Integrated real-time supervisory management for off-normal-event handling and feedback control of tokamak plasmas

TL;DR

This paper presents a real-time supervisory control system for tokamaks that dynamically switches control strategies during discharges to handle unexpected events, improving robustness and safety.

Contribution

It introduces a standardized evaluation method for off-normal-events and demonstrates a real-time decision-making architecture implemented on TCV tokamak.

Findings

Successful disruption avoidance in experiments

Enhanced robustness of control during off-normal-events

Flexible and extendable control scenario switching

Abstract

For long-pulse tokamaks, one of the main challenges in control strategy is to simultaneously reach multiple control objectives and to robustly handle in real-time (RT) unexpected events (off-normal-events -- ONEs) with a limited set of actuators. We have developed in our previous work a generic architecture of the plasma control system (PCS) including a supervisor and an actuator manager to deal with these issues. We present in this paper recent developments of real-time decision-making by the supervisor to switch between different control scenarios (normal, backup, shutdown, disruption mitigation, etc.) during the discharge, based on off-normal-event states. We first standardize the evaluation of ONEs and thereby simplify significantly the supervisor decision logic, as well as facilitate the modifications and extensions of ONE states in the future. The whole PCS has been implemented on the TCV tokamak, applied to disruption avoidance with density limit experiments, demonstrating the excellent capabilities of the new RT integrated strategy.