A review of the protection algorithms for multi-terminal VCD-HVDC grids

With the rapid development of renewable energy generation and consequently modern DC transmission technology, more complex HVDC installations are planned for power systems worldwide. Upgrading point to point (P2P) VSC-HVDC transmission lines to multi-terminal DC (VSC-MTDC) networks takes the DC transmission technology to the next level, but meets major technical difficulties in various aspects like control and protection of the grid equipment. This paper reviews the latest researches on the development of novel protection strategies for multi-terminal VSC (MTDC) transmission grids, as well as a brief categorization of converter modeling techniques. Many proposed strategies exist for the protection of HVDC systems based on traveling waves, transient based, voltage and current derivatives, advance signal processing methods, namely wavelet and Fourier transforms, artificial intelligence methods, etc. However, most of them are designed for P2P HVDC Grids and not applicable to MTDC systems.