Study of protection for serial multi-terminal DC grids

This paper develops protection principles for a serial multi-terminal DC grid. The difference between conventional HVDC systems and serial multi-terminal DC grids from protection aspect is analyzed. The problem of conventional protection principle applied in serial multi-terminal DC grid has been investigated. In order to supply main and back up protection with high reliability, high sensitivity and fast operation speed, a travelling wave protection algorithm based on the rate of changes in the local measured signals together with modified DC filter configuration is proposed in this paper. Simulation results verified the validity of the proposed solutions.