Overhead flexible DC (OFDC) transmission systems have a higher fault probability compared to cable-based systems

posing greater challenges than cables. This paper systematically reviews the full fault-handling process for overhead flexible DC systems

analyzes the principles and application scenarios of source-side current limiting (active voltage reduction) and grid-side current limiting (increased fault loop impedance)

and summarizes the main protection schemes

including main and backup protections

along with their coordination timelines. The evolution of recovery strategies such as adaptive reclosing is also discussed. Furthermore

the fault characteristics and response requirements under two typical DC grid structures are examined for large-scale multi-terminal overhead systems. Finally

future research directions are proposed in areas such as current-limiting strategy optimization

design of DC grid configuration

and fault arc modeling

aiming to support the development of reliable

fault-resilient

and cost-effective flexible DC systems.