Detailed discussion of HVDC-Transmission system fault mitigation by MMC based converter stations

Abstract:
High-voltage DC (HVDC) transmission lines based on self-commutated converters will add highly efficient transport capability to the German transmission grid. The first such system “Ultranet” will use overhead lines. Weather-induced faults (lightning, conductor bouncing und strong wind) are expected and have to be mastered by the converter stations. With regard to availability and resilience, master-slave-free multiterminal operation without explicit communication is demanded. As a consequence, all converter stations have to operate individually in all conceivable situations – while still influencing each other via the DC grid even in case of fault situations. This paper analyses the reaction of four independently controlled converter stations to a DC-side short circuit based on measurements at a test bench.