Commutation Failure Immunity Monitoring: the Italian Operation Experience

The interaction between the grid and the High Voltage Direct Current (HVDC) interconnections is extremely important as well as an ongoing challenge for guaranteeing the overall secure operation. The changes of the generation mix required for achieving carbon neutrality require a continuous monitoring of voltage and short circuit power levels. For LCC-HVDC, Commutation Failure (CF) is the main fault type caused by events in the AC grid. The literature on CF immunity for a HVDC link is quite poor. This paper presents WAMS-based methodology (Wide Area Monitoring System) for monitoring the Immunity of the HVDC against the Commutation Failure. The results obtained over three years of operation are shown, with particular emphasis on the sensitivity with respect to the type of fault triggering the phenomenon. The derived conclusions confirm the general background on the topic, highlighting major effects in case of large power flow through the HVDC link and multi-phase fault in the AC grid.