A protection system for long HVDC transmission lines

A recent review of the currently used HVDC line protection systems clearly indicated that these systems were not adequately equipped to protect HVDC schemes with extremely long HVDC transmission lines. Therefore, considering the increase in HVDC transmission line lengths projected for the future HVDC schemes, it is of vital importance that some type of solution be established to address the shortcomings of these existing schemes. This paper firstly discusses the shortcomings faced by the existing protection systems and then attempts to develop a protection system that is not plagued by the same shortcomings, to ensure that the proposed protection system will in fact be able to provide the required level of protection for HVDC systems with extremely long transmission lines. For increased reliability, the proposed system is able to make all protection decisions solely on local detection but telecommunications can be used, when available, to try and optimize the overall response of the protection system