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ENEA - Fusion division

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Power Electronics and Electric Plant Engineering for controlled thermonuclear fusion experimental systems

FTU motor flywheel generatorFig. 1: FTU motor flywheel generator


The Frascati Tokamak Upgrade machine at ENEA Frascati was constructed in the framework of the European Fusion Research Programme and availed of the relative financial contribution.
The FUS-ING Section was responsible for the system design, work supervision, and the setting up and testing of the various non-conventional pulsed electric power supplies:

  1. A high-power (250 MAA, 200 MJ) motor flywheel generator [Fig. 1];
  2. A 12-phase, 4-quadrant ac/dc thyristor converter system operating with voltage sequential control (5 kA V) and no-dead-time current inversion (25 kA) (installed power 700 MW) [Fig. 2];
  3. A system of segregated bus-bars, including a system for limiting fault currents within 3 ms (limit current 300 kA) by means of pyrobreakers [Fig. 3].
View of FTU ac/dc convertersFig. 2: View of FTU
ac/dc converters
View of FTU segregated bus-barFig.3: View of FTU segregated bus-bar

The FUS-ING Section collaborated with Ansaldo ASI (now Ansaldo ASI Robicon) in developing and testing the prototype module of the 2.5 kV, 45 kA ac/dc converter. The work was done in the framework of the International Thermonuclear Experimental Reactor (ITER) project, with the financial contribution of the European Fusion Research Programme. The system is based on the principle of fault suppression capability: when a fault occurs (up to 330 kA) the current is returned to zero, inverting the converter voltage without needing switches or fuses. This means that the converter can resume normal operation once the cause of the fault has been removed. The prototype built by Ansaldo ASI [figs. 4 and 5] was successfully tested up to the maximum current.

Prototype of an ac/dc converter for ITERFig. 4 Prototype of an ac/dc converter for ITERFig. 5: Prototype of the ac/dc converter for ITER