FMEA of a non-selective fault-clearing strategy for HVDC grids

The Failure Mode Effect Analysis (FMEA) is a technique used to investigate failures in a process or component and to identify the resultant effects of these failures on system operations. In this paper it is explained how the FMEA can be used to define and assess the impact of the failure modes (FM) of a protection strategy for High Voltage Direct Current (HVDC) grids. The risk assessment of HVDC protection strategies is important because, despite of being very unlikely, the occurrence of failures during the fault clearing can cause impacts of great severity to the system. Equations for the likelihood and methods to measure the severity of FMs are discussed in the paper. A non-selective protection strategy is used to illustrate the method and the meaning of the risks assessed are discussed.