Impact of DC grid contingencies on AC system stability

Abstract

In order to reliably and safely operate future multi-terminal HVDC grids, different protection strategies are currently being developed and presented in the literature.Especially for large DC grids, it is important to investigate how the choice of the protection strategy influences AC system stability during DC fault clearance and system restoration.This paper contributes to the understanding of these issues by giving an overview of the different protection strategies and their influence on frequency and transient stability.DC grid protection requirements are defined, based on the AC system constraints related to the level and duration of power transfer loss.