These Guidelines and Parameter Lists to Functional Specifications describe specific functional requirements forHVDC Grid Systems. The terminology "HVDC Grid Systems" is used here describing HVDC systems for powertransmission having more than two converter stations connected to a common DC circuit.

While this document focuses on requirements, that are specific for HVDC Grid Systems, some requirements areconsidered applicable to all HVDC systems in general, i.e. including point-to-point HVDC systems. Existing IEC,Cigre or other documents relevant have been used for reference as far as possible.