirements and possible structure of such an environment will also be presented.

Baseline architecture of ITER control system

The control system of ITER consists of thousands of computers processing hundreds of thousands of signals. The control system, being the primary tool for operating the machine, shall integrate, control and coordinate all these computers and signals and allow a limited number of staff to operate the machine from a central location with minimum human intervention. The primary functions of the ITER control system are plant control, supervision and coordination, both during experimental pulses and 24/7 continuous operation. The former can be split in three phases; preparation of the experiment by defining all parameters; executing the experiment including distributed feed-back control and finally collecting, archiving, analyzing and presenting all data produced by the experiment. We define the control system as a set of hardware and software components with well defined characteristics. The architecture addresses the organization of these components and their relationship to each other. We distinguish between physical and functional architecture, where the former defines the physical connections and the latter the data flow between components. In this paper, we identify the ITER control system based on the plant breakdown structure. Then, the control system is partitioned into a workable set of bounded subsystems. This partition considers at the same time the completeness and the integration of the subsystems. The components making up subsystems are identified and defined, a naming convention is introduced and the physical networks defined. Special attention is given to timing and real-time communication for distributed control. Finally we discuss baseline technologies for implementing the proposed architecture based on analysis, market surveys, prototyping and benchmarking carried out during the last year.

Multiple Fast Controller Synchronization for ITER Control System Model

ITER control system model (ICM) is a currently developed simulation platform for control, data access, and communication (CODAC), which is a central control system responsible for integrating and controlling all plant systems of ITER. ICM is a large-scale implementation of CODAC that follows hardware and software standards but does not have any interfaces to other physical components of ITER. ICM will serve as an excellent test environment for performance and scalability of upcoming plant system modules and new releases of CODAC software. This paper focuses on performance and reliability of the real-time components of ICM, consisting of eight fast controllers connected over physical networks and their dedicated high-performance switches. Two crucial ITER requirements are satisfied with 12.4-

ITER instrumentation and control: Status and plans

\mu \text{s}

ITER prototype fast plant system controller

1-kB packet transfer latency and system clock synchronization with a standard deviation as low as 16.7 ns. This performance evaluation is required for demonstrating the reliability of the CODAC infrastructure and gathering important data for considering future plant system modules.