Electrical Design in Hydrogen production. Integrated solutions of power conversion systems

Giuseppe Grassi - Derec Consulting

Integrated solutions of power conversion systems for - Renewable energy plants - Green hydrogen production plants - Energy storage systems

Renewable energy plants are characterized by an uncertainty of the availability of energy when it is required compared to the
time when it is actually available
- The "on-site exchange", that is the injection of excess energyinto the grid, has proved less and less convenient from an
economic point of view
- The introduction of storage systems has improved both selfconsumption and the convenience of selling energy on a deferred
basis.
- The production and storage of hydrogen (for P2G or P2P use) can be a valid storage alternative to electrochemical systems
(batteries)

Green Hydrogen and Electrical Design
Green Hydrogen is produced by electrolysis of water that require a DC power supply.
Power Quality Requirements (THD, PF, DC Ripple)-

Hydrogen Production Electrolysis Technologies
- Alkaline Water Electrolysis (AWE)
- Alkaline Water with Anion Exchange Membrane Electrolysis (AEM)
- Proton Exchange Membrane Electrolysis (PEM)
- Solid Oxide Electrolyser Cell (SOEC)

DC Power Supply technologies - 1
Power Converters can be fit with thyristors (SCR) or IGBT and we have identified three configurations that can be used for electrolysers:
- IGBT Active Front End (AFE) Inverter with DC/DC converter (if required)
- Diodes (or SCR) bridge (usually 12 pulses) with with DC/DC converter
- Thyristor (SCR) Graetz Bridge converter (usually 12 or 24 pulses)
The selection of DC Power Supply is the result of the evaluation of power quality (PF, THD, DC voltage ripple), efficiency and CAPEX/OPEX.

DC Power Supply technologies - 2
IGBT Active Front End (AFE) Inverter with DC/DC converter (if required)
Diodes bridge with with DC/DC converter
The first 1 MW plant in Italy: 3800 A - 330 V

DC Power Supply technologies - 3
This solution could satisfy "soft" requirements of THD and ripple or even more strict ones by installing filters, but it needs definitively a power factor compensation system when power factor > 0,95 is requested.

DC Power supply technology SCR

Electrolysers and Renewable Energy Plants
PV plant and hydrogen production <>
PV plant and hydrogen production - <>