Conceptualizing the protection properties of DC networks: Requirements engineering and system design

Abstract:
For the widespread integration of DC- and hybrid AC/DC grids, a structured planning process for network protection is necessary. This paper closes a gap in the planning process at concept level by illustrating how functional requirements derived from stakeholder needs can be interfaced with the design process. For this purpose, protection systems are characterized according to the IEC TS 63291 HVDC standard using the concepts of “continued operation”, “temporary stop” and “permanent stop”, which are delimited by the fulfilment or possible violation of aforementioned requirements. For the characterization and assessment of different possible protection strategies, “affected interruption zones” and “affected isolation zones” are introduced, which define the scope of the area that experiences an interruption of power flow during fault clearing. The presented HVDC concepts are then transferred to LVDC systems, which requires the redefinition of the IEC TS 63291 concepts “continued operation”, “temporary stop” and “permanent stop” for that use case.