Overvoltages experienced by DC cables within an HVDC transmission system in a rigid bipolar configuration

Recent developments in MMC – HVDC schemes have resulted in increased power ratings and dc-side voltage levels which surpass 500 kV. Additionally, besides offshore applications, cable transmission is increasinglypromoted also for onshore applications. To tackle challenges related to those developments, the rigid bipolar HVDC configuration is considered an attractive solution. First projects of this system type in the voltage range of 500 kV are already under construction. This paper evaluates characteristic overvoltage transients in the rigid bipolar configuration. Selected EMT–simulationresults highlight the different performance related to transient voltage stresses occurring in symmetrical monopolar schemes. Related findings help stakeholders to develop an understanding of the rigid bipolar configuration, and therefore contributes to ongoing discussions within the community.