The European DEMOnstration fusion reactor, presently under Pre-Conceptual Design, will adopt superconducting coils rated for several tens of kA. The DEMO operation will be pulsed; the present estimation of active power required during the plasma formation is of some hundreds of MW, which could be provided by the generator or could be still required to the electrical grid. However, the acceptability to absorb high peaks of active power from the grid could be further reduced in the future, with the increase of distributed generation networks. Furthermore, if the traditional design approach, based on thyristor converters, was adopted to supply the superconducting coils, a huge amount of reactive power, higher than 2 GVar, would be required during most of the plasma pulse. Thus, large Reactive Power Compensation systems should be provided, which calls for additional plant area occupation and further issues in terms of quality of the compensation to be assured at so high power level. In the frame of the R&D in progress to face these issues, a new magnetic energy storage and transfer system has been conceived, which can improve the power handling. It is particularly suitable to supply the DEMO Central Solenoid (CS), without the need for resistive switching networks, but can be applied to supply the other coils, too. The operating principle of this system, described for CS coils, is to recover the energy from the CS in an additional Superconducting Magnetic Energy Storage coil (TC), pre-charged along with the CS one to the same current value, to perform the flux decrease. After the CS current zero crossing, the energy stored in the TC is transferred back to the CS for the plasma sustainment. The magnetic energy transfer between the CS and the TC is obtained via switched-capacitor. With this approach, the energy is exchanged between the load and the storage system, thus flattening the active power profile to be required to the grid and substantially nullify the reactive power absorbed. In this paper, the application of this concept to the European DEMO is studied, starting from the present CS magnet and circuits configuration and from the current and voltage scenario under consideration for the plasma breakdown and ramp-up, with the main aim to evaluate if the required dynamics for the switching system is compatible with the so high power level of this specific application. A tentative rating of the system components will be reported, discussing also the future R&D stages to explore the industrial feasibility of such a scheme.
MEST, a New Magnetic Energy Storage and Transfer System: Application Study to the European DEMO
Gaio E;Piovan R;
2019
Abstract
The European DEMOnstration fusion reactor, presently under Pre-Conceptual Design, will adopt superconducting coils rated for several tens of kA. The DEMO operation will be pulsed; the present estimation of active power required during the plasma formation is of some hundreds of MW, which could be provided by the generator or could be still required to the electrical grid. However, the acceptability to absorb high peaks of active power from the grid could be further reduced in the future, with the increase of distributed generation networks. Furthermore, if the traditional design approach, based on thyristor converters, was adopted to supply the superconducting coils, a huge amount of reactive power, higher than 2 GVar, would be required during most of the plasma pulse. Thus, large Reactive Power Compensation systems should be provided, which calls for additional plant area occupation and further issues in terms of quality of the compensation to be assured at so high power level. In the frame of the R&D in progress to face these issues, a new magnetic energy storage and transfer system has been conceived, which can improve the power handling. It is particularly suitable to supply the DEMO Central Solenoid (CS), without the need for resistive switching networks, but can be applied to supply the other coils, too. The operating principle of this system, described for CS coils, is to recover the energy from the CS in an additional Superconducting Magnetic Energy Storage coil (TC), pre-charged along with the CS one to the same current value, to perform the flux decrease. After the CS current zero crossing, the energy stored in the TC is transferred back to the CS for the plasma sustainment. The magnetic energy transfer between the CS and the TC is obtained via switched-capacitor. With this approach, the energy is exchanged between the load and the storage system, thus flattening the active power profile to be required to the grid and substantially nullify the reactive power absorbed. In this paper, the application of this concept to the European DEMO is studied, starting from the present CS magnet and circuits configuration and from the current and voltage scenario under consideration for the plasma breakdown and ramp-up, with the main aim to evaluate if the required dynamics for the switching system is compatible with the so high power level of this specific application. A tentative rating of the system components will be reported, discussing also the future R&D stages to explore the industrial feasibility of such a scheme.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
