HVDC Fault Detection Performance in Mixed Overhead Line and Cable Systems

As the use of HVDC for transmission increases and more complex system configurations are developed it becomes more important to understand the fault behavior of mixed overhead line and cable DC systems. The impact of having an heterogeneous transmission medium in protection algorithms has not yet been fully explored in literature. This paper identifies the main challenges for fault detection in mixed underground and overhead systems through the use of a simulation based case study. The analysis of the results show how algorithms can be severely impacted by the transition between sections with different surge impedances. In addition, the most problematic fault cases are singled out along with system parameters that can further reduce protection algorithm performance.