Hi @kmaruani and welcome to the OpenEMS Community.
While Sn0w3y is right, that most productive systems based on OpenEMS use photovoltaics in one way or the other, this is not a restriction. For example our own developments around Time-of-Use tariff based control of an energy storage system, does work very well even without PV (Mehr Freiheit in der Nutzung dynamischer Stromtarife – OpenEMS).
This report of a successful implementation of OpenEMS to control Diesel Generators could also be interesting to you → Grid demand management control using Diesel Generators
In the public OpenEMS repository there is indeed no trace of Electrolysers yet, but a lot of people use the OpenEMS framework to solve their individual project requirements. This includes Electrolysers as well as Redox-Flow batteries, and others. I do not have any source code of that though.
OpenEMS has a very good abstraction layer that supports these kind of developments by separating logic from device connectivity and protocols (see Edge Architecture :: Open Energy Management System)
The diagram you showed would be implemented as a new custom Controller in OpenEMS. The protocols for the different devices like Inverters, Electrolysers, are either already in the code or would have to be implemented. Easiest is, if your devices communicate via Modbus. Then it is very simple to connect them.
Regards,
Stefan