BS PD CLC/TS 50654-1:2018 describe specific functional requirementsfor HVDC Grid Systems. The terminology "HVDC Grid Systems" is used here describing HVDC systems forpower transmission having more than two converter stations connected to a common d.c. circuit.While this document focuses on requirements, that are specific for HVDC Grid Systems, some requirementsare considered applicable to all HVDC systems in general, i.e. including point-to-point HVDC systems. ExistingIEC, Cigre or other documents relevant have been used for reference as far as possible.Corresponding to electric power transmission applications, this document is applicable to high voltagesystems, i.e. .only nominal d.c. voltages equal or higher than 50 kV with respect to earth are considered in thisdocument.Cross References:EN 61660-1:1997EN 60909IEC 61660-1:1997IEC 62747:2014 EN 62747 (IEC 62747:2014) ASEN 60633:1999IEEE P1899IEC 61000-4-15CIGRE 119EPRI EL-2708:1982CIGRE 657EN 61850 IEC TR 61000-3-6EN 61000-4-15IEC 61400-27-1:2015IEC 60633:1998EN 61400-27-1 (IEC 61400-27-1:2015)AS