Multi-pile PEM water electrolysis hydrogen production system and control method

The invention discloses a multi-pile PEM water electrolysis hydrogen production system and a control method. The hydrogen production system comprises an electrolytic hydrogen production device and a power supply device, the power supply device is configured to provide variable output power, the electrolytic hydrogen production device comprises a plurality of electrolytic cell units, and the hydrogen production system comprises an access allocation device. The access allocation device can connect a plurality of electrolytic cell units in a parallel and/or series manner and connect the power supply device, and is configured as follows: selecting the plurality of electrolytic cell units for series connection; obtaining an optimal series connection mode in which the total power consumption of the plurality of electrolytic cells in the series connection state is most matched with the output power of the power supply device; and in the optimal series connection mode, selecting one or more electrolytic bath units fo