Method for load control of an electrolysis plant and electrolysis plant

A method for load control of an electrolysis plant, the electrolysis plant including at least two electrolysis modules each comprising a plurality of electrolysis cells that are connected electrically in series, at least one transformer-rectifier unit for providing the electrolysis modules associated to the transformer-rectifier unit with an individual DC module voltage to meet a module load set point of the respective module, wherein the transformer-rectifier unit comprises a transformer for providing an AC intermediary voltage and a rectifier for converting the AC intermediary voltage into the respective DC module voltage, a control unit connected to the transformer-rectifier unit for setting the module load set points of the associated electrolysis modules, and at least one second transformer-rectifier unit, wherein the transformer-rectifier units are connected to a common power supply switchgear, the method comprising, by the control unit:

• determining a plant load set point of the electrolysis plant corresponding to a target energy supply and/or target product output of the electrolysis plant;
• determining a module efficiency of each of the electrolysis modules;
• optimizing a plant efficiency function of the electrolysis plant having the module load set points of the electrolysis modules as variables and the module efficiencies as parameters with the constraint to meet the plant load set point;
• and
• setting the module load set points of the modules according to the optimized plant efficiency function;
• wherein at least two of the electrolysis modules are associated to the transformer-rectifier unit;
• wherein the transformer-rectifier unit contains one common transformer and one rectifier per associated electrolysis module;
• wherein the AC intermediary voltages supplied by the common transformer to the associated rectifiers differ by a preset first phase difference;
• wherein the optimization step is carried out with the constraint that any two electrolysis modules associated to the same transformer-rectifier unit are to be operated at the same module load set point;
• wherein the AC intermediary voltages of the transformer-rectifier units pairwise differ by a preset second phase difference, wherein the second phase difference corresponds to the first phase difference divided by the number of transformer-rectifier units attached to the common switchgear, and wherein the optimization is carried out with the constraint that any two electrolysis modules connected to the same switchgear are to be operated at the same module load set point.

An electrolysis plant, comprising:

• at least two electrolysis modules each comprising a plurality of electrolysis cells that are connected electrically in series;
• at least one transformer-rectifier unit for providing the electrolysis modules associated to the transformer-rectifier unit with an individual DC module voltage to meet a module load set point of the respective module, wherein the transformer-rectifier unit comprises a transformer for providing an AC intermediary voltage and a rectifier for converting the AC intermediary voltage into the respective DC module voltage;
• a control unit connected to the transformer-rectifier unit for setting the module load set points of the associated electrolysis modules;
• and
• at least one second transformer-rectifier unit, wherein the transformer-rectifier units are connected to a common power supply switchgear wherein at least two of the electrolysis modules are associated to the transformer-rectifier unit;
• wherein the transformer-rectifier unit contains one common transformer and one rectifier per associated electrolysis module;
• wherein the transformer rectifier unit is configured such that the AC intermediary voltages supplied by the common transformer to the associated rectifiers differ by a preset first phase difference;
• wherein transformer rectifier units are configured such that the AC intermediary voltages of the transformer-rectifier units pairwise differ by a preset second phase difference, wherein the second phase difference corresponds to the first phase difference divided by the number of transformer-rectifier units attached to the common switchgear.