Plasma feedback controller reorganisation for ASDEX Upgrade's new discharge control and data acquisition system

Accompanying the introduction of the new discharge control and data acquisition system, ASDEX Upgrade's feedback control scheme is reworked. The present control system comprises magnetic and performance control with different organisations. Magnetic control consists mainly of multi-input/multi-output (MIMO) feedback loops. Performance control is made up by many heterogeneous standalone control algorithms with a typical structure: a single-input/single-output (SISO) feedback controller with some dedicated pre- and postprocessing. These algorithms are independent and have almost no interconnections to each other. While this simple structure is a perfect choice for explorative work, it is often not sufficient for achieving optimised performance, safe handling and easy maintainability, because shared output resources and cross-couplings are ignored. In our new approach, performance and magnetic control get a common structure. The isolated views of the single performance control applications are replaced by a more integrated view. Applications are rearranged, accounting for the limitations of common actuators and relations between controlled variables. Common data can be shared, special procedures are separated from generic ones. The resulting structure has three blocks: a measurement preprocessor with specialised diagnostic algorithms, a generic MIMO feedback controller with switchable operation mode, and optional output postprocessors to serve dedicated needs of actuators. In this paper, we present the guidelines we have developed for this procedure