Actuator management for the first ITER plasma operation campaign

An important goal of the Start of Research Operation (SRO) at ITER is the commissioning of the Plasma Control System (PCS) and the testing of algorithms for heating and MHD, shape, error field, density, reaching H-mode, and ELM control. The ITER PCS will utilize magnetic actuators (error field coils, poloidal field coils), fueling actuators (4 pellet injectors connectable to 6 pellet flight tubes, 60 gas valves), and heating actuators (48 gyrotrons connectable to 9 steerable mirrors and 1 ICRH antenna). This contribution focuses on the development of the Actuator Management (AM) for the fueling and heating actuators.

The purpose of the AM is to link controllers to multi-purpose actuators in order to properly manage conflicting requests, simplify the PCS architecture and increase its robustness. It is achieved by aggregating all of the fueling and heating actuators that have a similar impact on the plasma into Virtual Actuators (VA), which are treated as single entities by the controllers. The VAs provide the actuation limits to the controllers and distribute the controller command amongst their member actuators. It simplifies the controller design, increases its actuation amplitude, and robustness against actuator faults.

This contribution details the generic AM architecture and its extensions for specific features of the above listed control tasks using the actuators that are foreseen at ITER. In particular, we will present a method to treat actuators with steerable launchers, and a way to orchestrate pellet firing for both fueling and ELM pacing control tasks.

The presented algorithms are to be implemented into the ITER PCS and used for its operation in the SRO phase.