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10-40kV synthesized switches based on 1.2 to 3.3 kV existing switches for medium voltage / high power applications

Technological challenge: Smart Energy grids (learn more)

Department: Département des Technologies Solaires (LITEN)

Laboratory: Laboratoire Systèmes PV

Start Date: 01-09-2022

Location: Grenoble

CEA Code: SL-DRT-22-0695

Contact: guillaume.piquetboisson@cea.fr

In the majority of current high-power PV plants, DC-AC converters are used to inject on a 50Hz three-phase AC network under 320 to 800 V from the usual level of 1500 VDC on PV strings, before using 50Hz transformers to inject to the 50Hz-20kV AC grid. This approach imposes a very large current on both conductors and semiconductors, which can only worsen with the current trend toward higher-power PV plants. Another approach, promoted by CEA, consists in increasing the voltage of both the PV strings of the power plant and of the AC injection point. This approach can be based on commercially available semiconductors (1200 V, 1700 V, or 3300 V ratings) used in multilevel converters, whose topologies become quite complex at the highest voltages. It can advantageously also be based on high voltage semiconductors, used in converters with simpler topologies. However, these components currently do not exist except at the demonstration level in 6.5 kV, 10 kV and 15 kV ratings. During this thesis, it is proposed to synthesize high voltage switches (10 to 40 kV), from 1.2 to 3.3 kV SiC switches that are commercially available and already proven. The final objective will be the demonstration of these synthesized switches in real operation. One of the major scientific and technical obstacle will be the dynamic balancing of switches placed in series, necessary to ensure the correct switching operation of the synthetic switch.

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