Primary and backup fault detection techniques for multi-terminal HVdc systems: a review

Fault detection and location estimation in a multi-terminal high voltage direct current (MTdc) transmission system based on voltage source converter (VSC) technology plays a vital role in enabling the interconnection of renewable energy systems in Europe. In this study, a comprehensive overview of the development of fault detection and location estimation techniques in the area of VSC-based MTdc network is given. The progress in various primary and secondary protection algorithms is introduced and compared in terms of high fault resistance, complexity, and communication. Besides, this study investigates the suitability of existing fault detection techniques, compares techniques, and highlights their shortcomings. Additionally, this study also suggests unconventional ways to improve backup protection techniques and discusses futuristic methods to improve the fault diagnosis process.