B787 Captain reported multiple systems failures and electrical load shedding resulted in an air turn back and precautionary landing at departure airport.

Narrative

International flight from ZZZ to ZZZ1; Pilot Flying; Captain on this flight. In cruise for approximately 10 minutes at FL310 when we received an EICAS message of HYD pump failure and a CAC (Cabin Air Compressor) shut down due to load shed.Ran checklist for HYD pump failure. No checklist for CAC load shed...multiple other electrical system failure/ load shed status messages.Called Company Dispatch and Maintenance Control on SAT phone. Discussed failures and systems affected by the multiple electrical system load shed items. Original source of failure was indicated as an electrical Transformer/Rectifier failure.Myself; Dispatch and Maintenance Control all agreed that a diversion was best course of action and to not continue on flight to ZZZ1. ZZZ was chosen as diversion airport.Fuel dump was required in order to land below max landing weight.Return to ZZZ coordinated with ZZZZ Center; fuel dump also approved by ZZZZ Center and initiated at FL310.Dual flight management computer (FMCs) failures also occurred after turn around to ZZZ.Dispatch coordinated new flight plan; landing data and station coordination for our ZZZ arrival.Normal descent; approach; landing at ZZZ on Runway XXR in VFR conditions. Taxi to gate and normal shutdown.Debriefed Dispatch; Chief Pilot; Company Operations Manager after shut down and checklists completed.